Fireworks to temporarily worsen Michigan's air quality during Fourth of July

As Michigan prepares for Fourth of July celebrations, environmental experts say fireworks are expected to cause short-term spikes in air pollution, even as ozone levels have remained relatively stable during recent hot and humid weather.

Alex Kownacki, an air quality meteorologist with the Michigan Department of Environment, Great Lakes, and Energy, said ozone levels across Michigan have been “behaving” this week despite heat index values reaching above 100 degrees.

“Although we've had seen some elevated ozone levels, but it's only been for like an hour or so, the overall daily average has been pretty okay and good,” Kownacki said.

The greater concern heading into the holiday weekend is fine particulate matter, known as PM2.5, which is released by both wildfire smoke and fireworks. Officials say PM2.5 levels typically rise each year around the Fourth of July, especially in populated areas such as Detroit and Grand Rapids where fireworks displays are more frequent and larger in scale.

“These increases usually happen overnight, around 11 p.m. to 2 a.m., when fireworks are most active,” Kownacki said. “By morning, those levels typically return to normal as the smoke disperses.”

While extreme heat can contribute to ozone formation under certain conditions, Kownacki said there is no strong direct link between this week’s heat and prolonged air quality degradation from fireworks. Instead, ozone formation depends on a combination of sunlight, pollutants, and atmospheric stability.

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PM2.5 spikes are expected to last only a few hours unless weather conditions trap pollution near the surface. Rainfall and favorable wind patterns this weekend could further help disperse pollutants and keep air quality within acceptable ranges.

“If people look and pay attention to air quality and they see air quality in the poor range, we expect it to level out in the next hour, couple hours or so after that,” Kownacki said.

Still, officials encourage residents, especially those with asthma or other respiratory conditions, to monitor air quality forecasts during holiday celebrations, as short-term spikes can still cause irritation or breathing difficulties.

This story is brought to you as part of a partnership between WKAR and Michigan State University's Knight Center for Environmental Journalism.