CFCs are classified as halocarbons, a class of compounds that contain atoms of carbon and halogen atoms. Individual CFC molecules are labeled with a unique numbering system.
For example, the CFC number of 11 indicates the number of atoms of carbon, hydrogen, fluorine, and chlorine e. The best way to remember the system is the "rule of 90" or add 90 to the CFC number where the first digit is the number of carbon atoms C , the second digit is the number of hydrogen atoms H , and the third digit is number of the fluorine atoms F.
In the example CFC has one carbon, no hydrogen, one fluorine, and therefore 3 chlorine atoms. Refrigerators in the late s and early s used the toxic gases, ammonia NH 3 , methyl chloride CH 3 Cl , and sulfur dioxide SO 2 , as refrigerants.
After a series of fatal accidents in the s when methyl chloride leaked out of refrigerators, a search for a less toxic replacement begun as a collaborative effort of three American corporations- Frigidaire, General Motors, and Du Pont. Frigidaire was issued the first patent, number 1,,, for the formula for CFCs on December 31, By Frigidaire and its competitors had sold 8 million new refrigerators in the United States using Freon CFC made by the Kinetic Chemical Company and those companies that were licensed to manufacture this compound.
Public health codes in many American cities were revised to designate Freon as the only coolant that could be used in public buildings. During the late s and early s the CFCs made possible an inexpensive solution to the desire for air conditioning in many automobiles, homes, and office buildings.
Later, the growth in CFC use took off worldwide with peak, annual sales of about a billion dollars U. Whereas CFCs are safe to use in most applications and are inert in the lower atmosphere, they do undergo significant reaction in the upper atmosphere or stratosphere. In , two University of California chemists, Professor F. Sherwood Rowland and Dr.
Mario Molina, showed that the CFCs could be a major source of inorganic chlorine in the stratosphere following their photolytic decomposition by UV radiation. In addition, some of the released chlorine would become active in destroying ozone in the stratosphere 2. Ozone is a trace gas located primarily in the stratosphere see ozone. Ozone absorbs harmful ultraviolet radiation in the wavelengths between and nm of the UV-B band which can cause biological damage in plants and animals.
A loss of stratospheric ozone results in more harmful UV-B radiation reaching the Earth's surface. Chlorine released from CFCs destroys ozone in catalytic reactions where , molecules of ozone can be destroyed per chlorine atom. A large springtime depletion of stratospheric ozone was getting worse each following year. This ozone loss was described in by British researcher Joe Farman and his colleagues 3. The ozone hole was different than ozone loss in the midlatitudes.
Ozone loss also is enhanced in polar regions as a result of reactions involving polar stratospheric clouds PSCs 5 and in midlatitudes following volcanic eruptions. Under these Rules, most HFC uses in polyurethane and other foams and in new retail food refrigerated cases will be phased out between January 1, and January 1 Use of HFCs in mobile air conditioning will end with Model Year , while prohibitions on HFC use in new fire suppression systems, cold storage, residential refrigeration, and building chillers go into place on January 1 of , , and , respectively.
In addition to the various production bans, servicers and disposers of appliances and motor vehicle air conditioners are required to obtain technician certification, proper refrigerant recovery or recycling equipment, and keep records.
Skip to main content. Air How's the air? Efficient travel. Secure rights. Good food. Better homes. Liveable cities. Natural advantage. Decent work. Story of change. Back from the brink: how the world rapidly sealed a deal to save the ozone layer Posted on 11 June Wider relevance The success in negotiating, strengthening and enforcing the Montreal Protocol should give hope to embattled climate change negotiators around the world — as it is evidence that multilateral initiatives can be effective in tackling the global environmental challenges we face.
Context and background Chlorofluorocarbons CFCs are chemicals that were developed in the s which, before they were banned, were used in a wide array of commercial and industrial processes. Enabling factors Key to the rapid transition to phase out CFCs was the widespread acceptance amongst the general public, business actors and world leaders of the severity and urgency of the problem; a consensus that was forged following the discovery of the ozone layer in Scope and evidence It took only 2 years from the discovery of the ozone layer in for governments to agree to a global ban on the use of CFCsand a further 2 years for it to come into effect.
The Montreal Protocol is the only treaty ever to achieve universal ratification; with countries enforcing the ban on CFCs. Global observations have confirmed that atmospheric levels of key ozone depleting substances are going down and it is expected that by the middle of this century they will return to pre levels.
The United States estimates that by the year more than 6. As most ozone depleting chemicals are also greenhouse gases, the Montreal Protocol has averted greenhouse gas emissions equivalent to more than billion tonnes of CO2, making the Montreal Protocol an important contributor to the fight against global warming.
Lessons for a rapid transition International environmental negotiations can work. The success in the rapid negotiation, strengthening and enforcement of the Montreal Protocol to tackle ozone depleting substances is evidence of the ability of multilateral action to address clear and imminent environmental threats through regulation. Significantly, action was taken in a precautionary manner in advance of full scientific proof of the extent of the threat posed by ozone depletion.
The organisation of civil society globally was key to building public consciousness and changing consumer behaviour. The boycotts of CFC products like aerosols convinced companies that a phase out was inevitable, and government support for a ban often followed suit. Business interests are not uniform. You can work with those who stand to win from regulations in this case, the larger producers of CFCs that began to invest in alternatives early on to break the deadlock and spur change.
Manufacturers have used this compound to make cleaning solvents, refrigerants, and aerosol propellants, in some cases, even plastic foams. A few common products include Freon and other refrigerants. CFCs and their associated compounds were developed in the early s as a non-toxic, non-flammable solution to other more dangerous products such as ammonia. Over the years, it became an important chemical product for refrigeration. However,, today it is used less frequently because CFC components, needed for refrigerators release chlorine into the atmosphere.
The chlorine content can potentially destroy parts of the ozone when the right conditions appear. When the CFCs reach the ozone layer, ultraviolet radiation occurring at this altitude breaks down the compound and releases the chlorine.
Experts now believe that under special circumstances this chlorine destroys parts of the ozone layer, a rarity that has been observed over Antarctica and as a result of this release, environmentalists have also seen an increase in ultraviolet radiation causes damage to humans. Because of these harmful effects, the production of many of these products ceased in the early s. However, it is a compound still made in many countries for certain products.
For instance, some aircraft products need the halon fire suppression system needs CFCs as there a no suitable product alternatives.
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