Feature  Air quality data  Emissions data  Population density and degree of urbanization  Traffic and commuting patterns  Meteorology The process of designating areas that meet or do not meet these standards is very resource intensive. It would not have been possible to accomplish this task without the use of GIS. BAQ uses Esri ArcGIS 9.3 desktop and server products for performing spatial analysis, modeling, managing spatial data, creating maps, and disseminating the geographic information via Web services. The data layers used in nonattainment boundary designation were acquired from a number of sources. South Carolina state agencies maintain GIS database repositories and provide data via Web services or data download option. BAQ maintains Microsoft SQL Server and Oracle databases of air quality and emissions inventory data. The locations of all ambient air monitoring stations A trajectory density map of the Aiken area shows high ozone days. were acquired as GPS coordinates that were differentially corrected. Facilities in South Carolina must obtain operating permits based on the quantity of the pollutants to be emitted. The locations of permitted facilities are provided as either GPS coordinates or mapped using county orthophotos or 1:24,000-scale National Aerial Photography Program (NAPP) digital orthophoto quarter quadrangles (DOQQs). For areas containing an ozone monitoring station that showed an exceedance, that area and the neighboring counties were carefully evaluated using the nonattainment criteria. U.S. Census data from the American Community Survey (ACS) was helpful in analyzing the population to determine the degree of urbanization and understand commuting patterns. Since motor vehicle emissions are a significant contributor to ozone formation, the daily vehicle miles traveled were collected by the South Carolina Department Continued on page 28 ArcUser Summer 2010 27 Trajectory Analysis System allows users to load trajectories into a Microsoft SQL Server database and query the data. www.esri.com