Air pollution results from the emission of harmful substances into the air. Human-driven activities and, to some extent, natural sources contribute to air pollution. Forest fires, dust storms, volcanic eruptions, pollen dispersal, sea spray, evaporation of organic compounds and natural radioactivity are some of the natural events that may pollute the air. Human activities that contribute to air pollution include industrial processes, transport, cooking and heating using solid fuels, the use of various household and farming chemicals, and certain agricultural practices such as slash-and-burn.
United Nations Environment Programme
