The Bush administration surprised clean-air advocates and polluting industries alike on Friday when it announced that the U.S. EPA would reconsider parts of a decision to significantly relax air-pollution rules. In December, the EPA announced “final” revisions to the Clean Air Act’s New Source Review rule — changes that would have allowed tens of thousands of utilities, refineries, and factories to expand or update their operations without having to install state-of-the-art anti-pollution equipment. Now, thanks to lawsuits filed by environmental groups and attorneys general from Northeastern states, the EPA has agreed to revisit certain aspects of its rule changes as well as hold a public hearing and open up a 30-day public comment period. “I think the significance of this announcement is that the Justice Department looked at the case and realized they were very likely to lose in court because the rule changes are flatly illegal,” said Frank O’Donnell of the Clean Air Trust.