Entire states under air quality alerts as wildfire smoke spreads

Raging wildfires burning in Canada and Minnesota have sent thick smog and smoke into the northern U.S. and put millions of people under air quality alerts, according to the National Weather Service, which warns more major cities in the Northeast and Mid-Atlantic are likely to be impacted in the coming days.

Roughly 850 wildfires are burning in Canada, many of the largest in Ontario, and more than a dozen are ablaze in northern Minnesota as of Wednesday, coinciding with an extreme heat spell impacting much of the U.S.

A low pressure system making its way through southeast Canada has pushed smoke into the Lower 48, which is expected to result in orange sunrises and sunsets, fully-white or orange skies and air smelling like campfire smoke.

The Minnesota Pollution Control Agency’s West Duluth air quality monitor measured a new state record for wildfire smoke concentration Wednesday morning, and other major cities under dense and dangerous levels of smoke include Green Bay, Wisconsin; Detroit; Cleveland and Columbus, Ohio; and Buffalo and Rochester, New York.

The NWS has issued air quality alerts for parts of Minnesota, Michigan, Wisconsin, Illinois, Indiana, Ohio, New York, Connecticut and Massachusetts, and fire weather watches in Washington state and northern Minnesota.

What to watch for

How far the smoke spreads. It’s expected to filter further into the Northeast, Mid-Atlantic and Midwest through Friday and could reach New York City, Philadelphia, Baltimore, Washington, D.C., and Boston by Thursday morning.

130,000 acres. That's the size of the largest out-of-control wildfire in western Ontario, on the northern shores of Lake Superior, pushing smoke into the United States.

Canadian wildfire smoke has affected the U.S. for decades, but the scale and frequency of major smoke events have increased in recent years. (Source: Forbes)