An Ozone Event in Indianapolis

There are doubts concerning the sources of the pollutant ozone in an urban location. Current control regulations,¹ for example, are based on local sources. Many studies suggest that plumes of pollutants released by upwind areas are the cause. For example, New York City has been associated with high O₃ in New England,² Chicago with O₃ in Milwaukee,³ and St. Louis with O₃ in rural Illinois.⁴ Others^5,6 have suggested the problem must be treated on a synoptic scale. In an effort to understand the problem at Indianapolis better, a series of experiments involving aircraft flights were conducted in the Indianapolis area and their results are herein reported. Specifically, a cross country flight of over 100 mi both to the northeast and southwest of Indianapolis, a vertical spiral to 28,000 ft, low level data associated with takeoff and landing of the aircraft, and ground data at four sites, are available for the afternoon of June 9,1976.