Proposed rule · 2025-20357

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 proposing to determine that the Phoenix-Mesa nonattainment area ("Phoenix-Mesa area") would have attained the 2015 ozone national ambient air quality standards (NAAQS) by the August 3, 2024 "Moderate" area attainment date, but for emissions emanating from outside the United States. If we finalize this proposed action, the Phoenix-Mesa area would no longer be subject to the Clean Air Act (CAA) requirements pertaining to reclassification upon failure to attain and therefore would remain classified as a Moderate nonattainment area for the 2015 ozone NAAQS. This action, when finalized, will fulfill the EPA's statutory obligation to determine whether the Phoenix-Mesa area attained the NAAQS by the attainment date.