This report was prepared as part of the Ohio River Basin Energy Study (ORBES), a multi-disciplinary research program supported by the Environmental Protection Agency. The extensive air quality analysis undertaken for the ORBES included examination of pollutant emissions and resulting concentrations under various policy assumptions; collection of additional particulate and sulfur oxide measurements from the utilities for use in the analysis of current conditions; evaluation of the meteorological conditions under which maximum pollutant concentrations are likely to occur; examination of the validity of using conventional dispersion models for predicting worst-case pollution conditions; and cataloguing meteorological conditions under which regional pollution episodes occur. In this report, the focus is on the factual materials used to formulate the key air quality findings set forth in the main report of this study. It draws from Volumes II and III of the same series. Volume II is entitled 'Air Quality and Meteorology in the Ohio River Basin: Baseline and Future Impacts;' Volume III, 'Selected Impacts of Electric Utility Operations in the Ohio River Basin (1976-2000):An Application of the Utility Simulation Model.'