Air pollution comes from many different sources. Natural processes that affect air quality include volcanoes, which include sulfur, chlorine, and ash. Many forms of pollution are human-made. Industrial plants, power plants and vehicles with internal combustion engines produce nitrogen oxides, VOCs, carbon monoxide, carbon dioxide, sulfur dioxide and particulates. In cities, cars are the main source pollutant. Other human-made sources include aerosol sprays and leaky refrigerators, as well as fumes from paint, varnish, and other solvents. One thing about air pollution is that it doesnt stay in one place.Winds and weather flow the pollution around locally.