Pollution is caused from natural or man-made actions. There are many types of pollutants produced from a variety of sources. Pollutants are classified as primary or secondary:
Primary Pollutants These are gases or particles that are blown into the air. Historically, the main air pollution problem has typically been high levels of smoke and sulphur dioxide emitted following the combustion of sulphur-containing fossil fuels such as coal, used for domestic and industrial purposes. These days, the pollutant of most particular concern is is carbon monoxide that comes from motor vehicle traffic.
- Sulphur dioxide
- Nitrogen oxides – Road transport is the main source, followed by the electricity supply industry
- Particular matter (PM10, PM2.5 and PM1) – In the UK the biggest human-made sources are stationary fuel combustion and transport.
- Toxic Organic Micro-Pollutants (TOMPS) –
- Benzene – Domestic and industrial combustion and road transport.
- 1,3-Butadiene – Combustion of petrol and other processes such as production of synthetic rubber for tyres.
- Carbon monoxide – Road transport, residential and industrial
- Lead and heavy metals – Smelters and the combustion of coal or iron and steel combustion
Secondary Pollutants These are just as harmful as primary pollutions and are not emitted directly; they form in the atmosphere when primary pollutants join together in a chemical reaction:
- Ozone – Arises from chemical reactions between various air pollutants, primarily NOX and VOCs, initiated by strong sunlight.
- Smog – Industrial and car emissions can react with sunlight
- CFC gas (Chlorofluorocarbon) – Commonly found in cleaning products or refrigerators. They dissolve into the atmosphere causing damage to the ozone.
- Landfills – improper containment can produce water contamination. Gas can be generated if not properly handle, methane, ammonia and carbon dioxide to name but a few
- Acid Rain – Caused by nitric and sulphuric acids and created by burning fossil fuels, it changes the pH of the rain or snow.
Please click on The effects of air pollution page to understand the effects the pollutants have to our health and the environment.