Dispersion of sulfur dioxide emissions from area sources

Methods used in evaluating surface concentrations of sulfur dioxide emitted generally over an area are described. The most common example of an area source is provided by urban domestic and industrial heating, for which it is necessary to consider the sum of a large number of individual sources over an area of some convenient size. Given an area-source inventory, a simple, systematic procedure for calculating the surface concentration at any point, averaged over an hour, a day, or a year is presented. The basic physical model of atmospheric diffusion employed is the same as for tall-stack emissions. Area-source concentration calculations are a recent development compared with calculations of concentrations from isolated sources. There are discussions of some of the methods now available, but these all require the use of a high-speed electronic computer. The method to be described, although very simple, has been shown to provide results of a precision comparable with that of the more elaborate computer calculations and can be used with confidence for area-source calculations in urban air pollution and regional air quality studies. An even simpler area-source calculation suitable for many air pollution control purposes is also described. The model is described here in such a way that all the calculations can be done by hand. For the purpose of making many applications of the model, it has also been programmed in Fortran