US cities under air quality alerts amid haze of Canada wildfires

Several cities in the United States have again been placed under air quality alerts as smoke from still raging wildfires in Canada settled over the US Midwest.

Warnings were issued on Wednesday across large swathes of the region, stretching to the eastern coast of the US. Those warnings were issued as far south as Georgia and Alabama, three weeks after haze from the Canadian fires had initially blanketed cities across the US and turned skies orange in some places.The worst affected cities on Wednesday were Detroit, Michigan; Minneapolis, Minnesota; and Chicago, Illinois, all of which ranked in the top four cities with the worst air quality in the world, according to IQ AIR, a Swiss air quality technology company and monitor. Toronto, Canada, was ranked sixth on the list.

For its part, the US Environmental Protection Agency (EPA) rated a stretch covering Madison, Wisconsin; Indianapolis, Indiana; and Pittsburgh Pennsylvania, as having “very unhealthy” air – its second most severe rating.

Meanwhile, moderately poor air quality stretched all the way to Florida’s northern edge, according to the EPA’s real time tracker. A patch near Detroit was labeled “hazardous” on Wednesday.In Chicago, Mayor Brandon Johnson urged young people, older adults and residents with health issues to spend more time indoors while unsafe conditions continued.He pledged “swift action to ensure that vulnerable individuals have the resources they need to protect themselves and their families”.

Officials in New York City warned that while the worst air quality was currently in the western reaches of the state, conditions could get increasingly worse.

“Poor air quality can affect people differently, so individuals must assess their own sensitivities and adjust to conditions at the time,” the New York City Department of Health and Mental Hygiene said in a statement.

While air quality remained moderate in the largest US city on Wednesday, “wind patterns can quickly change without notice”, the department said.

Canada is wrestling with its worst-ever start to the wildfire season, which has already burned 6.5 million hectares (16 million acres) ahead of the hottest months of the year.