Environmental pollution

Environmental pollution, contamination of the air, land and water caused by human products. The sources of pollution include chemicals released by industrial processes, exhaust from gasoline-powered vehicles like automobiles, refuse and gases emitted by factories, sewage and garbage disposed of by cities, and pesticides used in agriculture. Greater awareness of health and environmental hazards has created pressure for laws that control the amount of released pollutants. Conservation efforts, such as recycling, also help to reduce pollution, and new technologies allow industry to release fewer pollutants into the environment. The long-term effects of pollution are not yet precisely known, but it is widely believed by scientists that global warming—the heating of the earth's atmosphere as a result of the greenhouse effect—is a threat to most forms of life on the planet.