Attainment/Unclassifiable Designations for the 2015 Ozone National Ambient Air Quality Standards (NAAQS) Are Now Final!



On Thursday, November 16, 2017, the United States Environmental Protection Agency (EPA) finalized the designations of 2,646 counties in the United States as attainment/unclassifiable; or unclassifiable in regards to the 2015 ozone NAAQS of 0.070 parts per million (ppm). This standard was reduced from the previously enforceable 2008 ozone NAAQS of 0.075 ppm.

The following counties in Arizona were designated as attainment/unclassifiable:

  • Apache County;
  • Cochise County;
  • Greenlee County; and
  • Santa Cruz County.

These are counties with one or more ambient background monitors attaining the 2015 ozone NAAQS; or counties for which EPA does not have reason to believe are violating the 2015 ozone NAAQS or are contributing to a violation of the 2015 ozone NAAQS in another county. These designations will become effective starting January 16, 2018.

For other areas not addressed in this final rule, the EPA is not prepared to issue final designations and will be addressing these areas in a separate future action.