In the U.S., wildfire smoke has reached states from Montana to Wisconsin but was especially heavy in Minnesota on Sunday.

With over 100 active wildfires burning in Canada, wildfire smoke has drifted across the border into the United States, prompting Minnesota officials to issue the state’s first air quality alert of 2024.

At least 37 of the 141 active fires burning in Canadian wildfires have been labeled “out of control,” including one that started on Friday in British Columbia and has since spread to 4,200 acres, forcing the evacuation of the small town of Fort Nelson, and the Fort Nelson Indian Reserve, officials said.

Most of the active wildfires, at least 90, are in British Columbia and Alberta provinces.

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The effects of wildfire smoke are an increasing worry across the United States that is only expected to worsen, according to a study released in February.

By mid-century, the effects of wildfire smoke could bring startling health risks to 125 million Americans, according to the First Street Foundation, a climate-risk data provider.