DES MOINES, Iowa — As fires continue to burn across the western U.S. and Canada, smoke is now causing serious health problems in the Midwest.
Minnesota, South Dakota and Wisconsin experienced some of the worst air quality in the country on Thursday - even worse than locations near the wildfires out west.
The air quality index reached hazardous levels from central Minnesota to eastern South Dakota.
Visibility fell as low as less than a mile in some locations.
Most of the smoke this summer has stayed thousands of feet above the ground. Why is this different?
A cold front moved through the region Wednesday night through Thursday. The air behind cold fronts tends to sink toward the surface.
That is leading to smoky conditions at ground level.
This thick plume of smoke is forecast to move south into Iowa Thursday night through at least Friday.
An air quality alert is in effect for all of Iowa until 4 p.m. Friday.
Iowa DNR recommends elderly, those with respiratory or heart disease and children limit prolonged outdoor exertion until air quality improves.
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