AIR POLLUTANTS


Air Pollutants

The release into the air of chemicals and particles can cause direct damage to the troposphere (air pollution); alter the composition and function of atmospheric layers (greenhouse effect) or other indirect damages (ozone layer depletion). An air pollutant is a substance in the air that can cause harm to humans and the environment. Pollutants can be classified as primary or secondary. Usually, primary pollutants are directly emitted from a process, such as ash from a volcanic eruption, the carbon monoxide (CO) gas from a motor vehicle exhaust or sulfur dioxide (SO2) released from factories. Secondary pollutants are not emitted directly. One example is ground-level ozone.


The transport sector has become one of the main emitters of polluting compounds in the world and one of the main causes of the greenhouse effect. Through the burning of fuel, motor vehicles, cars and trucks emit a range of health damaging pollutants, such as particulate matter, nitrogen oxides, sulphur dioxide, carbon monoxides and Volatile Organic Compounds (VOCs). Some of the substances in motor vehicle exhaust also cause ‘secondary pollutants’ such as ozone, which are formed through chemical reactions in the air.

Air pollution is especially a problem in urban areas, where there is a lot of traffic. Some pollutants however can travel long distances and may accumulate in suburban or rural areas because of weather conditions such as wind or low pressure.

Main air pollutants are:

Sulphur dioxides (SO2)

Nitrogen dioxides (NO2)

Particulate matter

Ozone (O3)

Carbon monoxide (CO)

Carbon dioxide (CO2)

Heavy metals, such as arsenic (As), cadmium (Cd), lead (Pb) and nickel (Ni)

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