The Sierra Club is suing the U.S. Environmental Protection Agency over what it says was a faulty decision about ozone in southeast Michigan.
Ground-level ozone, often called smog, forms when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight. Major sources include industrial emissions and car exhaust. Ozone is known to worsen or even cause conditions including asthma, bronchitis, and emphysema.
In May, the EPA found that a seven-county region in southeast Michigan — broadly the Detroit Metro area — had officially come into attainment with federal ozone standards, after years of not meeting the standards. But they were only able to do that after discounting some data from Detroit in August 2022.
In that case, the EPA agreed with the Michigan Department of Environment, Great Lakes, and Energy (EGLE) that high ozone levels on those days were due to Canadian wildfires. They allowed those days to be considered exceptional circumstances, and found that the area was otherwise in attainment.
The Sierra Club is disputing both findings. Nicholas Leonard, executive director of the Great Lakes Environmental Law Center, who filed the suit on the Sierra Club’s behalf, said the attainment finding allows the state to avoid taking stronger steps to regulate industrial and vehicle pollution.
Leonard said that puts health and lives at risk — especially for those living close to the East 7 Mile air quality monitor, an already pollution-burdened community where the discounted ozone readings came from. “We thought that this decision prioritized industry over people, and we think that's obviously the inverse of what we want to see,” he said.
Leonard noted that ozone action days have jumped in Michigan so far this year, indicating an ongoing problem. “What EGLE told us when they when the redesignation was approved this spring was, 'Don't worry, ozone pollution is getting better. Things are under control.' And it's clear that it's not,” he said.
The increased number of ozone action days — 14 so far in 2023, according to the Southeast Michigan Council of Governments — are separate from Air Quality Action Days recently declared due to smoke from this year’s Canadian wildfires. It’s known that wildfires can increase ozone levels as well as increasing dangerous particulate matter, but it’s currently unclear how much they’ve contributed to southeast Michigan’s levels this summer.
The EPA could not immediately be reached for comment on the lawsuit. EGLE released a statement saying that the “EPA’s decision to re-designate SE Michigan to attainment for ozone was consistent with sound science and the process outlined by the Clean Air Act. … EGLE’s commitment to continuing air quality improvements in SE Michigan and across the state has not changed.”
Although it’s officially in attainment status for ozone as of May, southeast Michigan is also still considered in “maintenance status,” which means EGLE must submit a plan to the EPA on how it plans to maintain compliance with federal standards. Three counties in West Michigan are currently considered in “moderate non-attainment” for ozone.
