Ozone Pollution Continues to Decline Under President Trump, EPA Proposes to Retain Existing NAAQS for Ozone

U.S. Environmental Protection Agency (EPA) is announcing its proposal to retain, without changes, the existing, more stringent 2015 National Ambient Air Quality Standards (NAAQS) for ozone. This proposal comes after careful review and consideration of the most current available scientific evidence and risk and exposure information, and with consultation of the Agency’s independent science advisors.

“Under President Trump, the U.S. has made significant progress in reducing ozone concentrations across the nation,” said EPA Administrator Andrew Wheeler. “Based on a review of the scientific literature and recommendation from our independent science advisors, we are proposing to retain existing ozone standards which will ensure the continued protection of both public health and the environment.”

From 2017 to 2019, ozone concentrations fell 4 percent. Since the beginning of the Trump Administration, EPA has also re-designated 13 nonattainment areas for the 2008 8-hour ozone standards to attainment meaning these communities are now breathing cleaner air.

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 a 5-year timeframe. EPA is on track to finalize the 2015 ozone NAAQS review in 2020 – marking only the second time the agency has met the 5-year timeframe in its history. This is a needed departure from the previous administration’s failure to meet statutory deadlines, often taking twice as long to promulgate updated standards.

While consulting the Clean Air Science Advisory Committee (CASAC) on the draft Policy Assessment, which included current scientific evidence and quantitative air quality, exposure and risk analyses, a majority of CASAC members recommending the agency retain the primary standard, and reaching consensus to recommend EPA retain the secondary standard.

As a result of Clean Air Act programs and efforts by state, local, and tribal governments, from 1990-2019, U.S. emissions of nitrogen oxides and volatile organic compounds – air pollutants that contribute to the formation of ground-level ozone – have dropped by 65 percent and 47 percent respectively. During that same time, national average ozone concentrations have dropped 25 percent.