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.