Wildfire smoke approaching Chicago as air quality alert remains in effect

Lila Hempel-Edgers, Chicago Tribune on Jul 15, 2026

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CHICAGO — An air quality alert remained in effect for parts of northeast Illinois Wednesday ahead of Canadian wildfire smoke expected to reach the Chicago area later in the day, weather officials said.

“You can see it coming down the lake,” said Zachary Yack, a meteorologist with the National Weather Service.

Unhealthy ozone levels across parts of northeast Illinois and northwest Indiana first prompted the air quality alert Tuesday morning, and weather officials extended it through Wednesday as Canadian wildfire smoke approached the region.

Elevated ozone pollution is common during the summer, Yack said. With record-high temperatures settling over the Chicago area this week, ozone levels were already elevated before the wildfire smoke’s arrival.

“When you get these more hot and humid days, the air can be a little bit heavier, so the atmosphere doesn’t necessarily vent itself as well,” said Yack. “It’s not anything out of the ordinary, most people wouldn’t probably even notice too much of a difference.”

On Wednesday morning, particulate matter levels in the Chicago area reached an Air Quality Index of 59 on a 500-point scale, a level considered unhealthy for sensitive groups. Conditions are expected to remain similar Thursday.

People in affected areas should limit time outdoors, and those sensitive to air pollution should watch for symptoms such as coughing or shortness of breath, according to the National Weather Service. Officials recommend keeping pets indoors and using clean air conditioner filters to reduce smoke particles inside homes.

“Cut down on pollution by carpooling to work if (you) can,” said Yack. “Find ways to not use energy as much, so that way the power plants don’t have to produce as much pollutants.”

A heat advisory remained in effect Wednesday for portions of northeast Illinois, as well as northwest Indiana, with heat indexes expected to approach 100 degrees. But while wildfire smoke could worsen air quality as it reaches northern Illinois late Wednesday night, Yack said it could also slightly temper the heat.

“The smoke in some cases could actually help block out some of the incoming sun which may help keep temperatures a little bit lower,” said Yack. “It all depends on smoke thickness and density.”

Scientists say climate change driven by human activity is increasing the frequency, size and severity of wildfires by creating hotter, drier conditions. Changing wind patterns can also carry smoke hundreds or even thousands of miles, making it difficult to predict where poor air quality will develop.

Last May, a rare dust storm blanketed the Chicago area in agricultural sediment, and smoke from Canadian wildfires left the city’s air quality ranked the worst in the nation for a stretch in June, the Tribune reported. The intense 2023 Canadian wildfire season also made Chicago the country’s second-most-polluted major city that year.

Wednesday’s air quality alert remains in effect until midnight, and experts said it could be extended later in the week. Officials urge residents to help reduce emissions by limiting activities that contribute to air pollution. Tips on reducing emissions can be found at www.airnow.gov.

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