Air quality has taken a serious hit across the United States as a twofold blow of wildfires in the West and in Canada have sent smoke pouring across large sections of the country — a problem that’s set to linger for days.

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 Michigan and New York.

Breathing in polluted air for extended periods of time can pose a serious health risk for people, especially for vulnerable populations.