Aerosol Link

Exploring the ozone loss

When the Government cracked down on the use of chemicals called chlorofluorocarbons in aerosol sprays three years ago, a major row erupted. Some scientists welcomed the ban, contending that the synthetic compounds--like Freon --were destroying the earth's ozone layer, a shield against the sun's ultraviolet rays. They warned that loss of ozone could cause more cancer and perhaps alter the weather. Other scientists pooh-poohed such doomsday scenarios as unproved.

Last week the controversy was revived when Donald Heath, a physicist at NASA's Goddard Space Flight Center, reported actual evidence of ozone depletion. His study, based on long-term weather satellite observations, indicated a reduction of about 1% in total ozone volume, with most of the losses concentrated at an altitude of about 25 miles. Though Heath acknowledged that his findings could not be tied directly to the chemicals, he pointed out that there is a suggestive link: calculations have shown that if chlorofluorocarbons were, in fact, damaging atmospheric ozone, the greatest harm would probably occur at about 25 miles.

Herbert Wiser, an EPA science adviser, called the findings no more than "mildly suggestive." One problem, added Shelby Tilford, NASA'S chief of atmospheric processes, is that the amount of ozone may fluctuate with variations in the sun's ultraviolet radiation. To help settle the argument, Harvard's James G. Anderson plans to launch a huge balloon, 450 ft. in girth, in New Mexico next fall. Equipped with a battery of sensitive devices, its gondola will move up and down like a yo-yo through the upper atmosphere, between altitudes of 12 miles and 25 miles, not only measuring the ozone but detecting chemicals that may be destroying it.

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