The Canadian government’s map of wildfire smoke fine particulate matter models for Aug. 2-3 shows smoke will intensify over parts of the Northwest Territories, Saskatchewan, Manitoba and Ontario. (Aug.

With hundreds of wildfires burning across Canada, smoke has drifted into the northern United States, lowering air quality across roughly a dozen states.

Smoke from Canadian wildfires is causing air quality concerns for millions of Americans in the Midwest and Northeast.