A review of national monitoring networks in North America

Over 4300 monitoring sites operate in North America as part of three nation air quality monitoring networks (the Canadian – National Air Pollution Surveillance (NAPS) network; the United States – State and Local Air Monitoring Stations (SLAMS) and National Air Monitoring Stations (NAMS), and the Mexican – Metropolitan Networks of Mexico). These three networks as well as the recently implemented US Photochemical Assessment Monitoring Stations (PAMS) are reviewed in terms of their design objectives, siting criteria, quality assurance, and data analysis requirements. The principal objective of this paper is to review the current state of national air quality monitoring networks in North America and to assess the effectiveness and adequacy of these networks in addressing the critical needs of the various user communities they were designed to serve. The review specifically focuses on the network contributions to the measurement of ozone, particulate matter (PM10 and PM2.5) and their associate precursor compounds. Network data and analysis needs for the air quality management/regulatory and science communities are compared and contrasted with several illustrative examples of data analysis applications supportive of the needs of the user communities provided. Specific performance issues regarding PAMS instrumentation and/or measurements methods, quality assurance and data analysis and distribution are reviewed and recommendations made with regard to improvements for consideration in future upgrades of national networks.