2026-15168Proposed RuleWallet

Air Plan Approval; Michigan; Redesignation of the Detroit, MI Area to Attainment of the 2015 Ozone Standards

Published Date: 7/28/2026

Proposed Rule

Summary

The Environmental Protection Agency (EPA) is proposing to approve a request from the Michigan Department of Environment, Great Lakes, and Energy (EGLE) to redesignate the Detroit, Michigan area to attainment for the 2015 ozone National Ambient Air Quality Standards (NAAQS) because the request meets the statutory requirements for redesignation under the Clean Air Act (CAA). EGLE submitted this request on January 3, 2022, and submitted a supplement to this request on May 18, 2026. The EPA is also proposing to approve, as a revision to the Michigan State Implementation Plan (SIP), the State's updated maintenance plan for the 2015 ozone NAAQS through 2040 in the Detroit area, including motor vehicle emissions budgets for 2035 and 2040, for both volatile organic compound (VOC) and oxides of nitrogen (NO<INF>X</INF>). The EPA is also initiating the adequacy process for these maintenance plan budgets. Additionally, the EPA is proposing to adjust the SIP submission and control measure implementation deadlines for certain Moderate requirements. Finally, the EPA is proposing to take final agency action on an exceptional events request submitted by EGLE on April 15, 2026, and concurred on by the EPA on June 4, 2026.

Analyzed Economic Effects

4 provisions identified: 3 benefits, 1 costs, 0 mixed.

Detroit Redesignation to Ozone Attainment

The EPA is proposing to change the legal status of the Detroit, MI area (Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne Counties) from nonattainment to attainment for the 2015 ozone standard. The decision is based on ozone design values at monitoring sites being at or below 0.070 parts per million (ppm) and relies on EGLE submissions from January 3, 2022 and a supplement on May 18, 2026.

Basic Vehicle I/M Deadline Extended to 2030

The EPA proposes to allow Michigan to delay implementing a Basic vehicle inspection and maintenance (I/M) program in the Detroit area until no later than December 5, 2030. This changes the date by which Basic I/M must be in place in the Detroit area.

Maintenance Plan Approved Through 2040

The EPA proposes to approve Michigan's updated maintenance plan that keeps the Detroit area in attainment of the 2015 ozone standard through 2040 and to approve motor vehicle emissions budgets for the years 2035 and 2040 for volatile organic compounds (VOC) and oxides of nitrogen (NOX).

Wildfire Data Excluded as Exceptional Events

The EPA proposes final action on Michigan's exceptional events request to exclude ozone monitoring data influenced by wildfire smoke on June 29-30, 2023 and July 15, 2025 from the regulatory dataset used to calculate design values. The EPA concurred with EGLE on these dates on June 4, 2026.

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Key Dates

Published Date
Comments Due
7/28/2026
8/27/2026

Department and Agencies

Department
Independent Agency
Agency
Environmental Protection Agency
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