Can Michigan air quality rules adapt to a smoky future?

Scientists and advocates say EPA rules allowing states to discount air quality data influenced by wildfire smoke should be reconsidered.
Hazy skies above Detroit as wildfire smoke blows in from Canada on July 18, 2023—photo by Nick Hagen.

As metro Detroiters experienced an intense summer of wildfire smoke with hazy skies, odors compared to burning plastic and some of the world’s worst air quality, experts and activists began to ask: can air quality rules adapt to this growing threat?

Wildfire smoke increases PM 2.5 or fine particulate matter in the air, which favors the formation of ground-level ozone. Both air pollutants are known to trigger asthma, while ozone can aggravate bronchitis and emphysema. PM 2.5 can lead to cardiac problems and decreased lung function. 

This poses a serious problem in Detroit, which the Asthma and Allergy Foundation of America recently identified as the fifth worst city in the U.S. for people with asthma. This year, Michigan’s Department of Environment, Great Lakes, and Energy issued 21 air quality alerts for ozone and PM 2.5 in Detroit, compared to five each year in 2021 and 2022. This was also the first year the agency issued results for PM2.5; previously, all air quality alerts had been for ozone.

 But it’s unclear whether the increased presence of wildfire smoke will be accounted for in air quality regulations. 

Earlier this year, Michigan’s Department of Environment, Great Lakes, and Energy requested the Environmental Protection Agency allow it to exclude ozone monitoring data it said was influenced by Canadian wildfire smoke. 

States can make such requests under an “exceptional event” provision in the Clean Air Act. This allows them to exclude air quality monitoring results outside of regulatory control –  things like wildfires, dust events, stratospheric ozone intrusions, and volcanic and seismic activities.

But wildfire smoke may no longer be so exceptional in Michigan. Scientists predict that the northern forests that burned and produced much of this year’s smoke will continue to experience severe fire seasons. Advocates say a failure to account for days with wildfire smoke could be especially harmful to vulnerable communities that also deal with high pollution levels from industry and vehicles.

Nick Leonard, executive director of the Great Lakes Environmental Law Center, said the new reality of recurring wildfire smoke could undermine the Clean Air Act’s National Ambient Air Quality Standards, designed to protect public health by limiting pollutants like PM 2.5 and ozone. 

He said this program functioned under the assumption that there are mobile and stationary pollution sources with some background pollution from events like wildfires that are deemed “natural.”

“That framework has changed,” Leonard said. “The question is going be how is the EPA (and) how are states going to change with it?”

Leonard fears states will rush to exclude more and more days from being considered when determining attainment status, shrinking the amount of data used to ensure residents have a baseline of air quality and giving a distorted picture.

A test of how regulators plan to respond to these questions may come with the Sierra Club’s appeal of EPA’s decision to exclude data from June 24 and 25, 2022, at the East 7 Mile monitor in Detroit, where Gov. Gretchen Whitmer’s administration argued wildfires caused high ozone readings. After discounting this data, the EPA determined southeast Michigan was in attainment for ozone, allowing EGLE to avoid measures like requiring vehicle emissions testing.

Leonard, who worked with the Sierra Club on the appeal, said the exclusions failed to account for disproportionate health impacts from ozone pollution in the area around the East 7 Mile monitor, which has one of the highest asthma hospitalization rates in the state. He believes that going forward, the EPA either needs to eliminate the exceptional events rule altogether or prohibit these exceptions for areas with environmental justice concerns, like the east side of Detroit.

However, business interests will likely push back against any changes that bring stricter enforcement. Mike Alaimo, director of environmental and energy affairs for the Michigan Chamber of Commerce, recently argued that if the EPA finds the region is in non-attainment for certain pollutants, it would impose new costs on businesses and make it more difficult to carry out needed upgrades to infrastructure like roads and bridges.

EGLE spokesperson Hugh McDiarmid said the agency won’t determine if it will ask to exclude any exceptional event days until later this year when they have all the data from the ozone and wildfire season. 

Previously, the agency has only asked to exclude high ozone days. ButPM 2.5 also emerged as a pervasive issue during the 2023 wildfire season.

A revised PM 2.5 standard is expected from the EPA this year or next. A stricter rule could lead to a nonattainment designation for southeast Michigan in two to three years if the region is found to be out of compliance. The region has been in compliance with PM 2.5 since 2013.

Meanwhile, the state is now in “maintenance status” for ozone, meaning this year’s increase in ozone pollution could compel EGLE to analyze the data and potentially implement contingency measures like vehicle emissions testing. McDiarmid says the area wouldn’t face another possible nonattainment designation until the ozone standard is revised, which is likely a few years away. The EPA could provide some protection for public health through periodic review and tightening of regulated pollution sources. 

Some scientists say the agency can no longer ignore wildfires as “natural” occurrences that fall outside the realm of regulation.

“These things are clearly, according to some in the scientific community, linked to climate change. That’s linked to humans,” Jonathan Skinner-Thompson, a former EPA attorney and a law professor at the University of Colorado Boulder, told CNN.

In a letter to EPA administrator Michael Regan, members of the Clean Air Scientific Advisory Committee, a group of academics, state officials and physicians who advise the agency on air quality, suggested it’s time to reconsider whether wildfires should be considered exceptional events.

“In some parts of the country, wildfires are no longer ‘exceptional.’ The dramatic increase in wildfires over the last decade is not natural,” the committee wrote. “Given the potential for significant adverse health events, it may be time to reconsider the current approach to excluding the high PM exposures from wildfire events…”


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