CIESIN Thematic Guides

Production and Use of Chlorofluorocarbons

The invention of chlorofluorocarbons (CFCs) in the late 1920s and early 1930s stemmed from the call for safer alternatives to the sulfur dioxide and ammonia refrigerants used at the time. Chlorofluorocarbons were chosen for their safety and for their advantageous chemical properties. These compounds are low in toxicity, nonflammable, noncorrosive, and nonreactive with other chemical species, and have desirable thermal-conductivity and boiling-point characteristics. These features led to increased demand as more applications arose for CFC use.

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 these categories are available for CFC-11 and CFC-12 from 1931 to 1991 (except total sales by category, for which data are available from 1976 to 1991). Similar statistics are available for CFC-113, 114, and 115 beginning in 1980 and for the hydrochlorofluorocarbon HCFC-22 from 1970, when records on these compounds began to be compiled. These data, along with a discussion of their trends and uncertainties, are given in the following AFEAS reports:

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.