Air pollution happens when harmful substances are in the air. These substances can be gases, such as ozone or nitrogen oxides, or tiny particles like soot and dust. Both outdoor and indoor air can be polluted.

Outdoor air pollution comes from burning fossil fuels for electricity and transportation, wildfires, certain industrial processes, waste management, demolition, and agriculture. Indoor air pollution often results from burning firewood or agricultural waste for cooking and heating. Other sources 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 7 to 8 million deaths each year. It increases the risk of many diseases, including stroke, heart disease, chronic obstructive pulmonary disease (COPD), asthma, coronavirus, and lung cancer. Particulate matter is the most dangerous type of pollution, both indoors and outdoors. Ozone harms crops, and forests are damaged by pollution that causes acid rain. The World Bank estimates that air pollution leads to over $8 trillion in annual economic losses due to premature deaths and reduced productivity.

Technologies and strategies help reduce air pollution. These include clean cookers, fire protection, better waste management, dust control, industrial scrubbers, electric vehicles, and renewable energy. National air quality laws have been effective, such as the 1956 Clean Air Act in Britain and the 1963 US Clean Air Act. International efforts have had mixed results: the Montreal Protocol nearly eliminated harmful ozone-depleting chemicals, but global climate change actions have been less successful.

Major pollutants

Air pollutants can be tiny solid or liquid particles spread out in the air (called aerosols) or gases. Pollutants are divided into two types: primary and secondary. Primary pollutants are directly released 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 directly released. Instead, they form in the air 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 — they are directly released and also formed from other primary pollutants.

Ammonia (NH₃) is mainly released from overuse of synthetic nitrogen fertilizers on farmland and from manure and urine from livestock. At typical air concentrations, it is not harmful to health directly. However, ammonia can react with other pollutants in the air to form ammonium sulfate or nitrate salts, contributing to particulate matter pollution. When ammonia is deposited onto soil, it can harm ecosystems through 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 responsible for climate change. Although the World Health Organization recognizes CO₂ as a climate pollutant, it does not include the gas in its Air Quality Guidelines or set targets for it. This terminology affects decisions, such as whether the U.S. Clean Air Act regulates CO₂ emissions. 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 is produced when fuels like natural gas, coal, or wood are burned. In the past, vehicle emissions were the main source of CO, but modern vehicles emit little of it. Now, wildfires and bonfires are the main outdoor sources of CO. Indoors, CO is a larger problem and mainly 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 is destroyed in the atmosphere, it can increase levels of CO₂ and CH₄.

Ground-level ozone (O₃) is mostly created when 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 most common on hot summer afternoons. It is the main gas in photochemical smog.

O₃ can harm human health and damage materials, forests, plants, and crops. Smog is a particular problem in large cities where wind cannot easily carry it away (e.g., cities in valleys surrounded by mountains). When ground-level ozone is produced, it can stay in the air for days or weeks and be transported far from where it was formed.

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

Particulate matter (PM), also called particle pollution, includes all airborne substances that are not gases. It is a mix of microscopic solid particles or droplets suspended in a gas.

Particulate matter can contain many materials and chemicals, including toxic substances, which vary in size. Coarse PM (PM₁₀) is 10 micrometers (μm) or smaller in diameter, fine PM (PM₂.₅) is smaller than 2.5 μm, and ultrafine particles are 0.1 μm or smaller. Smaller particles are more harmful to health because they can reach the bloodstream. A study published in 1993, the Harvard Six Cities study, 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 particulate matter forms in the atmosphere from precursor gases. For example, sulfate comes from SO₂, nitrate from NO₂, and ammonium from ammonia. Soot is directly emitted from combustion and consists of black carbon and organic compounds. Particulate matter can cool the climate locally by reflecting sunlight away from Earth's surface.

Sulfur dioxide (SO₂), an acidic and corrosive gas, is mainly produced by burning crude oil and coal. These fuels often contain sulfur compounds, and their combustion generates SO₂. In Europe and North America, SO₂ is mostly found in areas with significant shipping and industry, as road traffic fuels are regulated. Smaller amounts of SO₂ are released from smelting and volcanoes.

High concentrations of SO₂ in the air lead to the formation of other sulfur oxides (SOₓ). SOₓ can react with other compounds in the atmosphere to form small particles, contributing to particulate matter pollution. At high concentrations, gaseous SOₓ can harm plants by damaging leaves and reducing growth. Further oxidation of SO₂, mostly in cloud droplets, forms sulfuric acid (H₂SO₄), which is part of

Exposure

Air pollution affects people differently around the world and among different groups. Children are more exposed because they breathe more quickly and are closer to the ground, where pollution from cars and dust is stronger. People who do heavy physical activity also breathe in more pollutants than those who are resting. To reduce exposure, people can wear high-quality face masks or use air purifiers.

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

For some pollutants, like black carbon, exposure near busy roads or during traffic can be a major source of pollution, even if it happens for short periods. Much of the daily exposure to pollution occurs in brief moments of high concentration.

Air pollution affects many people, but some groups are more exposed. In many places, people of different races and income levels face unequal exposure to pollution. This is especially true in countries with large income and healthcare gaps, such as the United States. Polluting industries and roads are often located in poorer communities. People in these areas are more likely to work outdoors, increasing their exposure. Those living in public housing, who often have low incomes 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 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, which suggests that pollution is highest in countries focused on manufacturing but without strong environmental rules. Indoor air pollution is worst in low-income countries, especially in Southeast Asia, the Western Pacific, and Africa.

Outdoor air pollution is usually found in crowded cities. As cities grow quickly, especially in tropical areas, air pollution causes more deaths from illnesses. Indoor air 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 (tiny particles) and other harmful substances are released near the homes of about 1.6 billion people. Around 900 million of these people live near facilities that release large amounts of pollution, such as power plants, refineries, ports, and mines.

Health effects

Air pollution is a major cause of many serious health problems, such as COPD (a 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 the world’s population lives in areas where air pollution levels are higher than WHO’s recommended limits. Even at very low levels, fine particles in the air can still cause harm.

Pollutants that are strongly connected to health problems include tiny particles, carbon monoxide, nitrogen dioxide (NO₂), ozone (O₃), and sulfur dioxide (SO₂). Fine particles are especially harmful because they can enter the bloodstream through the lungs and reach other organs. Air pollution causes disease by causing inflammation, 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 affected by air pollution. Pregnancy is also riskier when exposed to air pollution. People in communities with low income or from minority groups are more likely to suffer from pollution than those in wealthier communities. Lower-income groups may have less access to healthcare.

Estimates of deaths caused by air pollution vary. A 2024 study found that air pollution was linked to 8.1 million deaths in 2021, more than one in eight deaths worldwide. Outdoor air pollution from tiny particles (PM₂.₅) was the biggest cause of death (4.7 million), followed by indoor air pollution (3.1 million) and ozone (0.5 million).

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

A 2019 study found that in 2015, air pollution caused about 8.8 million deaths, with 5.5 million of these being premature deaths from human-caused pollution. On average, air pollution reduced life expectancy by 2.9 years globally in 2015, much more than the 0.3 years lost due to all forms of direct violence.

The number of deaths from air pollution in different regions depends on how much pollution people are exposed to, how large and old the population is, and the overall health of the people.

In some countries, more than 20% of deaths are linked to air pollution, such as in 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 U.S., this number is less than 3%.

In total, 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 premature deaths each year are linked to air pollution. In the U.K., about 17,000 deaths in 2021 were due to air pollution, and in the U.S., about 64,000. Nigeria, Indonesia, and Pakistan each saw over 200,000 deaths from air pollution.

Burning fossil fuels is the biggest source of air pollution-related deaths. It is estimated that 4.5 million people die each year from pollutants released by power plants and vehicle exhaust. Tiny particles (PM₂.₅) from coal-fired power plants may be more harmful than other types of fine particles.

The WHO estimates that pollution from cooking causes 3.8 million deaths each year. A 2021 study found that cooking-related pollution caused 3.1 million deaths.

There is strong evidence that air pollution increases the risk of heart disease, including stroke, high blood pressure, and heart disease. Air pollution is responsible for 27% of global stroke deaths and 28% of heart disease deaths. The risks are highest in areas with high pollution levels, such as parts of Asia, for older people, and for 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 increases the risk of heart disease, but it likely involves harmful chemical reactions and inflammation in the body.

Air pollution is linked to more cases of COPD, hospital visits, and deaths. COPD is a common disease that causes trouble breathing and is the fourth leading cause of death globally. Nearly half of all COPD deaths are due 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 make them more likely to develop COPD later in life.

Air pollution is also linked to more asthma cases and worse symptoms, especially in children. For adults, tiny particles (PM₂.₅) and nitrogen dioxide (NO₂) may also increase the risk of developing asthma. Short-term exposure to ozone can make asthma worse in children. There is limited evidence that ground-level ozone and PM₂.₅ may increase the risk of life-threatening asthma attacks in children.

In 2019, about 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. People exposed to nitrogen dioxide (NO₂) and black carbon were more likely to develop lung cancer.

Outdoor air pollution may increase the risk of other cancers, but the evidence is not as clear as it is 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 or 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 increases the chance of a baby being born with a low birth weight. These effects may happen because pollutants directly harm the placenta or fetus, or indirectly by harming the mother’s health through inflammation and harmful chemical reactions.

In 2021, more than a third of all preterm births were linked to air pollution. It caused over half a million newborn deaths, which is a quarter of all deaths in newborns. The source of tiny particles (PM₂.₅) varies by region. In South and East Asia, pregnant women are often exposed to indoor air pollution from cooking with wood or other fuels, which causes over 80% of pollution in the region. In the

Social and environmental impacts

Water in the atmosphere is naturally slightly acidic. Some pollutants 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). HCl is produced when coal is burned. H₂SO₄ forms from sulfur dioxide (SO₂), which comes from burning coal and oil, as well as from industrial processes like smelting. HNO₃ forms from nitrogen dioxide (NO₂), which is created during high-temperature combustion. The term "acid rain" includes not only rain but also pollution from hail, fog, and snow.

Acid rain caused serious damage in the 1970s, such as lakes becoming more acidic and forests dying in Northern Europe. When water and soil became more acidic, important nutrients like magnesium and calcium dissolved and were washed away. Other harmful elements, like aluminum, became available for plant roots to absorb, which hurt plants. Acid rain also harms buildings and statues made of certain stones, such as marble, calcite, or freestone, because the acid in rainwater chemically reacts with the stone and causes it to erode.

Air pollution can settle on soil or in water, causing problems. For example, ammonia and nitric acid in the air can add too many nutrients to water, a process called eutrophication. At first, extra nutrients help plants grow, but dense plant growth blocks sunlight from reaching the bottom. Plants in lower layers then die, and with fewer plants producing oxygen, oxygen levels drop. This harms living things that need oxygen and can lead to the loss of sensitive species.

Studies have shown that air pollution, especially ozone, affects agriculture. Ozone reduces the ability of plants to perform photosynthesis. One study found that a 1% increase in ozone levels could cost the world economy $10 billion each year. A 1% increase in PM₂.₅ pollution could lead to about $5 billion in losses, especially in colder areas. After air pollutants enter agricultural areas, they directly harm crops and soil, and also enter water sources. Air pollution also lowers workers’ productivity by harming their health.

The lockdowns during the COVID-19 pandemic provided a chance to study how air quality affects agriculture. In India, the lockdown improved air quality, which increased surface greenness and plant activity. Both forests and crops benefited, with crops showing the most improvement.

Air pollution harms the economy through health effects, such as reduced work productivity and healthcare costs, and by lowering crop yields. It also affects tourism, biodiversity, forestry, and water quality. Tourism can suffer because of poor visibility and damage to cultural landmarks. People may be more likely to have accidents due to air pollution. Higher levels of nitrogen dioxide (NO₂), for example, are linked to more construction site accidents.

According to a World Bank study, PM₂.₅ pollution in 2019 cost the world economy over $8 trillion, which is more than 6% of global GDP. In India and China, the loss of GDP was over 10%. About 85% of this loss was due to lives lost, and the rest was from increased illness. The cost of lives lost is estimated using the Value of Statistical Life, a number that tries to measure how much people would pay to reduce their risk of dying. This number varies by country and is hard to calculate in low- and middle-income countries.

The OECD estimated that direct costs from productivity loss, healthcare use, and crop damage could reach 1% of global GDP by 2060. The Caspian region and China would be most affected. Air pollution also harms energy production by reducing sunlight that reaches solar panels and making the panels dirty, which lowers their energy output.

History of air pollution

Mummified remains found in Peru, Egypt, and Britain show that people in these areas had blackened lungs due to smoke from open fires in homes with poor ventilation. Complaints about air pollution date back to the Greek and Roman times. Outdoor air pollution became a problem as cities grew, caused by smoke from homes and early industrial activities like smelting and mining. Scientists found that lead levels in Arctic ice cores were about ten times higher during the Roman period than before.

During the Industrial Revolution, outdoor air pollution increased greatly because of the widespread burning of coal. This started in Britain, then spread to other parts of 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 fog reduced sunlight, leading to rickets, a disease in children caused by lack of sunlight and poor nutrition.

Leaders in industrial cities supported the industries because heavy smoke meant economic success, high profits, and better wages.

The miasma theory, popular in the 18th and 19th centuries, incorrectly claimed that diseases like cholera, yellow fever, and malaria were caused by breathing in "bad air" from decaying organic matter. This theory explained why epidemics often happened in summer, when people spent more time outdoors. It led to efforts to improve public sanitation by removing waste from streets and alleys. The theory was disproven when scientists accepted the germ theory of disease in the late 19th century, which showed that germs from infected people or mosquitoes caused illnesses.

In the 1830s, anti-smoke groups formed in Britain, and similar groups appeared in the United States in the 1880s. However, pollution laws were weak because they conflicted with industrial interests. During the 1920s and 1930s, air pollution decreased as coal was replaced by gas and oil, but this improved when World War II began. The worst air pollution in the United Kingdom occurred 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, prompting the government to regulate air pollution. Japan started regulating pollution in 1960, but countries like the Soviet Union and China did not take strong action.

Major technological disasters also caused serious air pollution. The worst pollution disaster happened in 1984 in India, when toxic vapors leaked from a Union Carbide factory, killing at least 20,000 people and harming about 600,000 others.

In the 1950s, smog in developed countries was controlled, but other pollutants remained. 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 many groups worked together. In 1975, scientists discovered that certain chemicals caused a hole in the ozone layer, which protects Earth from harmful sunlight. Global agreements led to the banning of these chemicals. Efforts to fight climate change have been less successful, and greenhouse gas emissions from fossil fuels continue to increase.

Measurement and monitoring

Air pollution can be tracked using several methods. For example, satellites and special tools called remote sensors are used to measure particles, nitrogen dioxide, and ozone. Many areas have networks of monitoring stations, with strong coverage in countries like India, China, Europe, and the United States. However, some highly polluted countries, such as Chad and Iran, have limited monitoring coverage. The number of pollution measurements is increasing because more affordable tools are now available to measure air pollution. These low-cost devices can also be used to check air quality indoors. 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 the health risks it may cause. An AQI is a tool that helps people reduce their short-term exposure to polluted air 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 poses a general risk to health.

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

Air quality models use weather data and pollution information to predict how pollutants spread and change in the atmosphere. Regulatory agencies use these models to determine if a new pollution source would cause pollution levels to exceed safe 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, like air pollution. It can involve changes in how industries and businesses operate, such as creating sustainable manufacturing processes and product designs. It also includes moving towards renewable energy sources, such as solar and wind power.

Various technologies and strategies help reduce air pollution. For example, industrial plants can install systems that remove harmful gases, such as flue-gas desulfurization or catalysts to remove nitrogen oxides (NOx). In the power sector, switching to renewable energy or nuclear power is a very effective way to reduce air pollution. Changing from coal-fired power plants to fossil gas lowers air pollution, but does not completely stop it.

Many countries manage waste through national or city-wide systems. These include managed landfills, systems that capture landfill gas for electricity, and separating waste for proper disposal. In agriculture, air pollution can be reduced by avoiding overuse of fertilizers and not giving livestock too much protein.

The avoid-shift-improve framework groups methods to reduce vehicle pollution into three areas: reducing travel, switching to sustainable transportation, and improving vehicle technology. Cutting down on car use can lower pollution. One way is to build compact cities where people can easily access amenities without needing cars. Walkable cities and better cycling infrastructure also reduce traffic. Working from home is another way to avoid car travel.

Traffic can be shifted to cleaner transportation by increasing public transport use, such as through higher parking fees or free public transit. Reducing traffic jams, which increase fuel use, through charging fees for congestion also encourages cleaner travel options. Finally, vehicles can be improved through better fuel efficiency, cleaner fuels, stricter emission rules, and switching to electric vehicles. For example, buses in New Delhi, India, changed to 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 a 5% increase in walkability was linked to several benefits, including a 6.5% decrease 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 technologies can replace traditional biomass stoves or three-stone fires. For example, using biogas, bioethanol, electricity, natural gas, or liquefied petroleum gas (LPG) significantly reduces air pollution. Improved cook stoves, which use biomass more efficiently, help air quality slightly but can be a temporary solution if clean cook stoves or their fuels are not available. These clean cooking devices, including those powered by fossil fuels, usually have a smaller climate impact than traditional biomass stoves.

Kerosene for lighting can be replaced with efficient LED lights, such as solar-powered LED lights. Using fossil fuels for heating can be replaced with heat pumps that use electricity. Ventilation improves indoor air quality but can cause outdoor air pollution, which may then lower indoor air quality in nearby areas.

Policy and regulation

Although many countries have laws to control air pollution, 43% do not have a legal definition of air pollution. Thirty-four percent lack outdoor air quality standards, and 31% do not have laws to address pollution that comes from other countries. Few countries have laws as strict as the World Health Organization's recommendations.

Some air pollution laws include specific standards for air quality, such as the U.S. National Ambient Air Quality Standards and the E.U. Air Quality Directive. These set limits for how much of certain pollutants can be in the air. Other examples of air quality laws include the Clean Air Act in Britain, the U.S. Clean Air Act, and the TA Luft in Germany. These laws may also set limits on how much pollution can be released, such as from vehicles.

The World Health Organization's Global Air Quality Guidelines suggest ways to improve air quality, similar to national standards. However, these guidelines are not legally required for countries to follow.

Some international efforts to reduce air 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, international efforts to address climate change have been less effective. The 1997 Kyoto Protocol set small pollution reduction goals for some countries but did not have strong rules to ensure compliance. The 2015 Paris Agreement did not set required limits but encouraged countries to improve their goals over time.

In 2022, the UN 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 declaration from the UN Human Rights Council published earlier that year.

Although many countries have air pollution laws, enforcement through legal actions varies. In the European Union, some countries, like France, have been fined by the EU for failing to meet air quality rules. A new Ambient Air Quality Directive allows individuals in the EU to seek compensation for air pollution. In China, legal actions related to environmental issues are rare because they are 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 take action to ensure clean air.