STI assisted the U.S. Environmental Protection Agency (EPA) in a national assessment of the Photochemical Assessment Monitoring Stations (PAMS) network, which is used to monitor ozone, NOx, and volatile organic compounds (VOC). STI assessed the existing network and identified and summarized the monitoring activities that exceeded the newly issued PAMS monitoring requirements. STI then performed multiple assessments of the monitoring sites and ranked each site according to its ability to meet the monitoring objectives. Using this information, STI provided the EPA with national, regional, and site-specific recommendations to improve the network and meet PAMS objectives.