Smoke from Canadian wildfires is causing air quality concerns for millions of Americans in the Midwest and Northeast. Air quality alerts were in effect Tuesday in several states, including Wisconsin,

Hazy skies descend over the New York City area again on Tuesday, re-upping some air quality alerts related to Canadian wildfire smoke. As of 9 a.m., the air quality index was 118, which is considered unhealthy for sensitive groups.

Smoke from ongoing Canadian wildfires has led to some of the worst air quality in the world across parts of the U.S.