The California Air Resources Board (ARB) GIS Maps and Data set is a collection of vector shapefiles, which contain data related to air quality management and monitoring within California. The ARB compiles the state's emissions inventory and performs air quality and emissions inventory special studies. This dataset contains ambiant air quality data and provides maps of areas that violate the state and national standards. ARB compiles these data in an effort to comply with standards set forth in the U.S. Clean Air Act. System requirements: Geographic Information Systems (GIS) software that reads ESRI shapefile format.