WASHINGTON (AP) — A federal appeals court is ordering the Environmental Protection Agency to relax some limits it set on smokestack emissions that cross state lines and taint downwind areas with air pollution from power plants.

At the same time, the court upheld the EPA's right to impose the clean-air standards, rejecting an argument by states and industry groups that the rule was overly burdensome.

Tuesday's ruling by the U.S. Court of Appeals for the District of Columbia Circuit orders the EPA to redo sulfur-dioxide or nitrogen-oxide standards for 13 southern and Midwestern states that contribute to soot and smog along the East Coast.

The ruling follows a Supreme Court decision last year upholding the so-called Cross State Air Pollution Rule, which blocks states from polluting other states.