Ozone Alert

Few things seem more uniquely American than spray cans, which are used for almost everything from deodorants to oven cleaners. Americans are the major consumers of the spray products sold in the world today. But they may soon have to learn to live without them. A committee of the National Research Council concluded in a report released last week that the fluorocarbon gases used as propellants for spray products deplete the ozone layer. It is that shield which protects the earth from an overdose of the sun's potentially deadly ultraviolet rays. The report sets the stage for an eventual ban on the sprays.

Conducted with the sponsorship of several Government agencies, the yearlong NRC study agreed that fluorocarbons do, as suspected, percolate upward into the stratosphere, where their chlorine atoms react with and thus destroy ozone molecules. According to the NRC report, if the fluorocarbon release continues at the 1973 rate, it could ultimately deplete the three-mile-thick ozone layer by as much as 7%. Public health authorities predict that the subsequent increase in the amount of ultraviolet light reaching the earth would raise by about 200 the number of Americans afflicted annually by malignant melanoma, a form of skin cancer that now strikes an estimated 8,400 and kills some 2,700 each year. The ozone loss would bring an increase in other forms of skin cancer as well.

Short Delay. In the light of this evidence, NRC scientists believe that some if not most uses of fluorocarbon sprays will eventually have to be curtailed. But the committee stopped short of advocating an immediate ban. Instead, it recommended a delay of not more than two years, during which science could learn even more about the sprays' effects on the ozone layer. The suggestion makes sense. Scientists are still uncertain about the rate at which ozone is destroyed or replaced and need time to learn more about atmospheric chemistry. Nor is a two-year delay thought to be dangerous. Even at 1973 rates, a two-year delay would not increase ozone depletion by more than one-sixth of 1 %.

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