Pure air is always needed for inhaling. If we take pure air, our health improves. On the other hand impure air causes diseases and impairs our health and causes our death. Smoke pollutes the air. It is the root of air pollution. The smoke which is discharged from industries, automobiles and kitchens is the mixture of carbon monoxide, carbon dioxide, methane etc. These are all poisonous gases. These cause lung-cancer, tuberculosis etc. which take a heavy toll of life. The glaring incident is the Bhopal gas leak in December 1984. Thousands of the residents of Bhopal died due to lungs problem which was caused by methylamine gas from the Union Carbide Plant.