What are important sources of air pollution in India? Mention chief pollutants and their harmful effects.

Air pollution is a serious global public health problem that is managed most effectively by collective (societal) action to control emissions of both primary air pollutants and precursors that react to form secondary air pollutants. Air pollution in India has increased rapidly due to population growth, increase in the numbers of vehicles, use of fuels , bad transportation systems , poor land use pattern, industrialization, and above all, ineffective environmental regulations.

• Sulphur dioxide: When sulfur dioxide combines with water and air, forms sulfuric acid, which is the main component of acid rain. Sulfur dioxide affects the respiratory system, particularly lung function, and can irritate the eyes. Sulfur dioxide irritates the respiratory tract and increases the risk of tract infections.
• Nitrogen dioxide: Nitrogen oxides are critical components of photochemical smog. They produce the yellowish-brown colour of the smog. Elevated levels of nitrogen dioxide can cause damage to the human respiratory tract and increase a person's vulnerability to, and the severity of, respiratory infections and asthma.
• Chlorofluorocarbons: CFCs are unlikely to have any direct impact on the environment in the immediate vicinity of their release. At a global level however, releases of CFCs have serious environmental consequences. CFCs also contribute to Global Warming (through "the Greenhouse Effect"). Although the amounts emitted are relatively small, they have a powerful warming effect.