A preliminary investigation was carried out by the US Environmental Protection Agency (EPA) on the impact of regional ozone concentrations on climate change in the country. The main objective of the investigation was to enhance the ability of air quality managers to consider global change in their decisions through improved characterization of the potential effects of global change on air quality, including O3, PM, and Hg. An integrated assessment framework was designed that supported the research and development efforts within the EPA and the academic research professionals. This design recognized the challenges of bridging spatial scales, temporal scales, and disciplines that characterize the global change and regional air quality problem. A major component of the assessment approach involved the development and application of global to regional climate and air quality modeling systems.