Alarming Loss

Reports about the ozone layer are as maddeningly variable as the protective shield itself. Estimates of the problem's severity fluctuate virtually with each new set of measurements from the atmosphere. Unfortunately, the estimates do seem to possess one common thread: they are getting worse. Last week's announcement from the Environmental Protection Agency that the shield may be | disappearing nearly twice as fast in northern latitudes as many scientists had predicted is the most alarming report to date. The study noted that the loss was occurring both farther south, over the most populous regions of the U.S., and later in the spring -- when more people spend time outside -- than had been thought. Worse, the additional thinning of this protective layer of gases is expected to increase substantially the amount of harmful ultraviolet radiation reaching the earth's surface, threatening a vast array of life-forms and boosting the number of skin-cancer deaths in the U.S. alone by 210,000 over the next 50 years.

The report, which was based on satellite readings collected between 1979 and 1990, is thought to present the most up-to-date picture of the problem yet. While earlier studies using data taken through 1986 had put the loss during the previous decade at about 2%, the new report says the number for the 1980s was closer to 5%. EPA chief William Reilly called the results "disturbing" and vowed to push for more stringent international controls on chlorofluorocarbons, the man-made chemicals thought to be largely responsible for triggering the problem. Most developed countries have agreed to ban the substances by the year 2000, but even that may not be soon enough, said Reilly.

Some scientists and officials feel the EPA may be overstating the case. Robert Watson, an ozone expert at NASA, commended the study in general but questioned the skin-cancer predictions, noting that the ozone layer still seems to be intact during the summer months, when most cases of skin cancer originate. Some critics also pointed out that Reilly may have timed the release of the report to rally public support for the environment one week before the National Academy of Sciences is scheduled to release a major paper on what the U.S. should be doing about global warming. The issue is one on which the White House, and chief of staff John Sununu, has been particularly intransigent. The science of ozone depletion may be complex, but no more so, it seems, than the politics of doing something about it.