Since the introduction of the Montreal Protocol on Substances That Deplete the Ozone Layer, over a decade ago, international use of ozone-depleting substances (ODSs) has declined significantly. The key component of the Montreal Protocol is the stipulation that the production and consumption of all identified compounds that deplete the ozone layer are to be phased out by 2030 in developed countries and 2040 in developing countries. The use of hydrofluorocarbons (HFCs), and to a much lesser extent perfluorocarbons (PFCs), has allowed the rapid phaseout of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and halons in the U.S. and other countries in applications for which other alternatives are not readily available. HFCs have generally been selected for applications where they provide superior technical (reliability) or safety (low toxicity and flammability) performance. In many cases, HFCs provide equal or better energy efficiency as compared to other available alternatives, thereby reducing long-term environmental impacts. HFCs are expected to replace a significant portion of past and current demand for ODSs in insulating foams, refrigeration and air-conditioning, propellants used in metered dose inhalers, specialized fire protection equipment, and in other applications.