- Climate change may boost ozone days in Michigan, less so than in the wildfire-hit west
- From March 1, Michigan’s ozone season starts, with EGLE issuing “Air Quality Advisories.”
- Post-Clean Air Act gains wane as climate change, local factors raise Great Lakes ozone levels.
Michigan and the Great Lakes region are likely to see an uptick in climate change-driven air pollution with more high ozone days, according to a new report from the First Street Foundation, a non-profit research group.
However, predicted increases in air pollution in the Great Lakes region are much smaller than the threat faced by western states dealing with prolonged wildfire seasons.
Jeremy Porter, head of climate implications research for the First Street Foundation, told Planet Detroit that this difference is one of “weeks rather than days.” For example, the Seattle and Portland metros could face an additional two weeks of ozone and fine particulate matter pollution over the next 30 years. Meanwhile, Wayne County would see one additional day on top of the roughly ten days of poor air quality it currently experiences.
The report defines a poor air quality day as any day that reaches or exceeds the orange or “unhealthy for sensitive groups” level of the Environmental Protection Agency’s Air Quality Index.
Yet, the study didn’t look at predicted impacts from Canadian wildfires, although Porter said First Street is looking to incorporate Canadian data in future modeling.
Last summer, smoke from Canadian wildfires created some of the worst air quality in the world. An analysis by the research organization World Weather Attribution Group, found those fires were twice as likely and 20% more intense because of human-caused climate change. Experts say the hot and dry conditions that drove the Canadian fires are likely to recur roughly every 20 to 25 years.
The First Street report notes that air quality improved nationwide after the passage of the Clean Air Act of 1970. But this pattern has gone into reverse over the last ten years, with wildfires producing more fine particulate matter or PM 2.5 and hot days driving ozone formation.
“We put all these regulatory policies in, we improved the air quality (but) climate is starting to reverse that trend,” Porter said.
This is primarily a Western story, with wildfire-related PM 2.5 producing the most extreme increases in pollution, Porter said. However, the Midwest and Northeast are seeing increases in ozone that are largely the result of heat rather than emissions.
What is ozone season?
Ozone is formed by a chemical reaction between substances like nitrogen oxides [NOx] and volatile organic compounds [VOCs] in the presence of heat and sunlight. Cars, trucks, factories, power plants and refineries all produce these ozone precursors. Wildfires can also produce gasses that contribute to ozone formation.
Porter said that in Great Lakes states, the abundance of water can add to ozone pollution because evaporation produces nitrogen oxides. A warming climate could increase this evaporation, adding more NOx to an environment already favorable to ozone formation.
Ozone pollution can cause respiratory problems and increase the frequency of asthma attacks.
In the past, the Michigan Department of Environment, Great Lakes, and Energy used the terms “Ozone Action Day” and “Clean Air Action Day” to alert residents to harmful levels of pollution.
Going forward, the agency will use the term “Air Quality Advisory” for days when ozone, PM 2.5 or both are expected to be in the “unhealthy for sensitive groups” range. EGLE will issue an “Air Quality Alert” when one or both pollutants are in the “unhealthy” range.
Michigan’s ozone season officially runs from March through October, but most high ozone days occur in the warmest months. However, climate change could extend the ozone season. Last year, metro Detroit had its earliest Ozone Action Day ever on April 15.
On days with high levels of ozone pollution, residents are advised to drive less, avoid refueling vehicles, which can release vapors that contribute to ozone formation, refrain from using gasoline-powered lawnmowers, leaf blowers, and string trimmers, and avoid outdoor activities if possible.
What is PM 2.5 and why is it so harmful?
Wildfire smoke could also become a bigger problem in the eastern U.S., according to the First Street Report, which notes that the South and Midwest are starting to show signs of increasing PM 2.5.
PM 2.5 is linked to cardiopulmonary problems and premature mortality. And a 2021 study found that because of the population density in eastern states, three quarters of the smoke-related asthma visits to emergency rooms and deaths occurred in the East, even though the West saw more pollution.
Recent studies have found that there is no safe level of PM 2.5. Even the World Health Organization’s threshold for PM 2.5, which is lower than the EPA’s recently updated standard, could still lead to significant increases in hospitalizations for cardiovascular disease and respiratory disease and emergency room visits for respiratory problems.
And yet, current air quality rules can allow regulators to ignore pollution if it’s being influenced by wildfire smoke, with states able to request the exclusion of “exceptional events” or days where air quality was influenced by things outside of regulatory control like wildfires or dust storms.In 2023, the Environmental Protection Agency found southeast Michigan met federal guidelines for ozone pollution for the first time since 2018, after EGLE successfully lobbied the agency to disregard air quality data from two days in 2022 that it said were affected by wildfire smoke.