When the Trump administration exempted parts of the Chicago area last year from federal limits on lung-damaging smog, it delivered a huge financial break to steel mills, chemical plants and other industries that are some of the region’s biggest polluters.
Scott Pruitt, who at the time headed the U.S. Environmental Protection Agency, also freed the Foxconn Technology Group from spending millions of dollars on pollution-control equipment as it builds a new electronics plant in southeast Wisconsin, just north of the Illinois border in an area with some of the region’s dirtiest air…