A steady-state two-dimensional diffusion model suitable for predicting ambient air pollutant concentrations averaged over a long time period (e.g., month, season, or year) and resulting from the transport of pollutants for distances greater than about 100 km from the source is described. Analytical solutions are derived for the primary pollutant emitted from a point source and for secondary pollutant formed from it. Depletion effects, whether due to wet or dry deposition or chemical conversion to another species, are accounted for in these models as first order processes. Thus, solutions for multiple point sources may be superimposed. The analytical theory for the dispersion of a primary pollutant is compared with the numerical predictions of a plume trajectory model for the case of steady emission from a point source. Good overall agreement between the two models is achieved. The theory for the dispersion of a secondary pollutant is compared with measurements of the annual average sulfate concentration in the U.S. Calculations are carried out using SO2 emissions from electric power plants in the United States as a source inventory.

Project Officer: Kenneth L. Demerjian. Massachusetts Institute of Technology "June 1979." "EPA-600/4-79-037." Includes bibliographical references (pages 22-24).