South Coast AQMD has conducted Multiple Air Toxics Exposure Studies (MATES) since 1986 to understand the impacts of air pollution in the region. Work is beginning on a new iteration of the study, MATES VI.

MATES VI aims to comprehensively assess and advance our understanding of cancer and chronic non-cancer risks associated with exposure to air toxics in the South Coast Air Basin, utilizing cutting-edge monitoring, modeling, and data visualization techniques to inform air quality management, public concerns, and policy decisions.

The approach taken by MATES VI is multifaceted. It includes soliciting feedback from a 21-member Technical Advisory Group, conducting a thorough modeling analysis of air toxics cancer risk with an updated emissions inventory, and utilizing real-world measurement data to determine health impacts. An ambitious air monitoring campaign at ten strategically chosen locations in the South Coast Air Basin and Coachella Valley will span a year, providing crucial insights into trends in concentrations and health risks over previous MATES campaigns.

Several significant updates are planned for MATES VI. These include measurements at two near-road sites, an expansion of measurements to the Coachella Valley, enhanced instrumentation to support a comprehensive source apportionment study to capture air toxic sources, ethylene oxide measurements and risk analysis, improvements to the emission inventory and air quality model, and an initial evaluation of brake and tire wear contributions to particulate matter.

The tentative timeline for this study spans from the first Technical Advisory Group (TAG) meeting in October of 2023 to the release of the MATES VI Report and Online Interactive Data Visualization Tools in the 2027-2028 timeframe. Air monitoring for MATES VI is expected to begin in early 2025. Until results are available, MATES V, published in the summer of 2021 provides the most up-to-date assessment of air toxics risk throughout the region.

For more information visit our MATES VI webpage or sign up for alerts on upcoming MATES VI TAG meetings and document releases on our Sign Up webpage (in the Clean Air Plans/CEQA section).