Cfc's

Chlorofluorocarbons

Chlorofluorocarbons are non-toxic, non-flammable chemicals that are mainly used in the manufacturing of aerosols, blowing agents for foams and packing materials, as solvents, and as refrigerants. They are classified as Halocarbons, a class of compounds that contain carbon and halogen atoms, and are amongst a group of substances called "greenhouse gases". They eat away at our ozone and raise the temperature of our planet significantly, causing detrimental damage to our planet.

Chlorofluorocarbons (CFC's) are a man-made substance that did not previously exist to the industrial area. They are a product of a collaboration of three American companies - Frigidaire, General Motors, and Du Pont -- after a series of fatal accidents during the 1920's where toxic gases, (Methyl Chloride), used as refrigerants leaked from refrigerators. Thomas Midgley, Jr. of General Motors first synthesized CFC's in 1928, and later, on December 31, 1928, Frigidaire was issued the first patent for this formula. CFC's went under the trade name of Freon (11 and 12), licensed by Du Pont, and by 1935, they and their competitors had sold over eight million new refrigerators in the United States containing the substance. Because of the CFC safety record for non-toxicity, especially when compared to that of previously used substances for coolants, Freon became the preferred substance in large air-conditioning systems. Public health codes in many American cities were even revised to mandate the use of Freon. Soon thereafter the production and use of CFC's took off, ranging from propellants for bug sprays, paints, hair conditioners, and in air-conditioning in automobiles. (See appendices 1) Peak annual sales of the product worldwide reached over one billion dollars US, and more then one million metric tons were produced.

CFC's at ground level are perfectly safe, being inert at lower atmospheric levels, but they do undergo a significant reaction in the upper atmosphere or stratosphere. The first proof of this was in 1974 when a study by two university professors showed that CFC's went through a process called "Photolytic Decomposition" (see appendices 2) thereby releasing chlorine atoms into the atmosphere where they would become active in the destruction of the Ozone. A loss of the stratospheric ozone would result in higher levels of harmful UV-B radiation reaching the earth's surface. Ozone helps to filter out ultraviolet radiation between the wavelengths of 280 and 320 nm, which causes biological damage in plants and animals. Chlorine released from CFC's destroys ozone in catalytic reactions where 100 000 molecules of ozone can be destroyed per chlorine atom. This is a staggering and disturbing statistic. Another major cause for alarm by CFC's is there ability to trap heat and contribute to global Warming. They are more then 10 000 times more effective then CO2 at trapping radiated heat from the sun. Although they have a relatively low concentration within our atmosphere, their strong ability to trap heat makes them a leading cause of global warming. They are second in global warming only to carbon dioxide. (With carbon dioxide having much higher concentrations.)

Though more than 90 % of CFC's are produced at the surface in the Northern Hemisphere (in Europe, Russia, Japan, Canada, and the United States), they do indeed "head south," but they also head east, north, west, and upward through diffusion. On a much larger scale, atmospheric circulation mixes air masses thoroughly. Within a year or two, CFCs can be well distributed worldwide throughout the troposphere heating up the world and eating up ozone. Uniformly mixed gases, including CFCs, rise into the stratosphere mainly in the tropics and then move pole ward as part of the general atmospheric circulation. Ultimately, CFCs become uniformly dispersed throughout the entire lower stratosphere. Their concentration begins to decrease above about 15 kilometers. Once above this level, reactions with high-energy solar ultraviolet radiation break up these molecules.

It took years of ignorance and looking the other way before the realization that CFC's have to be eliminated became glaringly urgent. The most apparent problem that created awareness of the hazards of CFC's was the large springtime depletion of stratospheric ozone over the Antarctic region that worsened each following year. In 1996, the Antarctic hole was over 8.3 million square miles, large enough to cover most of Africa. At this time, the large hole doesn't directly affect many humans as it covers an uninhabited area. It has only been in this past spring of 2000, that the Antarctic hole has reached the very tip of Africa, exposing one of South Africa's largest cities, Cape Town, to extensive amounts of harmful UV-B radiation. Luckily at this time, the hole only extends this far for a limited period, before retreating further south. The Antarctic area has undergone the largest amount of damage for depletion of the ozone simply because of its cold climate. After CFC's are broken up by sunlight radiation, the by-products do not cause any further damage until they participate in further chemical reactions on the surfaces of "polar stratospheric cloud particles". These clouds only form in cold weather, typically -80 degrees Celsius and below, and the most reliable place on earth for these clouds to form is the Antarctic area. (See appendices 3).

In 1987, 27 nations signed a global environmental

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