Washington ? Asthma sufferers may not be able to buy nonprescription inhalers much longer because the devices contain propellants that harm the ozone layer.

An advisory panel voted 11-7 Tuesday to recommend that the Food and Drug Administration remove the “essential use” status that Primatene Mist and other similar nonprescription inhalers require to be sold, spokeswoman Laura Alvey said. Final revocation of that status would mean a de facto ban on their sale.

If the agency opts to follow the recommendation, it would begin a rulemaking process that would include public comment, Alvey said.

Wyeth Consumer Healthcare estimates that 3 million Americans use Primatene Mist for mild or intermittent cases of asthma, spokesman Fran Sullivan said. About two-thirds also use a prescription inhaler but rely on Primatene as a backup. About 700,000 asthma sufferers use Primatene alone because they can’t get a prescription or lack health insurance, he said.

The over-the-counter inhalers proposed to be banned contain the drug epinephrine along with chlorofluorocarbons, or CFCs, which propel epinephrine into the lungs of asthmatics.

CFCs were long used as aerosol propellants in a variety of products but are being phased out because they harm the Earth’s protective ozone layer.

In March, the FDA said inhalers using CFCs to dispense the prescription drug albuterol would be banned at the end of 2008.