Air pollution is a severe problem that affects human health, forests, and crops worldwide. The main causes of air pollution are industrial activities and individual actions, such as domestic coal fires and car exhausts. The effects of air pollution include damage to human health, acid rain, forest blight, dying fish and plants, respiratory disorders, and the erosion of historic buildings. To address these problems, international steps should be taken by politicians and individuals, such as forcing power stations to install filters, using gas, hybrid or electric cars, introducing speed limits on motorways, and providing more financial support for renewable energy sources.