Policy Assessment for the Reconsideration of the National Ambient Air Quality Standards for Particulate Matter

This U.S. Environmental Protection Agency (EPA) Policy Assessment evaluates the latest scientific evidence and policy considerations supporting the reconsideration of the National Ambient Air Quality Standards (NAAQS) for particulate matter (PM₂.₅ and PM₁₀). The assessment synthesizes findings from the Integrated Science Assessment, exposure and risk analyses, and air quality data to examine whether the existing standards provide adequate protection for public health and welfare, as required under the U.S. Clean Air Act. It focuses on the health effects associated with both short- and long-term exposure to particulate matter, particularly among vulnerable populations.

The report provides a comprehensive evidence base to inform regulatory decision-making by assessing policy options for revising or retaining the PM standards. It discusses the scientific rationale for strengthening the annual PM₂.₅ standard, evaluates uncertainties in the evidence, and considers public health, environmental, and welfare impacts. Although developed for the U.S. regulatory context, the document is a valuable reference for policymakers, air quality practitioners, and researchers seeking to understand how health evidence can be translated into ambient air quality standards and air quality management policies.