As of Aug. 6, there are about 750 active Canadian wildfires, with at least 190 labeled “out of control,” according to the Canadian Interagency Forest Fire Centre. More than 16 million acres (6.8 million hectares) of land have been scorched this year, making this one of Canada’s worst wildfire seasons on record.

Air quality alerts are in effect on Tuesday in 10 states as toxic smoke from hundreds of wildfires burning in Canada continues to waft into the United States, creating hazy, gray skies over major metropolitan areas,