Wildfires are still raging in Canada, where there have been dozens of active fires, and over 33,000 people have been forced to evacuate their homes.

Parts of Canada are seeing some of their most unhealthy air yet, and the smoke is likely to move over the United States again this weekend.

Wildfire smoke from blazes burning in the Canadian prairie has drifted across New York and Chicago, contributing to air-quality alerts that warn of breathing problems for children and older adults.