A few months ago, Eileen Claussen thought that the earth's protec tive ozone layer--and perhaps the globe's inhabitants--had been saved from a grim fate. After all, the Environmental Protection Agency's ozone chief reasoned, an international accord reached last summer would speed the elimination of chemicals that destroy the ozone shield and let excess deadly ultraviolet (UV) light reach the earth. And in the 1990 Clean Air Act, Congress committed the U. S. to start phasing out the chemicals, known as chlorofluorocarbons (CFCs), even faster. "We thought we had done it," Clausen says.
But the champagne flowed too early. On Apr. 4, the EPA announced the results of a sobering new study. Measurements from a NASA satellite revealed that the fragile ozone layer has shrunk as much as 5% over the U. S. in the past 10 years, at least 50% more than previously estimated. Now, Clausen is searching for new ways to get rid of ozone-killers. "We're going to take another squeeze at what's left," she says.
The question is, what's left to squeeze? Some 67 nations have now signed last June's updated Montreal protocol to ban, by the year 2000, CFCs and other chlorine-containing compounds that gobble ozone. This conversion is a vast undertaking, since the chemicals are used in everything from refrigerators and car air conditioners to semiconductor factories. Driven in part by new taxes on CFCs, most U. S. companies are on schedule to meet the deadline. "We're going pretty darn fast as it is," says John P. Romanovsky, manager of corporate environmental engineering at American Telephone & Telegraph Co. It aims to be CFC-free in its chip plants and labs by the end of 1994.
REAL DANGER? Any EPA push for a brisker phaseout would probably be opposed by the White House and a number of scientists. In part, that's because it's still unclear whether the thinning ozone layer will cause 200,000 skin-cancer deaths in the U. S. by 2050, as EPA experts predict, or imperil crops and ecosystems. "Before we make substantial policy decisions or ask other countries to, we need to reassure ourselves that the science is correct," says Michael R. Deland, chairman of the White House Council on Environmental Quality.
Consider the effects of the springtime Antarctic ozone hole, which is caused by a combination of CFCs, ice, sunlight, and meteorology. Under the hole, UV levels soar. Scientists have shown that this slows the growth of some plankton, which form the basis of the ocean's highly productive food chain. That raises the specter of ecological catastrophe. But researchers also have found that many species make protective "suntanning" chemicals. "Clearly there is an impact," says oceanographer Raymond Smith of the University of California, Santa Barbara, who is analyzing recent Antarctic experiments. "But whether it is significant or not, we don't know."
There are similar uncertainties closer to home. By growing soybeans under tanning lamps, University of Maryland botanist Alan H. Teramura has found that a 1% decline in ozone causes a 1% drop in the crop's yield. Worse, the effects of added UV appear to be cumulative in long-lived species, such as trees. But some plants seem to adapt. Teramura has found the same species growing both at sea level and on mountaintops, where UV light is 40% stronger.
For humans, the thinning ozone layer's biggest direct threat is skin cancer. Studies by epidemiologists show that basal and squamous skin-cancer rates increase with greater exposure to UV light. Moving from low, cloudy Seattle to high, sunny Albuquerque, for example, where ultraviolet radiation is twice as strong, raises the chances of getting such skin cancers fourfold.
The connection isn't as clear with the most dangerous skin cancer, melanoma, which strikes more affluent office workers more often than those who toil in the sun. The suspected causes include bad sunburns in early childhood or jolts of sun on unprepared skin during winter vacations in the tropics. While melanoma rates have been rising by 4% a year since the mid-1970s, says National Cancer Institute epidemiologist Joseph Scotto, "I would hesitate to say it was because of the ozone." Scotto's own measurements of UV radiation striking the ground in eight U. S. cities showed no increase from 1974 to 1985. "I think EPA has to redo its cancer numbers," he says.
Despite the uncertainty, no one doubts that protecting the gossamer sheet of ozone is a vital necessity. And in the wake of the NASA data, says F. A. Vogelsberg Jr., environmental manager with Du Pont Fluorochemicals, "the EPA is going to feel compelled to get people to move more rapidly."
PHASEOUT. The European Community has agreed to end CFC use by 1997, prompting pressure from environmentalists for the U. S. to follow suit. But EPA officials aren't sure the U. S. can discard its $135 billion worth of CFC-based devices that quickly. Ford Motor Co. has vowed to use only chlorine-free air conditioners in its cars by 1995, and General Motors Corp. plans to follow a year later. But older cars will stay on the road for years. And the EPA estimates that a faster U. S. phaseout would cut worldwide ozone depletion by less than 10%.
Still, the EPA might set tighter standards for temporary CFC replacements that contain some chlorine. For jobs such as blowing foam to make containers, the best current alternative is a compound in the hydrochlorofluorocarbon family. It has 85% less ozone-depleting power than the CFC it would replace. The Clean Air Act calls for phasing out interim substitutes--in favor of entirely harmless ones--by 2015. Now, says EPA Administrator William K. Reilly, "they may have to be phased out sooner."
The agency also sees a lot to gain from leaning on developing countries. Under the current international accord, participating Third World nations have until 2010 to stop using CFCs. But some key nations, such as India and China, aren't on board. "It's really important that they all join and that we all phase out together" by 2000, says Claussen.
That's why the EPA is working with companies such as Northern Telecom Inc., to bring nonchlorine solvents to Mexican factories. The agency also has high hopes for a $240 million international fund that will help countries such as China cut their use of CFCs by transferring U. S. technology. U. S. companies think that's a great idea. "It is a marketing opportunity that U. S. industry doesn't want to miss," says Kevin Fay, executive director of the Alliance for Responsible CFC Policy, an industry group.
With the EPA trying to persuade the developing world to move faster, and the White House opposed to new rules at home, Corporate America may have dodged a bullet. At least until the stratosphere delivers its next nasty surprise.