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 treaty, the Montreal Protocol to Reduce Substances that Deplete the Ozone Layer, which had a provision to reduce 1986 production levels of these compounds by 50% before the year 2000. Later, an amendment in London mandated the total elimination of production by the year 2000. The environmental concerns for CFC’s continued to progress, with studies showing that life expectancies of this chemical proved to be very long – 55 years for CFC-11, and 140 years for CFC-12 – resulting in the Copenhagen amendment which was approved in 1992.
This further limited production of CFC’s, with the only exceptions being for production in developing countries, and for some medicinal purposes. The manufacturing of CFC’s had essentially ended by January 1, 1996. A total of 148 countries have now signed that Montreal Protocol. (See appendices 4) On the upside, atmospheric levels of CFC’s reported in 1993 seem to have either leveled off, or in some cases even begun to decrease thanks to voluntary and mandatory reductions in emissions.
Unfortunately, at the same time, the existing levels of CFC’s will remain in “our” atmosphere destroying “our” ozone well into the 22-century. The effects on humans through CFC’s causing Ozone depletion will be great, worsening throughout the 21st century. The ozone depletion over the northern hemisphere is expected to account for between a 10% and 20% skin cancer increase in the Pacific Northwest in the next few decades. Studies show that a 1% reduction in Ozone, would result in over 10 000 additional cases of skin cancer in America alone. Australia has one of the most severe UV-B related problems anywhere in the world. It is estimated that 2 out of 3 people in most parts of the country will develop skin cancer, in Queensland, which has the highest UV-B levels, that number is raised to 3 out of 4.
In America, in 1935, the chances of developing the most serious form of skin cancer (malignant melanoma), was 1 in 1500. In 1991, it had soared to 1 in 150, and it is predicted that by the year 2000, it will be 1 in 75. In an effort to curb the devastation by CFC’s, industries have created two new classes of Halocarbons – Hydrochloroflourocarbons (HCFC’s) and Hydroflourocarbons (HFC’s). HCFC’s are identical to CFC’s, but also contains a hydrogen atom.
With this hydrogen atom, the HCFC’s react differently with ozone, and although they still destroy it (having 4000 to 10000 times the destructive level of CO2), they have a much shorter life span, of about 13 years. The Copenhagen Amendment calls for their elimination by 2020. The HFC’s are considered to be the best substitute to CFC’s, as they do not contain chlorine (the substance that destroys ozone), their inability to trap heat and their short lifespan. In America, all new air conditioners in automobiles contain HFC’s, and their rate of use is growing rapidly, at a rate of 100% a year. After nearly a century of use, CFC’s have finally been almost totally eliminated from production on the face of the planet. It seems as though we have finally taken a step in the right direction as far as preserving our ozone and our climate.
Unfortunately, the repercussions of CFC’s will not go away anytime in the near future. Their effects will be felt well into the next century, as they continue to eat up what remains of our ozone and heat up our planet. Even after all of the CFC’s have decomposed, it will take generations before the ozone can begin to regenerate. That is one positive aspect of all this, and our future depends on it — the damage done today is not irreversible — but without immediate and drastic action, it will be.
