The Center for Biological Diversity sued the U.S. Environmental Protection Agency and its administrator, Michael S. Regan, Tuesday in Pennsylvania Eastern District Court. The lawsuit, brought by Fair Shake Environmental Legal Services and Environmental and Animal Defense, accuses the EPA of unreasonable delay in publishing a final rule regarding Pennsylvania's state implementation plan to address smog. The case is 2:23-cv-01843, Center For Biological Diversity v. United States Environmental Protection Agency et al.