Human activities and natural processes release chemicals into the atmosphere and can result in air pollution. Once in the atmosphere, the chemicals are subjected to various atmospheric processes that control their transport, and can alter their chemical and physical form. The eventual environmental impact of chemicals released to the atmosphere is therefore greatly influenced by these processes.
The impacts of air pollution can range from poor air quality in the close vicinity of a source, to the disruption of natural chemical cycles and physical processes that occur on a global scale. The properties that are attributable to the different environmental impacts of some of the major pollutants are shown in the table below.
| Environmental impact | Pollutant | Pollutant properties |
|---|---|---|
| Reduction of local air quality - affecting human health and vegetation growth, and causing damage to materials. | Lead, volatile organic compounds, sulphur dioxide, nitrogen oxides, carbon monoxide, benzene, 1,3-butadiene, fine particles*. | These chemicals are emitted directly into the atmosphere and are known as primary pollutants. (An exception is NO2 which is mainly a secondary pollutant, rapidly formed from NO released to the atmosphere) |
| *fine particles can be both primary and secondary pollutants. | ||