Asthma sufferers will soon be paying more for increasingly scarce emergency inhalers as part of the price of protecting the environment.

By the end of 2008, the government says, the makers of albuterol “rescue” inhalers – used by millions of people to reopen airways during asthma attacks – will have to stop using the ozone-destroying chlorofluorocarbon propellants that power the devices.

Three decades ago, scientists discovered that the CFCs were damaging the atmospheric ozone layer that shields Earth from harmful ultraviolet radiation, and the United States began to phase in a ban on their use.

The transition to other propellants for asthma inhalers has already begun. But some manufacturers have dropped out of the market, and others have encountered manufacturing snags. The rest are struggling to meet increased demand, and doctors and pharmacists say they are beginning to see supplies of inhalers tighten.

“This has the potential to be serious, because all asthmatics need to have a bronchodilator available as a rescue medicine,” said Dr. Glenn M. Silber, an allergist and immunologist with a practice in Howard County, Md.

There were about 20 million asthma sufferers in the United States in 2003, including 6.2 million children, according to the American Lung Association’s latest estimates. Manufacturers say consumers buy 59 million rescue inhalers a year.

To ensure there are no supply problems, the Food and Drug Administration is working with manufacturers, said spokeswoman Susan Cruzan, and “does not see a drug shortage associated with the use of albuterol.”

But the prices patients pay are going to go higher. The tightening supply for the CFC inhalers is pushing more patients from generics to brand-name versions of the same drug and to CFC-free devices – both of which are significantly more expensive.

Patients typically pay $15 to $22 for a generic CFC albuterol inhaler, and most use about one a month, doctors say. The non-CFC and brand-name versions can cost $45 to $55, according to Brad Houck, a retail pharmacist in Salem, Va., who specializes in hard-to-find pharmaceutical products.

He and others fear that a “gray market” is developing in which middlemen are stockpiling the inhalers and waiting for prices to rise.

In setting the deadline for eliminating CFCs from albuterol inhalers, the FDA reasoned that by Dec. 31, 2008, the drug industry would have time to reformulate and switch to more environmentally benign propellants called hydrofluoroalkanes.