Environmentally friendly propellants may soon replace the ozone-eating chlorofluorocarbons (CFCs) in metered dose inhalers used for asthma medications. CFC-free formulations of albuterol and salbutamol, two common asthma drugs, are already available for testing, but since the new propellants change the amounts of drug delivered to the lungs, it may be a few years before drug manufacturers release these new products to the market.