Final rule · 2026-05601

Determination of Attainment by the Attainment Date But for International Emissions for the 2015 Ozone National Ambient Air Quality Standards; Phoenix-Mesa Nonattainment Area, Arizona

The Environmental Protection Agency (EPA or "Agency") is taking final action to determine that the Phoenix-Mesa nonattainment area ("Phoenix-Mesa area") would have attained the 2015 ozone national ambient air quality standards (NAAQS or "standards") by the August 3, 2024 "Moderate" area attainment date, but for emissions emanating from outside the United States. As a consequence of this action, the Phoenix-Mesa area is not subject to the Clean Air Act (CAA) requirements pertaining to reclassification upon failure to attain and remains classified as a Moderate nonattainment area for the 2015 ozone NAAQS. This final action fulfills the EPA's statutory obligation to determine whether the Phoenix-Mesa area attained the NAAQS by the attainment date. As a result of this final action, the State is no longer required to submit attainment and reasonable further progress (RFP) contingency measures for this area.