From the Document: "The Clean Air Act (CAA) requires the U.S. Environmental Protection Agency (EPA) to review the standards for national ambient air quality every five years. In 2018, EPA announced strategies to expedite the National Ambient Air Quality Standard (NAAQS) review process while concurrently disbanding a pollutant-specific scientific review panel that has historically advised agency staff during their reviews. Although the CAA allows the EPA Administrator to specify the procedures for review of the NAAQS, past EPA reviews and revisions have garnered considerable congressional oversight. This In Focus discusses the status of EPA's current NAAQS reviews for ozone and particulate matter (PM), which EPA intends to complete in 2020, and issues of potential interest to Congress."
CRS In Focus, IF11288
Congressional Research Service: https://crsreports.congress.gov/