Overview:
- Sierra Club says it will sue EPA after the agency missed February 2025 deadline to determine whether Detroit meets federal ozone standards.
- Environmental lawyer says monitoring data shows Southeast Michigan should be moved from moderate to serious nonattainment status, requiring stricter pollution controls.
- Detroit ranks 39th worst nationally for ozone pollution and received an F grade in the American Lung Association's 2026 air quality report.
The Sierra Club announced last week that it plans to sue the Environmental Protection Agency for failing to determine whether the Detroit area meets federal ozone standards.
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Why it matters
Higher ozone pollution can inflame airways, trigger asthma attacks, and worsen lung diseases for Detroit residents. Detroit’s air quality received an F grade from the American Lung Association.
Who's making public decisions
The EPA has authority to determine whether Southeast Michigan meets federal ozone standards, while Michigan regulators decide whether to submit an addendum requesting compliance approval.
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What to watch for next
The Sierra Club’s 60-day notice period expires on June 22, after which it can sue the EPA for missing an ozone determination deadline.
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A seven-county area in Southeast Michigan is in moderate nonattainment for ozone. Nick Leonard, executive director at the Great Lakes Environmental Law Center, who is representing the Sierra Club, said monitoring data shows the area should be bumped up to serious nonattainment.
This change in Southeast Michigan’s attainment status would entail greater restrictions on pollutants that lead to ozone formation, an enhanced inspection and maintenance program for cars and trucks, and tighter controls for stationary pollution sources, Leonard told Planet Detroit.
The EPA and Michigan’s Department of Environment, Great Lakes, and Energy (EGLE) both declined to comment on the litigation threat.
Last week, EGLE held a hearing on a proposed addendum request to the EPA to find that Southeast Michigan complies with federal ozone standards.
EGLE is still reviewing public comments and has yet to make a final decision on whether it will submit this addendum to the EPA, EGLE spokesperson Josef Stephens said.
This proposal follows a Dec. 5 ruling by the U.S. Court of Appeals for the Sixth Circuit that found the EPA violated the Clean Air Act when it redesignated Southeast Michigan from nonattainment to attainment for federal ozone standards.
Ozone a serious issue that needs fixing: Environmental lawyer
The EPA failed to meet its non-discretionary Feb. 3, 2025, deadline to determine whether the Detroit area met the federal ozone air quality standard, Leonard said.
“That’s typically how the Clean Air Act functions in order to make sure that states are taking timely action to lower pollution,” he said, although he added the agency missed such deadlines “shockingly frequently.”
An analysis of ozone levels, especially at the East Seven Mile air monitor in Detroit, would show the area fails to meet the ozone standard and should be moved into serious nonattainment, Leonard said.
“For the first time in 2025 we saw some additional monitors creeping above the ozone standard at Oak Park and Port Huron,” he said. “So, the problem seems to be getting worse rather than better.”
If EGLE decides to submit its proposed addendum to the EPA and the federal agency finds the area meets federal ozone standards, the Sierra Club will almost certainly sue the EPA again, Leonard said.
“It’s frustrating to spend so much time trying to get EGLE to do something about ozone pollution … this is a pretty serious issue that they should be dedicated to fixing,” he said.
The Clean Air Act requires the Sierra Club to wait 60 days after its written notice before suing. This period is set to expire on June 22, Leonard said.
EGLE says Detroit meets ozone standards when wildfire smoke discounted
Elena Saxonhouse, an attorney with Sierra Club, which brought the case against the EPA for the ozone redesignation, previously told Planet Detroit regulators would need to throw out a number of days to show Southeast Michigan met federal ozone standards over the last three years.
EGLE is seeking to remove air monitoring data for several days in June 2023 and July 2025 from monitors in Oak Park and Port Huron, using the EPA’s exceptional events rule.
The EPA defines exceptional events as unusual or naturally occurring events that can’t be reasonably controlled by government agencies. EGLE said smoke from Canadian wildfires affected ozone data on these days.
EGLE’s Stephens said the “area has been meeting the standard since 2021.”
Ozone pollution can inflame and damage airways, make the lungs more susceptible to infection, increase the frequency of asthma attacks, and aggravate lung diseases such as asthma, emphysema, and chronic bronchitis, according to the EPA.
Detroit’s air quality received an F in the American Lung Association’s 2026 State of the Air report.
The Detroit-Warren-Ann Arbor area ranks 39th worst nationally for ozone pollution, according to the 2026 report, worse than its 2025 ranking of No. 45.
AIR QUALITY NEWS
Detroit air quality gets another F from American Lung Association
Detroit’s air quality receives another F grade from American Lung Association, ranking among the nation’s worst for particle pollution.
Detroit’s ozone status in focus Wednesday at Michigan regulatory hearing
Michigan regulators will hold a virtual hearing Wednesday on a proposal that could weaken air quality protections in Southeast Michigan, following a court ruling that found the EPA violated the Clean Air Act.
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