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.

Wildfire smoke from the Prairies prompted special air quality statements and warnings across the country Saturday.

Toronto’s air quality index was at eight, or “high risk,” this morning. Environment Canada says reduced air quality can cause mild eye, nose and throat irritation while more serious but less common symptoms include chest pains and a severe cough.