Where are the areas of exceedances for the current and proposed ozone standards?

The exceedances of the current 1-hour 120 ppb ozone standard have been evaluated using data from 600 monitoring stations in the OTAG region. The ozone database compiled for these analyses is extremely comprehensive, including data from routine stations as well as from several research-oriented networks not normally reported in the EPA's national database. The entire network includes 102 urban sites, 259 suburban sites, and 238 rural or remote sites (13 sites in the network are not classified). The spatial pattern of the current (1991-1995) exceedances shows that the Washington-New York corridor, Chicago, Atlanta, Dallas-Ft. Worth, Houston, St. Louis, are the major metropolitan areas that exceed the standard two or more times a year. Spatial extrapolation from the monitoring sites can yield estimated areas where exceedances of the standards occur. The results indicate that virtually all areas where exceedances of the current standard occur are confined to the near vicinity (<100 miles) of the above metropolitan areas. In contrast, areas exceeding the proposed 8-hour 80 ppb ozone standard extend further from the major metropolitan areas and include a large portion of the central part of the OTAG domain.