Air pollution

Air pollution, contamination of the atmosphere by harmful vapors, aerosols, and dust particles, resulting principally from the activities of humans, but to a lesser extent from natural processes. Natural pollutants include pollen particles, saltwater spray, wind-blown dust, and fine debris from volcanic eruptions. Pollution attributable to humans includes the products of fossil fuel combustion (from municipal, industrial, and domestic furnaces and automobiles): carbon monoxide, lead, oxides of nitrogen and sulfur dioxide, and smoke particles; crop spraying; and atmospheric nuclear explosions. Most air pollution arises in the urban environment, with a large portion coming from the automobile. Pollution control involves identifying the sources of contamination, developing improved or alternative technologies and sources of raw materials, and persuading industries and individuals to adopt these, if need be under the sanction of legislation. Key areas for current research are automobile emission control, the recycling and thorough oxidation of exhaust gases, the production of lead-free gasoline, and the development of alternatives to the conventional internal combustion engine.