Millions in the United States are facing another day of hazy skies fueled by hundreds of smoky wildfires burning across North America, impacting air quality in parts of the U.S. and raising health concerns.

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.

Air quality alerts are now in place for 10 states from Minnesota to Connecticut and, on Tuesday afternoon, Boston is expected to see a nice break from the smoke thanks to onshore winds keeping smoke inland as Detroit and New York City may catch more of a break due to winds from the east as well.