At least twelve states have issued air quality alerts and advisories due to the ongoing Canadian wildfires sending smoke down to the Great Lakes region and the northeastern United States, the National Weather Service reported on 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.

Smoke from Canadian wildfires is causing air quality concerns for many Americans in the Midwest and Northeast for another day this week.  Air quality alerts were in effect Wednesday morning in parts of Minnesota,

Smoke from ongoing wildfires across Canada continued to drift into parts of the United States on Wednesday, causing hazy skies and triggering air quality alerts in multiple states across the upper Midwest and Northeast.