Atmospheric dispersion modeling is the
mathematical simulation of how
air pollutants disperse in the ambient
atmosphere. It is performed with computer programs that solve the mathematical equations and
algorithms which simulate the pollutant dispersion. The
dispersion models are used to estimate the downwind ambient
concentration of air pollutants or toxins emitted from sources such as industrial plants, vehicular traffic or accidental chemical releases. They can also be used to predict future concentrations under specific scenarios (i.e. changes in emission sources). Therefore they are the dominant type of model used in air quality policy making. They are most useful for pollutants that are dispersed over large distances and that may react in the atmosphere. For pollutants that have a very high spatio-temporal variability (i.e have very steep distance to source decay such as
black carbon) and for
epidemiological studies statistical land-use regression models are also used.