VALIDATION OF SPECIATED NONMETHANE HYDROCARBON COMPOUND DATA COLLECTED DURING THE 1992 ATLANTA INTENSIVE AS PART OF THE SOUTHERN OXIDANTS STUDY (SOS)

Volatile hydrocarbons play an important role in the photochemical form ation of tropospheric ozone, especially in urban atmospheres. In order to assess the significance and relative impact of biogenic and anthro pogenic hydrocarbon emissions as precursors of ozone formation, a prog ram to monitor a suite of 56 common nonmethane hydrocarbons (NMHCs), t he 1992 Atlanta Intensive, was implemented as part of the Southern Oxi dants Study (SOS). During the last decade, Atlanta has averaged approx imately 12 days of ozone nonattainment per year, typically occurring i n summer during periods of air stagnation. Under current EPA guideline s, this classifies the Atlanta metropolitan area as having a serious o zone nonattainment problem. This study constituted a significant examp le of an intensive data collection effort for NMHCs. Three independent laboratory groups using a common standard operating procedure were in volved in the analysis of both time integrated (hourly) and discrete c anister samples collected over a wide perimeter in the Atlanta area du ring August-September, 1992. A total of 3,185 chromatograms were gener ated during the course of the intensive. The total NMHC data set was v alidated after the multiple factors affecting its reliability were com prehensively examined. This paper presents the systematic procedure us ed to validate the 1992 Atlanta Intensive NMHC data; that procedure is currently being used to validate other large sets of data, and is exp ected to be incorporated in upcoming SOS air quality measurement studi es.