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News Releases from HeadquartersAir and Radiation (OAR)

EPA Finalizes Ozone NAAQS, Retaining Current Standards

Trump Administration meets 5-year statutory deadline, congressional intent for second time in Clean Air Act history

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EPA Press Office ( )

WASHINGTON (December 23, 2020) — Today, the U.S. Environmental Protection Agency (EPA) is announcing its decision to retain, without changes, the 2015 ozone National Ambient Air Quality Standards (NAAQS) set by the Obama-Biden Administration. With this action, EPA is following the principles established in the earliest days of the Trump Administration to streamline the NAAQS review process and to fulfill the statutory responsibility to complete the NAAQS review within five-years. Today’s action marks the second time in Clean Air Act history that the agency has completed an ozone NAAQS review within the congressionally mandated five-year timeframe. This is a needed departure from previous administrations' failure to meet statutory deadlines, often taking years longer under court-imposed deadlines to complete reviews.

“For only the second time in agency’s history, EPA is fulfilling its statutory obligation to complete NAAQS review for ozone within a five-year time frame,” said EPA Administrator Andrew Wheeler. “Our actions today show the Trump Administration is fulfilling its promise of protecting human health and environment for all Americans, regardless of where they live.”

The decision to retain the existing ozone standards comes after careful review and consideration of the most recent available scientific evidence and technical information, consultation with the agency’s independent science advisors, and consideration of more than 50,000 public comments on the proposal.

Since the beginning of the Trump Administration, EPA has re-designated to attainment eight nonattainment areas for the 2008 8-hour ozone standards. In this same timeframe, U.S. nitrogen oxide emissions have dropped ten percent and volatile organic compound emissions have dropped three percent. Similarly, national average ozone concentrations have gone down four percent. Since 1990, national average ozone concentrations have dropped 25 percent.

“With air continuing to get cleaner as states implement existing standards, this measure strikes the right balance between protecting public health while supporting recovering communities... We commend EPA for [retaining] existing ozone standards. This proposal supports local communities now fighting to get back on their feet, while continuing to drive improved air quality under existing programs. It is backed by both EPA and its outside scientific advisors,” said U.S. Congressmen John Shimkus (IL-15), Greg Walden (OR-02), Cathy McMorris Rodgers (WA-05), Bob Latta (OH-05), Brett Gurthrie (KY-02), Pete Olson (TX-22), David McKinley (WV-01), Morgan Griffith (VA-09), Billy Long (MO-07), Larry Buschon (IN-08), Bill Flores (TX-17), Markwayne Mullin (OK-02), Buddy Carter (GA-01), Jeff Duncan (SC-03), Greg Gianforte (MT-At Large), Scott Perry (PA-10), Alex Mooney (WV-02), Glenn Grothman (WI-6), Randy Weber (TX-14), Carol Miller (WV-03), Troy Balderson (OH-12), Dan Newhouse (WA-04), Dan Crenshaw (TX-02), Tom Tiffany (WI-07), Steve Chabot (OH-01), Doug Lamborn (CO-05), Kelly Armstrong (ND-At Large), and Debbie Lesko (AZ-08). 

In May 2018, EPA issued a “Back-to-Basics” memo to improve EPA’s process for reviewing the NAAQS. The memo laid out goals to get EPA back on track with Clean Air requirements, statutory deadlines, and the issuance of timely implementation rules, to ensure continued improvements in air quality across the country. Today’s action is the first NAAQS review to do so and charts a path to continue this statutory responsibility in the future.   


The Clean Air Act requires EPA to set NAAQS for “criteria pollutants.” Currently, ozone (and related photochemical oxidants) and five other major pollutants are listed as criteria pollutants. The law requires EPA to periodically review the relevant scientific information and the standards and revise them, if appropriate, to ensure that the standards provide the requisite protection for public health and welfare.

In the prior review of the ozone standards, which was completed in 2015, the Obama-Biden EPA increased the stringency of the levels of the ozone standards to 70 parts per billion (ppb), from the 2008 standard of 75 ppb.

Learn more about EPA ozone standards at: