The main sources of air pollution are:
1. Natural sources:
Volcanic eruptions- release poisonous gases like SO2,H2S,CO etc
Forest fires-release smoke and trace gases
Decay of organic matter - release CH4
Pollen grains, fungal spores, bacteria etc
2. Man made sources
Population growth
Deforestation
Burning of fossil fuels
Automobile exhausts
Industrilization
Agricultural activities viz. use to fertilizers, pesticides etc