Air pollution facts for kids

Air pollution is when the air around us gets dirty with harmful gases or tiny particles. It's a type of pollution that makes the air unhealthy to breathe. This usually happens because of smoke or other bad gases, like those from burning things.

Even a long time ago, people noticed air pollution. About 2,000 years ago, the Romans complained about smoky air in their cities. Today, many big cities around the world have dirty air. Air pollution is a big problem for human health and for Earth's many ecosystems (like forests and oceans).

Claude Monet's painting of 19th century London smog. It was caused mainly by burning coal fires.

What is Air Quality?

Air pollution can be in the form of a gas, a liquid, or tiny solid pieces. Scientists can also sort pollutants by their chemicals, like oxides (which have oxygen) or acids.

Some pollutants come from natural sources. These include dust, salt from the sea, volcanic ash and gases from volcanoes, smoke from forest fires, and pollen from plants.

Ash from volcanic eruptions is an example of primary pollutants.

Primary and Secondary Pollutants

Air pollutants are usually called either primary or secondary.

• Primary pollutants are put directly into the air. This can be by humans or by nature.
  • Examples: Exhaust fumes from cars, soot (black powder) from smoke, dust storms, and ash from volcanic eruptions.

• Secondary pollutants are made when different chemicals mix in the air. This often happens when primary pollutants react with other things, like water vapor or even sunlight.
  • Examples: Ozone and smog. While ozone high up in the sky protects us from the sun's harmful rays, ozone near the ground can be dangerous for people and other living things.

There are many problems caused by air pollution, like the greenhouse effect and acid rain.

How Humans Cause Air Pollution

Most air pollution made by humans today comes from transportation. Cars, for example, create about 60% of human-made air pollution. The gases from car exhaust, like nitrogen oxide, help create smog and acid rain.

Air pollution from a diesel train.

Pollution from Industries

Many factories and power plants burn fossil fuels (like coal or oil) to get energy. Burning these fuels releases a lot of oxides into the air. For example, burning fossil fuels makes 96% of the sulfur oxides in the atmosphere. Some industries also create chemicals that make poisonous fumes.

Pollution Inside Buildings

Air pollution inside a home.

Air pollution doesn't just happen outside. The air inside homes, schools, and other buildings can also be polluted. Sometimes, the air inside a building, especially if windows are closed, can be worse than the air outside. Many everyday items can pollute the air, such as new carpets, paints, building materials, and furniture.

Acid Rain

Acid precipitation is rain, sleet, or snow that contains acids from air pollution. When fossil fuels are burned, they release oxides into the air. These oxides mix with water in the atmosphere to form acid, which then falls as precipitation.

Acid rain can harm living things like fish and trees by making their environment too acidic. It can also damage buildings made of limestone and concrete.

The Ozone Layer Problem

Smog in Cairo.

The ozone layer is high up in the sky, in the stratosphere. It protects life on Earth from the sun's harmful ultraviolet rays. However, in the 1970s, scientists discovered that some chemicals released into the atmosphere were turning ozone into oxygen. This means more harmful ultraviolet rays could reach Earth. In the 1980s, scientists found that the ozone layer above the South Pole had become much thinner.

Pollution Around the World

Outdoor air pollution is often worst in countries that rely on manufacturing but have not yet focused on environmental rules. Indoor air pollution is most common in low-income countries, especially in Southeast Asia, the western Pacific, and Africa.

Outdoor air pollution is usually highest in crowded metropolitan areas. As tropical cities grow quickly, more people are affected by air pollution. Indoor air pollution, however, is most common in rural areas where people might not have access to clean cooking fuels.

A map published in 2025 by Climate TRACE indicated that tiny particles (PM_2.5) and other harmful substances were released near the homes of about 1.6 billion people. About 900 million of these people lived near "super-emitting" places like power plants, refineries, ports, and mines.

How Air Pollution Affects Health

Air pollution can cause many health problems, especially for children, older people, and those with allergies. For example, studies have shown that air pollution from cars might be linked to some deaths from pneumonia.

The World Health Organization has said that millions of people have died because of health problems caused by air pollution. Some common problems include:

Effects on Farming

Air pollution can also affect how well crops grow. A report from India in 2014 showed that air pollution in 2010 had cut the amount of crops harvested by almost half in some areas compared to 1980. On the other hand, when air quality gets better, crops can sometimes grow better too.

A Look at Air Pollution History

The Industrial Revolution and Smoke

During the Industrial Revolution, outdoor air pollution grew rapidly. This was mainly due to burning large amounts of coal. Factories and buildings in cities became black with soot. Smoke-filled fogs reduced sunlight, contributing to diseases like rickets in children. At the time, heavy smoke was often seen as a sign of wealth and jobs.

Poster in the Soviet Union praising "The smoke of chimneys is the breath of Soviet Russia."

Early Efforts to Fight Pollution

In the 1830s, groups in Britain started to fight against smoke pollution. Similar groups appeared in the United States in the 1880s. However, laws against pollution were weak because they were seen as bad for industry. After World War II, air pollution worsened again.

The United Kingdom had its worst air pollution event during the 1952 Great Smog of London, which caused many deaths. This led to the Clean Air Act 1956. In the US, the 1948 Donora smog prompted the country to start regulating air pollution. Japan followed in 1960.

A terrible pollution disaster happened in 1984 in Bhopal, India. Leaked industrial gases killed many people and affected hundreds of thousands.

In the 1950s, developed countries started regulating smog. Later, acid rain became a big problem, spreading across borders. International cooperation was needed to control it. In 1975, scientists discovered that certain chemicals were creating a hole in the ozone layer. Thanks to international agreements, these chemicals were banned worldwide. However, fighting climate change has been less successful, and greenhouse gas emissions continue to rise.

How We Measure and Track Air Pollution

Monitoring Air Quality

Air quality monitoring in New Delhi, India.

We can monitor air pollution using different methods. Satellites and remote sensing track particles, nitrogen dioxide, and ozone. Many regions have networks of monitoring stations, especially in India, China, Europe, and the US. Low-cost monitors are making it easier to measure air pollution, even indoors. Sensors can also be put on drones to measure pollution higher up.

Air quality indexes (AQIs) help us understand air quality easily. An AQI tells people if the air is good, or if it's dangerous for sensitive groups (like children with asthma), or for everyone.

Predicting Pollution Levels

Map of simulated particle pollution. Wildfire smoke is in green, desert dust is in orange, light blue is sea salt, and white shows sulfate particle pollution.

When we don't have direct data, we can estimate future air pollution levels using models. These models use weather data and information about pollution sources. They help predict how pollutants spread and react in the air. Governments use these models to check if new pollution sources will be acceptable. They can also predict pollution levels under different policy plans.

What Can We Do to Make the Air Cleaner?

Thermal oxidisers help reduce harmful gases from factories.

Electric rickshaws in Nepal.

Tram in Alicante, Spain.

A kettle heated by a solar cooker at the Phugtal Monastery in Ladakh, India.

Air pollution in Shanghai, China, in 2013. China launched a "war against pollution" in 2014, which drastically lowered particle pollution levels across the country.

• Clean Energy: Switching from burning fossil fuels to cleaner energy sources like solar and wind power for electricity is a huge step.
• Cleaner Transportation: Using electric cars, buses, and trains, and encouraging people to walk, bike, or use public transport more often can greatly reduce pollution from vehicles. A study showed that a 5% increase in walkability led to a 6.5% reduction in vehicle miles driven. It also reduced nitrogen oxides and volatile organic compounds emissions.
• Better Industry and Waste Management: Factories can use special equipment called "scrubbers" to clean their emissions. We can also manage our waste better by recycling, composting, and making sure garbage isn't burned openly.
• Clean Cooking and Heating: Many technologies offer clean cooking options. Switching to biogas, bioethanol, electricity, natural gas, or LPG (liquified petroleum gas) greatly reduces air pollution. Improved cook stoves use biomass more efficiently and can be a good temporary solution. Kerosene for lighting can be replaced with efficient LED lights, like solar-powered ones. Burning fossil fuels for heating can be replaced by using electricity in heat pumps. Good ventilation also improves indoor air quality.
• Laws and Regulations: Governments around the world are making laws to limit how much pollution can be released. International agreements, like the Montreal Protocol that helped fix the ozone layer, show that when countries work together, big problems can be solved!

The Right to Clean Air

In 2022, the UN General Assembly recognized the right to a clean, healthy, and sustainable environment as a human right. This resolution is not legally binding.

Many countries have air pollution laws, but how they are enforced varies. In the European Union, countries have been fined for not following air quality rules. In Chile, the right to a healthy environment is in the constitution. This means the government must act to provide clean air.

Interesting Facts About Air Pollution

• Air pollution comes from both human activities and natural sources. Factories, mining, vehicles, forest fires, volcanic eruptions, and wind erosion can all cause it.
• About 92% of the world's population lives in areas where air pollution is higher than what is considered safe.
• Breathing polluted air is thought to shorten an average human life by 1-2 years.
• Babies whose mothers live in areas with heavy traffic have a higher risk of being born with weaker lungs.
• Air pollution is more dangerous for children because their bodies are smaller and their lungs are still developing.
• A child's IQ can be negatively affected by air pollution.
• ADHD can get worse or even be caused by certain chemicals in polluted air.
• Waiting in traffic and breathing in the pollution is thought to increase the chance of a heart attack.
• The 1952 Great Smog of London is believed to have killed 8,000 people.
• Scientists have estimated that by 2050, six million people per year could die because of air pollution.
• Many large cities control how much pollution vehicles can release to help clean the air.
• Deforestation (cutting down forests) is a major cause of air pollution because trees help clean the air.

Images for kids

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  Air pollution from a coking oven.

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  2016 air quality indicator – light colors have lower air quality and thus higher air pollution.

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  Deaths from air pollution per 100,000 inhabitants (IHME, 2019).

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  Aviation is a major source of air pollution.

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  Controlled burning of a field outside of Statesboro, Georgia, in preparation for spring planting.

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  Smoking of fish over an open fire in Ghana, 2018.

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  Dust storm approaching Stratford, Texas, in 1935.

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  Beijing air in 2005 after rain (left) and a smoggy day (right).

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  E-waste processing in Agbogbloshie, Ghana, using open-burning of electronics to access valuable metals like copper.

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  Air quality monitoring, New Delhi, India.

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  Burning of items polluting Jamestown environment in Accra, Ghana.

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  Using public transport like trams can help reduce air pollution.

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  Nets are often used to reduce dust from construction sites.

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  Nitrogen dioxide concentrations as measured from satellite 2002–2004.

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  Before special equipment was installed, the emissions from this power plant in New Mexico had too much sulfur dioxide.

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  Thermal oxidizers are machines that help reduce harmful air pollutants.

See also

In Spanish: Contaminación atmosférica para niños