Air Pollution: Everything You Need to Know

How smog, soot, greenhouse gases, and other top air pollutants are affecting the planet—and your health.

Smoke blows out of two tall industrial stacks

  • Share this page block

What Is Air Pollution?

What causes air pollution, effects of air pollution, air pollution in the united states, air pollution and environmental justice, controlling air pollution, how to help reduce air pollution, how to protect your health.

Air pollution  refers to the release of pollutants into the air—pollutants that are detrimental to human health and the planet as a whole. According to the  World Health Organization (WHO) , each year, indoor and outdoor air pollution is responsible for nearly seven million deaths around the globe. Ninety-nine percent of human beings currently breathe air that exceeds the WHO’s guideline limits for pollutants, with those living in low- and middle-income countries suffering the most. In the United States, the  Clean Air Act , established in 1970, authorizes the U.S. Environmental Protection Agency (EPA) to safeguard public health by regulating the emissions of these harmful air pollutants.

“Most air pollution comes from energy use and production,” says  John Walke , director of the Clean Air team at NRDC. Driving a car on gasoline, heating a home with oil, running a power plant on  fracked gas : In each case, a fossil fuel is burned and harmful chemicals and gases are released into the air.

“We’ve made progress over the last 50 years in improving air quality in the United States, thanks to the Clean Air Act. But climate change will make it harder in the future to meet pollution standards, which are designed to  protect health ,” says Walke.

Air pollution is now the world’s fourth-largest risk factor for early death. According to the 2020  State of Global Air  report —which summarizes the latest scientific understanding of air pollution around the world—4.5 million deaths were linked to outdoor air pollution exposures in 2019, and another 2.2 million deaths were caused by indoor air pollution. The world’s most populous countries, China and India, continue to bear the highest burdens of disease.

“Despite improvements in reducing global average mortality rates from air pollution, this report also serves as a sobering reminder that the climate crisis threatens to worsen air pollution problems significantly,” explains  Vijay Limaye , senior scientist in NRDC’s Science Office. Smog, for instance, is intensified by increased heat, forming when the weather is warmer and there’s more ultraviolet radiation. In addition, climate change increases the production of allergenic air pollutants, including mold (thanks to damp conditions caused by extreme weather and increased flooding) and pollen (due to a longer pollen season). “Climate change–fueled droughts and dry conditions are also setting the stage for dangerous wildfires,” adds Limaye. “ Wildfire smoke can linger for days and pollute the air with particulate matter hundreds of miles downwind.”

The effects of air pollution on the human body vary, depending on the type of pollutant, the length and level of exposure, and other factors, including a person’s individual health risks and the cumulative impacts of multiple pollutants or stressors.

Smog and soot

These are the two most prevalent types of air pollution. Smog (sometimes referred to as ground-level ozone) occurs when emissions from combusting fossil fuels react with sunlight. Soot—a type of  particulate matter —is made up of tiny particles of chemicals, soil, smoke, dust, or allergens that are carried in the air. The sources of smog and soot are similar. “Both come from cars and trucks, factories, power plants, incinerators, engines, generally anything that combusts fossil fuels such as coal, gasoline, or natural gas,” Walke says.

Smog can irritate the eyes and throat and also damage the lungs, especially those of children, senior citizens, and people who work or exercise outdoors. It’s even worse for people who have asthma or allergies; these extra pollutants can intensify their symptoms and trigger asthma attacks. The tiniest airborne particles in soot are especially dangerous because they can penetrate the lungs and bloodstream and worsen bronchitis, lead to heart attacks, and even hasten death. In  2020, a report from Harvard’s T.H. Chan School of Public Health showed that COVID-19 mortality rates were higher in areas with more particulate matter pollution than in areas with even slightly less, showing a correlation between the virus’s deadliness and long-term exposure to air pollution. 

These findings also illuminate an important  environmental justice issue . Because highways and polluting facilities have historically been sited in or next to low-income neighborhoods and communities of color, the negative effects of this pollution have been  disproportionately experienced by the people who live in these communities.

Hazardous air pollutants

A number of air pollutants pose severe health risks and can sometimes be fatal, even in small amounts. Almost 200 of them are regulated by law; some of the most common are mercury,  lead , dioxins, and benzene. “These are also most often emitted during gas or coal combustion, incineration, or—in the case of benzene—found in gasoline,” Walke says. Benzene, classified as a carcinogen by the EPA, can cause eye, skin, and lung irritation in the short term and blood disorders in the long term. Dioxins, more typically found in food but also present in small amounts in the air, is another carcinogen that can affect the liver in the short term and harm the immune, nervous, and endocrine systems, as well as reproductive functions.  Mercury  attacks the central nervous system. In large amounts, lead can damage children’s brains and kidneys, and even minimal exposure can affect children’s IQ and ability to learn.

Another category of toxic compounds, polycyclic aromatic hydrocarbons (PAHs), are by-products of traffic exhaust and wildfire smoke. In large amounts, they have been linked to eye and lung irritation, blood and liver issues, and even cancer.  In one study , the children of mothers exposed to PAHs during pregnancy showed slower brain-processing speeds and more pronounced symptoms of ADHD.

Greenhouse gases

While these climate pollutants don’t have the direct or immediate impacts on the human body associated with other air pollutants, like smog or hazardous chemicals, they are still harmful to our health. By trapping the earth’s heat in the atmosphere, greenhouse gases lead to warmer temperatures, which in turn lead to the hallmarks of climate change: rising sea levels, more extreme weather, heat-related deaths, and the increased transmission of infectious diseases. In 2021, carbon dioxide accounted for roughly 79 percent of the country’s total greenhouse gas emissions, and methane made up more than 11 percent. “Carbon dioxide comes from combusting fossil fuels, and methane comes from natural and industrial sources, including large amounts that are released during oil and gas drilling,” Walke says. “We emit far larger amounts of carbon dioxide, but methane is significantly more potent, so it’s also very destructive.” 

Another class of greenhouse gases,  hydrofluorocarbons (HFCs) , are thousands of times more powerful than carbon dioxide in their ability to trap heat. In October 2016, more than 140 countries signed the Kigali Agreement to reduce the use of these chemicals—which are found in air conditioners and refrigerators—and develop greener alternatives over time. (The United States officially signed onto the  Kigali Agreement in 2022.)

Pollen and mold

Mold and allergens from trees, weeds, and grass are also carried in the air, are exacerbated by climate change, and can be hazardous to health. Though they aren’t regulated, they can be considered a form of air pollution. “When homes, schools, or businesses get water damage, mold can grow and produce allergenic airborne pollutants,” says Kim Knowlton, professor of environmental health sciences at Columbia University and a former NRDC scientist. “ Mold exposure can precipitate asthma attacks  or an allergic response, and some molds can even produce toxins that would be dangerous for anyone to inhale.”

Pollen allergies are worsening  because of climate change . “Lab and field studies are showing that pollen-producing plants—especially ragweed—grow larger and produce more pollen when you increase the amount of carbon dioxide that they grow in,” Knowlton says. “Climate change also extends the pollen production season, and some studies are beginning to suggest that ragweed pollen itself might be becoming a more potent allergen.” If so, more people will suffer runny noses, fevers, itchy eyes, and other symptoms. “And for people with allergies and asthma, pollen peaks can precipitate asthma attacks, which are far more serious and can be life-threatening.”

air pollution project conclusion

More than one in three U.S. residents—120 million people—live in counties with unhealthy levels of air pollution, according to the  2023  State of the Air  report by the American Lung Association (ALA). Since the annual report was first published, in 2000, its findings have shown how the Clean Air Act has been able to reduce harmful emissions from transportation, power plants, and manufacturing.

Recent findings, however, reflect how climate change–fueled wildfires and extreme heat are adding to the challenges of protecting public health. The latest report—which focuses on ozone, year-round particle pollution, and short-term particle pollution—also finds that people of color are 61 percent more likely than white people to live in a county with a failing grade in at least one of those categories, and three times more likely to live in a county that fails in all three.

In rankings for each of the three pollution categories covered by the ALA report, California cities occupy the top three slots (i.e., were highest in pollution), despite progress that the Golden State has made in reducing air pollution emissions in the past half century. At the other end of the spectrum, these cities consistently rank among the country’s best for air quality: Burlington, Vermont; Honolulu; and Wilmington, North Carolina. 

No one wants to live next door to an incinerator, oil refinery, port, toxic waste dump, or other polluting site. Yet millions of people around the world do, and this puts them at a much higher risk for respiratory disease, cardiovascular disease, neurological damage, cancer, and death. In the United States, people of color are 1.5 times more likely than whites to live in areas with poor air quality, according to the ALA.

Historically, racist zoning policies and discriminatory lending practices known as  redlining  have combined to keep polluting industries and car-choked highways away from white neighborhoods and have turned communities of color—especially low-income and working-class communities of color—into sacrifice zones, where residents are forced to breathe dirty air and suffer the many health problems associated with it. In addition to the increased health risks that come from living in such places, the polluted air can economically harm residents in the form of missed workdays and higher medical costs.

Environmental racism isn't limited to cities and industrial areas. Outdoor laborers, including the estimated three million migrant and seasonal farmworkers in the United States, are among the most vulnerable to air pollution—and they’re also among the least equipped, politically, to pressure employers and lawmakers to affirm their right to breathe clean air.

Recently,  cumulative impact mapping , which uses data on environmental conditions and demographics, has been able to show how some communities are overburdened with layers of issues, like high levels of poverty, unemployment, and pollution. Tools like the  Environmental Justice Screening Method  and the EPA’s  EJScreen  provide evidence of what many environmental justice communities have been explaining for decades: that we need land use and public health reforms to ensure that vulnerable areas are not overburdened and that the people who need resources the most are receiving them.

In the United States, the  Clean Air Act  has been a crucial tool for reducing air pollution since its passage in 1970, although fossil fuel interests aided by industry-friendly lawmakers have frequently attempted to  weaken its many protections. Ensuring that this bedrock environmental law remains intact and properly enforced will always be key to maintaining and improving our air quality.

But the best, most effective way to control air pollution is to speed up our transition to cleaner fuels and industrial processes. By switching over to renewable energy sources (such as wind and solar power), maximizing fuel efficiency in our vehicles, and replacing more and more of our gasoline-powered cars and trucks with electric versions, we'll be limiting air pollution at its source while also curbing the global warming that heightens so many of its worst health impacts.

And what about the economic costs of controlling air pollution? According to a report on the Clean Air Act commissioned by NRDC, the annual  benefits of cleaner air  are up to 32 times greater than the cost of clean air regulations. Those benefits include up to 370,000 avoided premature deaths, 189,000 fewer hospital admissions for cardiac and respiratory illnesses, and net economic benefits of up to $3.8 trillion for the U.S. economy every year.

“The less gasoline we burn, the better we’re doing to reduce air pollution and the harmful effects of climate change,” Walke explains. “Make good choices about transportation. When you can, ride a bike, walk, or take public transportation. For driving, choose a car that gets better miles per gallon of gas or  buy an electric car .” You can also investigate your power provider options—you may be able to request that your electricity be supplied by wind or solar. Buying your food locally cuts down on the fossil fuels burned in trucking or flying food in from across the world. And most important: “Support leaders who push for clean air and water and responsible steps on climate change,” Walke says.

  • “When you see in the news or hear on the weather report that pollution levels are high, it may be useful to limit the time when children go outside or you go for a jog,” Walke says. Generally, ozone levels tend to be lower in the morning.
  • If you exercise outside, stay as far as you can from heavily trafficked roads. Then shower and wash your clothes to remove fine particles.
  • The air may look clear, but that doesn’t mean it’s pollution free. Utilize tools like the EPA’s air pollution monitor,  AirNow , to get the latest conditions. If the air quality is bad, stay inside with the windows closed.
  • If you live or work in an area that’s prone to wildfires,  stay away from the harmful smoke  as much as you’re able. Consider keeping a small stock of masks to wear when conditions are poor. The most ideal masks for smoke particles will be labelled “NIOSH” (which stands for National Institute for Occupational Safety and Health) and have either “N95” or “P100” printed on it.
  • If you’re using an air conditioner while outdoor pollution conditions are bad, use the recirculating setting to limit the amount of polluted air that gets inside. 

This story was originally published on November 1, 2016, and has been updated with new information and links.

This NRDC.org story is available for online republication by news media outlets or nonprofits under these conditions: The writer(s) must be credited with a byline; you must note prominently that the story was originally published by NRDC.org and link to the original; the story cannot be edited (beyond simple things such as grammar); you can’t resell the story in any form or grant republishing rights to other outlets; you can’t republish our material wholesale or automatically—you need to select stories individually; you can’t republish the photos or graphics on our site without specific permission; you should drop us a note to let us know when you’ve used one of our stories.

Related Stories

A city skyline is obscured by thick smog

The Particulars of PM 2.5

An aerial view of floodwaters overtaking a cluster of buildings

What Are the Effects of Climate Change?

Two people walk through a thick haze on a city street

Fossil Fuel Air Pollution Kills One in Five People

When you sign up, you’ll become a member of NRDC’s Activist Network. We will keep you informed with the latest alerts and progress reports.

Talk to our experts

1800-120-456-456

Causes of Air Pollution

Causes of air pollution which makes our lungs suffocate.

As the world is moving forward with advancements and progress in technology, the air quality is deteriorating day by day. The factories, industries, and petrol-driven cars that we, humans invented for development and comfort, have now become the sources of air pollution and started to suffocate our lungs with impure air. Many reasons for air pollution deprive us of the right to breathe fresh air and live in a healthy environment . In this article, we will emphasize What causes air pollution and how it is affecting our lives.

(Image will be Uploaded soon)

What is Air Pollution?

Air pollution refers to the deterioration of air quality by the suspension of solid, liquid, and gaseous harmful particles into the air. The solid and liquid particles released into the air are scientifically called aerosols. According to a study conducted by WHO, approximately seven million deaths around the globe are happening because of air pollution. The main causes of air pollution are the release of sulfur oxides, carbon monoxide, carbon dioxide, and volatile organic compounds, etc.

Types of Air Pollutants

Air can get polluted in two ways:

Primary pollutants : These are the ones that directly make the air polluted. For example, when factories release sulfur dioxide, it becomes a primary pollutant.

Secondary pollutants : These are formed when primary pollutants mix and react with each other. A good example is smog, which happens when smoke and fog mingle, creating a secondary pollutant.

How does Air get Polluted?  

Air pollution is one of the most serious and challenging environmental issues that the whole world is facing. Despite several attempts, agreements, and conferences, air pollution seems to be worsening in many countries. To understand why such a situation is being currently faced by the countries, we need to first learn what causes air pollution. It will give us a clear idea to map out what areas need to be controlled to bring down the air pollution. The list below shows the 7 causes of air pollution, which are as follows:

1. Burning fossils to Produce Energy

One of the major reasons for air pollution is the burning of fossils like coal, petroleum to generate electricity or use them for transportation. The burning of fossils leads to the release of carbon monoxide into the air. This reduces the heart’s pumping capacity to produce oxygen and leads to respiratory problems in humans.

2. Wildfires and Volcanic Eruption

The harmful gases released by the eruption of volcanoes or wildfires also lead to air pollution. These two are the natural causes of air pollution. The gases erupt by the wildfires raise the PM 2.5 level in the air which then collides with the toxic chemical components already present in the air. As a result, a heavy sheet of smog is created which leads to severe breathing problems.

3. Vehicle Movement: Automobiles

It’s a well-known fact that transportation is one of the major sources of air pollution, particularly in cities. The vehicle movement leads to emissions of several toxic gases such as carbon monoxide, nitrogen oxide, PM 10, and so on. All these gases raise the temperature of the air which ultimately leads to the depletion of the ozone layer.

4. Harmful Decay of Microbes

This is one of the causes of air pollution that is rarely acknowledged by many. The decay of microorganisms like bacteria and fungi in the environment by the emission of gases from chemical and textile industries leads to the release of methane gas.

5. Emission From Industries

Industrial emission is undoubtedly one of the biggest reasons for air pollution. Industries that are running primarily on wood and coal emit harmful gases like carbon monoxide, sulfur oxides, PM 2.5 and 10, and more. The release of such harmful gases in the air deteriorates our health and leads to either eye irritation, respiratory issues, or even chronic diseases.

6. Burning of Waste in an Open Area

Burning of waste and garbage at a large scale in the open is one of the main causes of air pollution in several cities around the world. This human activity leads to emissions of such hazardous gases that even exposure to it can lead to serious health threats like impairment of the reproductive system, liver problems, etc.

7. Indoor Activities  

Whenever we search for answers for what causes air pollution, we often consider the external factors only. The fact that our indoor activities can also lead to air pollution inside our homes never crosses our minds. But it’s one reality. The use of wood stoves or smoking cigarettes inside or using heaters to increase humidity without proper ventilation leads to air pollution and can pose serious health issues.

Effects of Air Pollution

Air pollution harms the environment in various ways:

1. Health Issues

Breathing polluted air can cause respiratory problems and heart diseases in humans. Lung cancer cases have risen, especially in the last few decades. Children living in polluted areas are more likely to suffer from pneumonia and asthma. Unfortunately, many people lose their lives each year due to the direct or indirect impacts of air pollution.

2. Global Warming

Greenhouse gas emissions upset the balance of gases in the air, leading to a rise in Earth's temperature known as global warming. This warming contributes to the melting of glaciers and a subsequent increase in sea levels, causing flooding in various regions.

3. Acid Rain

Burning fossil fuels releases harmful gases like nitrogen oxides and sulfur oxides. When these pollutants combine with water droplets, they form acidic rain that damages human, animal, and plant life.

4. Ozone Layer Depletion

The release of substances like chlorofluorocarbons into the atmosphere is a major contributor to the depletion of the ozone layer. This thinning of the ozone layer allows harmful ultraviolet rays from the sun to reach the Earth, leading to skin diseases and eye problems in individuals.

5. Impact on Animals

Air pollutants suspended in water bodies adversely affect aquatic life. Pollution also forces animals to leave their natural habitats, making them stray and contributing to the extinction of many animal species.

What are the Examples of Air Pollution?

Mostly, air pollutants cannot be seen by the naked eye or smell. But to imply that they won’t be available in high amounts because of this is outright wrong. Some major gases lead to the greenhouse effect and ultimately contribute to the depletion of the ozone layer. The common greenhouse gases that are examples of air pollution as well are carbon dioxide and methane.

The examples of air pollution are as follows:

Natural Causes of Air Pollution  

Increasing temperature 

Volcanic eruption  

Wind currents

Anthropogenic Sources of Pollution

Transportation 

Garbage Burning

Mining and chemical activities 

Construction activities 

Controlling Air Pollution: Simple Steps

To tackle air pollution, here are some straightforward measures you can take:

1. Limit Vehicle Use:

Opt for public transport when traveling short distances.

This not only helps prevent pollution but also saves energy.

2. Conserve Energy:

Turn off electrical appliances when not in use to reduce the burning of fossil fuels.

Use energy-efficient devices like CFLs to further control pollution.

3. Embrace Clean Energy:

Utilise solar, wind, and geothermal energies to decrease air pollution.

Many countries, including India, are adopting these resources for a cleaner environment.

4. Other Measures to Control Air Pollution:

Minimise the use of fire and fire-related products.

Control or treat pollutants at the source to minimise industrial emissions.

Substitute raw materials with less polluting alternatives.

Replace petrol and diesel with CNG-fueled vehicles to reduce vehicular emissions.

Ensure that existing air quality practices are enforced properly.

Test and regulate vehicle emissions to keep the roads cleaner.

Modify and maintain industrial equipment to minimise pollutant emissions.

Use process control equipment when controlling pollutants at the source is challenging.

Dilute air pollutants to control their concentration.

Plant trees in areas with high pollution levels as they effectively reduce pollutants in the air.

Conclusion  

From this article we have learnt about the various reasons why air pollution is caused. In order to curb air pollution, we need to take actions against the causes which are mentioned above. For example, we can limit the use of private vehicles and opt for public transport in order to curb air pollution.

FAQs on Causes of Air Pollution

1. How does air get polluted through agricultural activities?

Agricultural activities have a drastic impact on the quality of air. The pesticides and fertilizers that are used to proliferate the growth of the crops are the major contributors to contaminating the air. In recent days, these pesticides and fertilizers are mixed with some foreign, artificial species to quicken the crops’ growth. Once they are sprinkled over the crops, their smell and constituents remain in the environment. Some runoff and dissolve into the lakes or rivers flowing nearby while some penetrate the roots that contaminate the groundwater. The consumption of this contaminated water ultimately leads to serious health issues.

2. Why is air pollution considered a problem?

Air pollution is considered a problem because it not only affects the environment but also damages crops, forests, animals, and the human body. The causes of air pollution contribute to the problem of acid rain and the depletion of the ozone layer. The ozone layer is important for the earth because it protects the earth from the UV rays of the sun. But when it gets depleted, the UV rays can enter the Earth and affect humans. In this way, the air problem creates problems.

3. What are the effects of air pollution?

Air pollution can have a variety of harmful effects on human health and the environment. These effects can include:

Respiratory problems, such as asthma, bronchitis, and lung cancer

Heart disease

Damage to ecosystems

Climate change

4. What are the different types of air pollution?

There are many different types of air pollutants, but some of the most common include:

Particulate matter (PM): This is a mixture of tiny solid and liquid particles suspended in the air. PM can come from a variety of sources, including cars, trucks, factories, construction sites, and wildfires. PM2.5, which refers to particles with a diameter of 2.5 micrometers or less, is especially harmful because it can lodge deep in the lungs.

Ground-level ozone: This is a gas that is formed when sunlight reacts with nitrogen oxides from cars, trucks, and other sources. Ozone can irritate the lungs and worsen respiratory problems.

Nitrogen dioxide (NO2): This gas is a major component of smog and can also irritate the lungs. NO2 is primarily produced by motor vehicles.

Sulfur dioxide (SO2): This gas is released from the burning of fossil fuels and can cause respiratory problems and acid rain.

Carbon monoxide (CO): This gas is a colorless, odorless gas that is produced by the incomplete burning of fuels. CO can interfere with the body's ability to use oxygen and can lead to headaches, dizziness, and fatigue.

5. How can I measure the air quality in my area?

There are a few different ways to measure the air quality in your area:

You can purchase your own air quality monitor to measure the levels of pollutants in your home or neighborhood.

Many government websites provide real-time air quality data for specific locations. For example, in the United States, you can check the Air Quality Index (AQI) on the Environmental Protection Agency's website.

There are a number of smartphone apps that can provide real-time air quality data for your location.

6. What is being done to address air pollution?

There are a number of things that are being done to address air pollution, including:

Regulating emissions from cars, trucks, and factories: Governments are setting stricter limits on the amount of pollutants that can be released from these sources.

Promoting the use of clean energy sources: Governments and businesses are investing in renewable energy sources, such as solar and wind power, to reduce pollution from fossil fuels.

Improving public transportation: Improving public transportation can help to reduce the number of cars on the road, which can improve air quality.

Planting trees: Trees can help to filter air pollution, so planting trees is a good way to improve air quality.

It is important to note that air pollution is a complex problem with no easy solutions. However, by taking steps to reduce emissions and improve air quality, we can help to protect the health of ourselves and our planet.

U.S. flag

An official website of the United States government

Here’s how you know

Official websites use .gov A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS A lock ( Lock A locked padlock ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

JavaScript appears to be disabled on this computer. Please click here to see any active alerts .

Air Pollution: Current and Future Challenges

Despite dramatic progress cleaning the air since 1970, air pollution in the United States continues to harm people’s health and the environment. Under the Clean Air Act, EPA continues to work with state, local and tribal governments, other federal agencies, and stakeholders to reduce air pollution and the damage that it causes.
  • Learn about more about air pollution, air pollution programs, and what you can do.

Outdoor air pollution challenges facing the United States today include:

  • Meeting health-based standards for common air pollutants
  • Limiting climate change
  • Reducing risks from toxic air pollutants
  • Protecting the stratospheric ozone layer against degradation

Indoor air pollution, which arises from a variety of causes, also can cause health problems. For more information on indoor air pollution, which is not regulated under the Clean Air Act, see EPA’s indoor air web site .

Air Pollution Challenges: Common Pollutants

Great progress has been made in achieving national air quality standards, which EPA originally established in 1971 and updates periodically based on the latest science. One sign of this progress is that visible air pollution is less frequent and widespread than it was in the 1970s.

However, air pollution can be harmful even when it is not visible. Newer scientific studies have shown that some pollutants can harm public health and welfare even at very low levels. EPA in recent years revised standards for five of the six common pollutants subject to national air quality standards. EPA made the standards more protective because new, peer-reviewed scientific studies showed that existing standards were not adequate to protect public health and the environment.

Status of common pollutant problems in brief

Today, pollution levels in many areas of the United States exceed national air quality standards for at least one of the six common pollutants:

  • Although levels of particle pollution and ground-level ozone pollution are substantially lower than in the past, levels are unhealthy in numerous areas of the country. Both pollutants are the result of emissions from diverse sources, and travel long distances and across state lines. An extensive body of scientific evidence shows that long- and short-term exposures to fine particle pollution, also known as fine particulate matter (PM 2.5 ), can cause premature death and harmful effects on the cardiovascular system, including increased hospital admissions and emergency department visits for heart attacks and strokes. Scientific evidence also links PM to harmful respiratory effects, including asthma attacks. Ozone can increase the frequency of asthma attacks, cause shortness of breath, aggravate lung diseases, and cause permanent damage to lungs through long-term exposure. Elevated ozone levels are linked to increases in hospitalizations, emergency room visits and premature death. Both pollutants cause environmental damage, and fine particles impair visibility. Fine particles can be emitted directly or formed from gaseous emissions including sulfur dioxide or nitrogen oxides. Ozone, a colorless gas, is created when emissions of nitrogen oxides and volatile organic compounds react.  
  • For unhealthy peak levels of sulfur dioxide and nitrogen dioxide , EPA is working with states and others on ways to determine where and how often unhealthy peaks occur. Both pollutants cause multiple adverse respiratory effects including increased asthma symptoms, and are associated with increased emergency department visits and hospital admissions for respiratory illness. Both pollutants cause environmental damage, and are byproducts of fossil fuel combustion.  
  • Airborne lead pollution, a nationwide health concern before EPA phased out lead in motor vehicle gasoline under Clean Air Act authority, now meets national air quality standards except in areas near certain large lead-emitting industrial facilities. Lead is associated with neurological effects in children, such as behavioral problems, learning deficits and lowered IQ, and high blood pressure and heart disease in adults.  
  • The entire nation meets the carbon monoxide air quality standards, largely because of emissions standards for new motor vehicles under the Clean Air Act.

In Brief: How EPA is working with states and tribes to limit common air pollutants

  • EPA's air research provides the critical science to develop and implement outdoor air regulations under the Clean Air Act and puts new tools and information in the hands of air quality managers and regulators to protect the air we breathe.  
  • To reflect new scientific studies, EPA revised the national air quality standards for fine particles (2006, 2012), ground-level ozone (2008, 2015), sulfur dioxide (2010), nitrogen dioxide (2010), and lead (2008). After the scientific review, EPA decided to retain the existing standards for carbon monoxide.  EPA strengthened the air quality standards for ground-level ozone in October 2015 based on extensive scientific evidence about ozone’s effects.

EPA has designated areas meeting and not meeting the air quality standards for the 2006 and 2012 PM standards and the 2008 ozone standard, and has completed an initial round of area designations for the 2010 sulfur dioxide standard. The agency also issues rules or guidance for state implementation of the various ambient air quality standards – for example, in March 2015, proposing requirements for implementation of current and future fine particle standards. EPA is working with states to improve data to support implementation of the 2010 sulfur dioxide and nitrogen dioxide standards.

For areas not meeting the national air quality standards, states are required to adopt state implementation plan revisions containing measures needed to meet the standards as expeditiously as practicable and within time periods specified in the Clean Air Act (except that plans are not required for areas with “marginal” ozone levels).

  • EPA is helping states to meet standards for common pollutants by issuing federal emissions standards for new motor vehicles and non-road engines, national emissions standards for categories of new industrial equipment (e.g., power plants, industrial boilers, cement manufacturing, secondary lead smelting), and technical and policy guidance for state implementation plans. EPA and state rules already on the books are projected to help 99 percent of counties with monitors meet the revised fine particle standards by 2020. The Mercury and Air Toxics Standards for new and existing power plants issued in December 2011 are achieving reductions in fine particles and sulfur dioxide as a byproduct of controls required to cut toxic emissions.  
  • Vehicles and their fuels continue to be an important contributor to air pollution. EPA in 2014 issued standards commonly known as Tier 3, which consider the vehicle and its fuel as an integrated system, setting new vehicle emissions standards and a new gasoline sulfur standard beginning in 2017. The vehicle emissions standards will reduce both tailpipe and evaporative emissions from passenger cars, light-duty trucks, medium-duty passenger vehicles, and some heavy-duty vehicles. The gasoline sulfur standard will enable more stringent vehicle emissions standards and will make emissions control systems more effective. These rules further cut the sulfur content of gasoline. Cleaner fuel makes possible the use of new vehicle emission control technologies and cuts harmful emissions in existing vehicles. The standards will reduce atmospheric levels of ozone, fine particles, nitrogen dioxide, and toxic pollution.

Learn more about common pollutants, health effects, standards and implementation:

  • fine particles
  • ground-level ozone
  • sulfur dioxide
  • nitrogen dioxide
  • carbon monoxide

Air Pollution Challenges: Climate Change

EPA determined in 2009 that emissions of carbon dioxide and other long-lived greenhouse gases that build up in the atmosphere endanger the health and welfare of current and future generations by causing climate change and ocean acidification. Long-lived greenhouse gases , which trap heat in the atmosphere, include carbon dioxide, methane, nitrous oxide, and fluorinated gases. These gases are produced by a numerous and diverse human activities.

In May 2010, the National Research Council, the operating arm of the National Academy of Sciences, published an assessment which concluded that “climate change is occurring, is caused largely by human activities, and poses significant risks for - and in many cases is already affecting - a broad range of human and natural systems.” 1 The NRC stated that this conclusion is based on findings that are consistent with several other major assessments of the state of scientific knowledge on climate change. 2

Climate change impacts on public health and welfare

The risks to public health and the environment from climate change are substantial and far-reaching. Scientists warn that carbon pollution and resulting climate change are expected to lead to more intense hurricanes and storms, heavier and more frequent flooding, increased drought, and more severe wildfires - events that can cause deaths, injuries, and billions of dollars of damage to property and the nation’s infrastructure.

Carbon dioxide and other greenhouse gas pollution leads to more frequent and intense heat waves that increase mortality, especially among the poor and elderly. 3 Other climate change public health concerns raised in the scientific literature include anticipated increases in ground-level ozone pollution 4 , the potential for enhanced spread of some waterborne and pest-related diseases 5 , and evidence for increased production or dispersion of airborne allergens. 6

Other effects of greenhouse gas pollution noted in the scientific literature include ocean acidification, sea level rise and increased storm surge, harm to agriculture and forests, species extinctions and ecosystem damage. 7 Climate change impacts in certain regions of the world (potentially leading, for example, to food scarcity, conflicts or mass migration) may exacerbate problems that raise humanitarian, trade and national security issues for the United States. 8

The U.S. government's May 2014 National Climate Assessment concluded that climate change impacts are already manifesting themselves and imposing losses and costs. 9 The report documents increases in extreme weather and climate events in recent decades, with resulting damage and disruption to human well-being, infrastructure, ecosystems, and agriculture, and projects continued increases in impacts across a wide range of communities, sectors, and ecosystems.

Those most vulnerable to climate related health effects - such as children, the elderly, the poor, and future generations - face disproportionate risks. 10 Recent studies also find that certain communities, including low-income communities and some communities of color (more specifically, populations defined jointly by ethnic/racial characteristics and geographic location), are disproportionately affected by certain climate-change-related impacts - including heat waves, degraded air quality, and extreme weather events - which are associated with increased deaths, illnesses, and economic challenges. Studies also find that climate change poses particular threats to the health, well-being, and ways of life of indigenous peoples in the U.S.

The National Research Council (NRC) and other scientific bodies have emphasized that it is important to take initial steps to reduce greenhouse gases without delay because, once emitted, greenhouse gases persist in the atmosphere for long time periods. As the NRC explained in a recent report, “The sooner that serious efforts to reduce greenhouse gas emissions proceed, the lower the risks posed by climate change, and the less pressure there will be to make larger, more rapid, and potentially more expensive reductions later.” 11

In brief: What EPA is doing about climate change

Under the Clean Air Act, EPA is taking initial common sense steps to limit greenhouse gas pollution from large sources:

EPA and the National Highway and Traffic Safety Administration between 2010 and 2012 issued the first national greenhouse gas emission standards and fuel economy standards for cars and light trucks for model years 2012-2025, and for medium- and heavy-duty trucks for 2014-2018.  Proposed truck standards for 2018 and beyond were announced in June 2015.  EPA is also responsible for developing and implementing regulations to ensure that transportation fuel sold in the United States contains a minimum volume of renewable fuel. Learn more about clean vehicles

EPA and states in 2011 began requiring preconstruction permits that limit greenhouse gas emissions from large new stationary sources - such as power plants, refineries, cement plants, and steel mills - when they are built or undergo major modification. Learn more about GHG permitting

  • On August 3, 2015, President Obama and EPA announced the Clean Power Plan – a historic and important step in reducing carbon pollution from power plants that takes real action on climate change. Shaped by years of unprecedented outreach and public engagement, the final Clean Power Plan is fair, flexible and designed to strengthen the fast-growing trend toward cleaner and lower-polluting American energy. With strong but achievable standards for power plants, and customized goals for states to cut the carbon pollution that is driving climate change, the Clean Power Plan provides national consistency, accountability and a level playing field while reflecting each state’s energy mix. It also shows the world that the United States is committed to leading global efforts to address climate change. Learn more about the Clean Power Plan, the Carbon Pollution Standards, the Federal Plan, and model rule for states

The Clean Power Plan will reduce carbon pollution from existing power plants, the nation’s largest source, while maintaining energy reliability and affordability.  The Clean Air Act creates a partnership between EPA, states, tribes and U.S. territories – with EPA setting a goal, and states and tribes choosing how they will meet it.  This partnership is laid out in the Clean Power Plan.

Also on August 3, 2015, EPA issued final Carbon Pollution Standards for new, modified, and constructed power plants, and proposed a Federal Plan and model rules to assist states in implementing the Clean Power Plan.

On February 9, 2016, the Supreme Court stayed implementation of the Clean Power Plan pending judicial review. The Court’s decision was not on the merits of the rule. EPA firmly believes the Clean Power Plan will be upheld when the merits are considered because the rule rests on strong scientific and legal foundations.

On October 16, 2017, EPA  proposed to repeal the CPP and rescind the accompanying legal memorandum.

EPA is implementing its Strategy to Reduce Methane Emissions released in March 2014. In January 2015 EPA announced a new goal to cut methane emissions from the oil and gas sector by 40 – 45 percent from 2012 levels by 2025, and a set of actions by EPA and other agencies to put the U.S. on a path to achieve this ambitious goal. In August 2015, EPA proposed new common-sense measures to cut methane emissions, reduce smog-forming air pollution and provide certainty for industry through proposed rules for the oil and gas industry . The agency also proposed to further reduce emissions of methane-rich gas from municipal solid waste landfills . In March 2016 EPA launched the National Gas STAR Methane Challenge Program under which oil and gas companies can make, track and showcase ambitious commitments to reduce methane emissions.

EPA in July 2015 finalized a rule to prohibit certain uses of hydrofluorocarbons -- a class of potent greenhouse gases used in air conditioning, refrigeration and other equipment -- in favor of safer alternatives. The U.S. also has proposed amendments to the Montreal Protocol to achieve reductions in HFCs internationally.

Learn more about climate science, control efforts, and adaptation on EPA’s climate change web site

Air Pollution Challenges: Toxic Pollutants

While overall emissions of air toxics have declined significantly since 1990, substantial quantities of toxic pollutants continue to be released into the air. Elevated risks can occur in urban areas, near industrial facilities, and in areas with high transportation emissions.

Numerous toxic pollutants from diverse sources

Hazardous air pollutants, also called air toxics, include 187 pollutants listed in the Clean Air Act. EPA can add pollutants that are known or suspected to cause cancer or other serious health effects, such as reproductive effects or birth defects, or to cause adverse environmental effects.

Examples of air toxics include benzene, which is found in gasoline; perchloroethylene, which is emitted from some dry cleaning facilities; and methylene chloride, which is used as a solvent and paint stripper by a number of industries. Other examples of air toxics include dioxin, asbestos, and metals such as cadmium, mercury, chromium, and lead compounds.

Most air toxics originate from manmade sources, including mobile sources such as motor vehicles, industrial facilities and small “area” sources. Numerous categories of stationary sources emit air toxics, including power plants, chemical manufacturing, aerospace manufacturing and steel mills. Some air toxics are released in large amounts from natural sources such as forest fires.

Health risks from air toxics

EPA’s most recent national assessment of inhalation risks from air toxics 12 estimated that the whole nation experiences lifetime cancer risks above ten in a million, and that almost 14 million people in more than 60 urban locations have lifetime cancer risks greater than 100 in a million. Since that 2005 assessment, EPA standards have required significant further reductions in toxic emissions.

Elevated risks are often found in the largest urban areas where there are multiple emission sources, communities near industrial facilities, and/or areas near large roadways or transportation facilities. Benzene and formaldehyde are two of the biggest cancer risk drivers, and acrolein tends to dominate non-cancer risks.

In brief: How EPA is working with states and communities to reduce toxic air pollution

EPA standards based on technology performance have been successful in achieving large reductions in national emissions of air toxics. As directed by Congress, EPA has completed emissions standards for all 174 major source categories, and 68 categories of small area sources representing 90 percent of emissions of 30 priority pollutants for urban areas. In addition, EPA has reduced the benzene content in gasoline, and has established stringent emission standards for on-road and nonroad diesel and gasoline engine emissions that significantly reduce emissions of mobile source air toxics. As required by the Act, EPA has completed residual risk assessments and technology reviews covering numerous regulated source categories to assess whether more protective air toxics standards are warranted. EPA has updated standards as appropriate. Additional residual risk assessments and technology reviews are currently underway.

EPA also encourages and supports area-wide air toxics strategies of state, tribal and local agencies through national, regional and community-based initiatives. Among these initiatives are the National Clean Diesel Campaign , which through partnerships and grants reduces diesel emissions for existing engines that EPA does not regulate; Clean School Bus USA , a national partnership to minimize pollution from school buses; the SmartWay Transport Partnership to promote efficient goods movement; wood smoke reduction initiatives; a collision repair campaign involving autobody shops; community-scale air toxics ambient monitoring grants ; and other programs including Community Action for a Renewed Environment (CARE). The CARE program helps communities develop broad-based local partnerships (that include business and local government) and conduct community-driven problem solving as they build capacity to understand and take effective actions on addressing environmental problems.

Learn more about air toxics, stationary sources of emissions, and control efforts Learn more about mobile source air toxics and control efforts

Air Pollution Challenges: Protecting the Stratospheric Ozone Layer

The  ozone (O 3 ) layer  in the stratosphere protects life on earth by filtering out harmful ultraviolet radiation (UV) from the sun. When chlorofluorocarbons (CFCs) and other ozone-degrading chemicals  are emitted, they mix with the atmosphere and eventually rise to the stratosphere. There, the chlorine and the bromine they contain initiate chemical reactions that destroy ozone. This destruction has occurred at a more rapid rate than ozone can be created through natural processes, depleting the ozone layer.

The toll on public health and the environment

Higher levels of  ultraviolet radiation  reaching Earth's surface lead to health and environmental effects such as a greater incidence of skin cancer, cataracts, and impaired immune systems. Higher levels of ultraviolet radiation also reduce crop yields, diminish the productivity of the oceans, and possibly contribute to the decline of amphibious populations that is occurring around the world.

In brief: What’s being done to protect the ozone layer

Countries around the world are phasing out the production of chemicals that destroy ozone in the Earth's upper atmosphere under an international treaty known as the Montreal Protocol . Using a flexible and innovative regulatory approach, the United States already has phased out production of those substances having the greatest potential to deplete the ozone layer under Clean Air Act provisions enacted to implement the Montreal Protocol. These chemicals include CFCs, halons, methyl chloroform and carbon tetrachloride. The United States and other countries are currently phasing out production of hydrochlorofluorocarbons (HCFCs), chemicals being used globally in refrigeration and air-conditioning equipment and in making foams. Phasing out CFCs and HCFCs is also beneficial in protecting the earth's climate, as these substances are also very damaging greenhouse gases.

Also under the Clean Air Act, EPA implements regulatory programs to:

Ensure that refrigerants and halon fire extinguishing agents are recycled properly.

Ensure that alternatives to ozone-depleting substances (ODS) are evaluated for their impacts on human health and the environment.

Ban the release of ozone-depleting refrigerants during the service, maintenance, and disposal of air conditioners and other refrigeration equipment.

Require that manufacturers label products either containing or made with the most harmful ODS.

These vital measures are helping to protect human health and the global environment.

The work of protecting the ozone layer is not finished. EPA plans to complete the phase-out of ozone-depleting substances that continue to be produced, and continue efforts to minimize releases of chemicals in use. Since ozone-depleting substances persist in the air for long periods of time, the past use of these substances continues to affect the ozone layer today. In our work to expedite the recovery of the ozone layer, EPA plans to augment CAA implementation by:

Continuing to provide forecasts of the expected risk of overexposure to UV radiation from the sun through the UV Index, and to educate the public on how to protect themselves from over exposure to UV radiation.

Continuing to foster domestic and international partnerships to protect the ozone layer.

Encouraging the development of products, technologies, and initiatives that reap co-benefits in climate change and energy efficiency.

Learn more About EPA’s Ozone Layer Protection Programs

Some of the following links exit the site

1 National Research Council (2010), Advancing the Science of Climate Change , National Academy Press, Washington, D.C., p. 3.

2 National Research Council (2010), Advancing the Science of Climate Change , National Academy Press, Washington, D.C., p. 286.

3 USGCRP (2009).  Global Climate Change Impacts in the United States . Karl, T.R., J.M. Melillo, and T.C. Peterson (eds.). United States Global Change Research Program. Cambridge University Press, New York, NY, USA.

4 CCSP (2008).  Analyses of the effects of global change on human health and welfare and human systems . A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks, (Authors). U.S. Environmental Protection Agency, Washington, DC, USA.

5 Confalonieri, U., B. Menne, R. Akhtar, K.L. Ebi, M. Hauengue, R.S. Kovats, B. Revich and A. Woodward (2007). Human health. In:  Climate Change 2007: Impacts, Adaptation and Vulnerability  .  Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change  Parry, M.L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, (eds.), Cambridge University Press, Cambridge, United Kingdom.

7 An explanation of observed and projected climate change and its associated impacts on health, society, and the environment is included in the EPA’s Endangerment Finding and associated technical support document (TSD). See EPA, “ Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act ,” 74 FR 66496, Dec. 15, 2009. Both the Federal Register Notice and the Technical Support Document (TSD) for Endangerment and Cause or Contribute Findings are found in the public docket, Docket No. EPA-OAR-2009-0171.

8 EPA, Endangerment Finding , 74 FR 66535.

9 . U.S. Global Change Research Program, Climate Change Impacts in the United States: The Third National Climate Assessment , May 2014.

10 EPA, Endangerment Finding , 74 FR 66498.

11 National Research Council (2011) America’s Climate Choices: Report in Brief , Committee on America’s Climate Choices, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington, D.C., p. 2.

12 EPA, 2005 National-Scale Air Toxics Assessment (2011).

  • Clean Air Act Overview Home
  • Progress Cleaning the Air
  • Air Pollution Challenges
  • Requirements and History
  • Role of Science and Technology
  • Roles of State, Local, Tribal and Federal Governments
  • Developing Programs Through Dialogue
  • Flexibility with Accountability
  • The Clean Air Act and the Economy

Do something for our planet, print this page only if needed. Even a small action can make an enormous difference when millions of people do it!

All official European Union website addresses are in the europa.eu domain.

Try our suggestions

  • Table of contents
  • Introduction
  • Health effects of air pollutants
  • Dispersal of air pollutants
  • Exposure pathways and monitoring
  • Taking actions to improve air quality
  • Some common air pollutants
  • Air pollutants and global effects
  • Sources of air pollution

The health of the public, especially those who are the most vulnerable, such as children, the elderly and the sick, is at risk from air pollution, but it is difficult to say how large the risk is. It is possible that the problem has been over-stressed in relation to other challenges in the field of public health.

As we have seen, there are considerable uncertainties in estimating both exposures and effects and their relationships. It may be, for example, that the effects of long-term exposure to lower concentrations of air pollutants could be more damaging to public health than short-term exposure to higher concentrations. For this reason alone, local authorities could take action to assess and improve local air quality. It is not sufficient to wait for an episode of severe air pollution and then try to deal with its effects.

Another reason for action on air pollution is that we do not know the contribution which exposure to air pollutants may make to deaths from, for example, heart disease. In many countries heart disease is a leading cause of death and even a small contribution from air pollution could mean a significant and important effect on public heath.

On an individual level, the risk to health from air pollution is very much smaller than that posed by active cigarette smoking or accidents. It is also true that healthy individuals are rather unlikely to be affected by exposure to the concentrations of outdoor air pollutants in many European countries on most days of the year. However, the old and the young, and especially those suffering from respiratory or heart diseases, are the groups who are most vulnerable to the effects of air pollution. It is only right that cost effective action should be taken to provide them with clean air, which The Times of 1881 described as "the first necessity of our existence."

For references , please go to https://www.eea.europa.eu/publications/2599XXX/page012.html or scan the QR code.

PDF generated on 18 Feb 2024, 08:39 AM

EEA Page URL QR

Document Actions

Share with others.

Engineered by: EEA Web Team

Software updated on 26 September 2023 08:13 from version 23.8.18

Software version: EEA Plone KGS 23.9.14

Code for developers

Systems Status

Legal notice

Creative commons license

air pollution project conclusion

  • Open access
  • Published: 19 September 2022

Engaging communities in addressing air quality: a scoping review

  • Fiona Ward 1   na1 ,
  • Hayley J. Lowther-Payne 2   na1 ,
  • Emma C. Halliday 1 ,
  • Keith Dooley 3 ,
  • Neil Joseph 4 ,
  • Ruth Livesey 5 ,
  • Paul Moran 4 ,
  • Simon Kirby 6 &
  • Jane Cloke 4  

Environmental Health volume  21 , Article number:  89 ( 2022 ) Cite this article

7469 Accesses

4 Citations

7 Altmetric

Metrics details

Exposure to air pollution has a detrimental effect on health and disproportionately affects people living in socio-economically disadvantaged areas. Engaging with communities to identify concerns and solutions could support organisations responsible for air quality control, improve environmental decision-making, and widen understanding of air quality issues associated with health. This scoping review aimed to provide an overview of approaches used to engage communities in addressing air quality and identify the outcomes that have been achieved.

Searches for studies that described community engagement in air quality activities were conducted across five databases (Academic Search Complete, CABI, GreenFILE, MEDLINE, Web of Science). Data on study characteristics, community engagement approach, and relevant outcomes were extracted. The review process was informed by a multi-stakeholder group with an interest in and experience of community engagement in air quality. Thirty-nine papers from thirty studies were included in the final synthesis.

A range of approaches have been used to engage communities in addressing air quality, most notably air quality monitoring. Positive outcomes included increased awareness, capacity building, and changes to organisational policy and practice. Longer-term projects and further exploration of the impact of community engagement on improving air quality and health are needed as reporting on these outcomes was limited.

Peer Review reports

Exposure to air pollution has a detrimental effect on health. Outdoor air pollution is estimated to cause 4.2 million premature deaths per year as a result of stroke, heart disease, respiratory disease, and lung cancer [ 1 ]. Exposure to air pollution has also been found to be associated with dementia [ 2 ], low birthweight [ 3 ], and type 2 diabetes [ 4 ]. Evidence suggests people living in disadvantaged areas are disproportionately affected, facing a so-called “ triple jeopardy ” where their proximity to sources of air pollution, disproportionate disease burdens, and psychosocial stressors are likely to have a greater negative impact on quality of life [ 5 ].

In recent years, there has been increasing attention paid to the participation of communities in identifying and responding to public health issues, such as air pollution. The Marmot Review of health inequalities described this process as “ creating the conditions for individuals to take control of their own lives ” [ 6 ]. In the USA, the Office of Environmental Justice recommends involvement of those most effected by poor air quality so that decisions “ best serve ” the interests of the most vulnerable communities [ 7 ]. In the UK, the promotion of community engagement is similarly evident with the Department for Environment and Rural Affairs (Defra) expounding the value of local knowledge and interaction with communities to establish the issues in a particular locality and implement solutions appropriate to local circumstances [ 8 ]. At a global level, the World Health Organisation (WHO) Helsinki Statement called for governments to include communities in the development, implementation, and monitoring of health considerations in all policies [ 9 ].

Community engagement, however, is complex and a term which covers a wide range of approaches to involvement in decision-making and in the planning, design, delivery and governance of initiatives [ 10 , 11 ]. Engagement approaches vary in the level of community participation, empowerment and control, and consequently have differential impacts on a range of outcomes. Information sharing and consultation exercises, for example, have little impact on health whereas communities who are able to exercise a greater degree of control in an initiative are likely to experience a greater impact [ 12 ]. It is also recognised that successful community engagement requires barriers and challenges to be recognised and addressed [ 13 ], including factors affecting the ability of organisations to develop and sustain more participatory relationships with communities [ 14 ].

Research has shown that community engagement can have positive outcomes for organisations, communities and individuals. Engaged communities working in collaboration with professional or policy stakeholders can increase the system’s understanding of the local context, leading to more culturally appropriate resources and solutions considered to be more responsive to community needs [ 15 ]. Pathways through which community engagement may improve health and wellbeing have been identified whereby engagement can have a positive impact on health behaviours and their consequences, either directly through participating in an intervention or via the resulting increase in self-efficacy and/or perceived social support [ 11 ]. At a community level, engagement may also engender a greater sense of neighbourhood belonging and improve mental health outcomes [ 16 ].

The concept of place is at the heart of community engagement and air quality. Social ties, shared identity or interests in a geographical location or setting are central to definitions of community [ 17 ], and “ place-making ” has been described as a way of strengthening connections between people and place [ 18 ]. However, the presence of air pollution caused, for example by heavy industry, may also intersect with the ways in which residents identify with their place of residence, as well as perpetuating stigma [ 19 ]. The links between health and place have also been widely examined [ 20 ], with local social, economic, and political influences identified as important factors in lay perceptions of exposure to air pollution, perceptions of its health impact, and the priority afforded to the issue [ 21 ].

Despite the encouragement to engage communities in public health issues and the recognition of the potential for positive outcomes, there has been limited exploration of the range of approaches adopted to engage communities in addressing air quality. This scoping review was conducted to explore the existing literature for possible avenues that communities, researchers and statutory organisations could pursue and identify any directions for further research in this area. Specifically, the review aimed to address the following questions;

What approaches have been used to engage communities in air quality?

What are the identified facilitators and challenges to engaging communities in air quality?

What outcomes have been achieved by engaging communities in air quality?

A scoping review, as opposed to a systematic review, aims to capture a broader range of existing literature on a topic, without being limited by study design or quality [ 22 ]. This scoping review was designed to collate existing examples of community engagement to addressing air quality and their related outcomes to inform communities, researchers, and statutory organisations wishing to address air quality issues, and to identify gaps for future research. Due to the heterogeneity of studies in this area, a scoping review enabled the synthesis of evidence from relevant studies in a structured and reproducible way. This review was conducted based on existing guidance for undertaking scoping reviews [ 22 , 23 ], and reported based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) checklist [ 24 ].

Search strategy

Preliminary searches were conducted in Web of Science to become familiar with the existing literature on this topic, and to generate and refine the eligibility criteria. A final search strategy was developed and piloted with the assistance of an information specialist. Studies were identified through searching five electronic databases (Academic Search Complete, CABI, GreenFILE, MEDLINE, Web of Science) from their inception to 7 th June 2020 using a combination of Medical Subject Headings and keywords. Search terms used across all searches are presented in Table 1 . Grey literature was not searched for as this was not feasible with the resources available.

Eligibility criteria

Eligibility criteria was developed based on the review questions and refined following preliminary searches of the literature. Studies were eligible if they were written in English, undertaken in developed economies and described the active participation of groups and/or individuals of all ages in activities related to air quality in the living environment. Active participation was defined as involving one or more of the following elements associated with research, decision-making and/or actions to address air quality: identifying a problem, priority setting, designing an activity, conducting/delivering, and/or dissemination/sharing learning. The rationale for this definition was to collate examples that go beyond providing information or consultation exercises. The living environment was taken to mean “ any aspect of an individual, group or population’s everyday physical and social environment, excluding the work environment … [including] both the socio-economic and psychosocial conditions in which people live ” [ 25 ]. The eligibility criteria are outlined in Table 2 .

Study selection

To increase consistency, two reviewers independently screened approximately 10% of the titles and abstracts of all retrieved citations against the eligibility criteria using Rayyan, a free web-based tool to support collaborative screening [ 26 ], and subsequently discussed conflicts in decisions for inclusion or exclusion. As very few conflicts were identified at this stage, the remainder of the titles and abstracts were screened by one reviewer. Full texts of potentially relevant citations were then obtained and independently assessed by two reviewers. Uncertainty or disagreements at any stage were resolved through discussion, and if consensus could not be reached, a third reviewer was consulted and where necessary the wider review group. Reasons for exclusion at the full text screening stage were documented.

Data charting and synthesis

Data were charted from each of the included papers by one reviewer using a pre-piloted form in MS Excel, all of which was then checked by a second reviewer for completeness and accuracy. The following key data items were taken from each paper: authors, year of publication, country, aim, study design, type and source of air pollution studied, characteristics of the community/study population, approach to engagement, facilitators and challenges to engagement, and reported outcomes associated with engagement. The extent to which health inequalities were considered was also noted during data charting, for example by referencing poor air quality and/or higher rates of respiratory illness in low income communities, environmental justice. As in the practice of scoping reviews, quality assessment was not conducted as studies were not going to be excluded on this basis [ 23 ].

To answer the review questions, an inductive approach was used to categorise the approaches used by the studies to engage communities in addressing air quality [ 27 ]. As the review aimed to synthesise a potentially broad and diverse area of research, and establish clear links between approaches utilised by the studies, an inductive approach was deemed more appropriate. Starting with the detailed description of the community engagement methods used provided by the authors, studies were grouped into higher-level categories to describe the approach adopted. The categorisation of studies as “ citizen science ” was informed by Den Broeder, Devilee [ 28 ], whilst other studies were defined by key words used in their approach to community engagement such as assessment/screening, internship/education, and policy. Detailed summaries of other study characteristics were collated; outcomes were categorised by those observed for individuals, the community, organisations, and those related to air quality and/or health, and the facilitators and challenges to engagement frequently identified by study participants or authors were also summarised. To standardise the categorisation of community engagement approaches and key themes derived from the data items, all included studies were reviewed through discussion until consensus was reached by both reviewers. Decisions were also discussed with the wider review group where necessary.

Stakeholder involvement

A working group made up of members of the public, environmental health professionals, a local social enterprise, and researchers, all with an interest in or experience of engaging communities in air quality, was formed to support the undertaking of this review. This working group, located within the National Institute for Health and Care Research Applied Research Collaboration North West Coast (NIHR ARC NWC), met on a monthly basis and kept in contact via email to refine the focus of the review, make decisions about the inclusion of studies and types of data to collect, and to interpret key findings. Members were involved in checking the data charting, interpreting the findings, and reviewing this article. An amended version of the GRIPP2 reporting checklist – short-form [ 29 ], outlining both public involvement and other stakeholder involvement practices is presented in the supplemental material (Additional file 1 ).

After the removal of duplicates, the search strategy identified a total of 3,146 citations. Based on screening titles and abstracts, 3,042 citations were excluded. A total of 95 full texts were assessed for eligibility, of which 39 papers were included in the review (Fig.  1 ).

figure 1

Flow diagram of the study selection process

Study characteristics

Thirty studies were described across 39 papers (Table 3 ). Papers were published between 1984 and 2020. Studies were conducted in the USA ( n  = 23), Europe ( n  = 6), and Canada ( n  = 1), most often in urban areas. Most studies focused on engaging communities in activities related to outdoor air pollution (e.g. traffic-related remissions, industrial activity). Study aims were varied, most commonly reported were; to raise individual and/or community awareness of air quality issues, to enable individuals and/or communities to drive action on improving local air quality, and to generate local knowledge of air quality to support environmental decision-making. Studies were often conducted within a community-based participatory research framework [ 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ] or action research framework [ 42 , 43 , 44 ]; others reported case studies of engagement initiatives [ 45 , 46 , 47 , 48 ]. Most studies provided little detail about the groups involved in the activities, generally referring to the study population as “ local population ”, “ youth ”, and “ community representatives ”. For studies which provided more information, study populations ranged from 10 to 3,000 members of the community. Evaluations using qualitative methods such as surveys or interviews with relatively small samples were conducted by most studies, usually to generate an understanding of the experience of involvement (e.g. satisfaction) or the impact of engagement (e.g. self-efficacy).

In the assessment of the extent to which health inequalities were considered, studies referred directly to the engagement activities being conducted with a disadvantaged and/or disproportionately affected group (e.g. low income, ethnic minority). Those undertaken in the USA frequently referred to these as environmental justice communities [ 38 , 40 , 45 ]. Disproportionate exposure to pollution [ 36 , 39 , 40 , 50 , 65 ], existing vulnerabilities such as age [ 43 , 62 ], and the marginalisation of certain groups [ 30 , 36 , 41 , 49 ] were repeated themes in those placed within the context of health inequalities. Ten studies contained very little reference to health inequalities, with an implicit or explicit suggestion that air pollution was a universal issue within a geographical area [ 33 , 46 , 48 , 51 , 52 , 54 , 55 , 64 , 67 , 68 ].

Approaches to community engagement

Citizen science.

The most frequent approach adopted was the participation of citizens in air quality monitoring activities; 16 studies featured individuals from local communities involved in the measurement of air quality using scientific equipment or tools. “C itizen science ”, a term used to describe where citizens contribute to scientific research [ 28 ], best encapsulates this type of study. Local residents worked alongside researchers and other stakeholders to identify concerns, influence the focus of the work, define neighbourhood boundaries and select monitoring sites [ 32 , 34 , 35 , 36 , 38 , 44 , 51 , 52 , 54 , 59 , 62 ]. Communities engaged in monitoring received training and were given low-cost sensors or sampling packages to measure local air quality [ 31 , 32 , 34 , 35 , 36 , 42 , 43 , 44 , 49 , 51 , 53 , 54 , 55 , 62 ]. In some studies, photographs, diaries and stories were also created by residents to supplement the monitoring data [ 42 , 43 , 49 , 51 , 55 ]. The timescale and extent of the monitoring varied across the studies identified, from mobile sampling over a few days [ 36 ], to maintaining monitoring sites for a number of years [ 41 ]. Residents also led workshops and community meetings, interpreted data findings, and disseminated information to the wider community and other stakeholders [ 31 , 32 , 53 ]. Fewer studies involved citizens using other scientific methods, including generating “ a lay model of local air quality ” [ 48 , 50 , 56 , 57 , 58 ], creating photo-maps to reflect lived experience of residing in polluted areas [ 45 ], and using a smell-reporting system to predict pollution events [ 68 ].

Environmental and health assessments

For five studies, communities were involved in undertaking environmental or health assessments in collaboration with researchers and statutory organisations. Two environmental assessment studies used participatory methods to identify and prioritise the community’s environmental concerns [ 30 , 40 ], both recognising this as a knowledge gap and using concerns to develop plans to address these concerns. Studies assessing the health effects of air pollution exposure included respiratory screening of children living near a railyard [ 39 ], symptom diaries and lung function assessments for children with asthma [ 63 ], and community exposure surveys [ 64 ]. For these studies, community members were engaged in multi-stakeholder oversight groups, and contributed to planning, publicity, engaging with the wider community, and dissemination.

Education and training

Three studies primarily used education or training programmes to engage the community in air quality activities. Wong, Wu [ 65 ] trained high school students to use an interactive pollution map, and supported the young people to teach older adults with English as a second language how to use the map through workshops. To expand a community monitoring network, an internship programme for young people was established by a community-based organisation [ 60 ]. An educational programme formed a large part of a community driven campaign to reduce vehicle idling near schools and thus children’s exposure to traffic-related air pollution [ 33 ]; videos, assemblies, presentations, signs and factsheets were developed by students and researchers and delivered to parents, students, school staff and bus drivers.

Policy development and review

Community engagement in developing and reviewing policies with statutory organisations was a substantial element of four studies [ 46 , 47 , 66 , 67 ]. Two reported the inclusion of community representatives on an advisory group to review air quality management policy decisions [ 46 , 67 ]. Stave [ 67 ] conducted a model-building exercise with residents to identify transportation problems and consider policy scenarios to solve these problems. Williams and James [ 47 ] described a package of activities to enhance engagement including a public-friendly air quality reporting system, door-to-door canvassing in disadvantaged neighbourhoods, environmental health forums, and citizen-collected evidence of air pollution. The ClairCity project engaged residents and local government in European cities using workshops and an online game to generate citizen-led policy scenarios to improve their cities [ 66 ].

The range of outcomes, facilitators and challenges associated with the community engagement approaches used in the included studies are summarised in Table 4 . Below, these aspects are described in more detail.

Facilitators to community engagement

Working with existing community-based organisations that had established links with the local neighbourhood was reported to facilitate community engagement. These organisations were trusted and as such enabled relationship-building between residents, researchers and statutory organisations [ 37 , 39 , 40 ]. Multi-stakeholder steering committees often provided a forum for residents, researchers and organisations with a range of expertise to design and develop activities to address air quality [ 30 , 31 , 43 ]. Trusting and equitable relationships between researchers and residents were seen as a facilitator [ 35 , 36 , 39 ]. Expertise and experience of community members was valued, for example recruiting members of the community with technical skills [ 35 ], or local experts to ensure that activities were tailored to residents [ 53 ].

Having a range of options for engagement was viewed as important: rather than having a “ one size fits all ” approach, considering each community individually and working in a “ culturally appropriate ” way supported engagement [ 30 , 37 , 47 ]. Effective strategies included using accessible methods [ 30 ], and adapting communication to reach different groups [ 40 , 54 ]. Some studies suggested the integration of community outreach and education from the outset provided a solid foundation for informed community engagement [ 35 , 41 , 52 ]. Diversity in both the community members and the research team was viewed as a critical to success across some studies, particularly in ensuring it was representative of the local population [ 35 , 43 , 53 , 65 ]. Lastly, financial recognition for the individuals involved and ensuring that community-based organisations received an appropriate share of the funding was also noted as a facilitator [ 39 , 41 ].

Challenges to community engagement

Using technical language and communicating scientific material was the most frequently cited challenge to engaging communities in air quality. Symanski, An Han [ 40 ] reported that the use of scientific jargon could decrease community engagement. A focus on the technical aspects limited the role of residents and diminished their sense of ownership [ 44 , 46 ]. An underlying tension between information being inadequately described or being inaccessible was identified in one study [ 50 ]. Communicating scientific information in communities where English was a second language was also acknowledged as a particular challenge [ 47 , 52 ].

A lack of capacity of community members to be involved in the activities was viewed as a challenge to community engagement; for example limited time available as a result of work or family commitments [ 32 , 40 , 43 , 67 ], lack of confidence to be involved in certain elements such as formal presentations [ 44 ], and limited access to the internet or equipment [ 34 , 66 ]. Participatory methods were viewed as more time-consuming and resource-intensive, which could cause capacity issues from an organisational perspective [ 32 , 44 ]. Additional challenges associated with limited time for researchers or organisations to complete community engagement activities, a lack of access to sufficient resources such as funding and IT experience, and inadequate equipment for residents to sample local air quality, were mentioned by some [ 34 , 36 , 43 , 54 , 65 ]. Scepticism or a lack of trust limited engagement in some studies; for example, identifying environmental issues being interpreted as criticism of living standards [ 47 ], a lack of confidence about the usefulness of air quality models [ 50 ], and an inability to overcome existing difficult relationships with statutory organisations [ 64 ].

Outcomes of community engagement

Individuals and communities.

Increased knowledge and understanding of air pollution, its causes and the associated health outcomes was identified across most studies: this was often highlighted as a prerequisite for engagement and studies frequently described an initial stage of outreach activities to share information with residents. Some studies highlighted an increased understanding of technical information and monitoring data [ 35 , 49 , 53 , 67 ], whilst others reported engagement increased awareness of the cumulative impacts of air pollution, the burden of ill health associated with social vulnerability, and the injustice of exposure [ 38 , 42 , 53 ]. In addition, studies suggested a consequence of this increased awareness would likely be personal behaviour change to reduce exposure [ 54 , 59 , 67 ], however this effect was not formally measured.

Many studies outlined how residents had developed skills and competencies in, for example, conducting research [ 30 , 62 ], using monitoring equipment [ 34 , 59 ], action planning [ 59 ], leadership [ 35 , 40 ], public speaking and dissemination [ 30 , 53 , 60 ], and advocacy [ 31 , 36 , 62 ]. Participation in air quality activities was found to have enhanced individual and collective confidence and motivation to act [ 31 , 42 , 43 , 44 , 49 , 52 , 64 , 68 ], built a sense of community [ 37 , 52 ], and increased self-efficacy [ 38 , 52 , 65 , 66 ]. Community engagement in some cases enabled the development of new connections [ 41 , 59 , 63 , 65 ], and partnerships between the community and organisations [ 37 , 47 , 53 ]. Community participation in air quality activities was found to elicit a sense of ownership, particularly in studies whereby residents has contributed to decision-making or collected their own data [ 30 , 35 , 38 , 68 ]. Individual or community empowerment was frequently described in the studies, a potential product of these linked competencies [ 35 , 40 , 42 , 43 , 52 , 55 ]. Some studies described the achievement of these linked outcomes as increased environmental health literacy [ 40 , 49 , 60 ].

For a small number of studies, communities reported experiencing disappointment or frustration at statutory organisations’ responses [ 37 , 50 , 68 ]. In two cases, the processes and/or inclination did not exist for lay knowledge and citizen-collected data to be integrated into the work of statutory organisations [ 46 , 51 ]. One study identified tensions with local media suggesting that the public were being misled about the extent of the links between air pollution and health [ 35 ], whilst another reported that the use of personal air monitors had the potential to prioritise individual behavioural responses, transferring the responsibility for action from the producers of emissions to vulnerable populations [ 49 ].

Organisations

Engaging the community often led to changes for statutory organisations. Additional funding or the maintenance of funding to address air pollution was secured as a result of the engagement activities in two studies [ 41 , 43 ]. New or revised policies emerged from some studies, such as the development of an air protection policy [ 41 ], formation of greener zones [ 38 ], and policy changes on vehicle idling and industrial site regulation [ 33 , 36 , 68 ]. Hayes, King [ 66 ] focused on a citizen-led review of existing policies and showcased new methods for policy co-creation with citizens. A wide range of changes to practice were described including implementing cleaner fuel for public transport [ 36 ], a 24-h call system to respond to community concerns [ 40 ], new monitoring sites [ 41 , 51 ], and changes to school environments [ 39 ]. In some studies, residents or community-based organisations continued to contribute to decision-making on air quality through ongoing engagement activities, including advisory and policy-making boards [ 37 ], environmental health forums [ 47 ], volunteering schemes [ 40 ], and embedding participatory modelling into usual practice [ 57 ]. Having engaged with local residents, additional information was now available to statutory organisations. An improved understanding of pollution sources was reported [ 59 , 61 , 62 ], in addition to increased awareness of local community concerns and the challenges they face [ 30 , 39 , 52 , 64 ].

Air quality and health

Very few studies evaluated the impact of their community engagement activities on local air quality and/or health. Two studies measured environmental outcomes: preliminary data indicated improvements in one study [ 63 ], and another saw a reduction in bus and car idling times, their simulation suggesting improved air quality [ 33 ]. Studies frequently concluded that if specified changes in policy and practice were successfully implemented, air quality in and around specific buildings such as schools, or in neighbourhoods close to sources of industrial pollution would improve [ 35 , 36 , 39 , 42 , 44 , 52 , 66 ]. As with the environmental impacts, there was an assumption, rather than measurement, of health improvement through the adoption of new practices and policies (such as the use of an air pollution alert system) which meant that residents were now equipped with information to protect their own health [ 41 , 65 ].

This scoping review aimed to explore approaches used to engage communities in efforts to address air quality. Disproportionate exposure to air pollution was frequently considered, particularly in studies conducted in the USA, which were often located within “ environmental justice ” communities. The approaches used by studies were varied, but have been usefully categorised into citizen science, environmental and health assessment, education and training, and policy development and review. The community engagement initiatives reported a number of positive outcomes for individuals and communities, including increased awareness, enhanced self-efficacy, community connectivity, and for the organisations involved, including access to local intelligence, and development of new policies and practices. However, limited evidence existed on the extent to which engagement led to changes in health or environmental outcomes for individuals and local populations, as these outcomes were largely not measured in studies.

Contributions to existing research

Although air quality monitoring initiatives were most prominent in this review, a range of other approaches to engage communities in air quality were also evident and reported positive outcomes. Including studies which utilised environmental and health assessments, education and training, and policy development and review, the findings add to the review of community participation in air quality monitoring studies conducted in the USA [ 69 ], by offering illustrative examples for communities, researchers and organisations wanting to collaborate in this area, and also suggesting alternatives where monitoring may not be appropriate. Case study examples of community action influencing policy changes reported in this review [ 33 , 35 , 36 , 44 ], reflect other studies that have demonstrated the potential for participatory approaches to result in policy change in addressing environmental concerns [ 70 , 71 ]. A case study of industrialised hog production cited by Whitehead, Pennington [ 25 ], for example, highlights how a community health and environmental partnership involving the local community and researchers led to heightened attention of the health hazards associated with hog production particularly among African American communities and was used to challenge the health damaging effects of industrial production. Israel, Schulz [ 72 ] and Wine, Ambrose [ 73 ] have highlighted how community-based participatory approaches are more likely to attend to issues of power and equitable relationships compared to other community engagement approaches, which in itself could be empowering for communities and have benefits for wellbeing and trust.

Whilst many of the facilitators (e.g. using existing partnerships, adapting methods to the community, building relationships) and challenges (e.g. limited community capacity, scepticism and trust, insufficient resources) to community engagement identified were consistent with findings from other reviews [ 13 , 72 ] and were not specific to air quality studies; others were more salient and require particular consideration such as the use of technical or scientific language, and internet access needed by participants to, for example, upload and view monitoring data. Furthermore, while positive organisational outcomes and changes to policy and practice were identified in this review, little information was provided about the capacity needed to facilitate community engagement and maintain ongoing relationships. Considerations included not only appropriately skilled staff but also an organisational ethos and culture that is positive about community engagement and systems in place to support this [ 14 ]. Additional resource in air quality initiatives may be required, for example, to obtain and maintain equipment [ 32 ].

The importance of considerations of place and health inequalities in addressing air quality was evident across the studies. Whilst there is impetus to reduce air pollution risks for all affected populations, communities living in more disadvantaged areas are at a disproportionate risk of inequities in air quality and health outcomes [ 5 ]. Engaging disadvantaged communities and locating air quality issues and solutions within the framework of the wider social and economic determinants of health may achieve health gains, both in terms of reduced health risk and health inequalities [ 5 ]. Whilst Noël, Vanroelen [ 21 ] found evidence that air pollution could be “ crowded out ” by other personal and urgent issues, the learning from this review is that, from the studies in environmental justice communities in particular, successful collaborations can be built in vulnerable communities. Using air quality monitoring and/or other activities, key components of these approaches included establishing public concerns, community capacity building, adapting strategies to meet the needs of the community, and having equitable partnerships amongst those involved [ 31 , 35 , 36 , 37 , 38 , 53 ]. A recent interpretative synthesis also highlighted the greater likelihood of environmental justice communities achieving “ structural change ” (e.g. impacting the wider determinants of health) when partnerships were long-term, project design included decision-makers and policy goals, and community members held leadership roles [ 74 ]. In addition, previous reviews have placed an emphasis on studies of community engagement addressing health at a more individual level (e.g. smoking cessation) or with groups that share a social or cultural identity [ 11 , 72 ]. For studies included in this review, communities have a specific shared identity based on place and this was grounded in their lived experience of poor air quality, and reinforces the need to implement place-based approaches to facilitate action on air quality in collaboration with local communities.

Limitations of the evidence base

Due to the varied nature of the literature and lack of detailed reporting, drawing on comparisons between community engagement approaches, the communities involved, and assessing effectiveness was challenging. Previous reviews have found similar limitations in the evidence base and challenges with associating outcomes with a specific approach to community engagement and the context in which it was conducted in [ 11 , 75 , 76 ]. The summary presented in Table 4 characterises the community engagement approaches and the variety of associated outcomes, facilitators and challenges found in this review. However, some caution should be noted in its interpretation because of the heterogeneity of the evidence base.

Related to this, a clear gap found consistently across the community engagement literature was in relation to outcomes and the wider determinants of health. Whilst positive impacts for engaged individuals, communities and organisations were reported in many studies, few theorised whether engagement contributed to changes which reduced air pollution or improved health, or measured this in their research. These findings are in line with other reviews [ 11 , 75 , 76 ], which identified short-term outcomes for community engagement (e.g. self-efficacy, empowerment, policy change), but found studies collected or reported insufficient data to test the effects of community engagement on longer-term health outcomes.

A paradox therefore remains in that while community engagement approaches demonstrate promise in tackling environmental justice, the availability of robust evidence is still limited. While in part this is down to a lack of theorisation or measurement, it’s “ grassroots ” nature can also make some community engagement less amenable to more traditional evaluation designs [ 77 ]. In this vein, Israel, Schulz [ 72 ] highlighted in a review of community-based participatory research that the ability to secure research (or other) funding for such initiatives stems from “ a challenge of selling a process without completely specifying all the outcomes beforehand, often troubling for researchers, health professionals, and community members, as well as funders ”. A review undertaken several years later which researched the effectiveness of initiatives to strengthen community control in the living environment, suggests this research gap still remains, with many examples of practice also still remain located in descriptive case studies or unpublished sources making it difficult to judge their “ comprehensive or quality ” [ 78 ].

Implications for future research and practice

Within recent years, there has been increased research and policy attention to air pollution and its impact of health [ 79 , 80 ], with recommendations that communities should be engaged in identifying issues and solutions to poor air quality in their neighbourhoods [ 7 , 8 , 9 ]. The findings of this scoping review can be used to inform the future development and implementation of these approaches. Firstly, in the context of addressing air quality, successful community engagement approaches appear to require strategies that enable effective collaboration between communities, researchers and organisations (e.g. multi-stakeholder forums), offer opportunities to embed lived experience and local knowledge of poor air quality (e.g. monitoring, mapping), and promote a wider “ outward gaze ” [ 81 ] to the political and social structures that influence addressing action on this public health issue. Secondly, developing a reporting checklist, similar to the Guidance for Reporting Involvement of Patients and Public (GRIPP2) [ 29 ], or the Template for Intervention Description and Replication (TIDieR) [ 82 ], may improve future reporting of community engagement initiatives and support attempts to compare and contrast approaches and their effectiveness. As far as the authors are aware, no such checklist exists. With enhanced reporting, communities, researchers, and organisations, could identify what form of community engagement may work best in their specific context and replicate the approach to achieve their desired outcomes. Lastly, although establishing a causal relationship between community engagement and reduced air pollution or improved health is difficult [ 79 ], future research should consider from the outset how the pathway from the engagement activity to any subsequent impact on air quality and health can be elucidated. In this respect, evaluation methods adopting systems approaches can help in elucidating the complexities in environmental settings, by enabling inter-related changes and pathways to health to be captured [ 83 ]. For example, air quality measures that have potential to benefit health directly (e.g. respiratory conditions) could also result in other impacts that are health enhancing (e.g. changes to traffic flows leading to improved road safety or increased physical activity and social engagement within a community).

Strengths and limitations of this review

A strength of this scoping review was the embedding of stakeholder and public involvement throughout the review process, enabling the review questions, data extraction, interpretation and writing to be shaped by a group of individuals with a range of personal and professional perspectives. The reflections on the impact of this involvement are outlined in the supplemental material (Table S 1 ). As the aim of this review was to capture a breadth rather than a specific standard of evidence, issues associated with quality appraisal were not addressed. It was however conducted in line with existing guidelines for scoping reviews [ 22 , 23 ]. This review was not intended to be exhaustive or comprehensive and some relevant examples may have been missed. For pragmatic reasons, including limited time and resources, additional citation tracking and grey literature searches were not conducted, and as such may have limited the extent to which further examples of community engagement initiatives in air quality were identified. This review was also limited to studies conducted in developed economies and to studies concerned with indoor and/or outdoor air quality in the living environment; additional insight of community engagement initiatives in other contexts may be beneficial.

This scoping review summarises the variety of approaches that have been used to engage communities in addressing air quality, highlighting some of the facilitators, challenges and possibilities available to communities, researchers and statutory organisations wishing to undertake work in this area. The findings suggest that positive individual, community and organisational outcomes can be achieved through multi-stakeholder collaborations working with researchers. The limited evidence available on the impact of community engagement on improving air quality and health, and consequently addressing associated health inequalities has identified a need for future studies to explore and clarify this pathway.

Availability of data and materials

All data generated and analysed in this review are included in this article and its supplementary information files.

Abbreviations

Applied Research Collaboration North West Coast

Guidance for Reporting Involvement of Patient and Public

National Institute for Health and Care Research

Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews

United Kingdom

United States of America

World Health Organisation

World Health Organisation. Air Pollution 2018. [Available from: https://www.who.int/health-topics/air-pollution#tab=tab_1 .]

Chen H, Kwong JC, Copes R, Tu K, Villeneuve PJ, Van Donkelaar A, et al. Living near major roads and the incidence of dementia, parkinson’s disease, and multiple sclerosis: a population-based cohort study. The Lancet. 2017;389(10070):718–26.

Pedersen M, Giorgis-Allemand L, Bernard C, Aguilera I, Andersen AMN, Ballester F, et al. Ambient air pollution and low birthweight: a European cohort study (ESCAPE). Lancet Res Med. 2013;1(9):695–704.

Article   CAS   Google Scholar  

Peters A. Air pollution and mortality from diabetes mellitus. Nat Rev Endocrinol. 2012;8(12):706–7.

Article   Google Scholar  

Brunt H, Barnes J, Jones S, Longhurst J, Scally G, Hayes E. Air pollution, deprivation and health: Understanding relationships to add value to local air quality management policy and practice in Wales. UK Journal of Public Health. 2017;39(3):485–97.

CAS   Google Scholar  

Marmot M, Allen J, Goldblatt P, Boyce T, McNeish D, Grady M, et al. The Marmot Review: Fair society, health lives: strategic review of health inequalities in England post-2010. London; 2010. [Available from: https://www.parliament.uk/globalassets/documents/fair-society-healthy-lives-full-report.pdf ]

Environmental Protection Agency. Environmental Protection Agency Office of Environmental Justice Factsheet 2017. [Available from: https://www.epa.gov/sites/production/files/2017-09/documents/epa_office_of_environmental_justice_factsheet.pdf .]

Defra. Air Quality: A Briefing for Directors of Public Health London 2017. [Available from: https://www.local.gov.uk/sites/default/files/documents/6.3091_DEFRA_AirQualityGuide_9web_0.pdf .]

World Health Organisation. The Helsinki statement on health in all policies. Health Promot Int. 2014;29(suppl_1):i17–8.

Swainston K, Summerbell C. The effectiveness of community enegagement approaches and methods for health promotion interventions. National Institute for Health and Clinical Excellence; 2008. [Available from: https://research.tees.ac.uk/en/publications/the-effectiveness-of-community-engagement-approaches-and-methods- ]

O'Mara-Eves A, Brunton G, McDaid G, Oliver S, Kavanagh J, Jamal F, et al. Community engagement to reduce inequalities in health: a systematic review, meta-analysis and economic analysis. Public Health Research. 2013;1(4).  https://www.journalslibrary.nihr.ac.uk/phr/phr01040/#/abstract .

Popay J. Community engagement for health improvement: questions of definition, outcomes and evaluation. London: National Institute for Health and Care Excellence; 2006.

Google Scholar  

Harden A, Sheridan K, McKeown A, Dan-Ogosi I, Bagnall A. Evidence Review of Barriers to, and Facilitators of, Community Engagement Approaches and Practices in the UK. London: Institute for Health and Human Development, University of East London; 2015.

Pickin C, Popay J, Staley K, Bruce N, Jones C, Gowman N. Developing a model to enhance the capacity of statutory organisations to engage with lay communities. J Health Serv Res Policy. 2002;7(1):34–42.

Kilpatrick S. Multi-level rural community engagement in health. Aust J Rural Health. 2009;17(1):39–44.

McGowan VJ, Wistow J, Lewis SJ, Popay J, Bambra C. Pathways to mental health improvement in a community-led area-based empowerment initiative: evidence from the Big Local ‘Communities in Control’ study. J Public Health. 2019;41(4):850–7.

MacQueen KM, McLellan E, Metzger DS, Kegeles S, Strauss RP, Scotti R, et al. What is community? An evidence-based definition for participatory public health. Am J Public Health. 2001;91(12):1929–38.

Ellery PJ, Ellery J. Strengthening community sense of place through placemaking. Urban Planning. 2019;4(2):238–48.

Bush J, Moffatt S, Dunn C. ‘Even the birds round here cough’: stigma, air pollution and health in Teesside. Health Place. 2001;7(1):47–56.

Elliott SJ. 50 years of medical health geography (ies) of health and wellbeing. Social Science Medicine. 2018;196((C)):206–8.

Noël C, Vanroelen C, Gadeyne S. Qualitative research about public health risk perceptions on ambient air pollution a review study. SSM Popul Health. 2021;15:100879.

Arksey H, O’Malley L. Scoping studies: towards a methodological framework. Int J Soc Res Methodol. 2005;8(1):19–32.

Peters MDJ, Godfrey CM, Khalil H, McInerney P, Parker D, Soares CB. Guidance for conducting systematic scoping reviews. JBI Evidence Implementation. 2015;13(3):141.

Tricco AC, Lillie E, Zarin W, O’Brien KK, Colquhoun H, Levac D, et al. PRISMA extension for scoping reviews (PRISMA-ScR): checklist and explanation. Ann Intern Med. 2018;169(7):467–73.

Whitehead M, Pennington A, Orton L, Nayak S, Petticrew M, Sowden A, et al. How could differences in ‘control over destiny’ lead to socio-economic inequalities in health? A synthesis of theories and pathways in the living environment. Health Place. 2016;39:51–61.

Ouzzani M, Hammady H, Fedorowicz Z, Elmagarmid A. Rayyan-a web and mobile app for systematic reviews. Syst Rev. 2016;5:210.

Thomas DR. A general inductive approach for analyzing qualitative evaluation data. Am J Eval. 2006;27(2):237–46.

Den Broeder L, Devilee J, Van Oers H, Schuit AJ, Wagemakers A. Citizen science for public health. Health Promot Int. 2018;33(3):505–14.

Staniszewska S, Brett J, Simera I, Seers K, Mockford C, Goodlad S, et al. GRIPP2 reporting checklists: tools to improve reporting of patient and public involvement in research. BMJ. 2017;358: j3453.

Ablah E, Brown J, Carroll B, Bronleewe T. A community-based participatory research approach to identifying environmental concerns. J Environ Health. 2016;79(5):14–9.

Brody JG, Morello-Frosch R, Zota A, Brown P, Perez C, Rudel RA. Linking exposure assessment science with policy objectives for environmental justice and breast cancer advocacy: the northern California household exposure study. Am J Public Health. 2009;99(Supp 3(s3)):600–9.

Downs TJ, Ross L, Mucciarone D, Calvache MC, Taylor O, Goble R. Participatory testing and reporting in an environmental-justice community of Worcester, Massachusetts: a pilot project. Environ Health. 2010;9(1):34.

Eghbalnia C, Sharkey K, Garland-Porter D, Alam M, Crumpton M, Jones C, et al. A community-based participatory research partnership to reduce vehicle idling near public schools. J Environ Health. 2013;75(9):14–9.

Jiang Q, Kresin F, Bregt AK, Kooistra L, Pareschi E, Van Putten E, et al. Citizen sensing for improved urban environmental monitoring. Journal of Sensors: Sensors for Environmental Monitoring. 2016.  https://www.hindawi.com/journals/js/si/853956/ .

Loh P, Sugerman-Brozan J, Wiggins S, Noiles D, Archibald C. From asthma to airbeat: community-driven monitoring of fine particles and black carbon in Roxbury. Massachusetts Environmental Health Perspectives. 2002;110(suppl 2):297–301.

Minkler M. Linking science and policy through community-based participatory research to study and address health disparities. Am J Public Health. 2010;100(S1):S81–7.

Parker EA, Chung LK, Israel BA, Reyes A, Wilkins D. Community organizing network for environmental health: using a community health development approach to increase community capacity around reduction of environmental triggers. J Primary Prevent. 2010;31(1–2):41–58.

Sadd J, Morello-Frosch R, Pastor M, Matsuoka M, Prichard M, Carter V. The truth, the whole truth, and nothing but the ground-truth: Methods to advance environmental justice and researcher–community partnerships. Health Educ Behav. 2014;41(3):281–90.

Spencer-Hwang R, Soret S, Valladares J, Torres X, Pasco-Rubio M, Dougherty M, et al. Strategic partnerships for change in an environmental justice community: the ENRRICH Study. Prog Community Health Partnersh. 2016;10(4):541–50.

Symanski E, An Han H, Hopkins L, Smith MA, McCurdy S, Han I, et al. Metal air pollution partnership solutions: building an academic-government-community-industry collaboration to improve air quality and health in environmental justice communities in Houston. Environ Health. 2020;19:1–12.

Wong M, Wilkie A, Garzón-Galvis C, King G, Olmedo L, Bejarano E, et al. Community-engaged air monitoring to build resilience near the US-Mexico border. Int J Environ Res Public Health. 2020;17(3):1092.

Brickle MB, Evans-Agnew R. Photovoice and youth empowerment in environmental justice research: a pilot study examining woodsmoke pollution in a pacific northwest community. J Community Health Nurs. 2017;34(2):89–101.

Evans-Agnew RA, Eberhardt C. Uniting action research and citizen science: Examining the opportunities for mutual benefit between two movements through a woodsmoke photovoice study. Action Research. 2019;17(3):357–77.

Harrison JL. Parsing “participation” in action research: navigating the challenges of lay involvement in technically complex participatory science projects. Soc Nat Resour. 2011;24(7):702–16.

McAndrews C, Marcus J. Community-based advocacy at the intersection of public health and transportation: the challenges of addressing local health impacts within a regional policy process. J Plan Educ Res. 2014;34(2):190–202.

Stewart TR, Dennis RL, Ely DW. Citizen participation and judgment in policy analysis: a case study of urban air quality policy. Policy Sci. 1984;17(1):67–87.

Williams MF, James DD. Embracing new policies, technologies, and community partnerships: a case study of the city of houston’s bureau of air quality control. Tech Commun Q. 2008;18(1):82–98.

Yearley S, Cinderby S, Forrester J, Bailey P, Rosen P. Participatory modelling and the local governance of the politics of UK air pollution: a three-city case study. Environ Values. 2003;12(2):247–62.

Johnston JE, Juarez Z, Navarro S, Hernandez A, Gutschow W. Youth engaged participatory air monitoring: a ‘day in the life’in urban environmental justice communities. Int J Environ Res Public Health. 2020;17(1):93.

Bailey P, Yearley S, Forrester J. Involving the public in local air pollution assessment: a citizen participation case study. Int J Environ Pollut. 1999;11(3):290–303.

Gabrys J, Pritchard H. Just good enough data and environmental sensing: Moving beyond regulatory benchmarks toward citizen action. Int J Spatial Data Infrastructures Research. 2018;13:4–14.

Hsu Y-C, Dille P, Cross J, Dias B, Sargent R, Nourbakhsh I. Community-empowered air quality monitoring system. Proceedings of the 2017 CHI Conference on human factors in computing systems. 2017:1607–19.  https://dl.acm.org/doi/proceedings/10.1145/3025453 .

Rickenbacker H, Brown F, Bilec M. Creating environmental consciousness in underserved communities: Implementation and outcomes of community-based environmental justice and air pollution research. Sustain Cities Soc. 2019;47: 101473.

Van Brussel S, Huyse H. Citizen science on speed? Realising the triple objective of scientific rigour, policy influence and deep citizen engagement in a large-scale citizen science project on ambient air quality in Antwerp. J Environ Planning Manage. 2019;62(3):534–51.

Mahajan S, Kumar P, Pinto JA, Riccetti A, Schaaf K, Camprodon G, et al. A citizen science approach for enhancing public understanding of air pollution. Sustain Cities Soc. 2020;52: 101800.

Cinderby S, Forrester J. Facilitating the local governance of air pollution using GIS for participation. Appl Geogr. 2005;25(2):143–58.

Cinderby S, Snell C, Forrester J. Participatory GIS and its application in governance: the example of air quality and the implications for noise pollution. Local Environ. 2008;13(4):309–20.

Yearley S. Bridging the science–policy divide in urban air-quality management: evaluating ways to make models more robust through public engagement. Eviron Plann C Gov Policy. 2006;24(5):701–14.

English PB, Olmedo L, Bejarano E, Lugo H, Murillo E, Seto E, et al. The imperial county community air monitoring network: a model for community-based environmental monitoring for public health action. Environ Health Perspect. 2017;125(7): 074501.

Madrigal D, Claustro M, Wong M, Bejarano E, Olmedo L, English P. Developing youth environmental health literacy and civic leadership through community air monitoring in imperial county, California. Int J Environ Res Public Health. 2020;17(5):1537.

Wong M, Bejarano E, Carvlin G, Fellows K, King G, Lugo H, et al. Combining community engagement and scientific approaches in next-generation monitor siting: the case of the imperial county community air network. Int J Environ Res Public Health. 2018;15(3):523.

Keeler GJ, Dvonch T, Yip FY, Parker EA, Isreal BA, Marsik FJ, et al. Assessment of personal and community-level exposures to particulate matter among children with asthma in Detroit, Michigan, as part of community action against asthma. Environ Health Perspect. 2002;110(suppl 2):173–81.

Parker EA, Israel BA, Williams M, Brakefield-Caldwell W, Lewis TC, Robins T, et al. Community action against asthma. J Gen Intern Med. 2003;18(7):558–67.

Jardine CG, Predy G, Mackenzie A. Stakeholder participation in investigating the health impacts from coal-fired power generating stations in Alberta. Can J Risk Res. 2007;10(5):693–714.

Wong C, Wu H-C, Cleary EG, Patton AP, Xie A, Grinstein G, et al. Visualizing air pollution: communication of environmental health information in a Chinese immigrant community. J Health Commun. 2019;24(4):339–58.

Hayes E, King A, Callum A, Williams B, Vanherle K, Boushel C, et al. Claircity project: Citizen-led scenarios to improve air quality in European cities. In: Casares J, Passerini G, Barnes J, Longhurst J, Perillo G, editors. Air Pollution XXVI. 230: WIT Press; 2018. p. 233–41.

Stave KA. Using system dynamics to improve public participation in environmental decisions. J Syst Dynamics Soc. 2002;18(2):139–67.

Hsu Y-C, Cross J, Dille P, Tasota M, Dias B, Sargent R, et al. Smell Pittsburgh: Community-empowered mobile smell reporting system. Proceedings of the 24th International Conference on Intelligent User Interfaces. 2019:65–79.  https://dl.acm.org/doi/proceedings/10.1145/3301275 .

Commodore A, Wilson S, Muhammad O, Svendsen E, Pearce J. Community-based participatory research for the study of air pollution: a review of motivations, approaches, and outcomes. Environ Monit Assess. 2017;189(8):378.

Minkler M, Vásquez VB, Shepard P. Promoting environmental health policy through community based participatory research: a case study from harlem, New York. J Urban Health. 2006;83(1):101–10.

Minkler M, Vásquez VB, Tajik M, Petersen D. Promoting environmental justice through community-based participatory research: the role of community and partnership capacity. Health Educ Behav. 2006;35(1):119–37.

Israel BA, Schulz AJ, Parker EA, Becker AB. Review of community-based research: assessing partnership approaches to improve public health. Annu Rev Public Health. 1998;19:173–202.

Wine O, Ambrose S, Campbell S, Villeneuve PJ, Burns KK, Vargas AO. Key components of collaborative research in the context of environmental health: a scoping review. J Res Prac. 2017;13(2):R2.

Davis LF, Ramírez-Andreotta MD. Participatory Research for Environmental Justice: A Critical Interpretive Synthesis. Environ Health Perspect. 2021;129(2): 026001.

Popay J, Attree P, Hornby D, Milton B, Whitehead M, French B, et al. Community engagement in initiatives addressing the wider social determinants of health: a rapid review of evidence on impact, experience and process. Lancaster: University of Lancaster; 2007.

Cyril S, Smith BJ, Possamai-Inesedy A, Renzaho AMN. Exploring the role of community engagement in improving the health of disadvantaged populations: a systematic review. Glob Health Action. 2015;8(1):29842.

South J, Phillips G. Evaluating community engagement as part of the public health system. J Epidemiol Community Health. 2014;68(7):692.

Whitehead M, Orton L, Pennington A, Nayak S, Ring A, Petticrew M, et al. Is control in the living environment important for health and wellbeing, and what are the implications for public health interventions? Public Health Research Consortium; 2014. [Available from: https://phrc.lshtm.ac.uk/assets/uploads/files/PHRC_004_Final_Report.pdf ]

Burns J, Boogaard H, Polus S, Pfadenhauer LM, Rohwer AC, van Erp AM, et al. Interventions to reduce ambient air pollution and their effects on health: an abridged cochrane systematic review. Environ Int. 2020;135: 105400.

World Health Organisation. Air pollution and child health: prescribing clean air summary: World Health Organisation. 2018.

Popay J, Whitehead M, Ponsford R, Egan M, Mead R. Power, control, communities and health inequalities I: theories, concepts and analytical frameworks. Health Promotion International. 2021;36(5):1253-63.

Hoffmann TC, Glasziou PP, Boutron I, Milne R, Perera R, Moher D, et al. Better reporting of interventions: template for intervention description and replication (TIDieR) checklist and guide. BMJ : British Medical Journal. 2014;348: g1687.

Orton L, Halliday E, Collins M, Egan M, Lewis S, Ponsford R, et al. Putting context centre stage: evidence from a systems evaluation of an area based empowerment initiative in England. Crit Public Health. 2017;27(4):477–89.

Download references

Acknowledgements

The authors would like to thank Ana Porroche-Escudero and Professor Catherine Walshe for their insightful comments, Cath Harris for her assistance in developing the search strategy, and Sian Guy as a member of the review group.

This research was funded by the National Institute for Health and Care Research (NIHR) Applied Research Collaboration North West Coast (ARC NWC). The view expressed in this publication are those of the authors and not necessarily those of the NIHR or the Department for Health and Social Care.

Author information

Fiona Ward and Hayley Lowther-Payne are joint first authors.

Authors and Affiliations

Division of Health Research, Lancaster University, Lancaster, UK

Fiona Ward & Emma C. Halliday

Applied Health Research Hub (AHRh), University of Central Lancashire (UCLan), Preston, UK

Hayley J. Lowther-Payne

Liverpool City Council, Liverpool, UK

Keith Dooley

National Institute for Health and Care Research Applied Research Collaboration North West Coast (NIHR ARC NWC), Liverpool, UK

Neil Joseph, Paul Moran & Jane Cloke

Regenerus, Bootle, UK

Ruth Livesey

Blackburn-With-Darwen Borough Council, Blackburn, UK

Simon Kirby

You can also search for this author in PubMed   Google Scholar

Contributions

All listed authors qualify for authorship based on making one or more substantial contributions to the intellectual content; conceptual design (FW, HJL, EH, KD, NJ, RL, PM, SK, JC), acquisition of the data (FW, HJL), analysis and interpretation of the data (FW, HJL, EH, KD, NJ, RL, PM, SK, JC). Furthermore, all authors participated in drafting the manuscript (FW, HJL, EH) or critical revision of the manuscript for important intellectual content (FW, HJL, EH, KD, NJ, RL, PM, SK, JC). All authors read and approved the final manuscript.

Corresponding author

Correspondence to Emma C. Halliday .

Ethics declarations

Ethics approval and consent to participate.

Not applicable.

Consent for publication

Competing interests.

The authors declare that they have no competing interests.

Additional information

Publisher’s note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

Additional file 1: table s1..

GRIPP2 reporting checklist – short form (amended)

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ . The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/ ) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and permissions

About this article

Cite this article.

Ward, F., Lowther-Payne, H.J., Halliday, E.C. et al. Engaging communities in addressing air quality: a scoping review. Environ Health 21 , 89 (2022). https://doi.org/10.1186/s12940-022-00896-2

Download citation

Received : 13 April 2022

Accepted : 19 August 2022

Published : 19 September 2022

DOI : https://doi.org/10.1186/s12940-022-00896-2

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

  • Community engagement
  • Participation
  • Air quality
  • Air pollution
  • Health inequalities

Environmental Health

ISSN: 1476-069X

air pollution project conclusion

U.S. flag

An official website of the United States government

The .gov means it's official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

  • Publications
  • Account settings
  • Browse Titles

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

Williams ML, Beevers S, Kitwiroon N, et al. Public health air pollution impacts of pathway options to meet the 2050 UK Climate Change Act target: a modelling study. Southampton (UK): NIHR Journals Library; 2018 Jun. (Public Health Research, No. 6.7.)

Cover of Public health air pollution impacts of pathway options to meet the 2050 UK Climate Change Act target: a modelling study

Public health air pollution impacts of pathway options to meet the 2050 UK Climate Change Act target: a modelling study.

Chapter 10 discussion and conclusions.

  • Scientific conclusions

Scenario emissions

The two ‘CCA-compliant’ scenarios, NRPO and LGHG, had a high proportion of energy generated through biomass use with a large increase in PM 2.5 emissions of approximately 50%, compared with 2011, and peaking in 2035. Although biomass use was projected to decrease again by 2050, primary PM 2.5 emissions in 2050 were still marginally higher than 2011 levels. The baseline and reference scenarios, which did not meet the CCA target, had lower levels of wood burning.

Both the LGHG and the NRPO had a high degree of switching from petrol and diesel fuels to electric, hybrid and alternatively fuelled vehicles in the UK road transport fleet, leading to reductions of around 90% from transport sector NO x emissions in all scenarios except the baseline. The baseline scenario had higher gas and biomass consumption in CHP plants compared with other scenarios, as well as no obligation to meet the CCA target, and this lead to increased NO 2 exposure. In the transportation sector, despite the exhaust emission reductions, the UKTM projections show large increases in traffic activity with car and heavy goods vehicle kilometres projected to increase by roughly 50% in all the scenarios and vans by a factor of about 2. This leads to a pro-rata increase in PM emissions from brake and tyre wear and resuspension of road dust, although these are uncertain as we have assumed in future that the emissions factors will remain at current levels. Consequently, non-exhaust emissions could be the dominant source of primary PM from vehicles in future, increasing PM 10 by about 15% compared with 2011 in the NRPO scenario, for example. This is more of an issue for PM 10 , as the non-exhaust emissions are coarser in size.

Pollutant concentrations

Annual mean concentrations of NO 2 are projected to decrease by about 60% in the LGHG scenario and by ≈50% in the NRPO scenario across the whole of GB and in London, but only by ≈20% across GB and ≈42% in London in the baseline scenario.

Annual mean PM 2.5 concentrations are also projected to fall by around 40% in the top 25% of grid squares, but by only ≈25% in the highest areas. However, concentrations of primary PM 2.5 are projected to increase in 2035 in the NRPO and LGHG scenarios, by around 30–60% in the more polluted grid squares, as a result of the increase in biomass use. By 2050, in those two scenarios, levels are only slightly lower than 2011 values and in the highest grid square are very similar to 2011 concentrations. If this amount of primary PM 2.5 were to be removed, by avoiding the high use of biomass, total PM 2.5 concentrations could fall even further than projected, down by ≈50% in the highest areas compared with ≈25% reduction with the increased biomass use.

Total PM 10 concentrations are projected to increase in 2035 in many areas of the UK in both the LGHG and NRPO scenarios, despite the reduction in secondary PM precursors, because of the increased use of biomass and the increased non-exhaust emissions from transport. PM 10 levels decrease again by 2050, but remain only about 15% smaller than 2011 in the more polluted areas of GB. This is a small reduction and is not larger because of the increasing contribution from non-exhaust emissions. This is of concern as these emissions are potentially toxic.

The reductions in NO x emissions result in increasing annual average O 3 concentrations in urban areas, leading to higher exposures using the metric recommended by COMEAP for short-term impact on mortality. In contrast, all scenarios show reductions in the metric suggested by the WHO for long-term O 3 exposure impact on mortality.

Both O 3 and NO 2 are strong oxidising agents and can play a role in oxidative stress in the human body. This can be quantified through the use of the metric O x or oxidant (O x  = O 3  + NO 2 ), which has been shown to be associated with adverse health outcomes. Annual average levels are projected to remain virtually constant to 2050. The significance of this for health is that the balance of O x will shift to O 3 as NO 2 reduces; the former is the more powerful O x so that the oxidising power of the urban atmosphere in the UK will increase with potentially increased adverse health effects, assuming that the global background of O 3 remains broadly constant.

Health impact

We have calculated impact arising from long-term exposures to the pollutants PM 2.5 , NO 2 and O 3 , on mortality, using a life table approach to calculate the loss of life-years in each of the scenarios. This now incorporates birth projections, projected improvements in mortality rates and mortality rates at local authority level. The two scenarios which achieve the CCA target result in more life-years lost from long-term exposures to PM 2.5 beyond the carbon policies already in place and the levels of PM 2.5 still result in a loss of life expectancy from birth in 2011 of around 4 months. This is an important opportunity lost and arises from the large increase in biomass use peaking in 2035. Our estimates suggest that in the more highly polluted areas of GB, total PM 2.5 concentrations could reduce by as much as 50% without the biomass contribution.

There is currently some uncertainty over the role of NO 2 vis-à-vis PM 2.5 , but using the CRFs currently suggested by COMEAP, reduced long-term exposures to NO 2 lead to more life-years saved and an improvement of 2 months in loss of life expectancy from birth in 2011 in the ‘CCA-compliant’ scenarios compared with the baseline scenario, with the largest benefits arising from the most ambitious scenario LGHG.

Evidence for impact on mortality of long-term exposures to O 3 is increasing, although using the quantification recommended by WHO we estimate life-years lost from this exposure to be smaller by factors of ≈6 and ≈3–4, than those from PM 2.5 and from NO 2 , respectively, if no threshold is assumed for NO 2 . However, the short-term O 3 exposure metric recommended by COMEAP suggests the number of DBF in a year could be around 22,000 compared with 29,000 from long-term PM 2.5 exposures.

However, it should be noted that the distinction between effects attributable to NO 2 and those attributable to PM 2.5 and the issue of how if, at all, one might add the effects of both pollutants is still a matter of some uncertainty. COMEAP is currently in the process of preparing a report on this subject, unpublished at the time of writing.

The issue of a no-effects threshold is also very important on quantifying the impact of O 3 concentrations. The long-term exposure metric recommended by WHO in the HRAPIE project 95 as a sensitivity study included a threshold of 35 p.p.b. or 70 µg/m 3 and resulted in an impact on life-years lost much smaller than those of PM 2.5 and NO 2 . However, the short-term exposure metric recommended by COMEAP did not incorporate a threshold, and a rough calculation suggests that the impact from this metric of O 3 concentrations could lead to the number of DBF of a similar order to that for PM 2.5 , approximately 20,000 from O 3 exposure compared with 29,000 from PM 2.5 .

We also investigated the effect of the changing concentrations on exposures in different socioeconomic classes. We observed differences in air pollution levels in subpopulations for all analysed pollutants and for each geographical area. Differences in exposure were most marked for NO 2 for ethnicity and for socioeconomic deprivation. Wards with higher proportions of non-white residence and higher deprivation are expected to be closer to roads and, therefore, exposed to these higher NO 2 levels. The ratios of exposures in white and non-white populations were much larger than those for the most deprived populations compared with least deprived populations in GB and Wales, but slightly smaller in London. Relative differences between most and least deprived populations were highest in Scotland, closely followed by London; relative differences in Wales were the smallest.

All future scenarios reduced the absolute levels of pollution exposure in all deprivation quintiles across GB, except in those cases in which there is a large increase in biomass burning. Differences in exposure between the most and least deprived populations remain in all scenarios, most clearly for NO 2 , in which there is little difference between the baseline scenario and the NRPO scenario.

  • Limitations of the research

Although we have presented an advanced and detailed modelling study of the air pollution impact on health from climate policies, there are inevitable limitations to the work. We used the complex UKTM energy model as this represents a much more detailed method of generating energy scenarios than our original proposal. Because of this we were able to run only a limited number of scenarios. A wider range of pathways to the CCA would have potentially quantified a larger degree of health improvements in future years. The complexity of the UKTM model and the system we have built requires significant computer resources so that it is impracticable to undertake a range of sensitivity analyses around the economic parameters and energy and transport futures in the UKTM model.

Air quality modelling is always limited by several factors, the most important of which is the accuracy of the emissions inventory input. We improved the existing inventories using the most up-to-date information, but there are inevitably limitations to this knowledge. Equally, our understanding of the mechanisms of particle formation is developing continuously and, although we have used the best available chemical/physical mechanism of particle formation, there are still uncertainties involved here.

The health impact calculations are limited by the uncertainty in the numerical coefficients relating health outcomes to air pollutant concentrations, although to a degree we have allowed for this via the confidence intervals incorporated in the epidemiological studies. An important limitation is the extent to which the science supports an independent effect of NO 2 compared with PM 2.5 and the degree of overlap between the two pollutants in the association with adverse health outcomes. The review of the evidence by COMEAP, due to be published near the time of writing, had not appeared as this report was finalised.

Although improving the modelling scale down to 20 m in urban areas is an important advance in picking up exposure contrasts (particularly close to roads), the health impact methodology used is not, at this stage, able to take full advantage of this. In order to be able to use routinely available statistics on population and mortality by age group, concentrations were averaged up to ward level. Depending on how small-scale variations in population and mortality line up with variations in pollutant concentrations (particularly NO 2 ), results could differ if finer-scale inputs were used for population and mortality as well as concentration.

  • Uncertainties

Uncertainties in emissions and air quality modelling

The energy scenario modelling represents a series of hypothetical futures, and, if we were trying to predict actual future energy use in a forecasting sense, we would have needed to explore the uncertainties around the economic forecasts, for example. However, in the sense that we have used the projections – in a ‘what if?’ sense – then these uncertainties become less relevant.

The development of a new energy and air quality model has been a significant undertaking and represents an important step forward as a policy development tool. The inputs to the model system are numerous and the uncertainties are difficult to test in a comprehensive way, and, although we have started to look at methods to test the CMAQ model uncertainties for O 3 predictions, these methods have not been used in the present work.

In lieu of a detailed uncertainty analysis we have provided results of a model evaluation exercise across GB using 80 measurement sites. Using the criteria in a recent model evaluation exercise, we have confidence that the combination of the WRF meteorological model, emissions and CMAQ/ADMS air pollution models is able to reproduce 2011 and 2012 concentrations of NO X , NO 2 , O 3 , PM 10 and PM 2.5 at spatial scales, from 10 km across the UK, down to 20-m scale in urban areas. Furthermore, comparison with PM component measurements (nitrate, sulphate, OA, etc.) from the London 2012 ClearfLo campaign show good agreement, which is encouraging both from a model chemistry point of view, but also because it supports the introduction of new emissions to the model, such as domestic wood burning, cooking and diesel IVOCs. The UKTM model has also been evaluated against 2010 energy statistics and WRF assessed against 169 UK Met Office measurement sites.

There is uncertainty in future emissions predictions over whether we use energy-related activity data from the UKTM model or emissions factor assumptions, although for the latter we have used UK NAEI 2030 emission factors as far as possible.

Specific examples include uncertainties in our understanding of PM 10 non-exhaust emissions, which are assumed to increase pro rata with vehicle kilometres to 2050. This assumption may change as some private cars become lighter, are fitted with lower rolling resistant tyres and use regenerative braking, whereas delivery vehicles become heavier, and as all vehicles are subject to increased city congestion and there are ongoing changes to the materials used in brakes and tyre manufacture. Without regulation of these sources future predictions should be considered with caution.

Furthermore, the treatment of domestic wood burning emissions makes assumptions regarding the mix of wood burning appliances resulting in a 19% reduction in PM emissions per kilogram of wood burnt, as a result of the introduction of stoves complying with emission limits in the Ecodesign Directive (53% reduction in PM emissions compared with existing wood burners) and large pelletised domestic appliances (93% reduction in PM emissions compared with existing wood burners) in the UK appliance stock. Another important uncertainty is the location of CHP stations, which we have assumed is the same as existing UK locations for this source (i.e. in northern UK cities). Although this is not unreasonable, the introduction of CHP is already happening in other cities such as London and, although not likely to change the total emissions in our model, will possibly spread the impact away more widely than we have assumed.

Finally, although there will always be uncertainty in future predictions, the project aims were to provide alternative future scenarios, pointing out the potential for undesirable air pollution impacts within climate change policy and accepting that a large range of outcomes are possible.

Uncertainties in health and inequalities

Calculations were done using the confidence intervals (or plausibility intervals in the case of PM 2.5 ) to give one indication of a range of possible answers. For PM 2.5 this gave a range for the life-years lost or gained from one-sixth to twice the result for the central estimate. This was in line with the range for the originating CRF. The proportion relative to the central estimate varied very slightly – because of the non-linearities in the calculations. This range is not that for a 95% confidence interval. The original COMEAP recommendations included wider uncertainties than just those relating to statistical sampling. In addition, uncertainties in other inputs are not included. The range for the differences between scenarios was derived by subtracting the lower ends of the ranges for each scenario from each other – this probably overestimates the range. The impact of the spatial scale of the modelling was investigated, but not other issues so far. Some inputs are well established (e.g. population and deaths data), but, even in that case, assumptions are required, for example inferring distribution by age at small local areas from distributions at a wider geographical scale. The uncertainties in the modelling data have been discussed above but have not, so far, been propagated to the health impact calculations. In principle, this could be done, but would involve a much larger resource than was available in this project. There are a variety of versions of mortality rate improvement projections and birth projections – we have used only the central ones. Migration was not included and it is very unclear at present in which direction this will go.

Many of the same issues apply to the calculations for NO 2 (with and without a cut-off point). In terms of the 95% confidence interval of the CRFs, the results varied from 41%/42% of the central estimate to 1.6 times the central estimate. This only represents one aspect of the uncertainty. Results can be sensitive to the choice of cut-off point.

As described in Chapter 8 , we assumed that deprivation and ethnicity patterns at the small area level observed in 2011 are representative for the years 2035 and 2050. This assumption is based on studies which have shown that, in particular, deprivation patterns are fairly stable over time. We used this approach because no information on future deprivation or ethnicity patterns is available that far into the future. Uncertainties associated with such future sociodemographic prediction would be expected to not be dissimilar to those associated with our approach.

Inevitably, assumptions have to be made when projecting into the future. Inclusion of projected mortality improvements and birth projections improved this, compared with assuming baseline mortality rates and births remaining the same. However, these projections themselves are uncertain. In addition, we did not include projections of migration at this stage.

The project’s contribution to advances in knowledge

This project has, for the first time in the UK, delivered a sophisticated tool to enable the explicit calculation of public health impact arising from future energy strategies in GB using a state-of-the-art air quality model with an energy systems model used to inform government policy on greenhouse gas mitigation. This represents a major improvement over previous approaches to the impact of greenhouse gas emissions. Our work has established a method of calculating public health impact of air pollution resulting from climate policies through the full ‘impact pathway’ approach rather than the cruder, more approximate, ‘damage cost’ approach. The latter approach has been used to date by government in the UK to appraise climate policies; it relies on simply assigning a monetary value to a unit of air pollution emission. Consequently, there is no explicit calculation of pollution concentrations in the air, or of the impact on mortality and morbidity. Our system now allows that to be done in a linked system beginning with the economic model of the British energy system, through a sophisticated air quality model to a detailed life table model for calculating impact on health, on exposures in socioeconomic classes and for calculating economic impact. Moreover, the system we have developed allows this impact to be calculated at the finest spatial resolution yet achieved in GB, in which we model the rural areas at 10 km and major urban centres at 2 km or as fine as 20 m.

The science of air quality and of PM has continued to evolve during the life of the project. During the study it was necessary for us to incorporate emerging research on the sources of PM from cooking sources that were not previously included in emission inventories in GB. We have also built on King’s College London’s expertise in understanding the contribution of wood (biomass) burning to air quality to improve the inventory of emissions from this source. We were also able to enhance our model to treat the major British cities at a spatial resolution of 20 m, where previously we had been able to do this only for London. We have evaluated this improved air quality model and shown it to behave well against accepted criteria.

During the course of the project, we formed a collaboration with the Institute for Sustainable Resources at UCL to allow us to link the UKTM energy systems model with our air quality model and our health impact capability. This formed a major advance and the link now establishes a credible system to assess the impact of energy futures and climate policies in GB.

There are several important policy messages which arise from this project. The CCA target, in principle, offers a great opportunity to make very large reductions in air pollution emissions as the UK energy system is decarbonised. However, the PM 2.5 emissions from the large increases in residential and CHP biomass use and the increase in non-exhaust PM emissions from transport in the two CCA-compliant scenarios we have studie mean that PM 2.5 and PM 10 concentrations do not fall as much as they would otherwise have done without the biomass use. This increase in biomass use has resulted in the finding that the CCA-compliant scenarios result in more life-years lost than the baseline scenario which incorporates no further climate action beyond that already in place.

Solutions to improve air quality impact on health could include measures to discourage the use of biomass in small installations, or to increase the stringency of the emission limits in the Ecodesign Directive. The related study by Lott et al. , 33 using the damage cost approach, carried out a calculation including damage costs for biomass use to attempt to account for the public health impact. This succeeded in reducing the use of biomass in the hypothetical calculation. In reality, measures to discourage biomass use would probably be best delivered through revisions to the renewable heat incentive. In terms of improving air quality and minimising the impact on public health, wood burning, if it were to be used at all, would be best deployed in large, efficient power stations rather than small-scale domestic or CHP use. Fiscal measures in the renewable heat incentive to encourage this shift would have benefits to public health without necessarily compromising the achievement of the CCA target.

Non-exhaust emissions of PM 10 , and to a lesser extent PM 2.5 , are projected to increase significantly by 2050 as traffic activity increases. The precise agents in tyre and brake wear and resuspended dust responsible for the potential toxicity of these emissions are, as yet, unclear, so reformulation of these products would need to await more clarification from toxicological research. However, in the meantime, the obvious solution to ameliorate potential impact from all emissions from road transport here would be to discourage traffic use, particularly in urban centres.

On the positive side, electrification of the road transport fleet results in large reductions in the potential adverse impact on health from NO 2 and potential compliance with legal standards. This will also have benefits for PM concentrations and will, to a limited degree, offset the impact of any continued increase in biomass use.

The use of economic appraisal provides a mechanism for assessing the efficacy of measures for further action, permitting direct comparison of costs and benefits of measures, and enabling collation of a variety of different types of effect. As shown above, economic damage associated with air pollution in the UK is substantial and will remain so over the period covered by the scenarios considered here. It is noted that the UK approaches to valuation appear highly conservative compared with assumptions followed in the wider international literature.

Further research with the linked UKTM and our air quality model, CMAQ-Urban, could investigate other possible scenarios which achieve the CCA target and which could minimise the problem with residential and CHP biomass use and the impact of non-exhaust road transport emissions.

  • Recommendations for future research

The system we have developed links together a sophisticated energy system model – used by government in the UK – with a detailed chemical–transport model for air quality, health impact calculations and assessments of exposures and impacts in different socioeconomic classes. It also allows the monetary valuation of this impact on health. Because of the complexity of the system we have been able to run only a small number of scenarios and, although we have demonstrated some significant issues for future climate change mitigation measures, there is still scope to address optimal pathways for attaining the CCA target by minimising the impact on air quality and public health.

The work has shown that trends in different fractions of the atmospheric particle mix may be different in future. Primary particles (containing known carcinogens) may increase, whereas secondary particles may decrease. This highlights the importance of studies to elucidate the differential toxicity of different particle fractions.

The work has shown that, with increased penetration of ultra-low and zero-emissions road vehicles, concentrations of NO 2 will decrease by large amounts. The precise role of NO 2 , compared with that of PM 2.5 and other pollutants, in affecting human health is still uncertain. More clarity is needed here before any health benefits from reductions in NO 2 can be confidently quantified.

The effects of long-term exposure to air pollution on mortality generally dominate cost–benefit analysis, but a full investigation of the health impact would involve quantifying the potential effects on a wider range of health outcomes. In addition, further sensitivity analyses on the data inputs and assumptions regarding CRFs (e.g. effect modification) would be helpful. There is a need to explore how using population and mortality inputs at a finer geographical scale affects the result. More meta-analyses of epidemiological studies on PM 2.5 and NO 2 will also be useful.

  • Cite this Page Williams ML, Beevers S, Kitwiroon N, et al. Public health air pollution impacts of pathway options to meet the 2050 UK Climate Change Act target: a modelling study. Southampton (UK): NIHR Journals Library; 2018 Jun. (Public Health Research, No. 6.7.) Chapter 10, Discussion and conclusions.
  • PDF version of this title (33M)

In this Page

  • The project’s contribution to advances in knowledge

Other titles in this collection

  • Public Health Research

Recent Activity

  • Discussion and conclusions - Public health air pollution impacts of pathway opti... Discussion and conclusions - Public health air pollution impacts of pathway options to meet the 2050 UK Climate Change Act target: a modelling study

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

Connect with NLM

National Library of Medicine 8600 Rockville Pike Bethesda, MD 20894

Web Policies FOIA HHS Vulnerability Disclosure

Help Accessibility Careers

statistics

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • View all journals
  • My Account Login
  • Explore content
  • About the journal
  • Publish with us
  • Sign up for alerts
  • Open access
  • Published: 29 October 2020

Urban and air pollution: a multi-city study of long-term effects of urban landscape patterns on air quality trends

  • Lu Liang 1 &
  • Peng Gong 2 , 3 , 4  

Scientific Reports volume  10 , Article number:  18618 ( 2020 ) Cite this article

56k Accesses

92 Citations

319 Altmetric

Metrics details

  • Environmental impact
  • Environmental sciences

Most air pollution research has focused on assessing the urban landscape effects of pollutants in megacities, little is known about their associations in small- to mid-sized cities. Considering that the biggest urban growth is projected to occur in these smaller-scale cities, this empirical study identifies the key urban form determinants of decadal-long fine particulate matter (PM 2.5 ) trends in all 626 Chinese cities at the county level and above. As the first study of its kind, this study comprehensively examines the urban form effects on air quality in cities of different population sizes, at different development levels, and in different spatial-autocorrelation positions. Results demonstrate that the urban form evolution has long-term effects on PM 2.5 level, but the dominant factors shift over the urbanization stages: area metrics play a role in PM 2.5 trends of small-sized cities at the early urban development stage, whereas aggregation metrics determine such trends mostly in mid-sized cities. For large cities exhibiting a higher degree of urbanization, the spatial connectedness of urban patches is positively associated with long-term PM 2.5 level increases. We suggest that, depending on the city’s developmental stage, different aspects of the urban form should be emphasized to achieve long-term clean air goals.

Introduction

Air pollution represents a prominent threat to global society by causing cascading effects on individuals 1 , medical systems 2 , ecosystem health 3 , and economies 4 in both developing and developed countries 5 , 6 , 7 , 8 . About 90% of global citizens lived in areas that exceed the safe level in the World Health Organization (WHO) air quality guidelines 9 . Among all types of ecosystems, urban produce roughly 78% of carbon emissions and substantial airborne pollutants that adversely affect over 50% of the world’s population living in them 5 , 10 . While air pollution affects all regions, there exhibits substantial regional variation in air pollution levels 11 . For instance, the annual mean concentration of fine particulate matter with an aerodynamic diameter of less than 2.5  \(\upmu\mathrm{m}\) (PM 2.5 ) in the most polluted cities is nearly 20 times higher than the cleanest city according to a survey of 499 global cities 12 . Many factors can influence the regional air quality, including emissions, meteorology, and physicochemical transformations. Another non-negligible driver is urbanization—a process that alters the size, structure, and growth of cities in response to the population explosion and further leads to lasting air quality challenges 13 , 14 , 15 .

With the global trend of urbanization 16 , the spatial composition, configuration, and density of urban land uses (refer to as urban form) will continue to evolve 13 . The investigation of urban form impacts on air quality has been emerging in both empirical 17 and theoretical 18 research. While the area and density of artificial surface areas have well documented positive relationship with air pollution 19 , 20 , 21 , the effects of urban fragmentation on air quality have been controversial. In theory, compact cities promote high residential density with mixed land uses and thus reduce auto dependence and increase the usage of public transit and walking 21 , 22 . The compact urban development has been proved effective in mitigating air pollution in some cities 23 , 24 . A survey of 83 global urban areas also found that those with highly contiguous built-up areas emitted less NO 2 22 . In contrast, dispersed urban form can decentralize industrial polluters, improve fuel efficiency with less traffic congestion, and alleviate street canyon effects 25 , 26 , 27 , 28 . Polycentric and dispersed cities support the decentralization of jobs that lead to less pollution emission than compact and monocentric cities 29 . The more open spaces in a dispersed city support air dilution 30 . In contrast, compact cities are typically associated with stronger urban heat island effects 31 , which influence the availability and the advection of primary and secondary pollutants 32 .

The mixed evidence demonstrates the complex interplay between urban form and air pollution, which further implies that the inconsistent relationship may exist in cities at different urbanization levels and over different periods 33 . Few studies have attempted to investigate the urban form–air pollution relationship with cross-sectional and time series data 34 , 35 , 36 , 37 . Most studies were conducted in one city or metropolitan region 38 , 39 or even at the country level 40 . Furthermore, large cities or metropolitan areas draw the most attention in relevant studies 5 , 41 , 42 , and the small- and mid-sized cities, especially those in developing countries, are heavily underemphasized. However, virtually all world population growth 43 , 44 and most global economic growth 45 , 46 are expected to occur in those cities over the next several decades. Thus, an overlooked yet essential task is to account for various levels of cities, ranging from large metropolitan areas to less extensive urban area, in the analysis.

This study aims to improve the understanding of how the urban form evolution explains the decadal-long changes of the annual mean PM 2.5 concentrations in 626 cities at the county-level and above in China. China has undergone unprecedented urbanization over the past few decades and manifested a high degree of heterogeneity in urban development 47 . Thus, Chinese cities serve as a good model for addressing the following questions: (1) whether the changes in urban landscape patterns affect trends in PM 2.5 levels? And (2) if so, do the determinants vary by cities?

City boundaries

Our study period spans from the year 2000 to 2014 to keep the data completeness among all data sources. After excluding cities with invalid or missing PM 2.5 or sociodemographic value, a total of 626 cities, with 278 prefecture-level cities and 348 county-level cities, were selected. City boundaries are primarily based on the Global Rural–Urban Mapping Project (GRUMP) urban extent polygons that were defined by the extent of the nighttime lights 48 , 49 . Few adjustments were made. First, in the GRUMP dataset, large agglomerations that include several cities were often described in one big polygon. We manually split those polygons into individual cities based on the China Administrative Regions GIS Data at 1:1 million scales 50 . Second, since the 1978 economic reforms, China has significantly restructured its urban administrative/spatial system. Noticeable changes are the abolishment of several prefectures and the promotion of many former county-level cities to prefecture-level cities 51 . Thus, all city names were cross-checked between the year 2000 and 2014, and the mismatched records were replaced with the latest names.

PM 2.5 concentration data

The annual mean PM 2.5 surface concentration (micrograms per cubic meter) for each city over the study period was calculated from the Global Annual PM 2.5 Grids at 0.01° resolution 52 . This data set combines Aerosol Optical Depth retrievals from multiple satellite instruments including the NASA Moderate Resolution Imaging Spectroradiometer (MODIS), Multi-angle Imaging SpectroRadiometer (MISR), and the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS). The global 3-D chemical transport model GEOS-Chem is further applied to relate this total column measure of aerosol to near-surface PM 2.5 concentration, and geographically weighted regression is finally used with global ground-based measurements to predict and adjust for the residual PM 2.5 bias per grid cell in the initial satellite-derived values.

Human settlement layer

The urban forms were quantified with the 40-year (1978–2017) record of annual impervious surface maps for both rural and urban areas in China 47 , 53 . This state-of-art product provides substantial spatial–temporal details on China’s human settlement changes. The annual impervious surface maps covering our study period were generated from 30-m resolution Landsat images acquired onboard Landsat 5, 7, and 8 using an automatic “Exclusion/Inclusion” mapping framework 54 , 55 . The output used here was the binary impervious surface mask, with the value of one indicating the presence of human settlement and the value of zero identifying non-residential areas. The product assessment concluded good performance. The cross-comparison against 2356 city or town locations in GeoNames proved an overall high agreement (88%) and approximately 80% agreement was achieved when compared against visually interpreted 650 urban extent areas in the year 1990, 2000, and 2010.

Control variables

To provide a holistic assessment of the urban form effects, we included control variables that are regarded as important in influencing air quality to account for the confounding effects.

Four variables, separately population size, population density, and two economic measures, were acquired from the China City Statistical Yearbook 56 (National Bureau of Statistics 2000–2014). Population size is used to control for the absolute level of pollution emissions 41 . Larger populations are associated with increased vehicle usage and vehicle-kilometers travels, and consequently boost tailpipes emissions 5 . Population density is a useful reflector of transportation demand and the fraction of emissions inhaled by people 57 . We also included gross regional product (GRP) and the proportion of GRP generated from the secondary sector (GRP2). The impact of economic development on air quality is significant but in a dynamic way 58 . The rising per capita income due to the concentration of manufacturing industrial activities can deteriorate air quality and vice versa if the stronger economy is the outcome of the concentration of less polluting high-tech industries. Meteorological conditions also have short- and long-term effects on the occurrence, transport, and dispersion of air pollutants 59 , 60 , 61 . Temperature affects chemical reactions and atmospheric turbulence that determine the formation and diffusion of particles 62 . Low air humidity can lead to the accumulation of air pollutants due to it is conducive to the adhesion of atmospheric particulate matter on water vapor 63 . Whereas high humidity can lead to wet deposition processes that can remove air pollutants by rainfall. Wind speed is a crucial indicator of atmospheric activity by greatly affect air pollutant transport and dispersion. All meteorological variables were calculated based on China 1 km raster layers of monthly relative humidity, temperature, and wind speed that are interpolated from over 800 ground monitoring stations 64 . Based on the monthly layer, we calculated the annual mean of each variable for each year. Finally, all pixels falling inside of the city boundary were averaged to represent the overall meteorological condition of each city.

Considering the dynamic urban form-air pollution relationship evidenced from the literature review, our hypothesis is: the determinants of PM 2.5 level trends are not the same for cities undergoing different levels of development or in different geographic regions. To test this hypothesis, we first categorized city groups following (1) social-economic development level, (2) spatial autocorrelation relationship, and (3) population size. We then assessed the relationship between urban form and PM 2.5 level trends by city groups. Finally, we applied the panel data models to different city groups for hypothesis testing and key determinant identification (Fig.  1 ).

figure 1

Methodology workflow.

Calculation of urban form metrics

Based on the previous knowledge 65 , 66 , 67 , fifteen landscape metrics falling into three categories, separately area, shape, and aggregation, were selected. Those metrics quantify the compositional and configurational characteristics of the urban landscape, as represented by urban expansion, urban shape complexity, and compactness (Table 1 ).

Area metrics gives an overview of the urban extent and the size of urban patches that are correlated with PM 2.5 20 . As an indicator of the urbanization degree, total area (TA) typically increases constantly or remains stable, because the urbanization process is irreversible. Number of patches (NP) refers to the number of discrete parcels of urban settlement within a given urban extent and Mean Patch Size (AREA_MN) measures the average patch size. Patch density (PD) indicates the urbanization stages. It usually increases with urban diffusion until coalescence starts, after which decreases in number 66 . Largest Patch Index (LPI) measures the percentage of the landscape encompassed by the largest urban patch.

The shape complexity of urban patches was represented by Mean Patch Shape Index (SHAPE_MN), Mean Patch Fractal Dimension (FRAC_MN), and Mean Contiguity Index (CONTIG_MN). The greater irregularity the landscape shape, the larger the value of SHAPE_MN and FRAC_MN. CONTIG_MN is another method of assessing patch shape based on the spatial connectedness or contiguity of cells within a patch. Larger contiguous patches will result in larger CONTIG_MN.

Aggregation metrics measure the spatial compactness of urban land, which affects pollutant diffusion and dilution. Mean Euclidean nearest-neighbor distance (ENN_MN) quantifies the average distance between two patches within a landscape. It decreases as patches grow together and increases as the urban areas expand. Landscape Shape Index (LSI) indicates the divergence of the shape of a landscape patch that increases as the landscape becomes increasingly disaggregated 68 . Patch Cohesion Index (COHESION) is suggestive of the connectedness degree of patches 69 . Splitting Index (SPLIT) and Landscape Division Index (DIVISION) increase as the separation of urban patches rises, whereas, Mesh Size (MESH) decreases as the landscape becomes more fragmented. Aggregation Index (AI) measures the degree of aggregation or clumping of urban patches. Higher values of continuity indicate higher building densities, which may have a stronger effect on pollution diffusion.

The detailed descriptions of these indices are given by the FRAGSTATS user’s guide 70 . The calculation input is a layer of binary grids of urban/nonurban. The resulting output is a table containing one row for each city and multiple columns representing the individual metrics.

Division of cities

Division based on the socioeconomic development level.

The socioeconomic development level in China is uneven. The unequal development of the transportation system, descending in topography from the west to the east, combined with variations in the availability of natural and human resources and industrial infrastructure, has produced significantly wide gaps in the regional economies of China. By taking both the economic development level and natural geography into account, China can be loosely classified into Eastern, Central, and Western regions. Eastern China is generally wealthier than the interior, resulting from closeness to coastlines and the Open-Door Policy favoring coastal regions. Western China is historically behind in economic development because of its high elevation and rugged topography, which creates barriers in the transportation infrastructure construction and scarcity of arable lands. Central China, echoing its name, is in the process of economic development. This region neither benefited from geographic convenience to the coast nor benefited from any preferential policies, such as the Western Development Campaign.

Division based on spatial autocorrelation relationship

The second type of division follows the fact that adjacent cities are likely to form air pollution clusters due to the mixing and diluting nature of air pollutants 71 , i.e., cities share similar pollution levels as its neighbors. The underlying processes driving the formation of pollution hot spots and cold spots may differ. Thus, we further divided the city into groups based on the spatial clusters of PM 2.5 level changes.

Local indicators of spatial autocorrelation (LISA) was used to determine the local patterns of PM 2.5 distribution by clustering cities with a significant association. In the presence of global spatial autocorrelation, LISA indicates whether a variable exhibits significant spatial dependence and heterogeneity at a given scale 72 . Practically, LISA relates each observation to its neighbors and assigns a value of significance level and degree of spatial autocorrelation, which is calculated by the similarity in variable \(z\) between observation \(i\) and observation \(j\) in the neighborhood of \(i\) defined by a matrix of weights \({w}_{ij}\) 7 , 73 :

where \({I}_{i}\) is the Moran’s I value for location \(i\) ; \({\sigma }^{2}\) is the variance of variable \(z\) ; \(\bar{z}\) is the average value of \(z\) with the sample number of \(n\) . The weight matrix \({w}_{ij}\) is defined by the k-nearest neighbors distance measure, i.e., each object’s neighborhood consists of four closest cites.

The computation of Moran’s I enables the identification of hot spots and cold spots. The hot spots are high-high clusters where the increase in the PM 2.5 level is higher than the surrounding areas, whereas cold spots are low-low clusters with the presence of low values in a low-value neighborhood. A Moran scatterplot, with x-axis as the original variable and y-axis as the spatially lagged variable, reflects the spatial association pattern. The slope of the linear fit to the scatter plot is an estimation of the global Moran's I 72 (Fig.  2 ). The plot consists of four quadrants, each defining the relationship between an observation 74 . The upper right quadrant indicates hot spots and the lower left quadrant displays cold spots 75 .

figure 2

Moran’s I scatterplot. Figure was produced by R 3.4.3 76 .

Division based on population size

The last division was based on population size, which is a proven factor in changing per capita emissions in a wide selection of global cities, even outperformed land urbanization rate 77 , 78 , 79 . We used the 2014 urban population to classify the cities into four groups based on United Nations definitions 80 : (1) large agglomerations with a total population larger than 1 million; (2) mid-sized cities, 500,000–1 million; (3) small cities, 250,000–500,000, and (4) very small cities, 100,000–250,000.

Panel data analysis

The panel data analysis is an analytical method that deals with observations from multiple entities over multiple periods. Its capacity in analyzing the characteristics and changes from both the time-series and cross-section dimensions of data surpasses conventional models that purely focus on one dimension 81 , 82 . The estimation equation for the panel data model in this study is given as:

where the subscript \(i\) and \(t\) refer to city and year respectively. \(\upbeta _{{0}}\) is the intercept parameter and \(\upbeta _{{1}} - { }\upbeta _{{{18}}}\) are the estimates of slope coefficients. \(\varepsilon \) is the random error. All variables are transformed into natural logarithms.

Two methods can be used to obtain model estimates, separately fixed effects estimator and random effects estimator. The fixed effects estimator assumes that each subject has its specific characteristics due to inherent individual characteristic effects in the error term, thereby allowing differences to be intercepted between subjects. The random effects estimator assumes that the individual characteristic effect changes stochastically, and the differences in subjects are not fixed in time and are independent between subjects. To choose the right estimator, we run both models for each group of cities based on the Hausman specification test 83 . The null hypothesis is that random effects model yields consistent and efficient estimates 84 : \({H}_{0}{:}\,E\left({\varepsilon }_{i}|{X}_{it}\right)=0\) . If the null hypothesis is rejected, the fixed effects model will be selected for further inferences. Once the better estimator was determined for each model, one optimal panel data model was fit to each city group of one division type. In total, six, four, and eight runs were conducted for socioeconomic, spatial autocorrelation, and population division separately and three, two, and four panel data models were finally selected.

Spatial patterns of PM 2.5 level changes

During the period from 2000 to 2014, the annual mean PM 2.5 concentration of all cities increases from 27.78 to 42.34 µg/m 3 , both of which exceed the World Health Organization recommended annual mean standard (10 µg/m 3 ). It is worth noting that the PM 2.5 level in the year 2014 also exceeds China’s air quality Class 2 standard (35 µg/m 3 ) that applies to non-national park places, including urban and industrial areas. The standard deviation of annual mean PM 2.5 values for all cities increases from 12.34 to 16.71 µg/m 3 , which shows a higher variability of inter-urban PM 2.5 pollution after a decadal period. The least and most heavily polluted cities in China are Delingha, Qinghai (3.01 µg/m 3 ) and Jizhou, Hubei (64.15 µg/m 3 ) in 2000 and Hami, Xinjiang (6.86 µg/m 3 ) and Baoding, Hubei (86.72 µg/m 3 ) in 2014.

Spatially, the changes in PM 2.5 levels exhibit heterogeneous patterns across cities (Fig.  3 b). According to the socioeconomic level division (Fig.  3 a), the Eastern, Central, and Western region experienced a 38.6, 35.3, and 25.5 µg/m 3 increase in annual PM 2.5 mean , separately, and the difference among regions is significant according to the analysis of variance (ANOVA) results (Fig.  4 a). When stratified by spatial autocorrelation relationship (Fig.  3 c), the differences in PM 2.5 changes among the spatial clusters are even more dramatic. The average PM 2.5 increase in cities belonging to the high-high cluster is approximately 25 µg/m 3 , as compared to 5 µg/m 3 in the low-low clusters (Fig.  4 b). Finally, cities at four different population levels have significant differences in the changes of PM 2.5 concentration (Fig.  3 d), except for the mid-sized cities and large city agglomeration (Fig.  4 c).

figure 3

( a ) Division of cities in China by socioeconomic development level and the locations of provincial capitals; ( b ) Changes in annual mean PM 2.5 concentrations between the year 2000 and 2014; ( c ) LISA cluster maps for PM 2.5 changes at the city level; High-high indicates a statistically significant cluster of high PM 2.5 level changes over the study period. Low-low indicates a cluster of low PM 2.5 inter-annual variation; No high-low cluster is reported; Low–high represents cities with high PM 2.5 inter-annual variation surrounded by cities with low variation; ( d ) Population level by cities in the year 2014. Maps were produced by ArcGIS 10.7.1 85 .

figure 4

Boxplots of PM 2.5 concentration changes between 2000 and 2014 for city groups that are formed according to ( a ) socioeconomic development level division, ( b ) LISA clusters, and ( c ) population level. Asterisk marks represent the p value of ANOVA significant test between the corresponding pair of groups. Note ns not significant; * p value < 0.05; ** p value < 0.01; *** p value < 0.001; H–H high-high cluster, L–H low–high cluster, L–L denotes low–low cluster.

The effects of urban forms on PM 2.5 changes

The Hausman specification test for fixed versus random effects yields a p value less than 0.05, suggesting that the fixed effects model has better performance. We fit one panel data model to each city group and built nine models in total. All models are statistically significant at the p  < 0.05 level and have moderate to high predictive power with the R 2 values ranging from 0.63 to 0.95, which implies that 63–95% of the variation in the PM 2.5 concentration changes can be explained by the explanatory variables (Table 2 ).

The urban form—PM 2.5 relationships differ distinctly in Eastern, Central, and Western China. All models reach high R 2 values. Model for Eastern China (refer to hereafter as Eastern model) achieves the highest R 2 (0.90), and the model for the Western China (refer to hereafter as Western model) reaches the lowest R 2 (0.83). The shape metrics FRAC and CONTIG are correlated with PM 2.5 changes in the Eastern model, whereas the area metrics AREA demonstrates a positive effect in the Western model. In contrast to the significant associations between shape, area metrics and PM 2.5 level changes in both Eastern and Western models, no such association was detected in the Central model. Nonetheless, two aggregation metrics, LSI and AI, play positive roles in determining the PM 2.5 trends in the Central model.

For models built upon the LISA clusters, the H–H model (R 2  = 0.95) reaches a higher fitting degree than the L–L model (R 2  = 0.63). The estimated coefficients vary substantially. In the H–H model, the coefficient of CONTIG is positive, which indicates that an increase in CONTIG would increase PM 2.5 pollution. In contrast, no shape metrics but one area metrics AREA is significant in the L–L model.

The results of the regression models built for cities at different population levels exhibit a distinct pattern. No urban form metrics was identified to have a significant relationship with the PM 2.5 level changes in groups of very small and mid-sized cities. For small size cities, the aggregation metrics COHESION was positively associated whereas AI was negatively related. For mid-sized cities and large agglomerations, CONTIG is the only significant variable that is positively related to PM 2.5 level changes.

Urban form is an effective measure of long-term PM 2.5 trends

All panel data models are statistically significant regardless of the data group they are built on, suggesting that the associations between urban form and ambient PM 2.5 level changes are discernible at all city levels. Importantly, these relationships are found to hold when controlling for population size and gross domestic product, implying that the urban landscape patterns have effects on long-term PM 2.5 trends that are independent of regional economic performance. These findings echo with the local, regional, and global evidence of urban form effect on various air pollution types 5 , 14 , 21 , 22 , 24 , 39 , 78 .

Although all models demonstrate moderate to high predictive power, the way how different urban form metrics respond to the dependent variable varies. Of all the metrics tested, shape metrics, especially CONTIG has the strongest effect on PM 2.5 trends in cities belonging to the high-high cluster, Eastern, and large urban agglomerations. All those regions have a strong economy and higher population density 86 . In the group of cities that are moderately developed, such as the Central region, as well as small- and mid-sized cities, aggregation metrics play a dominant negative role in PM 2.5 level changes. In contrast, in the least developed cities belonging to the low-low cluster regions and Western China, the metrics describing size and number of urban patches are the strongest predictors. AREA and NP are positively related whereas TA is negatively associated.

The impacts of urban form metrics on air quality vary by urbanization degree

Based on the above observations, how urban form affects within-city PM 2.5 level changes may differ over the urbanization stages. We conceptually summarized the pattern in Fig.  5 : area metrics have the most substantial influence on air pollution changes at the early urban development stage, and aggregation metrics emerge at the transition stage, whereas shape metrics affect the air quality trends at the terminal stage. The relationship between urban form and air pollution has rarely been explored with such a wide range of city selections. Most prior studies were focused on large urban agglomeration areas, and thus their conclusions are not representative towards small cities at the early or transition stage of urbanization.

figure 5

The most influential metric of urban form in affecting PM 2.5 level changes at different urbanization stages.

Not surprisingly, the area metrics, which describe spatial grain of the landscape, exert a significant effect on PM 2.5 level changes in small-sized cities. This could be explained by the unusual urbanization speed of small-sized cities in the Chinese context. Their thriving mostly benefited from the urbanization policy in the 1980s, which emphasized industrialization of rural, small- and mid-sized cities 87 . With the large rural-to-urban migration and growing public interest in investing real estate market, a side effect is that the massive housing construction that sometimes exceeds market demand. Residential activities decline in newly built areas of smaller cities in China, leading to what are known as ghost cities 88 . Although ghost cities do not exist for all cities, high rate of unoccupied dwellings is commonly seen in cities under the prefectural level. This partly explained the negative impacts of TA on PM 2.5 level changes, as an expanded while unoccupied or non-industrialized urban zones may lower the average PM 2.5 concentration within the city boundary, but it doesn’t necessarily mean that the air quality got improved in the city cores.

Aggregation metrics at the landscape scale is often referred to as landscape texture that quantifies the tendency of patch types to be spatially aggregated; i.e., broadly speaking, aggregated or “contagious” distributions. This group of metrics is most effective in capturing the PM 2.5 trends in mid-sized cities (population range 25–50 k) and Central China, where the urbanization process is still undergoing. The three significant variables that reflect the spatial property of dispersion, separately landscape shape index, patch cohesion index, and aggregation index, consistently indicate that more aggregated landscape results in a higher degree of PM 2.5 level changes. Theoretically, the more compact urban form typically leads to less auto dependence and heavier reliance on the usage of public transit and walking, which contributes to air pollution mitigation 89 . This phenomenon has also been observed in China, as the vehicle-use intensity (kilometers traveled per vehicle per year, VKT) has been declining over recent years 90 . However, VKT only represents the travel intensity of one car and does not reflect the total distance traveled that cumulatively contribute to the local pollution. It should be noted that the private light-duty vehicle ownership in China has increased exponentially and is forecast to reach 23–42 million by 2050, with the share of new-growth purchases representing 16–28% 90 . In this case, considering the increased total distance traveled, the less dispersed urban form can exert negative effects on air quality by concentrating vehicle pollution emissions in a limited space.

Finally, urban contiguity, observed as the most effective shape metric in indicating PM 2.5 level changes, provides an assessment of spatial connectedness across all urban patches. Urban contiguity is found to have a positive effect on the long-term PM 2.5 pollution changes in large cities. Urban contiguity reflects to which degree the urban landscape is fragmented. Large contiguous patches result in large CONTIG_MN values. Among the 626 cities, only 11% of cities experience negative changes in urban contiguity. For example, Qingyang, Gansu is one of the cities-featuring leapfrogs and scattered development separated by vacant land that may later be filled in as the development continues (Fig.  6 ). Most Chinese cities experienced increased urban contiguity, with less fragmented and compacted landscape. A typical example is Shenzhou, Hebei, where CONTIG_MN rose from 0.27 to 0.45 within the 14 years. Although the 13 counties in Shenzhou are very far scattered from each other, each county is growing intensively internally rather than sprawling further outside. And its urban layout is thus more compact (Fig.  6 ). The positive association revealed in this study contradicts a global study indicating that cities with highly contiguous built-up areas have lower NO 2 pollution 22 . We noticed that the principal emission sources of NO 2 differ from that of PM 2.5. NO 2 is primarily emitted with the combustion of fossil fuels (e.g., industrial processes and power generation) 6 , whereas road traffic attributes more to PM 2.5 emissions. Highly connected urban form is likely to cause traffic congestion and trap pollution inside the street canyon, which accumulates higher PM 2.5 concentration. Computer simulation results also indicate that more compact cities improve urban air quality but are under the premise that mixed land use should be presented 18 . With more connected impervious surfaces, it is merely impossible to expect increasing urban green spaces. If compact urban development does not contribute to a rising proportion of green areas, then such a development does not help mitigating air pollution 41 .

figure 6

Six cities illustrating negative to positive changes in CONTIG_MN and AREA_MN. Pixels in black show the urban areas in the year 2000 and pixels in red are the expanded urban areas from the year 2000 to 2014. Figure was produced by ArcGIS 10.7.1 85 .

Conclusions

This study explores the regional land-use patterns and air quality in a country with an extraordinarily heterogeneous urbanization pattern. Our study is the first of its kind in investigating such a wide range selection of cities ranging from small-sized ones to large metropolitan areas spanning a long time frame, to gain a comprehensive insight into the varying effects of urban form on air quality trends. And the primary insight yielded from this study is the validation of the hypothesis that the determinants of PM 2.5 level trends are not the same for cities at various developmental levels or in different geographic regions. Certain measures of urban form are robust predictors of air quality trends for a certain group of cities. Therefore, any planning strategy aimed at reducing air pollution should consider its current development status and based upon which, design its future plan. To this end, it is also important to emphasize the main shortcoming of this analysis, which is generally centered around the selection of control variables. This is largely constrained by the available information from the City Statistical Yearbook. It will be beneficial to further polish this study by including other important controlling factors, such as vehicle possession.

Lim, C. C. et al. Association between long-term exposure to ambient air pollution and diabetes mortality in the US. Environ. Res. 165 , 330–336 (2018).

Article   CAS   PubMed   PubMed Central   Google Scholar  

Yang, J. & Zhang, B. Air pollution and healthcare expenditure: implication for the benefit of air pollution control in China. Environ. Int. 120 , 443–455 (2018).

Article   PubMed   Google Scholar  

Bell, J. N. B., Power, S. A., Jarraud, N., Agrawal, M. & Davies, C. The effects of air pollution on urban ecosystems and agriculture. Int. J. Sust. Dev. World 18 (3), 226–235 (2011).

Article   Google Scholar  

Matus, K. et al. Health damages from air pollution in China. Glob. Environ. Change 22 (1), 55–66 (2012).

Bereitschaft, B. & Debbage, K. Urban form, air pollution, and CO 2 emissions in large US metropolitan areas. Prof Geogr. 65 (4), 612–635 (2013).

Bozkurt, Z., Üzmez, Ö. Ö., Döğeroğlu, T., Artun, G. & Gaga, E. O. Atmospheric concentrations of SO2, NO2, ozone and VOCs in Düzce, Turkey using passive air samplers: sources, spatial and seasonal variations and health risk estimation. Atmos. Pollut. Res. 9 (6), 1146–1156 (2018).

Article   CAS   Google Scholar  

Fang, C., Liu, H., Li, G., Sun, D. & Miao, Z. Estimating the impact of urbanization on air quality in China using spatial regression models. Sustainability 7 (11), 15570–15592 (2015).

Khaniabadi, Y. O. et al. Mortality and morbidity due to ambient air pollution in Iran. Clin. Epidemiol. Glob. Health 7 (2), 222–227 (2019).

Health Effects Institute. State of Global Air 2019 . Special Report (Health Effects Institute, Boston, 2019). ISSN 2578-6873.

O’Meara, M. & Peterson, J. A. Reinventing Cities for People and the Planet (Worldwatch Institute, Washington, 1999).

Google Scholar  

World Health Organization. Ambient Air Pollution: A Global Assessment of Exposure and Burden of Disease . ISBN: 9789241511353 (2016).

Liu, C. et al. Ambient particulate air pollution and daily mortality in 652 cities. N. Engl. J. Med. 381 (8), 705–715 (2019).

Anderson, W. P., Kanaroglou, P. S. & Miller, E. J. Urban form, energy and the environment: a review of issues, evidence and policy. Urban Stud. 33 (1), 7–35 (1996).

Hart, R., Liang, L. & Dong, P. L. Monitoring, mapping, and modeling spatial–temporal patterns of PM2.5 for improved understanding of air pollution dynamics using portable sensing technologies. Int. J. Environ. Res. Public Health . 17 (14), 4914 (2020).

Article   PubMed Central   Google Scholar  

Environmental Protection Agency. Our Built and Natural Environments: A Technical Review of the Interactions Between Land Use, Transportation and Environmental Quality (2nd edn.). Report 231K13001 (Environmental Protection Agency, Washington, 2013).

Chen, M., Zhang, H., Liu, W. & Zhang, W. The global pattern of urbanization and economic growth: evidence from the last three decades. PLoS ONE 9 (8), e103799 (2014).

Article   ADS   PubMed   PubMed Central   CAS   Google Scholar  

Wang, S., Liu, X., Zhou, C., Hu, J. & Ou, J. Examining the impacts of socioeconomic factors, urban form, and transportation networks on CO 2 emissions in China’s megacities. Appl. Energy. 185 , 189–200 (2017).

Borrego, C. et al. How urban structure can affect city sustainability from an air quality perspective. Environ. Model. Softw. 21 (4), 461–467 (2006).

Bart, I. Urban sprawl and climate change: a statistical exploration of cause and effect, with policy options for the EU. Land Use Policy 27 (2), 283–292 (2010).

Feng, H., Zou, B. & Tang, Y. M. Scale- and region-dependence in landscape-PM 2.5 correlation: implications for urban planning. Remote Sens. 9 , 918. https://doi.org/10.3390/rs9090918 (2017).

Rodríguez, M. C., Dupont-Courtade, L. & Oueslati, W. Air pollution and urban structure linkages: evidence from European cities. Renew. Sustain. Energy Rev. 53 , 1–9 (2016).

Bechle, M. J., Millet, D. B. & Marshall, J. D. Effects of income and urban form on urban NO2: global evidence from satellites. Environ. Sci. Technol. 45 (11), 4914–4919 (2011).

Article   ADS   CAS   PubMed   Google Scholar  

Martins, H., Miranda, A. & Borrego, C. Urban structure and air quality. In Air Pollution-A Comprehensive Perspective (2012).

Stone, B. Jr. Urban sprawl and air quality in large US cities. J. Environ. Manag. 86 (4), 688–698 (2008).

Breheny, M. Densities and sustainable cities: the UK experience. In Cities for the new millennium , 39–51 (2001).

Glaeser, E. L. & Kahn, M. E. Sprawl and urban growth. In Handbook of regional and urban economics , vol. 4, 2481–2527 (Elsevier, Amsterdam, 2004).

Manins, P. C. et al. The impact of urban development on air quality and energy use. Clean Air 18 , 21 (1998).

Troy, P. N. Environmental stress and urban policy. The compact city: a sustainable urban form, 200–211 (1996).

Gaigné, C., Riou, S. & Thisse, J. F. Are compact cities environmentally friendly?. J. Urban Econ. 72 (2–3), 123–136 (2012).

Wood, C. Air pollution control by land use planning techniques: a British-American review. Int. J. Environ. Stud. 35 (4), 233–243 (1990).

Zhou, B., Rybski, D. & Kropp, J. P. The role of city size and urban form in the surface urban heat island. Sci. Rep. 7 (1), 4791 (2017).

Sarrat, C., Lemonsu, A., Masson, V. & Guedalia, D. Impact of urban heat island on regional atmospheric pollution. Atmos. Environ. 40 (10), 1743–1758 (2006).

Article   ADS   CAS   Google Scholar  

Liu, Y., Wu, J., Yu, D. & Ma, Q. The relationship between urban form and air pollution depends on seasonality and city size. Environ. Sci. Pollut. Res. 25 (16), 15554–15567 (2018).

Cavalcante, R. M. et al. Influence of urbanization on air quality based on the occurrence of particle-associated polycyclic aromatic hydrocarbons in a tropical semiarid area (Fortaleza-CE, Brazil). Air Qual. Atmos. Health. 10 (4), 437–445 (2017).

Han, L., Zhou, W. & Li, W. Fine particulate (PM 2.5 ) dynamics during rapid urbanization in Beijing, 1973–2013. Sci. Rep. 6 , 23604 (2016).

Article   ADS   CAS   PubMed   PubMed Central   Google Scholar  

Tuo, Y., Li, X. & Wang, J. Negative effects of Beijing’s air pollution caused by urbanization on residents’ health. In 2nd International Conference on Science and Social Research (ICSSR 2013) , 732–735 (Atlantis Press, 2013).

Zhou, C. S., Li, S. J. & Wang, S. J. Examining the impacts of urban form on air pollution in developing countries: a case study of China’s megacities. Int. J. Environ. Res. Public Health. 15 (8), 1565 (2018).

Article   PubMed Central   CAS   Google Scholar  

Cariolet, J. M., Colombert, M., Vuillet, M. & Diab, Y. Assessing the resilience of urban areas to traffic-related air pollution: application in Greater Paris. Sci. Total Environ. 615 , 588–596 (2018).

She, Q. et al. Air quality and its response to satellite-derived urban form in the Yangtze River Delta, China. Ecol. Indic. 75 , 297–306 (2017).

Yang, D. et al. Global distribution and evolvement of urbanization and PM 2.5 (1998–2015). Atmos. Environ. 182 , 171–178 (2018).

Cho, H. S. & Choi, M. Effects of compact urban development on air pollution: empirical evidence from Korea. Sustainability 6 (9), 5968–5982 (2014).

Li, C., Wang, Z., Li, B., Peng, Z. R. & Fu, Q. Investigating the relationship between air pollution variation and urban form. Build. Environ. 147 , 559–568 (2019).

Montgomery, M. R. The urban transformation of the developing world. Science 319 (5864), 761–764 (2008).

United Nations. World Urbanization Prospects: The 2009 Revision (United Nations Publication, New York, 2010).

Jiang, L. & O’Neill, B. C. Global urbanization projections for the shared socioeconomic pathways. Glob. Environ. Change 42 , 193–199 (2017).

Martine, G., McGranahan, G., Montgomery, M. & Fernandez-Castilla, R. The New Global Frontier: Urbanization, Poverty and Environment in the 21st Century (Earthscan, London, 2008).

Gong, P., Li, X. C. & Zhang, W. 40-Year (1978–2017) human settlement changes in China reflected by impervious surfaces from satellite remote sensing. Sci. Bull. 64 (11), 756–763 (2019).

Center for International Earth Science Information Network—CIESIN—Columbia University, C. I.-C.-I.. Global Rural–Urban Mapping Project, Version 1 (GRUMPv1): Urban Extent Polygons, Revision 01 . Palisades, NY: NASA Socioeconomic Data and Applications Center (SEDAC) (2017). https://doi.org/10.7927/H4Z31WKF . Accessed 10 April 2020.

Balk, D. L. et al. Determining global population distribution: methods, applications and data. Adv Parasit. 62 , 119–156. https://doi.org/10.1016/S0065-308X(05)62004-0 (2006).

Chinese Academy of Surveying and Mapping—CASM China in Time and Space—CITAS—University of Washington, a. C.-C. (1996). China Dimensions Data Collection: China Administrative Regions GIS Data: 1:1M, County Level, 1 July 1990 . Palisades, NY: NASA Socioeconomic Data and Applications Center (SEDAC). https://doi.org/10.7927/H4GT5K3V . Accessed 10 April 2020.

Ma, L. J. Urban administrative restructuring, changing scale relations and local economic development in China. Polit. Geogr. 24 (4), 477–497 (2005).

Article   MathSciNet   Google Scholar  

Van Donkelaar, A. et al. Global estimates of fine particulate matter using a combined geophysical-statistical method with information from satellites, models, and monitors. Environ. Sci. Technol. 50 (7), 3762–3772 (2016).

Article   ADS   PubMed   CAS   Google Scholar  

Gong, P. et al. Annual maps of global artificial impervious area (GAIA) between 1985 and 2018. Remote Sens. Environ 236 , 111510 (2020).

Article   ADS   Google Scholar  

Li, X. C., Gong, P. & Liang, L. A 30-year (1984–2013) record of annual urban dynamics of Beijing City derived from Landsat data. Remote Sens. Environ. 166 , 78–90 (2015).

Li, X. C. & Gong, P. An, “exclusion-inclusion” framework for extracting human settlements in rapidly developing regions of China from Landsat images. Remote Sens. Environ. 186 , 286–296 (2016).

National Bureau of Statistics 2000–2014. China City Statistical Yearbook (China Statistics Press). ISBN: 978-7-5037-6387-8

Lai, A. C., Thatcher, T. L. & Nazaroff, W. W. Inhalation transfer factors for air pollution health risk assessment. J. Air Waste Manag. Assoc. 50 (9), 1688–1699 (2000).

Article   CAS   PubMed   Google Scholar  

Luo, Y. et al. Relationship between air pollutants and economic development of the provincial capital cities in China during the past decade. PLoS ONE 9 (8), e104013 (2014).

Hart, R., Liang, L. & Dong, P. Monitoring, mapping, and modeling spatial–temporal patterns of PM2.5 for improved understanding of air pollution dynamics using portable sensing technologies. Int. J. Environ. Res. Public Health 17 (14), 4914 (2020).

Wang, X. & Zhang, R. Effects of atmospheric circulations on the interannual variation in PM2.5 concentrations over the Beijing–Tianjin–Hebei region in 2013–2018. Atmos. Chem. Phys. 20 (13), 7667–7682 (2020).

Xu, Y. et al. Impact of meteorological conditions on PM 2.5 pollution in China during winter. Atmosphere 9 (11), 429 (2018).

Hernandez, G., Berry, T.A., Wallis, S. & Poyner, D. Temperature and humidity effects on particulate matter concentrations in a sub-tropical climate during winter. In Proceedings of the International Conference of the Environment, Chemistry and Biology (ICECB 2017), Queensland, Australia, 20–22 November 2017; Juan, L., Ed.; IRCSIT Press: Singapore, 2017.

Zhang, Y. Dynamic effect analysis of meteorological conditions on air pollution: a case study from Beijing. Sci. Total. Environ. 684 , 178–185 (2019).

National Earth System Science Data Center. National Science & Technology Infrastructure of China . https://www.geodata.cn . Accessed 6 Oct 2020.

Bhatta, B., Saraswati, S. & Bandyopadhyay, D. Urban sprawl measurement from remote sensing data. Appl. Geogr. 30 (4), 731–740 (2010).

Dietzel, C., Oguz, H., Hemphill, J. J., Clarke, K. C. & Gazulis, N. Diffusion and coalescence of the Houston Metropolitan Area: evidence supporting a new urban theory. Environ. Plan. B Plan. Des. 32 (2), 231–246 (2005).

Li, S., Zhou, C., Wang, S. & Hu, J. Dose urban landscape pattern affect CO2 emission efficiency? Empirical evidence from megacities in China. J. Clean. Prod. 203 , 164–178 (2018).

Gyenizse, P., Bognár, Z., Czigány, S. & Elekes, T. Landscape shape index, as a potencial indicator of urban development in Hungary. Acta Geogr. Debrecina Landsc. Environ. 8 (2), 78–88 (2014).

Rutledge, D. T. Landscape indices as measures of the effects of fragmentation: can pattern reflect process? DOC Science Internal Series . ISBN 0-478-22380-3 (2003).

Mcgarigal, K. & Marks, B. J. Spatial pattern analysis program for quantifying landscape structure. Gen. Tech. Rep. PNW-GTR-351. US Department of Agriculture, Forest Service, Pacific Northwest Research Station, 1–122 (1995).

Chan, C. K. & Yao, X. Air pollution in mega cities in China. Atmos. Environ. 42 (1), 1–42 (2008).

Anselin, L. The Moran Scatterplot as an ESDA Tool to Assess Local Instability in Spatial Association. In Spatial Analytical Perspectives on Gis in Environmental and Socio-Economic Sciences (eds Fischer, M. et al. ) 111–125 (Taylor; Francis, London, 1996).

Zou, B., Peng, F., Wan, N., Mamady, K. & Wilson, G. J. Spatial cluster detection of air pollution exposure inequities across the United States. PLoS ONE 9 (3), e91917 (2014).

Bone, C., Wulder, M. A., White, J. C., Robertson, C. & Nelson, T. A. A GIS-based risk rating of forest insect outbreaks using aerial overview surveys and the local Moran’s I statistic. Appl. Geogr. 40 , 161–170 (2013).

Anselin, L., Syabri, I. & Kho, Y. GeoDa: an introduction to spatial data analysis. Geogr. Anal. 38 , 5–22 (2006).

R Core Team. R A Language and Environment for Statistical Computing (R Foundation for Statistical Computing, Vienna, 2013).

Cole, M. A. & Neumayer, E. Examining the impact of demographic factors on air pollution. Popul. Environ. 26 (1), 5–21 (2004).

Liu, Y., Arp, H. P. H., Song, X. & Song, Y. Research on the relationship between urban form and urban smog in China. Environ. Plan. B Urban Anal. City Sci. 44 (2), 328–342 (2017).

York, R., Rosa, E. A. & Dietz, T. STIRPAT, IPAT and ImPACT: analytic tools for unpacking the driving forces of environmental impacts. Ecol. Econ. 46 (3), 351–365 (2003).

United Nations, Department of Economic and Social Affairs Population Division 2011: the 2010 Revision (United Nations Publications, New York, 2011)

Ahn, S. C. & Schmidt, P. Efficient estimation of models for dynamic panel data. J. Econ. 68 (1), 5–27 (1995).

Article   MathSciNet   MATH   Google Scholar  

Du, L., Wei, C. & Cai, S. Economic development and carbon dioxide emissions in China: provincial panel data analysis. China Econ. Rev. 23 (2), 371–384 (2012).

Hausman, J. A. Specification tests in econometrics. Econ. J. Econ. Soc. 46 (6), 1251–1271 (1978).

Greene, W. H. Econometric Analysis (Pearson Education India, New Delhi, 2003).

ArcGIS GIS 10.7.1. (Environmental Systems Research Institute, Inc., Redlands, 2010).

Lao, X., Shen, T. & Gu, H. Prospect on China’s urban system by 2020: evidence from the prediction based on internal migration network. Sustainability 10 (3), 654 (2018).

Henderson, J.V., Logan, J.R. & Choi, S. Growth of China's medium-size cities . Brookings-Wharton Papers on Urban Affairs, 263–303 (2005).

Lu, H., Zhang, C., Liu, G., Ye, X. & Miao, C. Mapping China’s ghost cities through the combination of nighttime satellite data and daytime satellite data. Remote Sens. 10 (7), 1037 (2018).

Frank, L. D. et al. Many pathways from land use to health: associations between neighborhood walkability and active transportation, body mass index, and air quality. JAPA. 72 (1), 75–87 (2006).

Huo, H. & Wang, M. Modeling future vehicle sales and stock in China. Energy Policy 43 , 17–29 (2012).

Download references

Acknowledgements

Lu Liang received intramural research funding support from the UNT Office of Research and Innovation. Peng Gong is partially supported by the National Research Program of the Ministry of Science and Technology of the People’s Republic of China (2016YFA0600104), and donations from Delos Living LLC and the Cyrus Tang Foundation to Tsinghua University.

Author information

Authors and affiliations.

Department of Geography and the Environment, University of North Texas, 1155 Union Circle, Denton, TX, 76203, USA

Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing, China

Tsinghua Urban Institute, Tsinghua University, Beijing, 100084, China

Center for Healthy Cities, Institute for China Sustainable Urbanization, Tsinghua University, Beijing, 100084, China

You can also search for this author in PubMed   Google Scholar

Contributions

L.L. and P.G. wrote the main manuscript text. All authors reviewed the manuscript.

Corresponding author

Correspondence to Lu Liang .

Ethics declarations

Competing interests.

The authors declare no competing interests.

Additional information

Publisher's note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ .

Reprints and permissions

About this article

Cite this article.

Liang, L., Gong, P. Urban and air pollution: a multi-city study of long-term effects of urban landscape patterns on air quality trends. Sci Rep 10 , 18618 (2020). https://doi.org/10.1038/s41598-020-74524-9

Download citation

Received : 11 June 2020

Accepted : 24 August 2020

Published : 29 October 2020

DOI : https://doi.org/10.1038/s41598-020-74524-9

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

This article is cited by

The association between ambient air pollution exposure and connective tissue sarcoma risk: a nested case–control study using a nationwide population-based database.

  • Wei-Yi Huang
  • Yu-Fen Chen
  • Kuo-Yuan Huang

Environmental Science and Pollution Research (2024)

The evolution of atmospheric particulate matter in an urban landscape since the Industrial Revolution

  • Ann L. Power
  • Richard K. Tennant

Scientific Reports (2023)

Simulation of particle resuspension by wind in an urban system

  • Amir Banari
  • Daniel Hertel
  • Gregory Lecrivain

Environmental Fluid Mechanics (2023)

Simulating the effect of urban sprawl on air quality and outdoor human thermal comfort in a cold city, Erzurum, Turkey

  • Merve Yavaş
  • Doğan Dursun
  • Süleyman Toy

Environmental Monitoring and Assessment (2023)

Observing the compact trend of urban expansion patterns in global 33 megacities during 2000–2020

  • Wenhui Kuang

Journal of Geographical Sciences (2023)

By submitting a comment you agree to abide by our Terms and Community Guidelines . If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Quick links

  • Explore articles by subject
  • Guide to authors
  • Editorial policies

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

air pollution project conclusion

  • Skip to main content
  • Skip to secondary menu
  • Skip to primary sidebar
  • Skip to footer

ImportantIndia.com

Indian History, Festivals, Essays, Paragraphs, Speeches.

Essay on Air Pollution – Causes, Effects, Solutions, Conclusion

Category: Essays and Paragraphs On November 20, 2018 By Aparna

Air Pollution

The whole world has been suffering from lots of problems since its existence, and the problems are getting bigger and bigger day by days.

One of the biggest problems that the entire planet faces is the amount of pollution on the planet. Pollution is of several kinds, but the pollution that affects the most to our nature and environment is Air pollution .

Air pollution is the pollution in which the pollutants get released in the air, and those pollutants then pollute the air which affects the health of a human being.

Air pollution is the pollution when the dirt, dirt particles and other kinds of pollutants get mixed to air and make the air polluted.

Today, every city in the world is suffering from air pollution , and that is why a lot of people and organizations in the world are trying their best to save the world from air pollution.

Air Pollution in India

Indian cities are much polluted and that can get seen from various visuals. Land and air pollution are connected directly as if the land is dirty, after a few days, that dirty land will lead to air pollution. In India, there are only a few surfaces where the pollution level is less. For example, the pollution level in Chandigarh city is lesser than a lot of cities in India. However, the pollution level in various cities of NCR, UP and Bihar is way higher than a lot of cities in India. The air pollution in India is getting increased day by day. But, the good news is that the people who had no interest in cleaning their country before, are now getting involved in schemes like Swachh Bharat Abhiyan, etc.

There are lots of causes of air pollution in the world and here are a few of those causes:

  • The burning of fossil fuels is the biggest cause of air pollution, and that is why it has been prohibited at a lot of places in the world.
  • Cars, buses, motorbikes are another big cause of air pollution because they emit a lot of pollution also.
  • Volcano eruptions are another big cause of air pollution.
  • When we cook at home, sometimes we need wood and charcoal for it, and these materials cause a huge amount of air pollution.
  • People smoking cigarettes is another big cause of air pollution.
  • If due to some reason a forest catches fire , then it becomes one of the biggest reasons for air pollution.

These are a few effects on human beings, plants, and animals due to air pollution:

  • The rainwater flows through the surface and ends in the river, and when the surface gets polluted, all the rainwater will take the polluted surface particles with itself which will not only pollute the river, but it will also pollute the land through which the water flows .
  • A lot of people suffer from allergies which are a side effect of living in an air-polluted
  • Air pollution can also lead to severe diseases like cancer, heart diseases, and other respiratory problems, etc.
  • One should restrict the use of charcoal , wood, thus the pollution caused by these resources would not be there in the world.
  • A restriction should be there on industries to use the kind of materials which causes zero to no air pollution at all.
  • The cities which have the maximum air pollution should get asked as to how they will reduce the air pollution and what are their plans for it.

Air pollution is a huge problem not only in India but the whole world, various organizations do their bit to make sure that plans are made to restrict air pollution , but unfortunately those plans never get executed rightly. That is why even after knowing that the air is getting polluted every day, the organizations around the world are unable to provide a good solution to it. As a human being, we must contribute, that is why, we need to gather and make sure that all the places, suffering from air pollution, should get organized in a manner so that air pollution should not exist. Everyone should participate in schemes like Swachh Bharat Abhiyan which will not only reduce the air pollution in the country but will also reduce various other kinds of pollution.

  • History of Mughal Empire
  • Modern History of India
  • Important India
  • Indian Geography
  • Report an Article
  • Terms of Use, Privacy Policy, Cookie Policy, and Copyrights.

National Academies Press: OpenBook

Building a Foundation for Sound Environmental Decisions (1997)

Chapter: 5 summary, conclusions, and recommendations, 5 summary, conclusions, and recommendations.

Pressures on the environment will continue to increase. Global population increase, rising incomes, and agricultural and industrial expansion will inevitably produce unanticipated and potentially deleterious ecological, economic, and human health consequences. Environmental research has proven its value in helping to respond to and prevent many environmental problems, and it continues to be a wise and necessary investment.

The charge to this committee was to provide an overview of significant emerging environmental issues; identify and prioritize research themes and projects that are most relevant to understanding and resolving these issues; and consider the role of EPA's research program in addressing these issues, in the context of research being conducted or sponsored by other organizations. After careful deliberation, the committee decided not to simply present a limited list of "emerging" issues with specific research projects to address them. Such an exercise would provide a mere snapshot in time, based on the insights of one particular collection of individuals. Instead—and hopefully more valuably—this report provides an overview of important environmental issues and presents a framework for organizing environmental research. The report also describes major research themes and programs of relevance to EPA; suggests criteria that can be used to identify and prioritize among important research areas; recommends actions EPA should take to build its scientific capacity; and provides illustrations of the kinds of research projects that EPA should consider.

CONCLUSIONS

As a key environmental agency, EPA needs to support and maintain a strong research program. An evolving understanding of the complexity, magnitude,

and inter-relatedness of environmental problems leads us to conclude that a new balance of research programs may be helpful. This report describes a framework for conducting research in a way that will help alleviate the problems of the moment while providing a basis for solving tomorrow's problems.

In the past, pressing environmental issues have been addressed primarily through focused research efforts directed toward solving particular problems. Although this approach to environmental research can be effective, has often been necessary, and will surely continue, it also has limitations. In order to address the abundance of established, emerging, and as-yet-unknown environmental issues, an expanded understanding of the scientific principles underlying environmental systems is needed. Achieving this understanding will require innovative, interdisciplinary approaches.

To develop the knowledge needed to address current and emerging environmental issues, EPA should undertake both problem-driven research and core research . Problem-driven research is targeted at understanding and solving identified environmental problems, while core research aims to provide broader, more generic information that will help improve understanding of many problems now and in the future. Core research includes three components: (1) understanding the processes that drive and connect environmental systems; (2) development of innovative tools and methods for understanding and managing environmental problems; and (3) long-term collection and dissemination of accurate environmental data.

Research activities within problem-driven and core research programs may often overlap. Fundamental discoveries can be made during the search for a solution to a narrowly defined problem; likewise, as illustrated earlier in this report, breakthroughs in problem-solving often occur as a result of core research efforts. Both kinds of investigations are needed, and feedback between them will greatly enhance the overall environmental research endeavor (see Figure 5-1 ).

Because EPA's task of protecting the environment and human health is so vast and difficult, and because resources to undertake the necessary research are very limited, choices will have to be made among many worthwhile projects. The approaches for making these choices will be different in the core and problem-driven portions of the research program. The former should seek better understanding of fundamental phenomena and generate broadly relevant research tools and information. The latter will be more responsive to regulatory activities and other immediate needs and should be guided by the paradigm of risk reduction. Because there are so many specific issues of importance to the public, the Congress, and EPA's own program and regional offices, there is a temptation to include many problems for attention. It is important to resist this trend: it will inevitably lead either to the dilution of efforts to solve the most pressing problems or to the reduction of funding available for critical core research needs.

air pollution project conclusion

FIGURE 5-1 A framework for environmental research at EPA.

Interactions among the natural environment, plants, animals, and the evergrowing human population are highly complex and inherently unpredictable. Although this report provides a broad overview of current and emerging environmental issues, it is important to note that this is merely a snapshot in time. Identification of issues requiring attention is a dynamic, continuous process.

With its limited budget, staff, and mandate, it is not possible or reasonable for EPA to act alone in understanding and addressing all environmental problems. Many other federal agencies, state agencies, other organizations (including utilities), universities, and private companies have played and will continue to play important roles in environmental research. Cooperation with others will be particularly needed in the area of environmental monitoring, a complex and costly undertaking, and in the investigation of global-scale issues.

Another factor to consider in determining EPA's research role on a particular environmental issue is whether the private sector has any incentive to study or develop better solutions, or whether the primary research must originate from the public sector to serve the public good. Examples of areas of "public good" that might deserve EPA attention include municipal wastewater and drinking water treatment, nonpoint-source pollution control, restoration of degraded ecosystems, and large-scale regional and global air pollution problems.

RECOMMENDATIONS

To enhance the productivity and effectiveness of EPA's research efforts, the committee makes recommendations in three areas: a general approach to research, core research themes, and problem-driven research themes.

Approach to Research

EPA should establish a balance between problem-driven and core research. Although there is currently an emphasis on problem-driven research projects in EPA, the core component of EPA's research program should be developed to be approximately equal in magnitude.

EPA should develop an internal mechanism for continually identifying emerging issues and then applying a risk assessment evaluation to these issues to determine the highest priorities and areas of greatest uncertainty. One important method for identifying emerging issues is to review and synthesize new findings from the core research program. EPA research personnel should be fully engaged in the issue identification and research planning process.

EPA should cooperate closely with agencies, organizations, municipalities, universities, and industries involved in environmental research. In addition to providing research support, mechanisms for cooperation might include participation of EPA management in interagency coordination efforts, participation of staff in scientific meetings and conferences, and incentives and rewards for individuals who seek out and work with their counterparts in other organizations. Collaboration should be maintained in research endeavors, environmental monitoring, data archiving, and environmental policy formulation and evaluation. EPA should continue to act as a coordinator in bringing various environmental researchers together to exchange information and ideas, possibly in the form of interdisciplinary workshops on particular environmental topics. This would also help in ''scanning the horizon" to identify new environmental trends and emerging problems. Through these meetings, EPA can discuss the relative risks as well as solutions and policies and can determine which areas require more research.

EPA should compile, publish, and disseminate an annual summary of all research being conducted or funded by the agency in order to facilitate both better cooperation with others and better internal planning. The report should be organized into broad strategic categories, with sub-categories describing program areas. Publications and other output should be listed and made available upon request.

Core Research Themes

The core component of EPA's research program should include three basic objectives:

Acquisition of systematic understanding about underlying environmental processes (such as those displayed in Table 2.2 );

Development of broadly applicable research tools, including better techniques for measuring physical, chemical, biological, social, and economic variables of interest; more accurate models of complex systems and their interactions; and new methods for analyzing, displaying, and using environmental information for science-based decision making;

Design, implementation, and maintenance of appropriate environmental monitoring programs, with evaluation, analysis, synthesis and dissemination of the data and results to improve understanding of the status of and changes in environmental resources over time and to confirm that environmental policies are having the desired effect.

Core research projects should be selected based on their relevance to EPA's mission, whether such research is already being sponsored by other agencies, and the quality of the work proposed, as determined by a peer-review process. Cross-cutting, interdisciplinary studies that take advantage of advances in many different fields will be particularly valuable.

As part of its core research efforts, EPA should conduct retrospective evaluations of the effectiveness of environmental policies and decisions. Retrospective evaluations are critical to ensuring that environmental policies are achieving their intended goals without creating unpredicted, undesirable side-effects.

EPA should make a long-term financial and intellectual commitment to core research projects. Progress in core research generally does not come quickly; therefore it is important that the agency provide adequate long-term support to this kind of knowledge development, allowing it to follow its often unpredictable course. Tool development and data collection must be ongoing endeavors in order to be fully effective.

Problem-Driven Research Themes

EPA should maintain a focused, problem-driven research program. The problem-driven and core research areas will be complementary and result in the interaction of ideas and results.

Evaluation of problem-driven research areas should focus on reducing the risks and uncertainties associated with each problem. EPA should retain its emphasis on risk assessment to prioritize among problem-driven research areas. Using criteria such as timing, novelty, scope, severity, and probability satisfies this requirement, as does the more detailed risk assessment framework described in the EPA strategic plan for ORD. Although risk assessment and

TABLE 5-1 Recommended Actions for EPA

management provide a good framework for choosing among issues, the methodology must be refined to achieve more accurate assessments.

EPA should concentrate efforts in areas where the private sector has little incentive to conduct research or develop better solutions to environmental problems.

Problem-driven research should be re-evaluated and re-focused on a regular basis to ensure that the most important problems are being addressed. Unlike core research priorities, which may not change much over time, in the problem-driven area EPA must develop adaptive feedback capabilities to allow it to change directions when new issues arise and old issues are "solved" or judged to pose less risk than expected.

This committee was not asked to, and did not, address issues concerning EPA's research infrastructure, the appropriate balance between internal and external research, mechanisms for peer review, and other research management issues. Recommendations in these areas will be made by the Committee on Research and Peer Review at EPA (see Chapter 1 ). Table 5-1 summarizes recommended

actions that are intended to provide EPA with the knowledge needed to address current and emerging environmental issues.

Good science is essential for sound environmental decision-making. By implementing the recommendations contained in this report, EPA can increase the effectiveness of its research program and thus continue to play an important role in efforts to protect the environment and human health into the next century.

Over the past decades, environmental problems have attracted enormous attention and public concern. Many actions have been taken by the U.S. Environmental Protection Agency and others to protect human health and ecosystems from particular threats. Despite some successes, many problems remain unsolved and new ones are emerging. Increasing population and related pressures, combined with a realization of the interconnectedness and complexity of environmental systems, present new challenges to policymakers and regulators.

Scientific research has played, and will continue to play, an essential part in solving environmental problems. Decisions based on incorrect or incomplete understanding of environmental systems will not achieve the greatest reduction of risk at the lowest cost.

This volume describes a framework for acquiring the knowledge needed both to solve current recognized problems and to be prepared for the kinds of problems likely to emerge in the future. Many case examples are included to illustrate why some environmental control strategies have succeeded where others have fallen short and how we can do better in the future.

Welcome to OpenBook!

You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

Do you want to take a quick tour of the OpenBook's features?

Show this book's table of contents , where you can jump to any chapter by name.

...or use these buttons to go back to the previous chapter or skip to the next one.

Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

Switch between the Original Pages , where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

To search the entire text of this book, type in your search term here and press Enter .

Share a link to this book page on your preferred social network or via email.

View our suggested citation for this chapter.

Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

Get Email Updates

Do you enjoy reading reports from the Academies online for free ? Sign up for email notifications and we'll let you know about new publications in your areas of interest when they're released.

Book cover

Marine Organisms: A Solution to Environmental Pollution? pp 267–269 Cite as

Conclusion: Environmental Protection—Our Common Responsibility

  • Alberto A. C. C. Pais 4 &
  • Telma Encarnação 4 , 5 , 6  
  • First Online: 06 January 2023

257 Accesses

Part of the Environmental Challenges and Solutions book series (ECAS)

Environmental pollution is increasing globally and, together with climate change, is a priority on the environmental, political, business, and scientific agendas. Air, land, and water pollution have an impact on all ecosystems and our lives and can jeopardize our future and future generations.

The importance of policies on public awareness and perception is recognized and can have an effective role in the protection of the environment. Policymakers, companies and industries, civil society, scientists, all sectors of society should be involved for the same purpose; coordinated efforts at an international level are needed to tackle all the challenges planet Earth face.

Therefore, it is crucial to stimulate the discourse, narrative, and debate about environmental pollution and degradation and mitigation strategies.

  • Environment
  • Marine pollution
  • Civil society
  • Public awareness
  • Climate challenge

This is a preview of subscription content, log in via an institution .

Buying options

  • Available as PDF
  • Read on any device
  • Instant download
  • Own it forever
  • Available as EPUB and PDF
  • Compact, lightweight edition
  • Dispatched in 3 to 5 business days
  • Free shipping worldwide - see info
  • Durable hardcover edition

Tax calculation will be finalised at checkout

Purchases are for personal use only

Brouwer R, Hadzhiyska D, Ioakeimidis C, Ouderdorp H (2017) The social costs of marine litter along European coasts. Ocean Coastal Manag 138:38–49

Article   Google Scholar  

Gelcich S, Buckley P, Pinnegar JK, Chilvers J, Lorenzoni I, Terry G, Guerrero M, Castilla JC, Valdebenito A, Duarte CM (2014) Public awareness, concerns, and priorities about anthropogenic impacts on marine environments. PNAS 111:15042–15047

Article   CAS   Google Scholar  

Latinopoulos D, Mentis C, Bithas K (2018) The impact of a public information campaign on preferences for marine environmental protection. The case of plastic waste. Mar Pollut Bull 131:151–162

Roberts KE, Valkan RS, Cook CN (2018) Measuring progress in marine protection: a new set of metrics to evaluate the strength of marine protected area networks. Biol Conserv 219:20–27

Xu G, Shi Y, Sun X, Shen W (2019) Internet of Things in marine environment monitoring: a review. Sensors 19:1711–1731

Download references

Author information

Authors and affiliations.

CQC-IMS, Department of Chemistry, University of Coimbra, Coimbra, Portugal

Alberto A. C. C. Pais & Telma Encarnação

Centre for Rapid and Sustainable Product Development, Polytechnic Institute of Leiria, Marinha Grande, Portugal

Telma Encarnação

PTScience Avenida do Atlântico, Lisbon, Portugal

You can also search for this author in PubMed   Google Scholar

Corresponding author

Correspondence to Telma Encarnação .

Editor information

Editors and affiliations.

Coimbra Chemistry Centre (CQC-IMS), Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal

Alberto Canelas Pais

Rights and permissions

Reprints and permissions

Copyright information

© 2023 The Author(s), under exclusive license to Springer Nature Switzerland AG

About this chapter

Cite this chapter.

Pais, A.A.C.C., Encarnação, T. (2023). Conclusion: Environmental Protection—Our Common Responsibility. In: Encarnação, T., Canelas Pais, A. (eds) Marine Organisms: A Solution to Environmental Pollution?. Environmental Challenges and Solutions. Springer, Cham. https://doi.org/10.1007/978-3-031-17226-7_13

Download citation

DOI : https://doi.org/10.1007/978-3-031-17226-7_13

Published : 06 January 2023

Publisher Name : Springer, Cham

Print ISBN : 978-3-031-17225-0

Online ISBN : 978-3-031-17226-7

eBook Packages : Biomedical and Life Sciences Biomedical and Life Sciences (R0)

What is air pollution?

Air pollution is a gas (or a liquid or solid dispersed through ordinary air) released in a big enough quantity to harm the health of people or other animals, kill plants or stop them growing properly, damage or disrupt some other aspect of the environment (such as making buildings crumble), or cause some other kind of nuisance (reduced visibility, perhaps, or an unpleasant odor).

Natural air pollution

Photo: Forest fires are a completely natural cause of air pollution. We'll never be able to prevent them breaking out or stop the pollution they cause; our best hope is to manage forests, where we can, so fires don't spread. Ironically, that can mean deliberately burning areas of forest, as shown here, to create firebreaks. Forests are also deliberately burned to regenerate ecosystems. Photo by courtesy of US Fish and Wildlife Service .

Top-ten kinds of air pollution Photo: Flying molecules—if you could see air pollution close up, this is what it would look like. Image courtesy of US Department of Energy. Any gas could qualify as pollution if it reached a high enough concentration to do harm. Theoretically, that means there are dozens of different pollution gases. It's important to note that not all the things we think of as pollution are gases: some are aerosols (liquids or solids dispersed through gases). In practice, about ten different substances cause most concern: Sulfur dioxide : Coal, petroleum, and other fuels are often impure and contain sulfur as well as organic (carbon-based) compounds. When sulfur (spelled "sulphur" in some countries) burns with oxygen from the air, sulfur dioxide (SO 2 ) is produced. Coal-fired power plants are the world's biggest source of sulfur-dioxide air pollution, which contributes to smog, acid rain, and health problems that include lung disease. [5] Large amounts of sulfur dioxide are also produced by ships, which use dirtier diesel fuel than cars and trucks. [6] Carbon monoxide : This highly dangerous gas forms when fuels have too little oxygen to burn completely. It spews out in car exhausts and it can also build up to dangerous levels inside your home if you have a poorly maintained gas boiler , stove, or fuel-burning appliance. (Always fit a carbon monoxide detector if you burn fuels indoors.) [7] Carbon dioxide : This gas is central to everyday life and isn't normally considered a pollutant: we all produce it when we breathe out and plants such as crops and trees need to "breathe" it in to grow. However, carbon dioxide is also a greenhouse gas released by engines and power plants. Since the beginning of the Industrial Revolution, it's been building up in Earth's atmosphere and contributing to the problem of global warming and climate change . [8] Nitrogen oxides : Nitrogen dioxide (NO 2 ) and nitrogen oxide (NO) are pollutants produced as an indirect result of combustion, when nitrogen and oxygen from the air react together. Nitrogen oxide pollution comes from vehicle engines and power plants, and plays an important role in the formation of acid rain, ozone and smog. Nitrogen oxides are also "indirect greenhouse gases" (they contribute to global warming by producing ozone, which is a greenhouse gas). [9] Volatile organic compounds (VOCs) : These carbon-based (organic) chemicals evaporate easily at ordinary temperatures and pressures, so they readily become gases. That's precisely why they're used as solvents in many different household chemicals such as paints , waxes, and varnishes. Unfortunately, they're also a form of air pollution: they're believed to have long-term (chronic) effects on people's health and they play a role in the formation of ozone and smog. VOCs are also released by tobacco smoke and wildfires. [10] Particulates : There are many different kinds of particulates, from black soot in diesel exhaust to dust and organic matter from the desert. Airborne liquid droplets from farm pollution also count as particulates. Particulates of different sizes are often referred to by the letters PM followed by a number, so PM 10 means soot particles of less than 10 microns (10 millionths of a meter or 10µm in diameter, roughly 10 times thinner than a thick human hair). The smaller ("finer") the particulates, the deeper they travel into our lungs and the more dangerous they are. PM 2.5 particulates are much more dangerous (they're less than 2.5 millionths of a meter or about 40 times thinner than a typical hair). In cities, most particulates come from traffic fumes. [11] Ozone : Also called trioxygen, this is a type of oxygen gas whose molecules are made from three oxygen atoms joined together (so it has the chemical formula O 3 ), instead of just the two atoms in conventional oxygen (O 2 ). In the stratosphere (upper atmosphere), a band of ozone ("the ozone layer") protects us by screening out harmful ultraviolet radiation (high-energy blue light) beaming down from the Sun. At ground level, it's a toxic pollutant that can damage health. It forms when sunlight strikes a cocktail of other pollution and is a key ingredient of smog (see box below). [12] Chlorofluorocarbons (CFCs) : Once thought to be harmless, these gases were widely used in refrigerators and aerosol cans until it was discovered that they damaged Earth's ozone layer. We discuss this in more detail down below. [13] Unburned hydrocarbons : Petroleum and other fuels are made of organic compounds based on chains of carbon and hydrogen atoms. When they burn properly, they're completely converted into harmless carbon dioxide and water ; when they burn incompletely, they can release carbon monoxide or float into the air in their unburned form, contributing to smog. Lead and heavy metals : Lead and other toxic "heavy metals" can be spread into the air either as toxic compounds or as aerosols (when solids or liquids are dispersed through gases and carried through the air by them) in such things as exhaust fumes and the fly ash (contaminated waste dust) from incinerator smokestacks. [14] What are the causes of air pollution?

Photo: Even in the age of electric cars, traffic remains a major cause of air pollution. Photo by Warren Gretz courtesy of US DOE National Renewable Energy Laboratory (NREL) (NREL photo id#46361).

Photo: Brown smog lingers over Denver, Colorado. Photo by Warren Gretz courtesy of US DOE National Renewable Energy Laboratory (NREL) (NREL photo id#56919).

Chart: Most of the world's major cities routinely exceed World Health Organization (WHO) air pollution guidelines, though progress is being made: you can see that the 2022 figures (green) show a marked improvement on the 2016 ones (orange) in almost every case. This chart compares annual mean PM 2.5 levels in 12 representative cities around the world with the recently revised (2021) WHO guideline value of 5μg per cubic meter (dotted line). PM 2.5 particulates are those smaller than 2.5 microns and believed to be most closely linked with adverse health effects. For more about this chart and the data sources used, see note [22] .

Photo: Smokestacks billowing pollution over Moscow, Russia in 1994. Factory pollution is much less of a problem than it used to be in the world's "richer" countries—partly because a lot of their industry has been exported to nations such as China, India, and Mexico. Photo by Roger Taylor courtesy of US DOE National Renewable Energy Laboratory (NREL) .

What effects does air pollution have?

Photo: Air pollution can cause a variety of lung diseases and other respiratory problems. This chest X ray shows a lung disease called emphysema in the patient's left lung. A variety of things can cause it, including smoking and exposure to air pollution. Photo courtesy of National Heart, Lung and Blood Institute (NHLBI) and National Institutes of Health.

" In 2016, 91% of the world population was living in places where the WHO air quality guidelines levels were not met." World Health Organization , 2018

Photo: For many years, the stonework on the Parthenon in Athens, Greece has been blackened by particulates from traffic pollution, but other sources of pollution, such as wood-burning stoves, are increasingly significant. Photo by Michael M. Reddy courtesy of U.S. Geological Survey .

How air pollution works on different scales

Indoor air pollution.

Photo: Air freshener—or air polluter?

Further reading

Acid rain—a closer look.

Photo: Acid rain can turn lakes so acidic that fish no longer survive. Picture courtesy of U.S. Fish and Wildlife Service Division of Public Affairs. Why does that matter? Pure water is neither acidic nor alkaline but completely neutral (we say it has an acidity level or pH of 7.0). Ordinary rainwater is a little bit more acidic than this with about the same acidity as bananas (roughly pH 5.5), but if rain falls through sulfur dioxide pollution it can turn much more acidic (with a pH of 4.5 or lower, which is the same acidity as orange or lemon juice). When acid rain accumulates in lakes or rivers, it gradually turns the entire water more acidic. That's a real problem because fish thrive only in water that is neutral or slightly acidic (typically with a pH of 6.5–7.0). Once the acidity drops below about pH 6.0, fish soon start to die—and if the pH drops to about 4.0 or less, all the fish will be killed. Acid rain has caused major problems in lakes throughout North America and Europe. It also causes the death of forests, reduces the fertility of soil, and damages buildings by eating away stonework (the marble on the US Capitol in Washington, DC has been eroded by acid-rain, for example). One of the biggest difficulties in tackling acid rain is that it can happen over very long distances. In one notable case, sulfur dioxide air pollution produced by power plants in the UK was blamed for causing acid rain that fell on Scandinavian countries such as Norway, producing widespread damage to forests and the deaths of thousands of fish in acidified lakes. The British government refused to acknowledge the problem and that was partly why the UK became known as the "dirty man of Europe" in the 1980s and 1990s. [18] Acid rain was a particular problem in the last 30–40 years of the 20th century. Thanks to the decline in coal-fired power plants, and the sulfur dioxide they spewed out, it's less of a problem for western countries today. But it's still a big issue in places like India, where coal remains a major source of energy. Global air pollution It's hard to imagine doing anything so dramatic and serious that it would damage our entire, enormous planet—but, remarkable though it may seem, we all do things like this everyday, contributing to problems such as global warming and the damage to the ozone layer (two separate issues that are often confused). Global warming Every time you ride in a car, turn on the lights, switch on your TV , take a shower, microwave a meal, or use energy that's come from burning a fossil fuel such as oil, coal, or natural gas, you're almost certainly adding to the problem of global warming and climate change: unless it's been produced in some environmentally friendly way, the energy you're using has most likely released carbon dioxide gas into the air. While it's not an obvious pollutant, carbon dioxide has gradually built up in the atmosphere, along with other chemicals known as greenhouse gases . Together, these gases act a bit like a blanket surrounding our planet that is slowly making the mean global temperature rise, causing the climate (the long-term pattern of our weather) to change, and producing a variety of different effects on the natural world, including rising sea levels. Read more in our main article about global warming and climate change . Ozone holes

How can we solve the problem of air pollution?

Photo: Pollution solution: an electrostatic smoke precipitator helps to prevent air pollution from this smokestack at the McNeil biomass power plant in Burlington, VT. Photo by Warren Gretz courtesy of US DOE National Renewable Energy Laboratory (NREL).

What can you do to help reduce air pollution?

Photo: Buying organic food reduces the use of sprayed pesticides and other chemicals, so it helps to reduce air (as well as water) pollution.

If you liked this article...

Find out more, on this site.

  • Climate change and global warming
  • Environmentalism (introduction)
  • Land pollution
  • Organic food and farming
  • Renewable energy
  • Water pollution

Breathless by Chris Woodford paperback book cover rendered as dummy book.

  • Breathless: Why Air Pollution Matters—and How it Affects You by Chris Woodford. Icon, 2021. My new book explores the problem in much more depth than I've been able to go into here. You can also read a bonus chapter called Angels with dirty faces: How air pollution blackens our buildings and monuments .
  • The Invisible Killer: The Rising Global Threat of Air Pollution and How We Can Fight Back by Gary Fuller. Melville House, 2018.
  • Reducing Pollution and Waste by Jen Green. Raintree/Capstone, 2011. A 48-page introduction for ages 9–12. The emphasis here is on getting children to think about pollution: where it comes from, who makes it, and who should solve the problem.
  • Pollution Crisis by Russ Parker. Rosen, 2009. A 32-page guide for ages 8–10. It starts with a global survey of the problem; looks at air, water, and land pollution; then considers how we all need to be part of the solution.
  • Earth Matters by Lynn Dicks et al. Dorling Kindersley, 2008. This isn't specifically about pollution. Instead, it explores how a range of different environmental problems are testing life to the limit in the planet's major biomes (oceans, forests, and so on). I wrote the section of this book that covers the polar regions.
  • State of Global Air : One of the best sources of global air pollution data.
  • American Lung Association: State of the Air Report : A good source of data about the United States.
  • European Environment Agency: Air quality in Europe : A definitive overview of the situation in the European countries.
  • World Health Organization (WHO) Ambient (outdoor) air pollution in cities database : A spreadsheet of pollution data for most major cities in the world (a little out of date, but a new version is expected soon).
  • Our World in Data : Accessible guides to global data from Oxford University.
  • The New York Times Topics: Air Pollution
  • The Guardian: Pollution
  • Wired: Pollution
  • 'Invisible killer': fossil fuels caused 8.7m deaths globally in 2018, research finds by Oliver Milman. The Guardian, February 9, 2021. Pollution of various kinds causes something like one in five of all deaths.
  • Millions of masks distributed to students in 'gas chamber' Delhi : BBC News, 1 November 2019.
  • 90% of world's children are breathing toxic air, WHO study finds by Matthew Taylor. The Guardian, October 29, 2018. The air pollution affecting billions of children could continue to harm their health throughout their lives.
  • Pollution May Dim Thinking Skills, Study in China Suggests by Mike Ives. The New York Times, August 29, 2018. Long-term exposure to air pollution seems to cause a decline in cognitive skills.
  • Global pollution kills 9m a year and threatens 'survival of human societies' by Damian Carrington. The Guardian, October 19, 2017. Air, water, and land pollution kill millions, cost trillions, and threaten the very survival of humankind, a new study reveals.
  • India's Air Pollution Rivals China's as World's Deadliest by Geeta Anand. The New York Times, February 14, 2017. High levels of pollution could be killing 1.1 million Indians each year.
  • More Than 9 in 10 People Breathe Bad Air, WHO Study Says by Mike Ives. The New York Times, September 27, 2016. New WHO figures suggest the vast majority of us are compromising our health by breathing bad air.
  • Study Links 6.5 Million Deaths Each Year to Air Pollution by Stanley Reed. The New York Times, June 26, 2016. Air pollution deaths are far greater than previously supposed according to a new study by the International Energy Agency.
  • UK air pollution 'linked to 40,000 early deaths a year' by Michelle Roberts, BBC News, February 23, 2016. Diesel engines, cigarette smoke, and even air fresheners are among the causes of premature death from air pollution.
  • This Wearable Detects Pollution to Build Air Quality Maps in Real Time by Davey Alba. Wired, November 19, 2014. A wearable pollution gadget lets people track their exposure to air pollution through a smartphone app.
  • Air pollution and public health: emerging hazards and improved understanding of risk by Frank J. Kelly and Julia C. Fussell, Environmental Geochemistry and Health, 2015
  • Health effects of fine particulate air pollution: lines that connect by C.A. Pope and D.W. Dockery. Journal of the Air and Waste Management Association, 2006
  • Ambient and household air pollution: complex triggers of disease by Stephen A. Farmer et al, Am J Physiol Heart Circ Physiol, 2014

Text copyright © Chris Woodford 2010, 2022. All rights reserved. Full copyright notice and terms of use .

Rate this page

Tell your friends, cite this page, more to explore on our website....

  • Get the book
  • Send feedback

Air Pollution Solutions

While air pollution is a serious problem, it is a problem that we can solve! In the United States and around the world, people are taking action to reduce emissions and improve air quality.

The Clean Air Act: How Laws Can Help Clean Up the Air

Creating policies and passing laws to restrict air pollution has been an important step toward improving air quality. In 1970, fueled by persistent visible smog in many U.S. cities and industrial areas and an increase in health problems caused by air pollution, the Clean Air Act paved the way for numerous efforts to improve air quality in the United States. The Clean Air Act requires the Environmental Protection Agency (EPA) to set air quality standards for several hazardous air pollutants reported in the Air Quality Index (AQI) , requires states to have a plan to address air pollution and emissions reduction, and also addresses problems such as acid rain, ozone holes, and greenhouse gas pollution which is causing the climate to warm.

Since the Clean Air Act was passed:

  • The amounts of the six common pollutants in the atmosphere measured by the EPA (particulates, ozone, lead, carbon monoxide, nitrogen dioxide, and sulfur dioxide) are declining.
  • The risks of premature death, low birth weight, and other health problems due to air pollution have decreased.
  • Vehicle emissions have decreased, despite increases in the number of miles driven each year, due to stricter emissions standards and increased efficiency in vehicle engines.
  • Emissions and toxic pollutants (such as mercury and benzenes) from factories and power plants have decreased, due to new technologies.
  • There is less acid rain, due to decreased power plant emissions.
  • The ozone hole continues to shrink as a result of banning the use of CFCs.
  • Pollution-caused haze in cities and wilderness areas has decreased.

Source: EPA

Most industrialized countries have laws and regulations about air quality. The United Kingdom first passed its Clean Air Act in 1956 following a deadly smog event that killed many London residents. In China, where rapid industrial and urban growth in recent decades resulted in a sharp decrease in air quality, numerous laws about air pollution have been passed, including a frequently updated five-year national plan to meet target reductions in air pollution.

It is important to note that while laws and regulations are helping, the effects of air pollution are still apparent. The decline of toxic air pollutants and health improvements are welcome changes, yet the growing threat of climate change due to fossil fuel emissions remains a problem that still needs to be solved.

There Are Many Solutions to Air Pollution

In order to improve air quality and slow climate warming, change needs to happen on a national and global scale. However, actions at the individual and community level are also important.

  • Burn less coal. Pollution from burning all fossil fuels is harmful to the atmosphere, but burning coal has a larger impact on air pollution than burning oil or gas because it releases more carbon dioxide, sulfur dioxide, and heavy metal pollutants per unit of energy. Also, over one-third of the electricity produced in the world comes from burning coal. As of 2014, the global demand for coal is beginning to decline. In North America, coal plants are being replaced by natural gas. Some countries, such as Japan and South Korea, rely more on nuclear energy, and there is a global increase in electricity supplied by clean, renewable sources like wind, solar, and water.

This is an illustration showing ways that you can help reduce air pollution: wind turbines are a source of renewable energy; drive low pollution vehicles; choose alternative transportation modes, such as walking, riding the bus, or riding a bicycle; refueling in the evening; and around the house choose low VOC products, use less energy, forgo the fire, and mow the grass in the evening.

  • Conserve energy — at home, work, and everywhere! The demand for electricity, which is most often produced by burning fossil fuels, has grown exponentially over the past decades. Conserve energy by turning off lights, buy appliances rated for energy efficiency, and keep the thermostat set higher in the summer and lower in the winter. Whenever possible, invest in renewable energy sources to power your home. Several countries are using renewables, nuclear power, or lower-emission sources like natural gas to meet their increasing power demand. And many countries plan to significantly increase their use of renewable energy sources in the future.
  • Monitor air quality warnings and take action on poor air quality days. On days when pollution levels are high, taking action can help reduce the risk of harm to those who are most vulnerable. Reducing overall car usage and avoiding idling your car can help on days with high levels of ozone pollution. Save refueling and use of gas-powered yard equipment for the evening when it is cooler and ozone levels are lower. On days when particle pollutants are high, avoid burning yard waste and wood. Choosing to carpool or using a clean transportation method is always helpful, especially on days with high levels of air pollution. Check on the air quality in your area at the AirNow website .
  • Take action within your community to find solutions to air pollution. Around the world, many of the current solutions are the result of communities coming together to demand change. Citizens in Shenzhen, China, inspired a switch to electric buses in their city. In Brussels, Belgium, a movement started by parents concerned about poor air quality in schools led to a plan to invest in public transportation and bicycling, along with a ban on fueled cars by 2030. And in many countries, governments are closing coal plants and exploring new sources of energy because of citizens who are concerned about climate warming.

Check out the EPA's website to learn more about actions you can take to reduce air pollution.

  • Air Quality Activities
  • Air Quality Gallery
  • Solving Climate Change

Logo

  • Free Resources
  • Project Search
  • Featured Projects
  • Member Benefits

1059 Main Avenue, Clifton, NJ 07011

The most valuable resources for teachers and students

logo

(973) 777 - 3113

[email protected]

1059 Main Avenue

Clifton, NJ 07011

07:30 - 19:00

Monday to Friday

123 456 789

[email protected]

Goldsmith Hall

New York, NY 90210

Logo

  • Why We’re Unique

Air Pollution

Introduction: (initial observation).

Air pollution is the contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health. In addition to many economical and agricultural losses, air pollution is the main cause of many diseases and deaths every year. Excessive growth rate of air pollution is a major concern for many countries and scientists from all over the world are studying on causes, prevention methods and cleanup of the air pollution.

air pollution project conclusion

This project is an opportunity to follow the foot steps of other scientists and learn about the air pollution causes and cleanups.

This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “ Ask Question ” button on the top of this page to send me a message.

If you are new in doing science project, click on “ How to Start ” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.  

Project advisor

Information Gathering:

Find out about air pollution. Read books, magazines or ask professionals who might know in order to learn about the causes of air pollution and methods of prevention and cleanup. Keep track of where you got your information from.

For basic general information,  encyclopedia  is a good start.

Air Pollution Control

To show how air pollution is controlled.

Grade level

6th, 7th & 8th grades

Essential Elements

(Science) 1 (A) Properly demonstrate the use of laboratory equipment; 2 (A) Observe physical and chemical properties of matter; 5 (A) Measure physical and chemical properties of matter.

At the end of the lesson the student will be able to distinguish between an electrostatic precipitator and a wet scrubber and the principles behind the operation of these control techniques.

When any product is made by industry, waste may be produced that can pollute the air. Wet scrubbers and electrostatic precipitators are two devices used to clean up the air waste stream before it enters the atmosphere.

Air contaminants are emitted into the atmosphere as particulates, aerosols, vapors, or gases. The most common methods of eliminating or reducing pollutants to an acceptable level are destroying the pollutant by thermal or catalytic combustion, changing the pollutant to a less toxic form, or collecting the pollution by use of equipment to prevent its escape into the atmosphere. Pollutant recovery may be accomplished by the use of one or more of the following:

Baghouses  – Dry particulates are trapped on filters made of cloth, paper or similar materials. Particles are shaken or blown from the filters down into a collection hopper. Baghouses are used to control air pollutants from steel mills, foundries, and other industrial furnaces and can collect more than 98 percent of the particulates. Cyclones  – Dust-laden gas is whirled very rapidly inside a collector shaped like a cylinder. The swirling motion creates centrifugal forces causing the particles to be thrown against the walls of the cylinder and to drop into a hopper. Cyclones are used for controlling pollutants from cotton gins, rock crushers, and many other industrial processes and can remove up to 95 percent of solid pollutants. Electrostatic precipitators  – By use of static electricity, they attract particles in much the same way that static electricity in clothing picks up small bits of dust and lint. Electrostatic precipitators, 98 to 99 percent effective, are used instead of baghouses when the particles are suspended in very hot gases, such as in emissions from power plants, steel and paper mills, smelters, and cement plants. Wet scrubbers  – Particulates, vapors, and gases are controlled by passing the gas stream through a liquid solution. Scrubbers are used on coal burning power plants, asphalt/concrete plants, and a variety of other facilities that emit sulfur dioxides, hydrogen sulfides, and other gases with a high water solubility. Wet scrubbers are often used for corrosive, acidic, or basic gas streams. ( Note that recovery control devices include adsorption and condenser techniques as well.)
  • Which type of air cleaner would be the best for removing particles?
  • Which type of air cleaner would be the best for removing waste gases?
  • Does a wet scrubber clean up all of the pollutants?
  • What problems are produced by having too many pollutants in the air we breathe?
  • If industry is just part of the problem, what can we do to control the amount of air pollution that we cause?

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

The purpose of this project is to demonstrate at least one of the air filtration methods. Construct a filter and show that it actually does collect or filter some pollutants.

Possible questions are:

Which filtration method is best for particle pollution? Which area has the highest amount of invisible pollutants? What are the causes of air pollution and how can it be prevented? (After identifying the cause of pollution, we can simply stop it by switching to other methods that do not cause pollution. For example if we identify fossil fuels such as coal and oil as a source of pollution, we can try using solar energy, hydroelectric energy or wind energy.) How effective is any system of air filtration?

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other. For question 1, variables are:

The independent variable (also known as manipulated variable) is the filtration method.

The dependent variable (also known as responding variable) is the amount of pollutants they filter.

Constants are the type of pollutants and filtration time.

For question 2, variables are:

The independent variable (also known as manipulated variable) is the location.

The dependent variable (also known as responding variable) is the pollution rank.

Constants are the experiment method, time and supplies.

Hypothesis:

Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.

Sample Hypothesis:

My hypothesis is that by passing polluted air through water we can filter pollutants and produce clean air. This hypothesis is based on my observation of air freshness after a heavy rain.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

Experiment 1:

(Visible and Invisible pollutants)

Which area has the highest amount of invisible pollutants?

The atmosphere is almost completely made up of invisible gaseous substances. Most major air pollutants are also invisible, although large amounts of them concentrated in areas such as cities can be see as smog. One often visible air pollutant is particulate matter, especially when the surfaces of buildings and other structures have been exposed to it for long periods of time or when it is present in large amounts. Particulate matter is made up of tiny particles of solid matter and/or droplets of liquid. Natural sources include volcanic ash, pollen, and dust blown by the wind. Coal and oil burned by power plants and industries and diesel fuel burned by many vehicles are the chief sources of man-made particulate pollutants, but not all important sources are large scale. The use of wood in fireplaces and wood-burning stoves also produces significant amounts of particulate matter in localized areas, although the total amounts are much smaller than those from vehicles, power plants, and industries.

In this experiment we will test for visible and invisible pollutants in the air and try to tell the difference between visible and invisible air pollution.

chart paper measuring cups small glass jars large glass jars petroleum jelly 3 bean plants approximately the same size tap water vinegar vinegar-water mixture in 1 to 3 ratio pH paper or indicator

Visible Pollutants test

Smear petroleum jelly on each small jar. Carefully place each small jar inside a large jar. Decide on several places around the school or home where you think visible pollutants will occur. Make predictions about which area will have more visible pollutants and why. Record predictions in journal. Place jars in test areas for several days. Check the jars daily. Record observations in journal. Collect jars for comparison. Observe and rank the jars from the one with the most visible pollutants to the one with the least. Assign each jar a number. Discuss why certain areas have more visible pollutants than others. Mark a map showing the ranking of areas from the lowest dust to the highest dust.

Invisible Pollutants test

Sets up a bean plant garden with three containers, each container having one bean plant. Determine and compare the pH of the three solutions and predict how the plants will be affected by each solution. Record pH and predictions in journal. Plants will be watered every day with 1/8 to 1/4 cup of a solution: one plant with tap water, one plant with straight vinegar, and one plant with the vinegar-water mixture. Procedure is recorded in journal. Observe plants daily. Record in journal what happens to each plant. Sketches may be part of the observations. Compare plants and discuss observations at the end of a day, week, two weeks, or until plants die. Using the observations, write a conclusion for this experiment. Record in journal. Invisible pollutants are like acid rain. Use the result of your experiment to conclude how does acid rain affect the plants.

Research the history of acid rain. Include information on the causes of acid rain, when we first became aware of the problem, what problems have been caused by acid rain, what measures have been taken to

combat acid rain. Has the situation improved? Post a chart for the causes of visible pollutants and what can be done to prevent them.

Experiment 2: Make a electrostatic precipitator Particles (called particulate matter) can be captured before they enter the atmosphere by an electrostatic precipitator. In this experiment we use a plastic tube and black pepper to see how particles are attracted to the sides of the tube much like the pollutants are attracted in large industrial electrostatic precipitators.

Materials, Equipment, and Preparation plastic tube (fluorescent light tube) wire coat hanger plastic grocery bag electric blow dryer punch holes, black pepper or rice crispies Picture on the right shows an industrial model of electrostatic precipitator.

air pollution project conclusion

The electrostatic precipitator works on the principle of a static electric charge attracting particles where they are removed.

A 2-foot plastic tube in which fluorescent lights are stored can be used to simulate an electrostatic precipitator. The plastic tube can be charged by running a coat hanger with a plastic grocery bag attached to it.

(The plastic bag as it moves through the tube strips the negatively charged electrons from the inside of the tube making the overall net charge positive. Anything that has a negative charge will be attracted to the tube because opposites attract.)

Hold the tube over some punch holes, black pepper, or rice crispies. Hold an electric hair dryer so the air stream blows across the top of the tube. The air mass creates a low pressure area at the top and the greater air pressure at the bottom pushes the punch holes up the tube. (This is called Bernoulli’s Principal)

***The Results*** If the tube is charged, the punch holes will stick to the sides. This activity can be used to study static electricity. If the tube is not charged, the holes will shoot out in a spray. This activity can be used to study Bernoulli’s principle.

Experiment 3: How to Make a Wet Scrubber

Warning: This experiment requires proper equipment and expert adult supervision. Please skip this experiment without proper equipment and supervision.

The wet scrubber is one of the most common pollution control devices used by industry. It operates on a very simple principle: a polluted gas stream is brought into contact with a liquid so that the pollutants can be absorbed. In this experiment we will try to build a wet scrubber. (See diagram A)

Materials Paper towels 12-cm piece of glass Three 2.5-cm pieces of glass tubing Three 55-ml flasks Two glass impingers (glass tubing drawn at one end to give it a smaller diameter so as to let out smaller bubbles) Heat source (burner or hot plate) Three 2-hole rubber stoppers (of a size to fit the mouths of the flasks) Two 30-cm pieces of rubber tubing Ring stand apparatus Vacuum source Procedure Write your answers on a separate sheet. Set up the apparatus as shown in attached figure . Put a paper towel in a 55-ml flask and place this above the burner. Using a 2-hole stopper that makes an air-tight seal with the flask, insert a 12-cm section of glass tubing through one of the holes. The tubing should reach to approximately 1.2-cm from the bottom of the flask. Insert a 2.5-cm piece of glass tubing into the other hole of the stopper. Connect a 30-cm piece of rubber tubing to the 2.5-cm piece of glass tubing, making sure an air-tight seal exists. Fill a second 500-ml flask approximately 3/4 full of water. Using a second double-hole stopper, put a 2.5-cm piece of glass tubing into one of the holes, and insert the glass impinger into the other. Construct a third flask like the second. Connect the rubber tubing and heat the first flask (combustion chamber) until smoke appears. Put a vacuum on the third flask to draw a stream of smoke through the second flask (the wet scrubber). If smoke collects in the second flask above the water, a second scrubber can be added. Ask the students if particles are the only pollutants produced by industry. Discuss how a wet scrubber collects not only particulate matter but also captures waste gases. Demonstrate how the water scrubber works. Discuss that the white plume you see coming from a smokestack may really be steam coming from a water scrubber. After observing the wet scrubber, answer the following questions: Why does the water in the wet-scrubber change color? Why does the wet-scrubber have an impinger (in other words, why is it important for small bubbles to be formed)? What does the scrubber filter out of the air? Not filter out? Suggest ways to dispose of the pollutants that are now trapped in the water.

Materials and Equipment:

List of material can be extracted from the experiment section.

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

Calculations:

Description

Summery of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.

Conclusion:

Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.

References:

List of References

air pollution project conclusion

It is always important for students, parents and teachers to know a good source for science related equipment and supplies they need for their science activities. Please note that many online stores for science supplies are managed by MiniScience.

Testimonials

" I called School Time and my husband and son came with me for the tour. We felt the magic immediately."

- Robby Robinson

" My husband and son came with me for the tour. We felt the magic immediately."

- Zoe Ranson

Contact Info

Our address, working hours.

Week Days: 07:00-19:00

Saturday: 09:00-15:00

Sunday: Closed

Science Project

HSC Projects

Evs Project On Air Pollution For Class 11th And 12th

Table of Contents

Acknowledgement:

I would like to take this opportunity to express my heartfelt gratitude to the individuals and organizations who have played a significant role in the completion of this Evs Project on Air Pollution. Their unwavering support, guidance, and contributions have been instrumental in the success of this endeavor.

First and foremost, I would like to extend my sincere appreciation to my teacher [mention teacher’s name] for providing me with valuable insights and guidance throughout the project. Their expertise and encouragement have been invaluable in shaping my understanding of the subject matter and guiding me in the right direction.

I am also grateful to [mention names of experts, environmentalists, or researchers] for their assistance and willingness to share their knowledge and experiences. Their valuable inputs during interviews, discussions, or consultations have enriched the project and provided a deeper understanding of the complexities surrounding air pollution.

I would like to acknowledge the support and cooperation received from [mention names of organizations or institutions]. Their provision of necessary resources, such as research materials, data, and access to facilities, has significantly contributed to the project’s comprehensiveness and credibility.

Furthermore, I extend my thanks to my friends and classmates who have been a constant source of encouragement and support throughout the project. Their feedback and constructive criticism have helped me refine my ideas and strengthen the project’s overall quality.

Lastly, I would like to express my gratitude to my family for their unwavering support and understanding during the project’s duration. Their encouragement, patience, and belief in my abilities have been vital in keeping me motivated and focused.

I acknowledge that this project would not have been possible without the collective effort and support of these individuals and organizations. Their contributions have truly made a difference in shaping this project on air pollution, and I am immensely grateful for their involvement.

Once again, I extend my heartfelt thanks to everyone who has played a role in this project. Your support and guidance have been invaluable, and I am grateful for the opportunity to work on such an important topic under your guidance.

Introduction:

Air pollution is a pressing environmental issue that has garnered significant attention worldwide due to its detrimental effects on human health, ecosystems, and the overall well-being of our planet. The continuous release of pollutants into the atmosphere from various sources has resulted in a degraded air quality that poses severe risks to both the environment and public health.  

The primary objective of this Evs Project on Air Pollution is to shed light on the seriousness of this issue and raise awareness among individuals, communities, and policymakers. By understanding the causes, consequences, and potential solutions related to air pollution, we can take proactive measures to address and mitigate its harmful effects.

Air pollution originates from multiple sources, both natural and human-induced. Natural sources include volcanic eruptions, wildfires, and dust storms, while human activities contribute significantly to the problem. Emissions from industries, power plants, vehicles, and improper waste disposal are among the primary culprits responsible for air pollution.

The consequences of air pollution are far-reaching and impact various aspects of our lives. It adversely affects human health, leading to respiratory problems, cardiovascular diseases, allergies, and even premature death. Additionally, air pollution has severe implications for ecosystems, harming plant and animal life and disrupting delicate ecological balances. Furthermore, it contributes to climate change by influencing the Earth’s radiation balance and exacerbating global warming.

Recognizing the urgency of the situation, it is essential to explore and implement effective measures to combat air pollution. Through this project, we aim to provide insights into the possible solutions and strategies that can be adopted at individual, community, and governmental levels. By promoting sustainable practices, advocating for stricter emission controls, and encouraging the use of clean energy sources, we can make significant progress in reducing air pollution levels and preserving the health of our planet.

By increasing awareness and understanding of air pollution, we can empower individuals to make informed choices and take actions that contribute to a cleaner and healthier future. This project serves as a platform to educate and inspire students, policymakers, and the general public to prioritize and actively engage in efforts to combat air pollution.

In conclusion, this Evs Project on Air Pollution aims to highlight the severity of the problem and emphasize the importance of addressing it promptly. By comprehending the causes and consequences of air pollution and exploring potential solutions, we can pave the way for a sustainable and healthier future for ourselves and future generations.

air pollution project conclusion

Evs Project on Air Pollution:

The Evs Project on Air Pollution is a comprehensive study that delves into the multifaceted aspects of air pollution. It encompasses an in-depth analysis of its causes, effects, and potential solutions. By conducting thorough research and gathering relevant data, this project seeks to enhance awareness among individuals, communities, and policymakers regarding the pressing need to tackle air pollution promptly and effectively.

One of the primary objectives of this project is to identify and examine the various causes of air pollution. It explores both natural and anthropogenic factors that contribute to the degradation of air quality. Natural causes include volcanic eruptions, dust storms, and pollen, while anthropogenic causes encompass emissions from industries, transportation, energy generation, and household activities. By understanding the root causes, this project highlights the need for comprehensive strategies to address and mitigate these sources of pollution.

Furthermore, the project investigates the wide-ranging effects of air pollution on the environment, public health, and climate change. It explores the detrimental impacts on ecosystems, including the depletion of biodiversity, disruption of ecological balance, and damage to vegetation. The project also emphasizes the severe health consequences for humans, such as respiratory illnesses, cardiovascular diseases, and impaired lung function. Additionally, it underscores the role of air pollution in exacerbating climate change by contributing to the greenhouse effect and altering weather patterns.

The Evs Project on Air Pollution goes beyond merely identifying the problems associated with air pollution. It aims to present potential solutions and strategies to mitigate this issue effectively. It explores both individual and collective actions that can be taken to reduce air pollution. These may include adopting sustainable transportation alternatives, promoting the use of clean energy sources, implementing stricter emission standards and regulations, advocating for effective waste management practices, and fostering public awareness and education on the importance of clean air.

By increasing awareness through this project, individuals, communities, and policymakers can be motivated to prioritize and take action against air pollution. It emphasizes the need for collaborative efforts involving government initiatives, industry practices, and individual responsibility to achieve substantial progress in addressing this environmental concern.

In conclusion, the Evs Project on Air Pollution aims to provide a comprehensive understanding of the causes, effects, and potential solutions to air pollution. By raising awareness and advocating for effective measures, this project seeks to empower individuals and communities to take proactive steps towards mitigating air pollution and safeguarding the well-being of the environment and future generations.

air pollution project conclusion

Examples of Air Pollution:

The section on examples of air pollution provides a detailed exploration of various sources that contribute to the deterioration of air quality. It focuses on highlighting specific instances or case studies related to air pollution, shedding light on their environmental and health impacts.

Industrial emissions are one of the prominent sources of air pollution. Factories and manufacturing facilities release a range of pollutants into the atmosphere, including particulate matter, sulfur dioxide, nitrogen oxides, and volatile organic compounds. These emissions can lead to smog formation, acid rain, and respiratory issues for nearby communities. For example, the industrial region of Norilsk in Russia has experienced severe air pollution due to metal smelting operations, resulting in significant environmental damage and adverse health effects on the local population.

Vehicular pollution is another major contributor to air pollution, particularly in urban areas. Exhaust emissions from automobiles release harmful pollutants like carbon monoxide, nitrogen dioxide, and particulate matter. Cities with high traffic congestion often experience elevated pollution levels and associated health problems. For instance, Delhi, the capital city of India, has witnessed severe air pollution due to the large number of vehicles on its roads, leading to respiratory ailments and reduced air quality indexes.

Indoor air pollution is a lesser-known but significant concern. Activities such as cooking with solid fuels like wood, coal, or biomass release harmful pollutants into indoor environments. This can have adverse effects on the health of individuals, especially women and children who are exposed to these pollutants for extended periods. In rural areas of developing countries, where clean cooking technologies are not readily available, indoor air pollution poses a serious health risk.

Agricultural activities, particularly the use of chemical fertilizers and pesticides, contribute to air pollution as well. The release of ammonia, pesticides, and other chemicals into the air can lead to smog formation and adversely affect air quality. This pollution can have detrimental effects on both human health and ecosystems.

The burning of fossil fuels, including coal, oil, and natural gas, is a significant source of air pollution globally. Power plants, residential heating systems, and industrial processes that rely on fossil fuel combustion emit greenhouse gases, sulfur dioxide, nitrogen oxides, and particulate matter. These pollutants contribute to climate change, smog formation, and respiratory diseases. For instance, the severe air pollution episodes witnessed in Beijing, China, were largely attributed to the burning of coal for heating and industrial purposes.

By examining these specific examples and case studies, the project aims to illustrate the diverse sources and impacts of air pollution. It emphasizes the urgency of addressing these sources through effective policies, technological advancements, and individual actions to safeguard the environment and public health.

air pollution project conclusion

Importance of Evs Project on Air Pollution:

The Evs Project on Air Pollution plays a vital role in today’s world by addressing one of the most pressing environmental challenges we face. It holds immense importance as it helps individuals, communities, and policymakers understand the gravity of the air pollution problem and its far-reaching consequences on ecosystems, human health, and climate change. By raising awareness through this project, it serves as a catalyst for inspiring action and driving changes in policies and personal behavior to effectively reduce air pollution.

Firstly, the project educates individuals about the detrimental effects of air pollution on ecosystems. It highlights how air pollutants can harm plant and animal life, disrupt ecological balances, and lead to the loss of biodiversity. By understanding these impacts, individuals gain a deeper appreciation for the interconnectedness of ecosystems and recognize the need to protect and preserve them.

Secondly, the project emphasizes the severe health implications of air pollution on human well-being. It sheds light on how air pollutants, such as particulate matter, ozone, and nitrogen dioxide, can contribute to respiratory problems, cardiovascular diseases, allergies, and even premature death. By creating awareness about these health risks, the project empowers individuals to prioritize their own well-being and take proactive measures to minimize exposure to air pollutants.

Furthermore, the Evs Project on Air Pollution addresses the critical link between air pollution and climate change. It highlights how certain pollutants, such as carbon dioxide and other greenhouse gases, contribute to global warming and the disruption of weather patterns. By understanding this connection, individuals recognize the urgency of reducing air pollution as part of the broader efforts to mitigate climate change and its associated impacts, such as rising sea levels, extreme weather events, and habitat loss.

Additionally, the project plays a crucial role in advocating for changes in policies and regulations. By raising awareness about the adverse effects of air pollution, it prompts individuals to engage with policymakers and demand stricter emission standards, increased investment in renewable energy sources, and sustainable urban planning. This project can contribute to the development and implementation of more effective environmental policies that prioritize air quality and protect public health.

Moreover, the Evs Project on Air Pollution encourages changes in personal behavior and lifestyle choices. By educating individuals about the sources of air pollution and their own contribution to it, the project promotes the adoption of sustainable practices. It inspires individuals to make conscious decisions such as reducing reliance on private vehicles, supporting clean energy alternatives, practicing proper waste management, and promoting indoor air quality.

In conclusion, the Evs Project on Air Pollution is of paramount importance in our world today. By raising awareness about the gravity of the problem, its detrimental effects on ecosystems, human health, and climate change, it inspires action and drives changes in policies and personal behavior to reduce air pollution. This project empowers individuals to make informed choices and actively contribute to creating a cleaner and healthier environment for ourselves and future generations.

How Can We Make It Happen?

This section explores practical steps and measures that can be taken to address air pollution. It discusses the importance of adopting sustainable transportation, promoting renewable energy sources, implementing stricter emission standards, encouraging waste management practices, and raising awareness among the general public. The focus is on individual and collective actions that can contribute to reducing air pollution.

The Three Pillars:

The three pillars of this project are:

Education and Awareness: This pillar emphasizes the need to educate individuals about the causes and impacts of air pollution. It promotes awareness campaigns, workshops, and educational programs to empower people with knowledge and encourage them to take action.

Policy and Regulation: This pillar emphasizes the importance of enacting and enforcing stringent policies and regulations to control air pollution. It discusses the role of government bodies, international agreements, and collaborations in formulating effective policies and implementing pollution control measures.

Technology and Innovation: This pillar focuses on the role of technology and innovation in combating air pollution. It explores advancements in clean energy technologies, air quality monitoring systems, and sustainable practices that can significantly reduce pollution levels.

Conclusion:

The Evs Project on Air Pollution serves as a catalyst for change, promoting awareness, sustainable practices, and policy advocacy to address the urgent issue of air pollution. By delving into the causes, effects, and potential solutions, this project empowers individuals, communities, and governments to take concerted action towards creating a cleaner and healthier future for ourselves and future generations.

Through this project, individuals gain a comprehensive understanding of the causes and effects of air pollution. Armed with knowledge, they can recognize the detrimental impact it has on ecosystems, human health, and climate change. This awareness fuels a sense of responsibility and urgency to take action against air pollution.

The project emphasizes the importance of collective efforts, urging individuals, communities, and governments to work together. By collaborating, sharing knowledge, and implementing sustainable practices, we can effectively combat air pollution. The project highlights the significance of initiatives such as adopting clean transportation alternatives, promoting renewable energy sources, implementing stricter emission regulations, and raising public awareness.

Furthermore, the Evs Project on Air Pollution underlines the importance of policy advocacy. It emphasizes the need for governments to enact and enforce stringent regulations and standards to control air pollution effectively. This includes collaboration on an international level to address transboundary pollution and foster sustainable practices across borders.

Ultimately, the project recognizes the shared responsibility of individuals, communities, and governments to protect our planet. By actively participating in efforts to reduce air pollution, we can contribute to the creation of a healthier environment for ourselves and future generations. It is crucial for us to recognize the interconnectedness of our actions and their impact on the planet.

In conclusion, the Evs Project on Air Pollution serves as a call to action, inspiring individuals, communities, and governments to work collectively towards combatting air pollution. By raising awareness, promoting sustainable practices, advocating for effective policies, and fostering collaboration, we can create a cleaner, healthier, and more sustainable future for all. It is our responsibility to protect and preserve our planet for current and future generations.

Certificate of Completion

This is to certify that I, [Student’s Name], a [Class/Grade Level] student, have successfully completed the project on “Evs Project On Air Pollution For Class 11th And 12th.” The project explores the fundamental principles and key aspects of the chosen topic, providing a comprehensive understanding of its significance and implications.

In this project, I delved into in-depth research and analysis, investigating various facets and relevant theories related to the chosen topic. I demonstrated dedication, diligence, and a high level of sincerity throughout the project’s completion.

Key Achievements:

Thoroughly researched and analyzed Evs Project On Air Pollution For Class 11th And 12th. Examined the historical background and evolution of the subject matter. Explored the contributions of notable figures in the field. Investigated the key theories and principles associated with the topic. Discussed practical applications and real-world implications. Considered critical viewpoints and alternative theories, fostering a well-rounded understanding. This project has significantly enhanced my knowledge and critical thinking skills in the chosen field of study. It reflects my commitment to academic excellence and the pursuit of knowledge.

In order to download the PDF, You must follow on Youtube. Once done, Click on Submit

Subscribed? Click on Confirm

Download Evs Project On Air Pollution For Class 11th And 12th PDF

Related articles.

air pollution project conclusion

Biology Project On Migratory Birds Of Maharashtra For Class 12

air pollution project conclusion

Marketing Management Project On Alcohol Wine For Class 12

air pollution project conclusion

Project On Ecofriendly Products For Class 10

air pollution project conclusion

Biology Project On Biopotential Of Freshwater Invertebrates for Class 12

Leave a reply cancel reply.

Your email address will not be published. Required fields are marked *

Notify me of follow-up comments by email.

air pollution project conclusion

Please Enable JavaScript in your Browser to Visit this Site.

IMAGES

  1. Air Pollution Conclusion Essay

    air pollution project conclusion

  2. Conclusion of Air Pollution

    air pollution project conclusion

  3. PPT

    air pollution project conclusion

  4. Airpollution Ppt

    air pollution project conclusion

  5. Conclusion of pollution essay.

    air pollution project conclusion

  6. Air Pollution Conclusion Essay

    air pollution project conclusion

VIDEO

  1. environmental education। Air pollution । Project file । our environment । e. v.s । science project

  2. Air Pollution

  3. Air Pollution project

  4. air pollution project.by akshara pathare

  5. water and air pollution project made by my mom and me for brother #Drawwithme #pollution

  6. AIR POLLUTION ( Project in em-tech. Arianne ft. ashley) credits to the rightful owner of the clip

COMMENTS

  1. Air Pollution: Everything You Need to Know

    Jillian Mackenzie What Is Air Pollution? Air pollution refers to the release of pollutants into the air—pollutants that are detrimental to human health and the planet as a whole....

  2. Air Pollution

    Air pollution is considered a problem because it not only affects the environment but also damages crops, forests, animals, and the human body. The causes of air pollution contribute to the problem of acid rain and the depletion of the ozone layer. The ozone layer is important for the earth because it protects the earth from the UV rays of the sun.

  3. Environmental and Health Impacts of Air Pollution: A Review

    Approach to the Problem The interactions between humans and their physical surroundings have been extensively studied, as multiple human activities influence the environment. The environment is a coupling of the biotic (living organisms and microorganisms) and the abiotic (hydrosphere, lithosphere, and atmosphere).

  4. Summary and Conclusion

    The harmful effects of air pollution were recognized by Hippocrates in his fifth-century treatise Air, Water and Places; Hippocrates noted that people's health could be affected by the air they breathe and that quality of the air differed by area (cited in Adams 1891 ).

  5. Air Pollution: Current and Future Challenges

    Outdoor air pollution challenges facing the United States today include: Meeting health-based standards for common air pollutants. Limiting climate change. Reducing risks from toxic air pollutants. Protecting the stratospheric ozone layer against degradation. Indoor air pollution, which arises from a variety of causes, also can cause health ...

  6. Air pollution: Impact and prevention

    CONCLUSIONS. Air pollution currently affects the health of millions of people. We have presented evidence on the effects of pollutants on patients with limitations in their respiratory capacities. For example, O 3 and PM may trigger asthma symptoms or lead to premature death, particularly in elderly individuals with pre-existing respiratory or ...

  7. Conclusion

    Publications Air and Health - Local authorities, ... Conclusion Local authorities, health and environment AIR AND HEALTH Conclusion The health of the public, especially those who are the most vulnerable, such as children, the elderly and the sick, is at risk from air pollution, but it is difficult to say how large the risk is.

  8. Engaging communities in addressing air quality: a scoping review

    Background Exposure to air pollution has a detrimental effect on health and disproportionately affects people living in socio-economically disadvantaged areas. Engaging with communities to identify concerns and solutions could support organisations responsible for air quality control, improve environmental decision-making, and widen understanding of air quality issues associated with health ...

  9. Discussion and conclusions

    Discussion and conclusions - Public health air pollution impacts of pathway options to meet the 2050 UK Climate Change Act target: a modelling study - NCBI Bookshelf

  10. Urban and air pollution: a multi-city study of long-term ...

    Most air pollution research has focused on assessing the urban landscape effects of pollutants in megacities, little is known about their associations in small- to mid-sized cities. Considering ...

  11. 6 CONCLUSIONS AND RECOMMENDATIONS

    Suggested Citation: "6 CONCLUSIONS AND RECOMMENDATIONS." National Research Council. 1985. Epidemiology and Air Pollution. Washington, DC: The National Academies Press. doi: 10.17226/841. ×. Save. Cancel. Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich ...

  12. Air Pollution

    CONCLUSION While the effects of air pollution on materials, vegetation, and animals can be measured, health effects on humans can only be estimated from epidemiological evidence. Most of the evidence comes from occupational exposure to much higher concentrations of pollutants than the general public is exposed to.

  13. Essay on Air Pollution

    Conclusion Air pollution is a huge problem not only in India but the whole world, various organizations do their bit to make sure that plans are made to restrict air pollution, but unfortunately those plans never get executed rightly.

  14. Summary, Conclusions, and Recommendations

    5 Summary, Conclusions, and Recommendations SUMMARY Pressures on the environment will continue to increase. Global population increase, rising incomes, and agricultural and industrial expansion will inevitably produce unanticipated and potentially deleterious ecological, economic, and human health consequences.

  15. Conclusion: Environmental Protection—Our Common Responsibility

    Conclusion: Environmental Protection—Our Common Responsibility Alberto A. C. C. Pais & Telma Encarnação Chapter First Online: 06 January 2023 252 Accesses Part of the Environmental Challenges and Solutions book series (ECAS) Abstract

  16. 16 projects that could end air pollution around the world

    Christopher McFadden Updated: May 02, 2023 05:00 PM EST lists 1 , 2 Air pollution poses a severe risk worldwide. Towns and cities are choked with smog and dangerous emissions, damaging both the...

  17. Causes, Consequences and Control of Air Pollution

    ... This declines the quality of air as well as increases the frequencies of fog and haze (Batterman et al., 2015). The release of toxic chemicals, particulate matter, and biological materials...

  18. Air Pollution

    This weather forecasting helps the general public and people who work in industries such as shipping, air transportation, agriculture, fishing, forestry, and water and power better plan for the weather, and reduce human and economic losses. Read more. Weather & Atmosphere Project Ideas. Environmental Science Project Ideas.

  19. Air pollution

    Air pollution is contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere. Household combustion devices, motor vehicles, industrial facilities and forest fires are common sources of air pollution. Pollutants of major public health concern include ...

  20. Air pollution

    World Health Organization, 2018. According to the World Health Organization (WHO), air pollution is one of the world's biggest killers: outdoor (ambient) pollution causes around four million people to die prematurely each year, while indoor (household) pollution (mainly from fuel burning) kills another 3.8 million.

  21. Air Pollution Solutions

    There Are Many Solutions to Air Pollution. In order to improve air quality and slow climate warming, change needs to happen on a national and global scale. However, actions at the individual and community level are also important. Burn less coal. Pollution from burning all fossil fuels is harmful to the atmosphere, but burning coal has a larger ...

  22. Air Pollution

    Air pollution is the contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health. In addition to many economical and agricultural losses, air pollution is the main cause of many diseases and deaths every year. Excessive growth rate of air pollution is a major ...

  23. Evs Project On Air Pollution For Class 11th And 12th

    In conclusion, this Evs Project on Air Pollution aims to highlight the severity of the problem and emphasize the importance of addressing it promptly. By comprehending the causes and consequences of air pollution and exploring potential solutions, we can pave the way for a sustainable and healthier future for ourselves and future generations. ...