A methodology is presented to account for the dispersion of air pollution emissions at a regional level to arrive at ambient ground-level concentrations. Air pollution due to energy is a major concern. This methodology has particular relevance to studies of alternative futures and to long-range environmental policy analysis. The methodology is developed using detailed dispersion model results and a Smeared Concentration Approximation (SCA) Dispersion Model is derived for Wisconsin using the methodology. A preliminary validation for sulfur dioxide and particulate matter pollution indicates that the methodology provides a reasonable picture of the urban air pollution concentrations. Results are presented to demonstrate that dispersion is important and relative impact is not at all proportional to a sector's percentage of total emissions. The results of the use of the SCA method in specific case studies indicates the value the method has for addressing air pollution impacts.