Climate change is undoing decades of progress on air quality

A choking layer of pollution-laced fog settled over Minneapolis last month, blanketing the city in its worst air quality since 2005. A temperature inversion acted like a ceiling, trapping small particles emitted from sluggish engines and overworked heaters in a gauze that shrouded the skyline. That haze arrived amid the hottest winter on record for the Midwest. Warmer temperatures melted what little snow had fallen, releasing moisture that helped further trap pollution.

Though summertime pollution from wildfire smoke and ozone receives more attention, climate change is making these kinds of winter inversions increasingly common — with troubling results. One in four Americans are now exposed to unhealthy air, according to a report by First Street Foundation. 

Jeremy Porter, head of climate implications research at the nonprofit climate research…