As Canada grapples with one of its worst wildfire seasons on record, smoke from the blazes have prompted air quality alerts across the U.S.

The Minnesota Pollution Control Agency (MPCA) has issued an Air Quality Alert (AQA) for the entire state of Minnesota due to another round of wildfire smoke. The alert will be in effect from 9 am Sunday to 9 am Tuesday.

Canadian wildfires burning across northern Manitoba and Saskatchewan are sending smoke through central Canada, the Great Lakes region and the northeastern United States, reducing air quality and visibility in major cities. Forecasters said they were “optimistic” that the lingering wildfire smoke would ease later in the day on Tuesday.