There are numerous sources of air pollution and most of them are attributed to human activities. Industries, fossil fuels burning, modern agriculture, and landfills are some.
Whereas some causes of air pollution are entirely anthropogenic, others are result of naturally-occuring phenomena, such as wildfires, dust storms, animal digestion, and volcanic eruptions.
- Particulate matter: Road dust, wear and tear of brakes and tyres on vehicles, construction activities, sea salt, forest fires, pollen, etc.
- Carbon monoxide: It is produced during incomplete combustion of any fuel like natural gas, charcoal, gasoline, coal.
- Ozone: It is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs). Emissions from industrial facilities, motor vehicle exhaust and chemical solvents are some of the major sources of NOx and VOCs.
- Nitrogen dioxide: Motor vehicles and any combustion of fossil fuels.
- Sulphur dioxide: Combustion of fossil fuels, volcanic eruptions.