The Environmental Protection Agency (EPA) has used ISCST3 to estimate concentrations of particulate matter (PM) at or beyond the property line. The modeled concentrations can be used to limit emissions from stationary and fugitive sources. The regulatory limits of PM include limits for PM₁₀, PM_2.5, and PM_coarse (PM_c). The EPA has considered transitioning to the use of AERMOD for predicting concentrations on the basis that AERMOD uses “better science”. Both AERMOD and ISCST3 use a Gaussian plume model to predict concentrations, but AERMOD has a more detailed set of meteorological inputs. Two other models that can be used to predict downwind concentrations are a backward Lagrangian stochastic model (WindTrax), and a forward Lagrangian stochastic model (AUSTAL View). The dispersion modeling program chosen by EPA to predict property line concentrations will have a direct effect on the cotton ginning industry. Each model may yield different results. Inaccurate predictions of property line concentrations for cotton gins could result in the unjust denial of air quality permits. It is important that the predicted downwind concentrations using ISCST3, AERMOD, WindTrax, and AUSTAL View be evaluated relative to appropriate regulations of the cotton ginning industry.