Designation of Areas for Air Quality Planning Purposes; Michigan; Technical Amendment
Key claim: Following a Sixth Circuit court ruling vacating the 2023 attainment redesignation, the EPA is amending its regulations to reclassify the Detroit, Michigan area as nonattainment (Moderate) for the 2015 ozone NAAQS.
Abstract
(Rule · Environmental Protection Agency) The Detroit, Michigan area was redesignated to attainment of the 2015 ozone National Ambient Air Quality Standards (NAAQS) on May 19, 2023. On December 5, 2025, the United States Court of Appeals for the Sixth Circuit vacated the Environmental Protection Agency’s (EPA’s) redesignation of the Detroit area. Therefore, pursuant to the Court’s decision, the EPA is making a technical amendment to the part 81 listing for the Detroit area to reflect the area’s designation as nonattainment for the 2015 ozone NAAQS, with a classification of Moderate.
Why this matters
Judicial review can reverse EPA attainment redesignations years after they take effect, restoring stricter nonattainment permitting (e.g., New Source Review) and SIP obligations for affected regions. For Detroit, this technical amendment reinstates Moderate nonattainment status for the 2015 ozone NAAQS, with practical consequences for industrial permitting, transportation conformity, and state planning timelines.