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Leading Ozone Depleting Chemicals Released to the Air by Major
Industries in Texas, 2001
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CHEMICAL
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RANKING OF ALL TOXIC AIR RELEASES
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TOTAL AIR RELEASES
(lbs.)
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Chlorodifluoromethane
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22
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688,510
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1,1,1-Dichloro-1- fluoroethane
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32
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323,750
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Dichloromethane
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40
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231,395
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Carbon Tetrachloride
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47
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155,689
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1,1,2 - Trichloroethane
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74
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53,821
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Dichlorodifluoromethane (CFC-12)
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62
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86,900
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Freon 113
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90
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28,693
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2-Chloro-1,1,1,2 - Tetrafluoroethane
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111
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12,688
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Source: Environmental Protection Agency, 2001 Toxics Release Inventory Database, 2003.
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Chlorinated fluorocarbons, or CFCs, is the name given to a family of chemicals
developed in 1928 by the DuPont Company under the name Freon. CFCs have been used for refrigeration and air conditioning, as well as in the manufacture of aerosol sprays,
computer chips, and many other products. When released into the air, these chemicals eventually rise to the stratosphere -- located between 6 to 30 miles above the Earth --
where they are broken down by sunlight. This degradation process releases chlorine, which damages the layer of atmospheric ozone that absorbs most of the sun's
ultraviolet-B radiation. The destructive influence of CFCs high in the atmosphere is significant: a single chlorine atom can lead to the destruction of more than 100,000 ozone molecules.*
Destruction of the ozone layer appears to be increasing. In the spring of 1985, British scientists found a hole about the
size of the continental United States in the ozone layer over the Antarctica. This hole has reappeared each spring when
meteorological conditions facilitate the breakdown in ozone. In fact, the ozone levels over the Antarctic can be 60
percent below "normal" during this period of the ozone hole. In 1992 satellite images recorded global ozone levels 4
percent lower than normal. In the United States, ozone levels in summer are about three percent below normal, and about five percent lower in the winter*. Meanwhile, the concentration of CFCs measured in the atmosphere continues to climb.* The use of other "ozone-depleters" like halons, methyl chloroform, carbon tetrachloride, and
hydrochlorofluorocarbons (HCFCs) also has been on the rise.* The high levels of ultraviolet-B radiation reaching the
earth as a result of ozone depletion have been shown to increase the incidence of skin cancer and cataracts in humans. This radiation also adversely affects plants and animals.
The dangers posed by the destruction of the ozone layer led 27 countries to sign the Montreal Protocol in 1987, which
committed these nations to limit the production of ozone-depleting substances. In the U.S., the 1990 amendments to
the federal Clean Air Act required a phase-out of the production of CFCs and halons by the year 2000. In fact,
production of halons, CFCs, carbon tetrachloride and methyl chloroform have ended in the U.S. Interim substitutes,
such as HCFCs, also will be eventually phased out. In Texas, major industries still release millions of pounds of the ten
chemicals the EPA has identified as ozone-depleters. Still, most CFCs do not come from industrial sources but rather
from refrigerants, automobile air conditioning, and solvents in oil-based paints. Automobiles are also slowly transitioning away from ozone-depleting air conditioning chemicals.
There is some evidence that things are getting better. The latest 2002 Scientific Assessment of Ozone Depletion
indicates the rate of ozone depletion is slowing, and the concentration of some chemicals -- like methyl chloroform --
have fallen. However, because these chemicals take years to reach the stratosphere, it will take decades for the full impact of the end of the production of these chemicals to occur*.
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