Environment Canada says air quality has improved across most of Quebec and Ontario as changes in wind and rain ease the situation east of the Prairies, where wildfires continue to rage.

A Chicago Air Quality Alert has been extended through Friday as smoke from Canada wildfires has pushed the AQI into unhealthy levels across the region.

Smoke from wildfires raging in Canada has drifted into the United States, affecting air quality as far south as Florida.