The Trump administration is exempting dozens of chemical manufacturers, oil refineries, coal plants, medical device sterilizers and other polluters from Clean Air Act rules. On Thursday, the White House announced it would exempt more than 100 plants from pollution limits established by the Biden administration. The limits are aimed at reducing the releases of toxic chemicals, including those that cause cancer. One rule that the Trump administration is exempting about 50 polluters from would have been expected to reduce cancer risks of people living within 6 miles of a chemical plant by 96 percent.