The Trump administration said late Wednesday that it would not delay an Obama-era regulation on smog-forming pollutants from smokestacks and tailpipes (Editor's note: the link could be paywalled; alternative source), a move that environmental groups hailed as a victory. From a report: The Environmental Protection Agency decision came a day after 16 state attorneys general, all Democrats, filed a lawsuit challenging the delay with the United States Court of Appeals for the District of Columbia. It reversed a decision that Scott Pruitt, the E.P.A. administrator, made in June to put off an Oct. 1 deadline for designating which areas of the country met new ozone standards. In announcing the ozone policy change, the agency appeared to leave the door open to extending the deadline again. But, officials said, the agency will work with states to help them deliver the needed information.