As of January 1, 2009, asthma inhalers containing chlorofluorocarbon (CFC) propellant will no longer be sold, in favor of environmentally safer hydrofluoroalkane (HFA) inhalers. The old inhalers are being phased out as a result of U.S. participation in the 1987 Montreal Protocol, an international treaty to ban substances that are damaging the earth’s ozone layer.