The Chicago skyline was not visible south of Diversey Avenue as air quality in the city reached reached very unhealthy levels, as seen from Montrose Harbor in Uptown on June 27, 2023. Credit: Colin Boyle/Block Club Chicago

CHICAGO — The air quality in Chicago is “unhealthy,” but it’s not as bad as it had been and thanks to the decreasing intensity of the Canadian wildfires, it should continue to improve, a climate expert said.

The air quality index was deemed “unhealthy for sensitive groups” Monday by AirNow, a federal air quality database.

The city had the worst air quality in the world in late June as a result of smoke from the Canadian wildfires. The build-up of pollution from the NASCAR Street Race and Fourth of July travel and fireworks didn’t help.

But this time around, with less smoke from “less intense” wildfires up north — and a change in the wind — air quality should improve again, according to Argonne National Laboratory atmospheric scientist Scott Collis.

“The closer the fire is to us in general, the worse it is. But of course, the intensity of the wildfire plays quite a large role. The wildfires at the moment are less intense,” Collis said.

According to Collis, “If you follow where the air is coming from, it’s no longer coming from the northern parts of Canada, but the West Coast.” That shift will “disconnect us from the wildfires, but also connect us to a warmer air mass,” he said.

The wildfire season typically comes to a close by the fall, though it’s hard to predict exactly when that could be, Collis said.

Collis and his team at Argonne National Laboratory will be visiting Chicago State University Tuesday to deploy instruments on the roofs of buildings on campus to further study air quality in the city.

“Instruments actually help capture the wildfire smoke. We can actually see where it is in the atmosphere,” Collis said. “We’re really interested in studying how this affects different neighborhoods, and whether things like extra trees, prairie plants can track the worst effects of wildfires.”

Chicago Public Schools said in an email to families Monday it moved programs indoors to reduce health risks.

People with heart or lung disease, older adults, children, teens and other vulnerable groups are advised to avoid strenuous outdoor activities and resume activities when the air quality is better.

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