CFCs have been regarded by the chemical industry as a miracle substance. Their properties were discovered by accident after being originally developed as the working fluid used in refrigerators. They were ideal since they boiled at about -40 F and at 32 F were nonflammable, nontoxic, inexpensive to manufacture, easy to store and chemically stable. CFCs had proven to be useful as solvents effective in such items as cleaning delicate semiconductor circuitry, blowing foams (e.g. the foamed hard plastic of coffee cups), and fast food packaging cartons.
Seventy-five percent of CFCs emission into the environment came from spray cans, 15 percent from leaky refrigerators and air conditioning systems, especially car air conditioners. Due to the stability of CFCs, they get into the atmosphere and remain there for a long period of time.
Lovelock believed that there is nothing known in the troposphere that can attack CFCs and break down their chemical structure. They do not interact with living things, nor dissolve in the ocean. They are not washed out of the air by precipita-tion. They do, however, gradually work their way upward into the stratosphere. It is in the stratosphere where they are chemically broken apart by ultraviolet radiation releasing chlorine atoms.
The problem presented by CFCs is that they contain chlorine. The compounds, chlorofluorocarbons indicate that they are built up from atoms of chlorine, fluorine, and carbon. DuPont gave his manufactured CFCs the brand name Freons and consequently, developed a labeling system that indicates how many atoms of each kind are present in a particular type of Freon. The two most commonly used CFCs are (F-11) trichlorofluoromethane (CCl3 F) and F-12 dichlorofluoromethane (CCl2 F2). F-11 is estimated to survive 75 years before being broken down in the atmosphere.
F-11, F-12, and F-13 do not absorb radiation with wavelengths longer than 240 nm. One nanometer is one-billionth of a meter. In the troposphere the ozone layer protects them from photodecomposition. Once the CFCs percolate up to ultraviolet radiation with wavelengths ranging from 200 to 220 nm, because of the exposure to ultraviolet radiation, decomposition can occur.
CCL + UV -> C1 + CCL F
CCL F + UV -> C1 + CC1 F
Free chlorine posing a hazard to ozone in the stratosphere once the chlorine catalytic chain is present.
C1 + 03 -> C10 + 02
C10 + -> C1 + 02
Net Effect
0 + 03 -> 02 + 02
Another threat is the remaining fragments of CFCs, CC12 F and CC1 F2 because they are chemically active and will react with other atmosphere molecules. The reason for the reaction is the odd number of elections that like to pair up with each other.
Sherry Rawland’s study revealed that a single atom of chlorine released into the stratosphere would destroy 100,000 molecules of ozone before being locked up in some less reactive form such as G12 . F-11 and F-12 are being put into the atmosphere six times faster than they are being destroyed by ultraviolet radiation in the stratosphere.
In 1980 the Environmental Protection Agency under the Carter administration made great strides in limiting the overall production of CFCs in the United States. In 1981 the Reagan administration killed off all the plans.
In 1970 environmental lobbyists won the war on the spray can in the United States, but only to realize that it was just the tip of the iceberg. Other countries continued their use of CFCs in spray cans and chemical fertilizer. There was also still the problem of pollution from car exhausts and volcanoes spewing chemicals into the atmosphere.
In April 1993 the “New Haven Register” published an article from the “Washington Post” stating that the ozone layer which has been under long assault had taken another blow from industrial chemicals. Credit was also given to Mount Pinatubo.
The article also stated that during late 1992 and early 1993 the ozone over our plant as a whole was 2 percent to 3 percent lower since 1979 when scientists started monitoring the ozone. The measurements took place over the temperate zone of the western United States and Eurasia. The past winters loss was 14 percent.
Researchers added that if Pinatubo caused a depletion of the ozone within 1 to 2 years, natural processes will start to replenish the loss amount of ozone. It is also believed that the ozone will continue to thin until around the year 2000. At that time there should start to be some visible changes. The ozone should start to get thicker.
The predicted turnaround is to be the result from the phase-out of ozone destroying CFCs and other chemicals mandated by an international treaty, the Montreal Protocol.
A collaboration of scientists from the National Aeronautics and Space Administration Goddard Space Flight Center in Greenbelt, Maryland and the National Oceanic and Atmospheric Administration pointed out that the Northern Hemisphere is not experiencing an ozone hole relative to that forming annually over the South Pole. The loss of the ozone does not pose a significant health hazard.
Richard S. Stolarski, a spokesperson from Goddard, pointed out that last winter’s great depletion came about when ozone levels were naturally at a high point in their annual cycle. Even though the ozone is being reduced there is still significant amounts overhead.
Data on the ozone is based on observations by several Earth-orbiting satellites operated by NASA and NOAA. Included also is data from latest shuttle flight and is confirmed by ground based ozone monitoring instruments.
If Pinatubo is to blame for ozone loss, it was a delayed effect. The chemicals from the volcano which is located in the Philippines reached into the stratosphere and began circling in an equatorial latitude. Over a period of months, the particles reach north and south. Universal ozone destruction occurred in late 1991. The particles also shaded the ground, contributing to a global cooling trend which brought about a temporary reversal of global warming.
Scientist speculate that Pinatubo possibly affected the ozone layer in three ways. One is by the injection of large quantities of particles into the stratosphere. This caused ozone destroying chemical reactions. The second is that Pinatubo altered the patter of winds in the stratosphere. Rising air could block normal winds causing ozone rich air. The third is the possibility that the warmed stratosphere would also alter the rates at which new ozone is formed or the rate at which old ozone is destroyed.