Field studies were conducted in the northeastern United States during the summers of 1979 and 1980 to obtain data for development and validation of urban and regional scale photochemical air quality simulation model and to study the physical and chemical processes important in long-range pollutant transport. This program consisted of four major components: (1) Regional mapping of pollutants over the northeastern U.S. using in situ aircraft sampling, airborne lidar, and surface sampling sites. (2) Eulerian and Lagrangian aircraft sampling of urban plumes and interacting urban plumes from their source areas to distance where they blend with the the regional backgrond burden (3) Removal of pollutants by dry deposition to the surface and venting by clouds from the mixed layer to a more stable cloud layer. (4) Deployment of Lagrangian atmospheric markers (tetroons) to track specific atmospheric air volumes for subsequent sampling and to obtain data for uncertainty analysis of diagnostic transport models. A brief overview of the program is presented with preliminary results of analyses for each of the above components.