The air pollutants are discharged into the atmosphere in very high concentrations. The concentrations are so high that even the scavenging ability of atmosphere is unable to control their effects.
In urban and industrial regions, the excessive amounts of pollutants adversely damage the health of human, animal’s plants and materials. The pollutants which cause community wide problems are mainly particulate matter, sulphur oxides, nitrogen oxides, carbon monoxides, hydrocarbon, photochemical oxidants and trace metals.
Air pollution is a threat to human health. Effect on health varies according to the intensity and duration of exposure and health status of exposed population. In recent years, it has been observed that indoor air can be more polluted than outdoor air even in cities with relatively poor air quality. It is likely that the risks of health may be more due to exposure the indoor air pollution.
Effects of air pollution may be divided in to two classes. These are acute and chronic effects. Acute effects manifest immediately upon short term exposure to air pollutants at higher concentration. On the other hand, chronic effects become evident only after continuous exposure to low levels of air pollution.