Zeotropic mixture harmful effects that hydrochlorofluorocarbons (HCFC) and chlorofluorocarbons (CFC) have on the ozone layer and global warming. Researchers have focused on using new mixtures that have the same properties as past refrigerants to phase out harmful halogenated substances, in accordance to the Montreal Protocol and Kyoto Protocol. For example, researchers found that zeotropic mixture R-404A can replace R-12, a CFC, in household refrigerators. However, there are some technical difficulties for using zeotropic mixtures. This includes leakages, as well as the high temperature glide associated with substances of different boiling points, though the temperature glide can be matched to the temperature difference
Montreal Protocol over the period 1991 to 2005. Funds are used, for example, to finance the conversion of existing manufacturing processes, train personnel, pay royalties and patent rights on new technologies, and establish national ozone offices. As of 23 June 2015, all countries in the United Nations, the Cook Islands, Holy See, Niue as well as the European Union have ratified the original Montreal Protocol (see external link below), with South Sudan being the last country to ratify the agreement, bringing the total to 197. These countries have also ratified the London, Copenhagen, Montreal, and Beijing amendments. Since the Montreal Protocol came