Ambient air pollutant concentrations are a function of the rate of pollutant emission, wind speed and direction, and the altitude to which pollutants can mix. Air pollution models based at least in part on relationships such as these are being used by control agencies to develop optimum control strategies. Information pertaining to mixing heights and wind speeds are integrated with other meteorological information in order for ESSA to furnish its forecasts of air pollution potential for the contigious United States. The project was performed in order to evaluate mixing height estimates made by the technique designated as the Holzworth method. (Author)