Air quality has taken a serious hit across the United States as a twofold blow of wildfires in the West and in Canada have sent smoke pouring across large sections of the country — a problem that’s set to linger for days.

On Monday morning, Environment Canada issued a special air quality statement for the vast majority of southern Ontario, predicting "poor air quality" as a result of forest fires.

The air quality in several U.S. states is taking a hit as smoke floats over the border from the Canadian wildfires. Here's what to know.