When scientists first warned in the 1970s that CFCs could attack ozone, the U.S. responded by banning their use in spray cans. But the rest of the world continued to use CFC - based aerosol cans , and overall CFC production kept growing. The threat became far clearer in 1985 , when researchers reported a "hole" in the ozone layer over Antarctic. Although the size of the hole varies with the seasons and weather patterns, at times Antarctic ozone has been depleted by as much as 50% in some spots. As a result of this disturbing development, 24 nations, including the U. S. and the Soviet Union, met in Montreal two summers ago and agreed to cut back on CFCs. The so - called Montreal Protocal is designed to achieve a 35% net reduction in worldwide CFC production by 1999. That’s not good enough, however, the same stability that makes CFC so safe in industrial use makes them extremely longlives, some of the CFCs released today will still be in the atmosphere a century from now. Moreover, each atom of chlorine liberated form a CFC can break up as many as 100, 000 molecules of ozone. For this reason, governments should ensure the careful handling and recycling of the CFC now in use. When plastic -foam burger holders are broken, the CFCs trapped inside escape. Discarded refrigerators release CFCs as well, and, a significant part of the U.S. contribution to CFC emissions comes from draining automobile air conditioners. Such release of CFCs could be prevented if consumers and businesses were offered cash incentives to return brokendown air conditioners and refrigerators to auto and appliance dealers. Then the units could be sent hack to the manufacturers so that the CFCs could be reused. While recycling will help, the only sure way to save the ozone is a complete ban on CFC manufacture, which should be phased out over the next five years. Fortunately, as the Montreal Protocal demonstrates, banning CFCs will be far simpler than reducing other dangerous gases. But a ban could admittedly be economically disruptive to the entire world: the annual market for CFCs is some $ 2.2 billion. The Soviet Union, which is a heavy user of CFCs, will have a particularly tough time phasing out the chemicals. "I agree with the ban in principle, "said Vladimir Sakharov, a member of the Soviet State Committee for Enviromental Protection, "but in practice it will be extremely difficult. Our economy is not flexible as others. " To make the transition easier, chemical companies are working hard to find practical substitutes for CFCs. The most promising approach so far is to use CFC family members that are chemically altered to make them less dangerous to the environment. The chlorine - free substitutes is the high cost of making them. It may be that until better manufacturing techniques are developed, consumers will have to pay more for affected products. The prospect is not a pleasant one, it is a small price to pay for curbing the green house effect and saving the life -preserving ozone layer.
A. that CFC manufacture is completely forbidden B. that the production of CFC is reducedC. to find substitutes for CFCs D. to reduce the danger of CFCs
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