A federal appeals court has cleared the way for EPA to begin implementing a program to reduce air pollution that drifts across state lines. The October order from the U.S. Court of Appeals for the District of Columbia Circuit comes after the Supreme Court upheld EPA’s cross-state air pollution rule in April. The program requires 28 states to reduce power plant emissions of nitrogen oxides and sulfur dioxide that drift across their borders and pollute the air in the Northeast and mid-Atlantic regions. The D.C. Circuit Court put the rule on hold in December 2011 and struck it down the next summer. But the Supreme Court resurrected the rule, finding that EPA had reasonably interpreted the so-called good neighbor provision of the Clean Air Act.