The report summarizes work done to compare a computer model for estimating air pollution concentrations from multiple sources with measured SO2 and particulate concentrations and with other model calculations. The model is capable of estimating short-term and long-term concentrations, and produces results which are equivalent in validity to results produced with other models. Since the model represents hourly variations in both emissions and meteorological condition, the report considers available sources of data and how these can best be used to estimate parameters for the model. Use of temperature and industrial and commercial activity indexes to estimate seasonal and diurnal variations in emissions is discussed. Use of slow-rise balloon soundings taken in urban areas is discussed as a possible supplement to conventional weather data. Finally, the applicability of using sampled calculations when estimating short-term maximum concentrations is evaluated.