Wildfire Smoke Chokes Chicago With Hazardous Air, Shutting Pools and Canceling Camps

A thick, reddish-brown haze settled over Chicago on Thursday as smoke from wildfires burning across Manitoba, Ontario and northern Minnesota drove the region's air quality to levels not seen in years. Pools and beaches closed, camps were canceled, and officials warned residents to stay inside.

The Illinois Environmental Protection Agency declared a Red Forecast Air Pollution Action Day for Thursday, its most serious designation, and the National Weather Service extended an air quality alert for the Chicago area through at least Friday night. City officials warned that the combination of wildfire smoke and other pollution could make the air hazardous enough to affect anyone, not just people with existing health conditions.

By midday, monitors in parts of the north suburbs were recording air quality index readings that blew past the top of the standard scale. Northbrook topped 770. Highland Park, Lake Forest and Waukegan all logged readings above 600 and 700. Chicago itself sat at just under 600 by mid-afternoon, according to NBC 5's Storm Team. An AQI of 301 or higher is classified as "hazardous," the worst of six categories tracked by AirNow.gov, meaning health warnings of emergency conditions for the entire population, not just sensitive groups.

"I've been here for 15 years and I've never seen parts of our viewing area in that hazardous category," NBC 5 meteorologist Alicia Roman said. "My maps don't even have the hazardous explanation on it, because we've only gotten into that 'very unhealthy,' purple category."

IQAir, which ranks air quality in major cities worldwide, had Chicago at the fourth-worst reading globally Thursday morning, behind only Detroit, Toronto and Minneapolis. By afternoon, as conditions shifted, Chicago had climbed to second-worst in the world, trailing just Minneapolis, with Detroit dropping to third.

Steven Freitag, a National Weather Service meteorologist based in Pontiac, Michigan, said a lingering high pressure system trapped smoke from dozens of fires burning in Canada and northern Minnesota over the region, holding the haze in place instead of letting it disperse. Jake Petr, another NWS meteorologist, told the Associated Press that even after northwest winds clear the skies later this week, smoke could keep drifting back into the region until the fires themselves are extinguished, a process that could take weeks or longer.

The smoke forced park districts and municipalities across the city and suburbs to move programs indoors or scrap them outright. In Chicago, the Park District shifted camps and activities inside and warned that pools and beaches could close depending on conditions. Evanston shut its beaches. Naperville closed Centennial Beach and the Paddleboat Quarry. Highland Park closed Hidden Creek AquaPark, Rosewood Beach and its golf learning center, and canceled the Ravinia food truck event. Lake Forest closed Forest Park Beach to swimming, Deerfield shut down Mitchell Pool until at least 3 p.m., and Glencoe temporarily closed its boat house and swimming areas. In Berwyn, the Chicago Fire soccer camp was called off. Across the state line, Kenosha closed several pools and a municipal golf course.

Waukegan Mayor Sam Cunningham told residents, particularly children, seniors and anyone with respiratory or cardiovascular conditions, to limit time outside. "Stay indoors with windows closed as much as possible today," Cunningham wrote in a social media post, adding that anyone who had to go outside should consider wearing a high-quality mask.

Dr. Juanita Mora, an allergist and immunologist with the American Lung Association, said children younger than 5 face the greatest risk because their airways and lungs are still developing. Older adults with little respiratory or cardiovascular reserve are similarly vulnerable, she said, especially when heat and particulate pollution combine.

The city's health department urged people with heart or lung disease, older adults and children to avoid strenuous outdoor activity altogether, keep any outdoor time brief, and move planned exercise indoors. Everyone else was told to swap running for walking and cut back on time spent active outside. Kim Biggs, the Illinois EPA's public information officer, recommended that susceptible residents stay inside, watch for breathing trouble, and use high-efficiency filters on home air conditioning systems where possible. She also advised against activities that generate more particulate matter indoors, including smoking or burning candles.

The fine particles carried in wildfire smoke, known as PM2.5, are small enough to lodge deep in the lungs and pass into the bloodstream, raising the risk of heart and lung problems. A study published earlier this year estimated that long-term exposure to wildfire smoke particles contributes to roughly 24,100 deaths annually across the lower 48 states. The study linked the exposure to worsened respiratory illness, cardiovascular disease and neurological disease.

Before the wildfire smoke arrived, Chicago had already logged two days of elevated ozone pollution earlier in the week, with the National Weather Service and Illinois EPA issuing separate air quality alerts Tuesday and Wednesday. National Weather Service meteorologist Zachary Yack said that ozone came from standard pollution sources and could be eased somewhat if residents carpooled and cut back on unnecessary energy use.

Forecasters expect gradual improvement Friday as winds shift out of the northwest, but Roman said some uncertainty remains over how far south the smoke will travel and how long the unhealthy air will linger before clearing. AccuWeather meteorologist Peyton Simmers said winds should push the smoke west starting Friday, though additional waves could return depending on how long the Canadian fires keep burning. NWS forecasters have flagged the possibility that a wind shift out of the north early next week could carry fresh smoke back into the region, meaning Thursday's hazardous readings may not be the last the city sees this summer. Residents can track hourly conditions through the EPA's AirNow app or by signing up for email alerts through the agency's Enviroflash service.