The Industrial Source Complex (ISC) model is currently the most popular air pollutant dispersion model approved for use by the United States Environmental Protection Agency (EPA) for modeling the dispersion of particulate matter. Agricultural sources of particulate pollutant are among the sources affected by the use of this model. The authors feel that the application of the parameters of the Gaussian dispersion equation, upon which the ISC model is based, is incorrect and results in extreme inaccuracy in estimation of concentrations of particulate downwind from a source. A new dispersion model, the Fritz-Zwicke Model ^&169;, has been developed by the authors to more accurately predict downwind concentrations of particulate.