杏吧原创

Ozone layer safe 鈥渇or 100 years鈥�

Further evidence that the chlorofluorocarbons 11 and 12 are a greater threat to the ozone layer in the stratosphere than any other chemical compound is cited in a report published by the Department of the Environment鈥檚 Central Unit on Environmental Pollution (CUEP). If the 1973 rate of CFCs 11 and 12 is continued, says the report, a maximum depletion of about 8 per cent in the ozone layer will occur in about 100 years鈥� time. This would cause an increase in ultraviolet radiation reaching the ground of about 16 per cent. To put this in perspective, this would be 鈥渘o worse than the increase currently experienced in moving from the north to the south of England鈥�.

Uncertainties exist, however, concerning the mechanism of CFC destruction in the troposphere. Research planned, or in progress, will resolve some of the outstanding issues during the next three years. In the meantime, the CUEP advises that precautionary steps should be taken in advance of a final decision on whether to ban CFCs or not. These include asking manufacturers of aerosols and plastic foams using CFCs to intensify their search for alternatives and requesting manufacturers and users of equipment using CFCs (mostly air-conditioning and refrigeration units) to minimise leakage.

In Britain, which accounts for about 6 per cent of world usage, 80 per cent of CFC consumption is in aerosol propellant, 7 per cent in refrigeration and air conditioning, and 10 per cent in the production of foam plastic. In the US, by contrast, 20 per cent of CFC production is used in air conditioning and refrigeration, and about 50 per cent as aerosol propellant.

From New 杏吧原创, 29 April 1976