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.

Smoke produced by hundreds of wildfires burning across Canada has drifted thousands of miles and nearly circled the entire globe, with hazy skies now seen across parts of North America, Europe and even parts of Russia.

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.