chlorofluorocarbons(CFCs)

A group of odourless, inert, synthetic, non‐toxic, and easily liquefied chemical compounds consisting of chlorine, fluorine, and carbon. They are very long‐lasting (50 to 200 years) and very efficient absorbers of infrared radiation. Until the early 1990s CFCs were widely used as propellants in aerosol cans, as refrigerants in refrigerators and air conditioners, and in the manufacture of foam boxes for take‐away food cartons. CFCs are important greenhouse gases that are broken down by strong ultraviolet light in the stratosphere and release chlorine atoms that then deplete ozone. Since the early 1990s most industrial countries (including the USA and UK) agreed under the Montreal Protocol to phase out production of CFCs and a range of other ozone‐depleting chemicals by the year 2000 . There are a number of important species of CFC, including CFC‐11 and CFC‐12 which remain active in the atmosphere for 50 to 100 years, the concentration of which is increasing at a rate of more than 5% a year, CFC‐113, the atmospheric concentration of which is increasing at a rate of about 10% a year, and CFC‐22, which remains active in the atmosphere for about 15 years, the concentration of which is increasing at a rate of about 11% a year.