Global climate change over the next century is predicted to have a direct impact in future meteorology (e.g. temperature, downward solar radiation, precipitation frequency) over the North America which, in turn, impacts air quality. The objective of this study is to assess the impacts of global climate change on regional air quality over North America (continental U.S, South Canada and North Mexico). We focus on O3 and PM2.5 (PM with an aerodynamic diameter less than 2.5 ìm) as they have suspected health effects. Nine (9) month summer episodes (JJA) in both historical (i.e. 2000 – 2002) and future years (i.e. 2049 - 2051) are simulated using US EPA's Models3 modeling system, MM5/SMOKE/CMAQ. Meteorological inputs to the CMAQ chemical transport model are developed by downscaling GISS Global Climate Model outputs using MM5. Both the direct (impact of climate change on meteorology) and indirect impacts (those caused by emission changes due to either/both controls and climate change) are evaluated using two different cases. In the first case, the impacts of changes on air quality by climate alone are examined by keeping emissions sources, activity levels and controls constant. In the second case, the future pollutant concentrations are estimated based on changes in climate and emissions using IPPC A1B emission scenarios and planned controls.