The New Source Review process is a seemingly minor bureaucratic detail of the Clean Air Act— but it has big implications for pollution levels. The process requires industrial facilities, like power plants, to obtain permits whenever they expand operations and increase their emissions. But now the Trump administration wants to roll it back. The U.S. Environmental Protection Agency proposed a revision that would allow industry to skirt the process by only calculating “net” pollution increases—rather than total—which lets them avoid installing pollution-control equipment. The move is essentially a math trick that reduces new emissions on paper, while our health and climate suffer in the real world.