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OZONE by T. Leeson ANTE A hole in the Earth’s protective ozone layer as large as Australia has opened over the Antarctic. d Strangely, debate still surrounds the cause of the breaking down of the ozone layer. Ozone, an ionised form of oxygen, shields the earth from most of the sun's harmful ultraviolet rays. Each year this layer thins out over the Antarctic with the lowest concentrations occuring in October. Although it regularly “rebuilds' in November, the level is 10% below the previous year's level. The ozone hole is from 12 to 20 kilometres up, with layers only 100 metres apart losing 20 to 80% of their ozone. Another hole about one third the size of the Antarctic hole has been discovered over Norway. A report issued by NASA last November suggested that the sun is responsible, as an unusually intense peak of solar activity during 1979 and 1980 was claimed to cause chemical changes that led to adecline in ozone levels. Heavy sunspot activity was also reported in October 1986. During August, a team of scientists flew to the Antarctic to measure trace gasses in the stratosphere, ANAL finding high levels of oxides of nitrogen which showed . the solar explanation was probably incorrect. Further tests some governments and large chemical companies. Sales of were also carried out by a joint Oz/US project in Darwin CFC's are worth over a billion dollars annually, with many during January. of the larger companies involved in projects in China and It is the use of chlorofluorocarbons and other chemical the Third World worth tens of millions of dollars. emissions that are the main cause for concern, with the US Unfortunately, many of the chemicals have no substitute government pushing for an international freeze on CFCs. as the alternatives are more dangerous. The US banned the use of CFCs in pressure pack cans a \ The | various effects are only now becoming more decade ago; Dupont (one of the largest chemical frighteningly apparent. An additional half a million cases manufacturers in the world) voluntarily stopped all production of skin cancer are estimated with a drop in ozone levels of of CFCs last year. They know the cause of the ozonc hole. 2.5%. For each 1% decrease in stratospheric ozone Chlorofluorocarbons are used in everything from aerosol there will be a2 to 5% increase in basal skin sprays to insulation foam in walls, ceilings and food cancer and 4 to 10% increase in squamous cell containers (such as eggcartons and the polystyrene bubble skin cancer. your Big Mac emerges from). Airconditioning units also The immune system will also be affected by an require CFCs. increase in UV radiation, with resultant increases in The principal compounds are the chloroflurocarbons hepatitis, herpes and many other diseases. (CFC-11,CFC-12, CFC-22, CFC-113, CFC-114 and Effects on the climate are not yet fully known, but CFC-115), three chlorinated solvents (carbon tetrachloride, severe changes in precipitation and freak weather patterns methyl chloroform and methyl chloride) and two bromide- will cause disruption in crop production, as will containing halons (Halon-1211 and Halon-1301). The ultraviolet damage. Field studies have shown a 20% production and use of all these products is “reduction in soya bean yicld from a simulated 25% ozone steadily increasing. depletion. Compounds of this nature remain unaltered in the More frightening is the fact that many of the lower atmosphere, but as they migrate to the Ocean's micro-organisms are photo-synthetic (relying on stratosphere they are decomposed by UV radiation. The sunlight for survival) and it is not known what effects an chlorine or bromine contained causes a chain reaction in increase in UV radiation will have on this base of the world which oma is pecan’ ; food chain. Krill, for example, is found entirely in Antarctic radiation Ariel a they also absorb rae latitudes (and provides a major part of the dict of whales). atria oes . eileen a of the AS we are only witnessing the first effects of this very A dex Shami vices te jouse Effect". ; real threat it may not be too long before the full extent of the a Convention for the Protection damage is realised further from the poles. of the Ozone Layer in December 1986, negotiations for an It may be a good idea to wear sunglasses and a wide- agreement to Jimit emissions were apparently hampered by brimmed hat. a2 the Nexus New Times