Program determines long-term (seasonal or annual) quasi-stable pollutant concentrations in rural or urban settings using average emission rates from point and area sources and a joint frequency distribution of wind direction, wind speed, and stability. The Gaussian plume hypothesis forms the basis for the calculations. Contributions are calculated assuming the narrow plume hypothesis, and involve and upwind integration over the area sources. Computations can be made for up to 200 point source sand 2500 area sources at an unlimited number of receptor locations. The number of point and area sources can be easily modified within the code. CDM2.is an enhanced version of CDM and includes the following options: 16 or 36 wind-direction sectors; stack-tip downwash; and gradual (transitional) plume rise. The user has a choice of seven dispersion parameter schemes. Optional output includes point and area concentration rises and histograms of pollutant concentration by stability class.