EPA Determination of Attainment for Phoenix-Mesa Under 2015 Ozone Standards

EPA Rules & Proposed Rules

Published April 6th, 2026

Detected April 4th, 2026

Summary

The EPA issued a correction to its earlier determination that the Phoenix-Mesa nonattainment area in Arizona has attained the 2015 Ozone National Ambient Air Quality Standards by the applicable attainment date, notwithstanding international emissions. The determination was made under Clean Air Act provisions addressing international emissions contributions.

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What changed

The EPA corrected a determination originally published on March 23, 2026, regarding the Phoenix-Mesa nonattainment area's attainment status under the 2015 Ozone National Ambient Air Quality Standards. The correction addresses the EPA's finding that this Arizona nonattainment area achieved the ozone standard by its attainment date when international emissions contributions are excluded from consideration. The determination relates to the 2015 ozone NAAQS and is codified under 40 CFR Part 52.

Regulated entities and state environmental agencies in the affected area should note that this attainment determination may affect future Clean Air Act obligations, including potential redesignation proceedings or relaxation of nonattainment area requirements. No immediate compliance actions are required as a result of this determination. The EPA's determination applies specifically to the Phoenix-Mesa area under the cited docket EPA-R09-OAR-2025-2833.

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Rule

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

A Rule by the Environmental Protection Agency on 04/06/2026

1.
This document is a correction of a document that was published on 03/23/2026.

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- Document Details Published Content - Document Details Agency Environmental Protection Agency Agency/Docket Numbers EPA-R09-OAR-2025-2833 FRL-13057-02-R9 CFR 40 CFR 52 Document Citation 91 FR 17144 Document Number C1-2026-05601 Document Type Rule Page 17144
(1 page) Publication Date 04/06/2026 Published Content - Document Details

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Document Details Published Content - Document Details Agency Environmental Protection Agency Agency/Docket Numbers EPA-R09-OAR-2025-2833 FRL-13057-02-R9 CFR 40 CFR 52 Document Citation 91 FR 17144 Document Number C1-2026-05601 Document Type Rule Page 17144 (1 page) Publication Date 04/06/2026 Published Content - Document Details
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| FRL-13057-02-R9
(2 Documents) | | | |
| --- | | | |
| Date | | Action | Title |
| | 2026-04-06 | | 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 |
| | 2026-03-23 | Final rule. | 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 |

| EPA-R09-OAR-2025-2833
(3 Documents) | | | |
| --- | | | |
| Date | | Action | Title |
| | 2026-04-06 | | 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 |
| | 2026-03-23 | Final rule. | 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 |
| | 2025-11-19 | Proposed rule. | 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 |

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