The major sources of air pollution in urban areas are growing industrialisation and increasing traffic of vehicles. Smoke and effluents emitted by the industrial units are responsible for industrial pollution, especially in case of such industries like iron and steel, paper, chemicals, etc. Small scale industries make their own contribution to air pollution. Thermal power plants release high quantity of ash and other pollutants into air.
Harmful effects of air pollution:

1. It can cause irritation of the eyes, nose and throat, leading to upper respiratory infections.
2. It affects the health of people and animal in the long run.
3. It can damage crops and forests.
4. It can contaminate and destroy the food supply.
5. It results in global warming caused by carbon dioxide building up in the environment.