Millions of nonprescription inhalers used for decades by asthma sufferers, often against the advice of doctors, could be taken off drugstore shelves because they contain propellants that harm the ozone layer. An advisory panel voted 11-7 Tuesday to recommend that the Food and Drug Administration [FDA] 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. Wyeth Consumer Healthcare estimates that 3 million Americans use Primatene Mist for mild or intermittent cases of asthma. About two-thirds also use a prescription inhaler but rely on Primatene as a backup. Another 700,000 use the inhalers because they don't have a prescription or lack health insurance.