Composition of air

The air we breathe is 99% nitrogen and oxygen with other gases making up just 1%. Since the industrial revolution, more and more harmful pollution is being released into our air. This pollution is a major cause of disease, especially in cities but also near industry.

What are the typical air pollutants?

While some air pollution comes from nature, the primary sources are from human activities. These pollutants have both long and short-term effects on human health, as well as being detrimental to wildlife and the environment.

Nitrogen dioxide (NO2)

An orange gas. Breathing it results in shortness of breath and coughing. It inflames the lining of the lung and reduces immunity to lung infections such as bronchitis.

Sulphur dioxide (SO2)

A colourless gas that can cause coughing, tightening of the chest and narrowing of the airways.

Carbon monoxide (CO)

A colourless and extremely toxic gas, produced by the incomplete combustion of fuels. It affects the way oxygen is moved around the body by the blood. Breathing low levels can give us headaches, but large concentrations can kill.

Particulate matter (PM)​

Tiny particles with a diameter of less than 2.5 micrometers (PM2.5) that can penetrate deep into the lungs and cardiovascular system, increasing the risk of disease. These particles also form smog, which is often found in densely populated cities.

Ozone (O3)

A harmful form of oxygen that causes breathing difficulties. Interestingly, Ozone in the upper atmosphere reduces harmful UV irradiation from the sun.

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Sources of air pollution

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  • 1. Natural sources

    Volcanoes, for example, produce vast amounts of dust and toxic gases

  • 2. Agriculture

    Emits methane and ammonia

  • 3. Electricity generation using coal and oil

    Up to 60% of sulphur dioxide is generated from energy production and distribution

  • 4. Industrial wastes

    High in toxic gases and other harmful chemicals

  • 5. Vehicles

    Fuel combustion is the main source of air pollution. Vehicles generate more than 40% of emissions of nitrogen oxides

  • 6. Buildings

    Generate soot and carbon monoxide, particularly if coal is used for cooking and heating

  • 7. Household items

    Some can release gases and chemicals

Enviromental effects of air pollution

Climate change

Carbon dioxide, carbon black, methane and aerosols affect the amount of heat that stays inside the earth as well as the amount of sunlight that hits the surface. This is increasing the average temperature of the earth and causing dangerous changes to our climate.

Acid rain

Acid rain damages forests and the soil, as well as poisoning lakes which make them toxic to crayfish, clams, fish and other aquatic life.

Ozone layer depletion

There is a layer of ozone in the atmosphere protecting our planet from the sun’s intense UV irradiation. Some pollutants react with ozone, reducing its concentration, making us more vulnerable to UV light.

Learn more about air pollutants

> European Environment Agency
> National Geographic