The major pollutants that cause air pollution are industries, power plants, road transport and domestic use of coal and fire-wood. Nuclear power plants also contribute to air pollution.
More than 130 crore urban people of the world are exposed to the danger of air pollution. While many cities in the developed countries have been able to lessen air pollution, in developing countries the air pollution problem specially in cities has worsened. Major pollutants like carbon-di-oxide, sulfur-di-oxide, particulate matter, lead compounds and carbon mono oxide have posed as serious health hazards.