Abstract. This review briefly illustrates the state of the art in the recognition of the various sources and natural sinks of gaseous pollutants. The removal mechanisms include absorption by vegetation, soil, stone, and water bodies, precipitation scavenging, and chemical reactions within the atmosphere. The nature and magnitude of anthropogenic and natural emissions of the gases (H2S, SO2, N20, NO, NO2, NH3, CO, 08, and hydrocarbons), along with their ambient background concentrations and information on their major sinks identified to date, are discussed. IntroductionThe recent interest in air pollution modeling is based on its potential value in nearly all practical problems involving quantitative consideration of air quality relative to the source location and emission rates. These include the forecasting of undesirable levels of pollution, abatement strategies, long range air resource management programs and urban planning.While considerable effort has been devoted to characterizing emissions from anthropogenic sources and their turbulent transport and convection, very little has been done to determine the extent of emission from natural sources and to characterize the processes that clean the atmosphere. Therefore, for a more realistic air pollution model, it is necessary to quantify natural emissions and removal mechanisms. The purpose of this study is to provide quantitative information on source and removal mechanisms so that a realistic air pollution model can be constructed.Pollutants may be emitted to the atmosphere from many diffuse natural and anthropogenic sources. The natural sources of many gases as shown in Table I far exceed the anthropogenic sources on a global basis. However, because such gases are usually well distributed throughout the atmosphere their concentration, known as the background concentration, is extremely low. Anthropogenic sources of many pollutants are cen-* All associated with