“Millions of people from the Great Plains to the Northeast were under air-quality alerts Monday as smoke billowed into the U.S. again from Canadian wildfires that may continue to rage into the fall.

Forecasters said smoke from western Canada was sweeping from Montana across the Midwest and into New York. The air quality was predicted to be unhealthy in some smoke-covered areas through Tuesday, but potentially for several more days along the East Coast, according to the National Weather Service.

States including Michigan and New York are under air-quality alerts as the smoke again was poised to upend summertime activities.”