CFCs proved to be one of the more useful classes of compounds ever developed because of their many desirable properties. They promote worker and consumer safety because they are nonflammable, noncorrosive, and very low in toxicity. They are used in a wide variety of applications, such as refrigerants, foam blowing agents, and cleaning solvents, because of their desirable physical properties that enhance energy efficiency and product reliability.

However, some of the properties that make CFCs desirable from a worker and consumer safety and applications standpoint have led to global environmental concerns. Because of their chemical stability, CFCs have long environmental residence times, and emissions lead to accumulation in the lower atmosphere. CFCs slowly mix into the upper atmosphere where they dissociate, releasing chlorine atoms that can catalyze destruction of ozone. Recent scientific findings have clearly linked chlorine from CFCs and other man-made compounds and bromine from man-made and natural sources to the seasonal ozone losses over Antarctica, the Antarctic ozone hole, and have indicated that these compounds are probably causing ozone losses over populated areas of both the northern and southern hemispheres as well. Since ozone provides a screen against solar ultraviolet radiation (UV-B) and excess UV-B has a potential to contribute to health and environmental concerns, significant reductions in ozone should be avoided. This information provides a sound basis for the Montreal Protocol, an international agreement amended in 1990 requiring a total phaseout of CFC production and consumption by 2000.