This paper presents a mathematical model for a quantitative evaluation of the polluting impact of single stack polluting facilities. Parameters are introduced quantifying both the maximum probable impact and the long-term time averaged impact. Realistic pollutant dispersion and stack performance models are employed. Local meteorological statistics are taken into account for the prediction of the spatial distribution of long-term pollution loads. The local population distribution is used for the evaluation of the overall polluting impact of the unit. The parameters introduced are suitable for quantitative evaluations of alternative stack designs and locations and may be used in models optimizing the location and stack design of polluting facilities. The methodology is applied to the case of an existing unit in the region of Thessaloniki - Greece.