On May 1, the U.S. Environmental Protection Agency (EPA) released its final list of county designations under the new National Ambient Air Quality Standards (NAAQS) for Ozone. The new ozone NAAQS was approved in 2015 and tightened the current ozone standard of 75 parts per billion (ppb), last set in 2008, to 70 ppb. Under the list, 209 counties in 22 states are considered to be in nonattainment under the new 70 ppb standard. According to EPA, designations were made based on the most recent three years of certified ozone air quality monitoring data from 2014-2016, as well as recommendations by the states.

Ozone is one of the six pollutants—along with carbon monoxide, nitrogen dioxide, sulfur dioxide, lead and particulate matter—regulated under the Clean Air Act (CAA), and forms when sunlight reacts with volatile organic compounds, such as nitrogen oxides (NOx), emitted from chemical plants, gasoline pumps, oil-based paints, and auto body and print shops. Under CAA, EPA is required to reassess standards for these pollutants every five years. Ozone designations can have a significant impact on county governments, as states and counties serve as co-regulators of CAA standards with the federal government and are ultimately responsible for ensuring that legislation’s goals are achieved and our constituents are protected.

In November 2017, EPA released a partial list of 2,646 counties that were considered in attainment and meet the 2015 standards for ground level ozone. Affected states containing the areas not in attainment – about 420 counties – were notified by the EPA in December 2017 on their intended recommendations, and were given 120 days to provide additional information for the EPA to consider before making final designation decisions.

NACo has previously called on EPA to delay implementation of the 2015 ozone standards until the 75 ppb standard set in 2008 can be fully analyzed for impact, and will continue to work closely with Congress and the Trump Administration to craft clear, concise and workable rules that take into account the role of counties as key regulatory partners with the federal government.