This has led to movements calling for reduction and eventual elimination of ozone-depleting substances. International agreements, such as the Montreal Protocol on Substances That Deplete the Ozone Layer , and national policy decisions have led industry and the scientific community to collaborate to find and develop safe alternatives to CFCs. Many factors need to be considered in the phaseout process and in selecting alternative substances. Replacements are evaluated on criteria such as toxicity, chemical stability, ozone depletion potential, global warming potential, and suitability for performing the task of the substance they are replacing. Metered-dose inhalers are one of the devices expected to receive exemption from the CFC ban.
Economic considerations are also a major factor in determining time frames for phaseouts.
Immediate replacement of CFCs may be prohibitively expensive for certain applications, resulting in requests for longer phaseout times for the industries involved. These compounds are slated to be banned early in the next century, which would result in additional replacement costs for devices using HCFCs. Among the panel's conclusions are that sufficient technology and alternative substances exist to warrant the accelerated phaseout schedules defined by the Protocol amendments. In addition, the panel concludes that the long-term economic interests of all countries, including developing nations, are served by following the time schedules set forth by the Protocol.