We previously reported that on June 6, 2017, EPA Administrator Scott Pruitt announced that EPA was extending the deadline for promulgating initial area designations, by one year, for the 2015 ozone National Ambient Air Quality Standards (NAAQS). The Obama Administration promulgated new ozone NAAQS in October 2015, lowering the standards from 75 parts per billion (ppb) to 70 ppb. Under the Clean Air Act, EPA had two years, or until October 1, 2017, to designate areas in the U.S. as being in attainment or nonattainment with the new ozone NAAQS. The one-year extension would have pushed the deadline for those designation to October 1, 2018.

On August 1, 2017, 15 states and Washington D.C. filed a petition in the D.C. Circuit Court challenging EPA’s one-year delay of the ozone NAAQS deadline. Then, on August 2, 2017, EPA changed course and withdrew the extension. Now, EPA must designate areas as being in attainment or nonattainment with the new, 70 ppb ozone NAAQS by October 1, 2017.

More information about the ozone NAAQS and area designations is available on EPA’s website.