Following in the footsteps of nine other northeastern states, Pennsylvania went to court yesterday to block new, less stringent federal air-pollution regulations from taking effect. The Pennsylvania case is separate from one filed by the other states, but the issue is the same: the New Source Review rules of the Clean Air Act, which once required industries to install state-of-the-art pollution-control equipment when upgrading their facilities but were replaced by more lenient Bush administration regulations on Dec. 31. Katie McGinty, Pennsylvania’s acting secretary of environmental protection, said the regulatory changes could harm the state’s environment by increasing unhealthful emissions. McGinty (who headed former President Clinton’s Council on Environmental Quality) added that the shift would damage the state’s economy by forcing industry to pay for cleaning up pollution drifting in from other states. So far, the U.S. EPA has declined to comment on Pennsylvania’s lawsuit.