Do you think that CFC substitutes should be allowed?

CFCs (chlorofluorocarbons), HCFCs, HFCs

Chlorofluorocarbons are man-made chemical compounds that contain a mixture of carbon, fluorine and chlorine atoms. They were invented by Thomas Midgley, Jr., in 1928. They used to be used as refrigerants, aerosol propellants and in foams under the proprietary name Freons. They are chemically inert, non-toxic and not flammable and therefore seemed safe for forty years and were used in many industrial processes. After it was found that they were responsible for ozone layer depletion (the ozone hole) many countries banned their production and use.

By the early 70s, James Lovelock of England developed the electron capture detector which was able to detect very low amounts of organic gases in the atmosphere, which showed that CFCs were already present throughout the atmosphere around the world.

Chlorofluorocarbon (CFC) gases can end up in the ozone layer, where the ultra-violet radiation can split them into their constituent atoms. These atoms, particularly the chlorine atom, can act as catalysts in the depletion of the ozone layer (ozone hole). A chlorine atom can destroy up to 100,000 ozone molecules.

Mario Molina and Sherwood Rowland realised in 1974 that chlorofluorocarbon (CFC) gases can also end up in the ozone layer, where the ultra-violet radiation could split them into their constituent atoms and that they could therefore contribute to ozone layer depletion. By that time millions of tonnes of CFCs had been manufactured and used.

CFCs are greenhouse gases, as is ozone. Over 100 years, each CFC molecule contributes the same to global warming as one thousand molecules of carbon dioxide. Being stable, they generally last between 50 and a hundred years in the atmosphere. They commonly have two or three atoms.

In 1987, the Montreal Protocol on Substances that Deplete the Ozone Layer was agreed. By September 2002 183 countries had ratified it. Under it, developed countries have ceased production of CFCs (and some other ozone-depleting chemicals). Developing countries were given until 1 January 2010 to phase them out. Neither is allowed to import or export from or to non-party countries. This gave countries an incentive to sign up. Environmentalists had put pressures on their governments prior to the protocol; for example, Friends of the Earth UK boycotted CFC aerosol products up to 1987.

Production of CFCs peaked in 1988. By 1996 it had fallen to nearly a tenth of its peak value. In spite of some smuggling (the black market was estimated at 20,000 to 30,000 tons per year in 1999 by the World Bank), the amount of CFCs reaching the atmosphere has also peaked. There is still the problem of what to do with stockpiles, which have to be treated as hazardous waste.

When CFCs were banned some manufacturers insisted on being allowed to use CFC substitutes. The main ones are called HCFCs, but HFCs are also used (see below). These are intended to be phased out when better alternatives have been developed. They are considered better for the ozone layer because some of the chlorine atoms are replaced by hydrogen atoms. They do not stay in the atmosphere for as long, so fewer molecules reach the ozone layer, and those that do contribute less chlorine.

Some hydrocarbons (compounds containing only hydrogen and carbon atoms) are also used. Hydrocarbons are greenhouse gases, and over 100 years, each molecule contributes the same to global warming as ten molecules of carbon dioxide, but one hundredth that of HCFCs or HFCs. They contain no chlorine and so do not affect the ozone layer.

HCFCs

Hydrochlorofluorocarbons are chemical compounds that contain a mixture of hydrogen, carbon, fluorine and chlorine atoms. They typically stay in the atmosphere for 20 years and they are about a tenth or twentieth less harmful to the ozone layer as CFCs.

HCFCs are greenhouse gases, and over 100 years, each molecule contributes the same to global warming as one thousand molecules of carbon dioxide.

HFCs

Hydrofluorocarbons are chemical compounds that contain a mixture of hydrogen, carbon and fluorine atoms. They typically stay in the atmosphere for 20 years and they are not damaging to the ozone layer, as they have no chlorine atoms.

HFCs are greenhouse gases, and over 100 years, each molecule contributes the same to global warming as one thousand molecules of carbon dioxide.

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