Smoke from Canadian wildfires is threatening air quality from the Midwest to western New York State, triggering warnings of “unhealthy” levels in some areas extending through the weekend.

Air quality alerts have been posted across Wisconsin and Minnesota as smoke from wildfires moves south, Zack Taylor, a senior branch forecaster with the US Weather Prediction Center, said in an interview. The pollutants could even spread to Iowa later Thursday, though forecasts suggest it won’t reach large East Coast cities such as New York for now, he said.

There are 1,062 fires burning across Canada, with almost two-thirds out of control, according to the Canadian Interagency Forest Fire Centre. Since the start of the year, 5,736 fires have scorched a record 13.7 million hectares. Wildfires forced the evacuation of Yellowknife, the capital of Canada’s Northwest Territories.

Read More: Raging Wildfires Prompt Evacuation of Northern Canada City

Fires in the Pacific Northwest have also caused “unhealthy” to “very unhealthy” conditions across parts of Washington, Oregon and Idaho, with some of that smoke spreading across Rocky Mountains.

Air quality conditions are currently classified as “moderate” around the eastern Great Lakes, including Toronto, Cleveland and Buffalo, New York, according to AirNow.gov. That rating means people who are unusually sensitive to pollutants should keep outdoor activities light and short and go indoors if they experience health symptoms.

--With assistance from Derek Decloet.

Author: Brian K. Sullivan