Air pollution is the presence of harmful substances in the air that can harm people, animals, plants, or the environment. These harmful substances, called pollutants, can be gases such as ozone or nitrogen oxides, or tiny particles like soot and dust. Both air inside and outside buildings can be polluted.

Outdoor air pollution comes from burning fossil fuels for electricity and transportation, wildfires, certain industrial activities, waste management, demolition, and farming. Indoor air pollution often happens when people burn firewood or agricultural waste for cooking and heating. Other sources of air pollution include dust storms and volcanic eruptions. Many local pollution sources, especially burning fossil fuels, also release greenhouse gases that contribute to global warming. However, air pollution can sometimes reduce warming in specific areas.

Air pollution causes about 7 to 8 million deaths each year. It increases the risk of serious health problems, such as stroke, heart disease, chronic obstructive pulmonary disease (COPD), asthma, coronavirus, and lung cancer. Tiny particles in the air are the most dangerous type of pollution, whether indoors or outdoors. Ozone harms crops, and pollution that causes acid rain damages forests. The World Bank estimates that air pollution leads to economic losses of over $8 trillion each year due to premature deaths and reduced productivity.

Many technologies and strategies help reduce air pollution. These include using clean cooking devices, improving fire safety, managing waste better, controlling dust, using industrial scrubbers, switching to electric vehicles, and using renewable energy sources. National laws, such as the 1956 Clean Air Act in Britain and the 1963 Clean Air Act in the United States, have been effective in improving air quality. International efforts have had mixed success: the Montreal Protocol greatly reduced harmful ozone-depleting chemicals, but global efforts to address climate change have been less effective.

Major pollutants

Air pollutants can be tiny solid or liquid particles in the air (called aerosols) or gases. Pollutants are divided into two types: primary and secondary. Primary pollutants are released directly from a source and stay in the same chemical form after entering the atmosphere. Examples include carbon monoxide gas from car exhaust and sulfur dioxide from factories. Secondary pollutants are not released directly. Instead, they form when primary pollutants react with each other or with other parts of the atmosphere. Ground-level ozone is an example of a secondary pollutant. Some pollutants can be both primary and secondary, meaning they are released directly and also form from other primary pollutants.

Ammonia (NH₃) is mainly released from overuse of synthetic nitrogen fertilizers on farms and from manure and urine from animals. At normal air levels, it is not harmful to health. However, ammonia can react with other pollutants to form ammonium sulfate or nitrate salts, which contribute to particulate matter pollution. When ammonia settles on soil, it can harm ecosystems through a process called eutrophication.

Carbon dioxide (CO₂) is mainly released by burning fossil fuels. CO₂ is sometimes called an air pollutant because it is the main greenhouse gas linked to climate change. While the World Health Organization recognizes CO₂ as a climate pollutant, it does not include it in its Air Quality Guidelines or set targets for it. This terminology affects laws, such as the U.S. Clean Air Act, which aims to improve air quality. The Inflation Reduction Act of 2022 changed the Clean Air Act to explicitly define CO₂ from fossil fuel burning as an air pollutant.

Carbon monoxide (CO) is a colorless, odorless, and toxic gas. It forms when fuels like natural gas, coal, or wood burn. In the past, vehicle emissions were the main source of CO, but modern vehicles emit little of it now. Wildfires and bonfires are now the main outdoor sources. Indoors, CO is a bigger problem and comes from cooking and heating. In poorly ventilated spaces, CO can build up to dangerous levels, causing people to lose consciousness or die. When CO breaks down in the atmosphere, it can increase levels of CO₂ and methane (CH₄).

Ground-level ozone (O₃) forms when nitrogen oxides (NOₓ) and volatile organic compounds mix in sunlight. It can also form from carbon monoxide or methane. Because temperature and sunlight influence this reaction, high ozone levels are common on hot summer afternoons. Ozone is the main gas in photochemical smog.

Ozone can harm human health and damage materials, forests, plants, and crops. Smog is a major issue in large cities where wind cannot easily carry it away, such as cities in valleys surrounded by mountains. Ground-level ozone can stay in the air for days or weeks and travel far from where it forms.

Nitrogen oxides (NOₓ), especially nitric oxide (NO), are mainly created by burning fossil fuels and, to a lesser extent, by lightning. Nitrogen dioxide (NO₂) forms when NO reacts with other gases in the atmosphere. NO and NO₂ can cause acid rain, form a haze, and lead to nutrient pollution in water. NO₂ is a reddish-brown gas with a strong smell, while NO is colorless and odorless.

Particulate matter (PM), also called particle pollution, includes all airborne substances that are not gases. It is a mix of tiny solid particles or droplets floating in a gas. PM can contain many materials and chemicals, including harmful substances. Coarse PM (PM₁₀) is 10 micrometers (μm) or smaller in size, fine PM (PM₂.₅) is smaller than 2.5 μm, and ultrafine particles are 0.1 μm or smaller. Smaller particles are more dangerous to health because they can enter the bloodstream. A study called the Harvard Six Cities study, published in 1993, found a clear link between fine particulate pollution and higher death rates in urban areas.

Natural sources of PM include sea spray, wildfires, volcanoes, and dust storms. Human sources include burning biomass and fossil fuels, as well as road emissions and dust resuspension. Human-made PM is usually finer than natural PM. Most PM forms in the atmosphere from gases like sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and ammonia. For example, sulfate comes from SO₂, nitrate from NO₂, and ammonium from ammonia. Soot, on the other hand, is directly released from combustion and includes black carbon and organic compounds. PM can cool the climate locally by reflecting sunlight away from Earth.

Sulfur dioxide (SO₂), an acidic and corrosive gas, is mainly produced by burning crude oil and coal. These fuels often contain sulfur, which releases SO₂ when burned. In Europe and North America, SO₂ is mostly found in areas with heavy shipping and industry because road fuel is regulated. Smaller amounts of SO₂ come from smelting and volcanoes.

High levels of SO₂ in the air can form other sulfur oxides (SOₓ). These can react with other compounds to create small particles that contribute to particulate matter pollution. At high concentrations, SOₓ can damage plants by harming leaves and reducing growth. Further chemical reactions, often in clouds, turn SO₂ into sulfuric acid (H₂SO₄), a component of acid rain.

Volatile organic compounds (VOCs) are carbon-based chemicals that exist as gases at room temperature. They are found indoors and outdoors. VOCs can form photochemical smog and create aerosols that affect the climate. Examples include methane, acetone, and toluene. Some VOCs, like butadiene and benzene, can cause cancer. Benzene is released from cigarette smoke. Methane is a greenhouse gas and the second-largest cause of global warming. Other VOCs contribute to climate change by helping form ground-level ozone, a greenhouse gas.

Some heavy metals are harmful to health. For example, lead exposure can cause learning disabilities in children. In the atmosphere, heavy metals can be in solid, liquid, or gaseous forms. Chromium in some forms can cause cancer. Mercury is harmful as an element and in organic compounds. In the atmosphere, mercury mainly comes from cement production, coal burning, and incinerators.

Persistent organic pollutants (POPs) are chemicals that do not break down easily in the environment. They remain in the environment for long periods, travel long distances, build up in humans and animals, and increase in concentration as they move up the food chain. The Stockholm Convention on POPs lists harmful substances like pesticides, dioxins, and furans, which form during waste burning. POPs are either semi-volatile (

Exposure

Air pollution affects people differently around the world and among different groups. Children are more exposed because they breathe faster and closer to the ground, where pollution from vehicles and dust is stronger. People who do heavy exercise also breathe in more pollutants than those who are resting. Wearing high-quality face masks or using air purifiers can help reduce exposure to pollution.

Some pollutants are safe at low levels, but others harm health even in small amounts. Evidence shows that even tiny amounts of air pollution can hurt health. Because of this, the World Health Organization (WHO) lowered its safe limit for tiny particles (PM 2.5) from 10 μg/m³ to 5 μg/m³ in 2021. Under the new rules, nearly 97% of the world’s population is exposed to unsafe levels of PM 2.5. The safe limit for nitrogen dioxide (NO₂) also dropped by 75%. Overall, the WHO found that 99% of the world’s population is exposed to harmful air pollution.

For some pollutants, such as black carbon, exposure from traffic is a major source even if it happens for short periods. This is because high pollution levels often occur near busy roads or during traffic. Many people’s daily exposure includes short bursts of very high pollution levels.

Air pollution affects many groups, but some are more exposed. In many areas, race and income influence how much pollution people face. This is especially true in countries with large income and healthcare gaps, like the United States. Polluting industries and roads are often located in poorer communities, and people in these areas are more likely to work outdoors, increasing their exposure. People in public housing, who are often low-income and cannot move to cleaner areas, are heavily affected by nearby factories and chemical plants. Lower-income communities also more often use solid fuels like wood or coal for cooking. In the United States, Black and Latino communities generally face more pollution than White and Asian communities.

Outdoor air pollution is worst in lower-middle income countries, as shown by the environmental Kuznets curve, a theory that suggests pollution is highest in countries focused on manufacturing but not yet prioritizing environmental rules. Indoor air pollution is worst in low-income countries, especially in Southeast Asia, the Western Pacific, and Africa.

Outdoor pollution is often found in crowded cities. Rapid urban growth increases deaths from air pollution in fast-growing tropical cities. Indoor pollution is more common in rural areas, where access to clean cooking fuels may be limited.

A 2025 map by Climate TRACE shows that PM 2.5 and other harmful substances are released near the homes of about 1.6 billion people. Around 900 million of these people live near "super-emitting" facilities like power plants, refineries, ports, and mines.

Health effects

Air pollution increases the risk of many health problems, such as COPD (a common lung disease), stroke, heart disease, lung cancer, and pneumonia. Indoor air pollution is also linked to cataracts. The World Health Organization (WHO) reports that 99% of people worldwide live in areas where air pollution is higher than recommended levels. Even at very low levels (below WHO guidelines), tiny particles in the air can still cause harm.

Pollutants strongly connected to health problems include tiny particles, carbon monoxide, nitrogen dioxide (NO₂), ozone (O₃), and sulfur dioxide (SO₂). Tiny particles are especially harmful because they can enter the bloodstream through the lungs and reach other parts of the body. Air pollution causes disease by creating inflammation and harmful chemical reactions in the body, weakening the immune system, and damaging DNA.

People living in poverty, babies, and older people are more likely to be harmed by air pollution. Pregnancy is also riskier when exposed to air pollution. Groups with lower income and minority communities are more likely to be affected by pollution than wealthier groups. Lower-income groups may have less access to healthcare.

Different studies give different numbers about how many people die from air pollution each year. The 2024 Global Burden of Disease Study estimates that air pollution caused 8.1 million deaths in 2021, more than 1 in 8 deaths. Outdoor pollution from tiny particles (PM₂.₅) was the biggest cause of death (4.7 million), followed by indoor pollution (3.1 million) and ozone (0.5 million).

The WHO estimates that 6.7 million people die from air pollution each year, with 4.2 million from outdoor air pollution. About 68% of deaths from outdoor pollution were due to heart disease and stroke, 14% from COPD, and 14% from lung infections.

A study from 2019 estimated that 8.8 million people died in 2015, with 5.5 million of those deaths linked to pollution from human activities. In 2015, air pollution reduced life expectancy worldwide by an average of 2.9 years, much more than the 0.3 years lost due to all forms of direct violence.

The number of deaths from air pollution varies by region. In some countries, more than 20% of deaths are linked to air pollution (e.g., China, Nepal, Bangladesh, Laos, and North Korea). In South America, about 4% of deaths are from air pollution, while in countries like Australia, Canada, and the US, this number is less than 3%.

In total numbers, India and China have the highest number of deaths from air pollution. In 2021, air pollution caused 2.1 million deaths in India and 2.4 million in China. In Europe, between 416,000 and 800,000 people die each year from air pollution. In the UK, 17,000 deaths in 2021 were linked to air pollution, and in the US, 64,000 deaths were linked. Nigeria, Indonesia, and Pakistan each had over 200,000 deaths from air pollution in 2021.

The burning of fossil fuels is the main cause of air pollution deaths. About 4.5 million people die each year from pollutants released by power plants and vehicles. Tiny particles from coal-fired power plants may be more harmful than other types of fine particles.

The WHO estimates that cooking-related pollution causes 3.8 million deaths each year. In 2021, the Global Burden of Disease Study estimated that 3.1 million deaths were linked to cooking-related pollution.

Air pollution increases the risk of heart disease, including stroke, high blood pressure, and coronary heart disease. Air pollution is responsible for 27% of stroke deaths worldwide and 28% of coronary heart disease deaths. The risks are highest in areas with high pollution levels, such as Asia, and among older people and those who are overweight.

Air pollution is a major cause of stroke, especially in developing countries where pollution levels are highest. A study of 188 countries found that air pollution is linked to nearly one in three strokes worldwide (29%), with 34% of strokes in developing countries and 10% in developed countries. Scientists are still learning exactly how air pollution causes heart-related deaths, but it likely involves inflammation and harmful chemical reactions in the body.

Air pollution is linked to more cases of COPD, hospitalizations, and deaths from the disease. COPD is a common condition that makes it hard to breathe and is the fourth-leading cause of death globally. Nearly half of all COPD deaths are linked to air pollution. Tiny particles (PM₂.₅) and nitrogen dioxide (NO₂) increase the risk of developing COPD. In children, air pollution can harm lung development, which may lead to COPD later in life.

Air pollution also increases the risk of asthma and worsens symptoms, especially in children. For adults, tiny particles (PM₂.₅) or NO₂ may lead to asthma. Short-term exposure to ozone can make asthma worse in children. There is limited evidence that ground-level ozone and PM₂.₅ increase the risk of severe asthma attacks in children.

In 2019, 265,000 lung cancer deaths worldwide were linked to exposure to tiny particles (PM₂.₅) in the air. Indoor air pollution, including radon, caused an additional 170,000 lung cancer deaths. Lung cancer was more common among people exposed to NO₂ and black carbon.

Outdoor air pollution may also increase the risk of other cancers, but the evidence is less clear than for lung cancer. For example, there may be a link between kidney cancer and levels of PM₂.₅ and NO₂. Indoor air pollution from cooking with solid fuels and radon in building materials has been linked to cervical, oral, and esophageal cancers.

Exposure to air pollution during pregnancy increases the risk of stillbirths, miscarriages, and birth defects. It also raises the chance of a baby being born with low

Social and environmental impacts

Water in the atmosphere is naturally slightly acidic. Some pollutants can create strong acids, making rainwater much more acidic. The main acids that cause acid rain are nitric acid (HNO₃), sulfuric acid (H₂SO₄), and hydrochloric acid (HCl). Hydrochloric acid comes from burning coal. Sulfuric acid forms when sulfur dioxide (SO₂) reacts with water, and SO₂ is produced by burning coal and oil, as well as industrial processes like smelting. Nitric acid forms when nitrogen dioxide (NO₂) reacts with water, and NO₂ is created during high-temperature combustion. The term "acid rain" includes not only rain but also hail, fog, and snow that contain acid.

In the 1970s, acid rain caused significant harm, such as making lakes more acidic and causing forests to die in Northern Europe. Changes in water and soil acidity caused important nutrients like magnesium and calcium to dissolve and be washed away. Toxic elements like aluminum, which harm plants, became available for plant roots to absorb. Acid rain also damages buildings and statues made of stones like marble, calcite, or freestone because the acid reacts with the stone and causes it to erode.

Air pollution can settle on soil or water, leading to problems. For example, ammonia and nitric acid in the air can increase nutrient levels in water, a process called eutrophication. At first, extra nutrients help plants grow, but too much plant growth blocks sunlight from reaching underwater plants. These plants then die, reducing oxygen levels. This harms organisms that need oxygen and can lead to the loss of sensitive species.

Studies show that air pollution affects agriculture, especially through ozone. Ozone reduces photosynthesis in plants. One study estimated that a 1% increase in ozone levels would cost the world economy $10 billion yearly. A 1% increase in PM₂.₅ pollution would cause about $5 billion in losses, especially in colder areas. After entering the environment, air pollutants affect crops and soil, and also harm workers’ health, reducing productivity.

The COVID-19 lockdowns provided an opportunity to study how air quality affects agriculture. In India, lockdowns improved air quality, increasing surface greenness and plant growth. Both forests and crops benefited, with crops showing the greatest improvement.

Air pollution harms the economy through health effects, such as lower worker productivity and healthcare costs, and by reducing crop yields. It also affects tourism, biodiversity, forestry, and water quality. Poor air quality can reduce visibility and damage cultural heritage, increasing the risk of accidents. Higher levels of nitrogen dioxide (NO₂) are linked to construction site accidents.

According to a World Bank study, PM₂.₅ pollution in 2019 cost the global economy over $8 trillion, more than 6% of the world’s GDP. In India and China, the loss was over 10% of GDP. About 85% of this cost came from lives lost, and the rest from health issues. The cost of lives lost is calculated using the Value of Statistical Life, a number that estimates how much people are willing to pay to reduce their risk of death. This value varies by country and is hard to calculate in low- and middle-income countries.

The OECD estimates that by 2060, direct costs from air pollution, including lost productivity, healthcare use, and crop losses, could reach 1% of global GDP. The Caspian region and China would be most affected. Air pollution also reduces energy production by blocking sunlight from reaching solar panels and by making the panels dirty, which lowers their efficiency.

History of air pollution

Mummified bodies found in Peru, Egypt, and Britain show that people in these areas had darkened lungs from breathing smoke from open fires in homes with poor ventilation. People wrote about air pollution as early as the Greek and Roman times. Outdoor air pollution became a problem when cities grew, due to smoke from homes and early industrial activities like smelting and mining. For example, lead levels in Arctic ice were about ten times higher during the Roman period than before.

During the Industrial Revolution, outdoor air pollution increased greatly because of the large burning of coal. This began in Britain, then spread to Northern Europe and the United States. By the 19th century, buildings near factories turned black, and plants in public parks began to die. Smoke-filled fogs blocked sunlight, which contributed to rickets, a disease in children caused by lack of sunlight and poor nutrition.

However, leaders in industrial cities supported the industry because heavy smoke meant wealth, high profits, and better wages.

The miasma theory, a popular belief in the 18th and 19th centuries, incorrectly claimed that diseases like cholera, yellow fever, and malaria came from "bad air" released by decaying matter. This idea led cities to focus on cleaning streets and removing waste to improve sanitation. The theory was disproven in the late 19th century when the germ theory showed that germs from infected people or mosquitoes caused diseases.

In the 1830s, anti-smoke groups formed in Britain, and similar groups appeared in the United States in the 1880s. Laws against pollution were weak because they conflicted with industrial interests. During the 1920s and 1930s, switching from coal to gas and oil reduced air pollution, but this changed during World War II. The worst air pollution in the United Kingdom happened during the 1952 Great Smog of London, which caused about 12,000 deaths and led to the Clean Air Act of 1956. In the United States, the 1948 Donora smog killed 20 people and pushed the country to regulate air pollution. Japan started regulating pollution in 1960, but countries like the Soviet Union and China did not act effectively.

Major accidents have caused serious air pollution. The worst pollution disaster was the 1984 Bhopal Disaster in India, where leaked chemicals from a factory killed at least 20,000 people and harmed about 600,000.

In the 1950s, smog in developed countries was controlled, but other pollutants were not. Acid rain, caused by sulfur dioxide, became a big problem because it spread across borders. For example, Japan faced acid rain from industries in China and South Korea in the 1990s. International cooperation was needed to reduce acid rain, and coalitions were formed. In 1975, scientists found that certain chemicals caused a hole in the ozone layer. Global agreements banned these chemicals. Efforts to fight climate change have been less successful, and greenhouse gas emissions from fossil fuels continue to rise.

Measurement and monitoring

Air pollution can be tracked using different methods. For example, satellites and remote sensing are used to monitor particles, nitrogen dioxide, and ozone. Many areas have networks of monitoring stations, with strong coverage in India, China, Europe, and the United States. However, some highly polluted countries, such as Chad and Iran, have limited coverage. The number of measurements is increasing because more low-cost tools are available to measure air pollution. These low-cost devices can also check indoor air quality. Additionally, air quality sensors can be attached to drones to measure pollution at higher altitudes. Some websites use available data to create maps showing pollution levels.

Air Quality Indexes (AQIs) provide a simple way to share information about air quality and health risks with the public. An AQI is a tool that helps people reduce their short-term exposure to pollution by adjusting their activities when pollution levels rise. These indexes show when air quality is good, when it is harmful to sensitive groups, such as children with asthma, and when it is a general danger.

When direct data is not available or when predicting future pollution levels, estimates can be made using models or emission factors. Emission factors are typical values that connect the amount of pollution released to a specific activity. For example, they might show how much particulate matter is released by a coal power plant. The United States Environmental Protection Agency and the European Environment Agency have published lists of emission factors for many industrial sources.

Air quality models use weather data and pollution information to simulate how pollutants spread and react in the atmosphere. Regulatory agencies use these models to determine if a new pollution source would cause pollution levels to exceed acceptable limits, which helps with permits. They can also predict future pollution levels under different policy plans. Some models focus on local pollution, while others study pollution that crosses borders.

Pollution reduction by sector

Pollution prevention aims to stop pollution, such as air pollution, by making changes in how industries and businesses operate. This can include designing manufacturing processes and products that are more sustainable, as well as moving toward energy sources like solar and wind power.

Many technologies and strategies exist to reduce air pollution. For example, industrial plants can use scrubbers, like systems that remove sulfur from exhaust gases, or catalysts to remove nitrogen oxides (NOx). In the power sector, switching to renewable energy, such as solar or wind power, or using nuclear power, is an effective way to reduce air pollution. Changing from coal-fired power plants to fossil gas reduces air pollution, but does not completely stop it.

More countries are managing waste through systems that control landfills, capture gas from landfills to make electricity, and sort waste for recycling. In agriculture, air pollution can be reduced by avoiding overuse of fertilizers and by not giving animals too much protein.

The avoid-shift-improve framework helps reduce vehicle-related pollution by cutting travel, using cleaner transportation, and improving vehicle technology. Reducing car use can lower pollution. One way to do this is by creating compact cities where people can access services without needing cars. Building walkable cities and adding bicycle lanes can also reduce traffic. Working from home is another way to avoid driving.

Traffic can be shifted to cleaner transportation by encouraging public transit, such as by charging more for parking or offering free public transportation. Charging fees for driving in crowded areas also helps people use cleaner transport. Finally, vehicles can be improved through better fuel efficiency, cleaner fuels, stricter emission rules, and switching to electric cars. For example, buses in New Delhi, India, began using compressed natural gas after 2000 to reduce smog.

In 2006, Lawrence D. Frank and his co-authors published a study with over 1,930 citations titled Many Pathways from Land Use to Health. The study showed that increasing walkability by 5% led to benefits, such as a 6.5% drop in vehicle miles driven, a 5.6% decrease in nitrogen oxides emissions, and a 5.5% reduction in volatile organic compounds (VOCs) emissions.

Clean cooking methods, such as using biogas, bioethanol, electricity, natural gas, or liquefied petroleum gas (LPG), can replace traditional stoves that burn biomass. Improved cook stoves, which use biomass more efficiently, reduce air pollution less but can be a temporary solution if cleaner options are unavailable. These devices usually have a smaller climate impact than traditional stoves.

Kerosene for lighting can be replaced with efficient LED lights, such as solar-powered ones. Using electricity in heat pumps instead of burning fossil fuels for heating can also reduce pollution. Ventilation improves indoor air quality but can cause outdoor pollution, which may worsen local indoor air quality.

Policy and regulation

Many countries have laws to reduce air pollution, but some do not have clear rules. About 43% of countries do not have an official definition of air pollution. Around 34% lack rules for outdoor air quality, and only 31% have laws to address pollution that comes from other countries. Few countries have rules as strict as those suggested by the World Health Organization (WHO).

Some air pollution laws set specific limits for harmful substances in the air. For example, the U.S. National Ambient Air Quality Standards and the E.U. Air Quality Directive define the highest allowed levels of certain pollutants. Other examples include the Clean Air Act in Britain, the U.S. Clean Air Act, and the TA Luft in Germany. These laws may also limit how much pollution can be released by sources like vehicles.

The World Health Organization’s Global Air Quality Guidelines suggest ways to improve air quality, similar to national rules. However, these guidelines are not required laws that countries must follow.

Some international efforts to reduce pollution have been successful. For example, the Montreal Protocol helped stop the use of harmful chemicals that damage the ozone layer. It was agreed to by all countries. However, efforts to address climate change have had less success. The Kyoto Protocol, created in 1997, set small pollution reduction goals but did not enforce them strongly. The Paris Agreement, from 2015, did not set strict limits but asked countries to improve their goals over time.

In 2022, the United Nations General Assembly passed a resolution stating that the right to a clean, healthy, and sustainable environment is a human right. This resolution is not legally binding. It followed a similar statement from the UN Human Rights Council earlier that year.

Although many countries have air pollution laws, how these laws are enforced can vary. In the European Union, some countries, like France, have been fined by the EU for failing to follow air quality rules. A new rule in the EU allows individuals to seek compensation for air quality violations. In China, people can take legal action for environmental issues, but this is uncommon because it is seen as risky. In Chile, the right to a healthy environment is written into the constitution, and the Supreme Court ruled that the government must act to ensure clean air.