Air Quality GIS tools increase efficiency and accuracy By Elzbieta Covington South Carolina Department of Health and Environmental Control The Clean Air Act forms the framework for all efforts leading to the protection of air quality. The mission of the Bureau of Air Quality (BAQ) at the South Carolina Department of Health and Environmental Control (SCDHEC) is to “conserve and enhance air resources and ensure that ambient air quality is maintained at the highest level.” Projects/Applications at BAQ BAQ protects air quality through regulating emission sources, planning, education, and the implementation of various air quality programs. GIS has become an important tool to assist in environmental decision making at BAQ. South Carolina Ozone Nonattainment Boundary Ground-level ozone is an air pollutant formed by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. The ozone season in South Carolina begins on April 1 and lasts through October 31 of each year. BAQ has developed an extensive ambient air quality monitoring network for ozone and other pollutants. In operation since 1959, the ambient monitoring network is used to establish general or background information in rural areas, determine the effects of NOx and/or VOC emissions from specific sources Protecting on ozone formation, monitor pollutant concentrations in suburban and urban areas, and ascertain interstate and intrastate transport of pollutants. In 2008, there were 16 ozone monitors strategically located throughout the state that had at least three years of quality assured data. These monitors were located in accordance with United States Environmental Protection Agency (EPA) monitor siting guidance. Ozone concentrations are measured 24 hours per day, and 8-hour moving averages are calculated. The maximum 8-hour average is reported each day. In March 2008, based on scientific evidence and human health studies, the EPA lowered the ozone standard to 0.075 parts per million (ppm). Areas where ozone levels violate national ambient air quality standards may be designated as nonattainment areas. BAQ was required to submit new nonattainment boundary recommendations to EPA. The factors considered in the recommendation designation of the new nonattainment boundaries were The AERMOD mapping application allows site visitors to download meteorological and National Elevation Dataset data. 26 ArcUser Summer 2010 www.esri.com