Principal uses of CFCs are for coolants in refrigeration systems and air conditioners, as solvents to clean electronic components, as blowing agents in the production of plastic foams, and as propellants in air conditioners. These uses are reviewed in the chapter "Controlled Substances" of The Montreal Protocol 1991 Assessment (United Nations Environment Programme 1991). Of the 682 million kilograms of chlorofluorocarbons consumed globally during 1991, the DuPont Corporation estimates the use for various applications as follows: 32 percent for refrigerants, 28 percent for blowing agents, 20 percent for cleaning agents, and 18 percent for propellants. The primary chlorine-containing products on the market are denoted by the industry nomenclature CFC-11, CFC-12, CFC-113, CFC-114, CFC-115, and the hydrochlorofluorocarbon HCFC-22.
Statistics on the production, sales, and release of several CFC compounds have been compiled by the Alternative Fluorocarbons Environmental Acceptability Study (AFEAS). These statistics are available for several categories:
Data for CFC-11 and CFC-12 show that, with few exceptions, total production rose continuously following their introduction in the 1930s. Deviations from this trend are noted following 1974, when the issue of possible ozone depletion by chlorine-containing species was first announced, and following the signing of the Montreal Protocol in 1987. HCFC-22 production shows a nearly constant increase since figures became available in 1970. Because HCFC-22 is currently considered a replacement for CFCs, it is not subject to the strict phaseout schedules of the CFCs. CFC-113 production shows significant increases through the early- and mid-1980s until the Montreal Protocol was issued, after which production sigificantly diminishes. CFCs 114 and 115 show nearly constant production levels since 1980, with slight decreases near the end of the decade, following the Protocol.