Hydrofluorocarbons, or HFCs, represent only about 3 percent of U.S. climate pollution, but can be 1,000 to 12,000 times as potent as CO2 emissions.

Paul Blowers, University Distinguished Professor in the Chemical and Environmental Engineering Department, said in an interview reprinted in Scientific American that 1 kilogram of HFCs can equal 1.7 tons of carbon dioxide pollution.

The EPA approved a federal rule to cut to HFCs in 2015 by mandating companies replace the gas in refrigerator cases. HFC manufacturers Mexichem Fluor and Arkema of France sued the EPA over the decision, and a three-judge panel decided the EPA overstepped its bounds.

According to Blowers, despite their potency, HFCs are easier to regulate than vehicular emissions because there are far fewer HFC-reliant refrigeration units in use than there are vehicles on the road.

The court’s decision can be appealed either to the Supreme Court to the full panel of 11 D.C. Circuit Court judges.

University of Arizona College of Engineering