A coalition of environmental groups sued the EPA Monday for withdrawing a policy that imposed strict limits on hazardous air pollutants from factories, plants and other types of facilities considered "major" polluters.

Under the "once-in-always-in" policy, established in 1995, major polluters failing to meet certain emission thresholds were required to meet those standards from then on, even if the facility made changes to reduce its pollution.

With the new Trump administration policy, issued in January, facilities labeled as “major sources” of pollution may be reclassified as “area” sources when they limit their potential to emit pollution.

Environmentalists say the EPA’s change would allow facilities to emit more pollution. Seven environmental groups, including the Sierra Club and Natural Resources Defense Council, filed suit in the D.C. Circuit Court of Appeals, arguing the EPA violated the law by not subjecting the move to public comment.

The EPA says the “once-in-always-in” policy has discouraged facilities from implementing pollution control technology to reduce emissions.