The paper summarizes combustion emissions using the results of past and ongoing research programs in U.S. emissions trends and detailed inventories, due to the availability of data and the distribution of total U.S. emissions, with emphasis on SO2 and NOx. The discussion includes both magnitude and transport emissions parameters, a review of the general methodologies employed by the referenced research, and a summary of results regarding aggregated, combustion emissions categories. Combustion categories are the most significant sources of SO2 and NOx emissions. Utilities contributed nearly 70% of the 1985 anthropogenic emissions of SO2. The two major sources of NOx in 1985 were utilities and transportation. On the other hand, VOC emissions in 1985 came from combustion and non-combustion sources, principally evaporative fugitive sources, in approximately equal amounts.