<P> After a 1976 report by the United States National Academy of Sciences concluded that credible scientific evidence supported the ozone depletion hypothesis a few countries, including the United States, Canada, Sweden, Denmark, and Norway, moved to eliminate the use of CFCs in aerosol spray cans . At the time this was widely regarded as a first step towards a more comprehensive regulation policy, but progress in this direction slowed in subsequent years, due to a combination of political factors (continued resistance from the halocarbon industry and a general change in attitude towards environmental regulation during the first two years of the Reagan administration) and scientific developments (subsequent National Academy assessments that indicated that the first estimates of the magnitude of ozone depletion had been overly large). A critical DuPont manufacturing patent for Freon was set to expire in 1979 . The United States banned the use of CFCs in aerosol cans in 1978 . The European Community rejected proposals to ban CFCs in aerosol sprays, and in the U.S., CFCs continued to be used as refrigerants and for cleaning circuit boards . Worldwide CFC production fell sharply after the U.S. aerosol ban, but by 1986 had returned nearly to its 1976 level . In 1993, DuPont Canada closed its CFC facility . </P> <P> The U.S. Government's attitude began to change again in 1983, when William Ruckelshaus replaced Anne M. Burford as Administrator of the United States Environmental Protection Agency . Under Ruckelshaus and his successor, Lee Thomas, the EPA pushed for an international approach to halocarbon regulations . In 1985 20 nations, including most of the major CFC producers, signed the Vienna Convention for the Protection of the Ozone Layer, which established a framework for negotiating international regulations on ozone - depleting substances . That same year, the discovery of the Antarctic ozone hole was announced, causing a revival in public attention to the issue . In 1987, representatives from 43 nations signed the Montreal Protocol . Meanwhile, the halocarbon industry shifted its position and started supporting a protocol to limit CFC production . However, this shift was uneven with DuPont acting more quickly than their European counterparts . DuPont may have feared court action related to increased skin cancer especially as the EPA had published a study in 1986 claiming that an additional 40 million cases and 800,000 cancer deaths were to be expected in the U.S. in the next 88 years . The EU shifted its position as well after Germany gave up its defence of the CFC industry and started supporting moves towards regulation . Government and industry in France and the UK tried to defend their CFC producing industries even after the Montreal Protocol had been signed . </P> <P> At Montreal, the participants agreed to freeze production of CFCs at 1986 levels and to reduce production by 50 percent by 1999 . After a series of scientific expeditions to the Antarctic produced convincing evidence that the ozone hole was indeed caused by chlorine and bromine from manmade organohalogens, the Montreal Protocol was strengthened at a 1990 meeting in London . The participants agreed to phase out CFCs and halons entirely (aside from a very small amount marked for certain "essential" uses, such as asthma inhalers) by 2000 in non-Article 5 countries and by 2010 in Article 5 (less developed) signatories . At a 1992 meeting in Copenhagen, the phase - out date was moved up to 1996 . At the same meeting, methyl bromide (MeBr), a fumigant used primarily in agricultural production, was added to the list of controlled substances . For all substances controlled under the protocol, phaseout schedules were delayed for less developed (' Article 5 (1)') countries, and phaseout in these countries was supported by transfers of expertise, technology, and money from non-Article 5 (1) Parties to the Protocol . Additionally, exemptions from the agreed schedules could be applied for under the Essential Use Exemption (EUE) process for substances other than methyl bromide and under the Critical Use Exemption (CUE) process for methyl bromide . </P> <P> Civil society including especially NGOs, played critical roles at all stages of policy development leading up to the Vienna Conference, the Montreal Protocol, and in assessing compliance afterwards . The major companies claimed that no alternatives to HFC existed . An ozone - safe hydrocarbon refrigerant was developed at a Hamburg technological institute in Germany, and in 1992 came to the attention of the non-governmental organization (NGO) Greenpeace . Greenpeace was given the patent, called it "Greenfreeze," and left the patent as open source . The NGO then worked successfully first with a small and struggling company to market an appliance beginning in Europe, then Asia and later Latin America, receiving a 1997 UNEP award . By 1995, Germany had already made CFC refrigerators illegal . Since 2004, corporations like Coca - Cola, Carlsberg, and IKEA have been forming a coalition to promote the ozone - safe Greenfreeze units . Production spread to companies like Electrolux, Bosch, and LG, with sales reaching some 300 million refrigerators by 2008 . In Latin America, a domestic Argentinian company began Greenfreeze production in 2003, while the giant Bosch in Brazil began a year later . By 2013 it was being used by some 700 million refrigerators, making up about 40 percent of the market . In the U.S., however, change has been much slower . To some extent, CFCs were being replaced by the less damaging hydrochlorofluorocarbons (HCFCs), although concerns remain regarding HCFCs also . In some applications, hydrofluorocarbons (HFCs) were being used to replace CFCs . HFCs, which contain no chlorine or bromine, do not contribute at all to ozone depletion although they are potent greenhouse gases . The best known of these compounds is probably HFC - 134a (R - 134a), which in the United States has largely replaced CFC - 12 (R - 12) in automobile air conditioners . In laboratory analytics (a former "essential" use) the ozone depleting substances can be replaced with various other solvents . Chemical companies like Du Pont, whose representatives even disparaged Greenfreeze as "that German technology," maneuvered the EPA to block the technology in the U.S. until 2011 . Ben & Jerry's of Unilever and General Electric, spurred by Greenpeace, had expressed formal interest in 2008 which figured in the EPA's final approval . </P>

Ozone layer depletion in antartica is due to which compound