At least twelve states have issued air quality alerts and advisories due to the ongoing Canadian wildfires sending smoke down to the Great Lakes region and the northeastern United States, the National Weather Service reported on Tuesday.

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, including New York City.

The air quality in several U.S. states is taking a hit as smoke floats over the border from the Canadian wildfires. Here's what to know.