Wildfires in Canada, the United States and Mexico often send smoke throughout the continent.

Ontario requested federal ​assistance to evacuate people from remote northern Canadian communities ravaged by wildfires on Thursday, as smoke brought poor air quality to Toronto ‌and much of the North...

The pungent wildfire blanketed cities such as Chicago and Detroit, where residents on Friday were warned to stay indoors and reduce activity levels after the air quality index reached a “hazardous” 36...