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The beginning of the CFC(chlorofluorocarbons) era started
in 1928, when CFC' were invented by a Du Pont chemist. CFC'
were best known as "freons" and became famous as a safe,
nonflammable refrigerant. It's invention became a great
triumph when Freon took the place of sulfur dioxide or
ammonia which was used as the working liquid in
refrigerators. It eventually became widely used in
automobile air conditioners and nontoxic propellants in
aerosol cans. It's insulating properties also was used for
blowing agents for plastics and foam cups. Thus CFCs became
used all over the world and its business got bigger and
bigger until late in 1973. Sherwood Rowland and Mario
Molina, two distinguished chemists, came up with a
surprising result in his calculations concerning the CFCs
and ozone layer. CFCs are basically inactive in the
troposphere(around the altitude of 50,000 feet) so it would
gradually drift upward until they reached the
mid-stratosphere.(about 100,000 feet) At this point CFCs
would be broken down by short-wavelength ultraviolet
radiation from the sun. This radiation is the one which
would not reach the lower atmosphere in large amounts
because of the ozone layer. When these CFCs do brake down,
they released atomic chlorine which then would react with
the ozone and convert it back into plain oxygen. The even
worse part of all this is that these chlorine molecules do
not become inactive after the first reaction with the ozone
and would be available to destroy more ozone molecules.
Thus this process would be the function of a catalyst; a
single chlorine atom involved in a chain reaction to
destroy many ozone molecules. Rowland and Molina eventually
agreed that this thinning of the ozone shield can cause a
catastrophe for Earth's living beings, including humans, by
allowing large amounts of the deadly ultraviolet-B
radiation to reach to Earth's surface. Rowland and Molina
checked their calculations again and again to make sure
that these figures had not a single mistake in it because
this conclusion was likely to destroy an $8 billion
industry already in the United States. However, the lives
of the living beings were far more important than
businesses so in 1974 Rowland and Molina, having their
calculations checked by their colleagues, explained their
theory in a paper in the eminent scientific journal Nature.
Later the only reasonable conclusion they drew out was that
the use of CFCs be banned. When these calculations were
released to the public, Du Pont, the major CFC
manufacturer, did everything they can to convince the
people that the calculations were unproven and theoretical.
However Rowland and Molina did a marvelous job of defending
their results and explaining the significance of these
dangerous CFCs to other scientists, government officials,
and the press. Eventually the CFC use in aerosols was
banned in the US in 1978. However the total ban of the use
of CFCs was almost impossible for Rowland and Molina due to
scientific confusion and the arrival of the
antienviornmental Reagan administration. Another problem
that they soon realized was that for example if a total ban
of CFCs is achieved by the year 2000, the atmosphere would
still contain more CFCs in the year 2000 than it does
today, and 90% of the CFCs in the air when the ban comes
into effect will still be there in 2010. So in the end "the
worldwide depletion of the Ozone will get worse before it
gets better." The Dangers and Costs of Ozone Depletion The
public realized that the calculations of Rowland and Molina
were absolutely correct at the end of the 1980's and in the
early 1990's when large holes in the ozone layer began
appearing around the world, especially over Antarctica. It
appeared that for every molecule of chlorine some 10,000 to
100,000 ozone molecules were being destroyed. Adding to
that depletion can also be caused by bromine, a close
chemical relative of chlorine, which can reach the
stratosphere carried by chemicals called halons; however
significantly in lesser amounts compared to CFCs. It was
clear that the amount of ozone in the Northern Hemisphere
stratosphere fell by 8 percent between 1979 and 1990,
across a region that covers virtually all of the contiguous
Untied States and Europe from the Mediterranean to the
south of England.
The results of the ozone depletion is very costly,
especially to the human health. UV-B radiation was a proven
cause of skin cancers and the disappearing ozone would
significantly increase in skin cancer patients. For a rough
estimate a 10% reduction in the ozone layer would result in
160,000 additional cases of nonmelanoma skin cancers
annually. Although many types of skin cancers are not
usually life threatening, Melanomas, which is rarer is
often fatal. Causes of this type of cancer is not exact but
strongly associated with dangerous patterns of UV exposure
such as getting heavily burned or tanned during rare
vacations. Other diseases caused by UV exposure are
Cataracts, which is the clouding of then lens of the eye,
and the suppression of the immune response through the
exposure of the skin and blood. This would result in
increased vulnerability to serious diseases such as
leishmaniasis, measles, herpes, TB, and leprosy. Immune
suppression can cause a person to become seriously ill and
even become fatal with mild illnesses, similar to the
effects of AIDS on its patients. Other than the health
threats to humans, UV radiation puts many other living
organisms in danger. Two thirds of the over 200 types of
plants tested became known to be sensitive to UV-B. Effects
in these plants include reduced stem and leaf growth, lower
dry weight, and reduced photosynthetic activity. Many crops
would also suffer because of nitrogen deficiencies, due to
the sensitivity that microorganisms such as
cyanobacteria(which fixes the nutrients) to UV-B. In short
the effects of UV-B has been detected all over the world in
all kinds of environments, even 60 feet under clear water
which hurts many types of fish, mollusks, and most
importantly phytoplankton. Destruction of these
phytoplanktons would give serious problems to fishes which
depend on these small creatures for food, and eventually
effect humans. Global warming can also be caused by the
reduction of phytoplanktons, because absorption of CO2
would be significantly reduced.


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