Air pollution means the ways in which the air is polluted. Air is the most important element of human environment. Man can not live a single moment without air. But we do not think that it is we who pollute this most vital element. Clean air is essential for life. Air is polluted in many ways. For example smoke pollutes air. Man makes fires to cook his food, to make bricks burns refuse, melts pitch for road construction and burns wood. All these things produce heavy smoke and this smoke pollutes air. The another example is that railway engines, power houses,mills and factories use coal and oil. Moreover, buses, trucks and cars use petrol and diesel oil. Again all these things create smoke and cause air pollution. Furthermore, the most serious air pollution also occurs in big cities where there are many mills and factories. Again serious air pollution also occurs in big cities where there are many buses, trucks and cars plying the street everyday. Sometimes men in big industrial area become so sick by inhaling polluted air that they cannot be cured. So proper measures and steps should be taken to prevent air pollution.