Chicago air quality plummets as Canada wildfire smoke chokes skies; AQI unhealthy or very unhealthy

Chicago air quality has plummeted into unhealthy territory as Canadian wildfire smoke has settled in an acrid haze over the area Thursday morning.

There is an Air Quality Alert in place for most of the Chicago area, with the worst AQI in the city and northern suburbs. The air quality in Chicago stood at 253 Thursday morning, well into the "very unhealthy" category.

The air quality in Waukegan had had crossed into the "hazardous," or maroon, category by 7:30 a.m., with an index of 446.

IQAir ranked Chicago as having the fourth worst air quality in the world Thursday morning, outranked by Minneapolis, Toronto, and at the top, Detroit — with an air quality index of 518.

The "unhealthy" category means some members of the general public may experience health effects, while members of more sensitive groups may experience serious health effects. Children, older adults, and people with disabilities should avoid strenuous outdoor activity under such conditions.

The "very unhealthy" category means the risk of health effects is increased for everyone.

The Illinois Environmental Protection Agency said everyone should reduce their time outdoors in the Chicago area on Thursday.

The concern is fine particles within the wildfire smoke, which travel deep into the lungs.

Health experts say early symptoms may include a scratchy throat, itchy eyes, or a stuffy nose. But anyone who develops a cough, shortness of breath, or a feeling of being winded more easily should take it as a sign to get inside and limit exposure.

"This is a time to look out for each other and remind each other, do you need to be outside? Are there other things you can do inside?" said Dr. Ruth McDermott-Levy of Villanova University. "If people are starting to act strange or complain of chest pain or shortness of breath, get them to the emergency department, because emergency departments are getting ready."

Why is air quality so bad today?

More than 100 wildfires are burning in Canada, where a train crew in northern Ontario filmed themselves surrounded by flames before being safely evacuated. Winds are carrying the smoke southeast.  

Dan Westervelt, associate professor at Columbia University's Climate School, said severe drought conditions combined with heat in Canada and the U.S. have created "a perfect storm for really dry conditions to provide a lot of fuel for these wildfires to burn." Research shows warming temperatures from burning coal, oil and gas are making fires more frequent and intense.

High levels of fine particulate matter in the air from wildfire smoke may be unhealthy for sensitive groups, such as children and people with heart or lung conditions. The particulates can cause shortness of breath, coughing, dizziness or fatigue and aggravate heart and lung diseases and other chronic health issues.

"The stuff that you're seeing there on the images of the skyline are actually the less risky particles," said Dr. Scott Budinger, chief of pulmonary and critical care at Northwestern Medicine. The more risky particles are the very, very small ones about 10 times smaller than a grain of sand that we call the 2.5 micron or less particles. Those particles that can travel deep into your lungs." 

Experts suggest wearing a N95 mask if you have to be outside and keeping your indoor air cleaner by closing windows and running an air purifier or air conditioner.

How to stay safe in "unhealthy" or "very unhealthy" AQI

During periods of reduced air quality from wildfire smoke, experts advise limiting outdoor exertion and time, keeping windows and doors closed, changing home air filters and running in-home air purifiers if available. Those who need to spend time outdoors are encouraged to wear N-95 masks, which are protective against PM2.5 pollution from wildfire smoke when fitted properly.

Highland Park resident Ellen Rogin went out for a morning walk early Thursday, and was taken aback by the smoke.

"After I walked out of the house, I thought, I really should be wearing a mask, and I saw people running by, and was thinking, I wonder if they realize how bad this is for them, no matter what age they are," Rogin said.

The Daley Plaza Farmers Market was on as usual Thursday, but some people wore masks to protect themselves from the bad air. Vendors took precautions to stay safe while selling their produce.

"For ourselves, we do have some masks back in the back in our bag if it gets bad enough if we need it, and like I said, we may take more frequent breaks just to kind of get some of the purified air," said vendor Kaleena Mark.

The CBS News Chicago First Alert Weather team said the smoke event could rival, or even exceed, the one Chicago experienced in June 2023, when thick orange haze blanketed the sky and the air quality also reached unhealthy levels.

That year, the Air Quality Index peaked at 228, well into the "very unhealthy" category.