Three major US cities ranked in the top four for most polluted air in the world today – where readings are multiple times worse than the notoriously noxious Delhi, India – due to raging wildfires in Canada.
Air pollution in Detroit, Michigan, was the worst in the world Thursday morning, with a score of 724 on the live global air quality index (AQI), according to IQAir – which shows that the atmosphere becomes “hazardous” starting at 301.
Toronto, Canada, saw the second-highest pollution levels, with a score of 271 – which falls within the “very unhealthy” category between 201 and 300.
Wildfire smoke hangs over downtown Detroit on Thursday, July 16, 2026. USA TODAY Network via Reuters Connect
An aerial shows smoke from Canadian wildfires blanketing Chicago on July 16, 2026. Getty Images
Smoke will raise significant air quality concerns today for an area spanning from the Upper Midwest into the Ohio Valley, Northeast, and Mid-Atlantic. Code orange and higher alerts are currently in effect for practically all affected areas.
Smoke will continue to slowly traverse… pic.twitter.com/7QKX2RzTgI
— Max Velocity (@MaxVelocityWX) July 16, 2026
The third- and fourth-most polluted air was found in Minneapolis, Minnesota, and Chicago, Illinois, where the scores were 257 and 250, respectively.
Delhi – which traditionally tops annual pollution reports – had a score of 150, within the “unhealthy for sensitive groups” range, ranking it sixth on Thursday, according to the list.
Over 800 wildfires are still burning across Canada, including dozens that are out of control, according to the Canadian Wildland Fire Information System.
Wildfire smoke hangs over downtown Detroit on Thursday, July 16, 2026. Getty Images
Businesses and attractions shuttered and events were moved indoors across Motor City after residents awoke to hazy skies, odors of burnt wood and an AQI score that topped 800 at one point Thursday morning, according to the Detroit Free Press.
Parts of the North Star State, meanwhile, saw record-breaking smoke concentration levels that hadn’t been experienced since 2014, according to the Minnesota Star Tribune.
Detroit, Minneapolis, and Chicago were in the top 5 of most polluted cities in the world. IQair.com
By Wednesday afternoon, the AQI reached a whopping 1008 in Michigan’s Upper Peninsula bordering Lake Superior, local news meteorologist Brian Niznansky wrote on X.
As the wildfires continue to surge, officials from the Midwest all the way to New York City are urging residents to stay inside.
“Every New Yorker should take precautions. Limit your time outdoors, especially strenuous activity,” Big Apple Mayor Zohran Mamdani said Thursday.
The same advice should go for people’s beloved pets, according to the American Veterinary Medical Association.
“As irritating as smoke can be to people, it can cause health problems for animals as well…If you can see or feel the effects of smoke yourself, you also should take precautions to keep your animals — both pets and livestock — safe,” the association said.