Asthma inhalers containing ozone-depleting chlorofluorocarbons will be phased out by the end of 2008, the U.S. Food and Drug Administration announced Friday. The phaseout of CFCs is required under the Montreal Protocol, an international treaty that the United States actually deigned to sign on to. Alternatives to CFC inhalers use hydrofluoroalkanem as a propellant; HFA inhalers may taste different, feel different, require more regular cleaning, and cost about $20 more. Some 52 million inhalers are prescribed in the U.S. each year, and the FDA estimates that some 65 percent of inhaler users have already switched to HFA.