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(Freon®-11) One of the principal greenhouse gases, a gas
with absorption bands in the infrared portion of the spectrum. There is
extensive evidence showing that a class of synthetic compounds, the
chlorofluorocarbons (CFCs), are responsible for the destruction of the
ozone layer. CFCs are molecules that contain one or more atoms of both
chlorine and fluorine. In September of l992, the ozone hole over
Antarctica was the largest ever recorded and was almost THREE times as
large as the area of the U.S. Because CFCs are so unreactive, they do not
break down when released into the air in the troposphere where they are
spilled. In time, air currents and diffusion carry them into the
stratosphere, where, under the influence of UV radiation, they release
chlorine radicals that initiate the destruction of ozone. Data collected
by NASA have shown conclusively, that there is an inverse relationship
between ozone concentration and the chlorine monoxide radical in the
stratosphere; ClO is formed by chlorine atom attack on O3. CFCs
are very useful inert, nontoxic, nonflammable compounds that had been used
for years as coolants and as spray can propellants for aerosol forms of
hair sprays and deodorants. They had been unsurpassed as solvents for
cleaning electronic microcircuits. Commercially, the most important CFCs
are the halogenated methanes, Freon-11 (trichlorofluoromethane) and
Freon-12 (dichlorodifluoromethane). Over 50% of asthma inhalers contain chlorofluorocarbns as the solvent and gaseous propellent. These CFCs have
relatively recently been prohibited in all products except in those
medicinal inhaler dispensers for asthmatics and a few other limited
exceptions. In Finland alone there are over a million medicinal dispensers
that disperse freons into the atmosphere. This is equal to the freon
concentration of the cooling devices in approximately l00,000
refrigerators.
[Buell and Girard, Chemistry, Prentice-Hall, Inc., l994.]
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