It is discouraging to see public policy driven by press releases, rather than proven science. Last month, an announcement by NASA, the US space agency, that an aircraft-borne instrument had detected a high reading of chlorine stampeded the US Senate only two days later into passing an amendment, 96-0, calling for an accelerated phase-out of the manufacture of chlorofluorocarbons. A week later, the White House ordered a unilateral phase-out of CFCs by 1995, five years ahead of schedule.

All this was accomplished by two NASA press releases and a lot of attention from the news media. The Natural Resources Defense Council, the activist environmental group that conned the US government into banning Alar a couple of years ago, had been pushing for an accelerated phase-out since December. It's worth noting, perhaps, that this time their maneuvering did not require the services of Meryl Streep or other Hollywood celebrities who regularly pose as experts on environmental science.

What really happened? As best as one can tell--absent any published information that can be checked by independent scientists--a chlorine detector, flying on a NASA research aircraft in the northern stratosphere, encountered high concentrations of an active form of chlorine, capable of attacking ozone. There is no evidence that ozone itself was being depleted. The press release pointed out only that this could happen in the future.

But, of course, it required careful reading of the artfully worded document to discover that nothing at all was happening to ozone. Most press reports fell into the trap and claimed ozone depletion or an ozone hole, with dire consequences to people living in the northern hemisphere. Some, like Time magazine, went overboard in a paroxysm of hype, fear, and scientific ignorance.

The NASA announcement was based on a peak chlorine reading, which occurred on January 20. "Peak" implies, however, that readings were lower--perhaps much lower--both before and after that date. The document was silent on this important point. Nor did it reveal that similar measurements in 1989, the date of the last such experiment, also encountered high chlorine values. Although widely anticipated and discussed at the time, there was no Arctic ozone "hole" in 1989, nor in any other year. The CFC-ozone theory, such as it is, is simply not good enough to predict chlorine values or ozone depletion.

The NASA press release may have told the truth, but it didn't tell the whole truth. It did not reveal that chlorine atoms cycle back and forth between an active and inactive form, depending on the presence of stratospheric ice particles, which in turn depend on whatever happens to be the temperature. Stratospheric "weather" has become the pacing variable for ozone depletion, not the level of chlorine. But this vital piece of information was withheld.

The press release claimed that the source of the chlorine was "mainly CFCs," a man-made chemical widely used in refrigeration, air-conditioning, and in the manufacture of foam plastics and electronic circuit boards. But according to the second press release, issued by the same NASA office on the same day, the volcano Pinatubo was emitting chlorine compounds and particles into the stratosphere that were actually depleting the ozone layer in the tropical regions. It would be quite a feat of science to differentiate between a chlorine atom from CFCs and one from a volcano.

And, curiously, the Pinatubo press release passed over the fact that depletion at low latitudes would lead to large increases of surface ultraviolet radiation--with all of the consequences that are usually reserved for ozone changes believed to be man-made: increases in skin cancer, cataracts, plankton death, and more. Apparently, natural ozone changes don't count.

The obvious question to ask is: Why a NASA press release on February 4, when the suite of aircraft experiments, which began last fall, continues on through the end of March? NASA's explanation is somewhat disingenuous. They felt they had to warn the public of an "ever increasing danger of ozone depletion."

A more likely explanation--and less charitable--is that if NASA waited until the end of the experiment and did not find an ozone hole, any announcement would immediately lose its publicity value. By holding out the possibility, however slim, that a hole might develop, the NASA project could improve its budget outlook and perhaps even have a policy impact. NASA's game plan has proven successful. (Shortly after the announcement, the "threatening" chlorine values dropped by 75 percent. Now the winter is over and there has been no Arctic ozone hole.)

An interview in Science News with the principal project scientist, Harvard Professor James Anderson, showed how NASA was hedging its bets. Without a viable theory, the best that Anderson could do was speculate that there will be a hole during "some year in the near future," perhaps in the next decade. He's probably right--if the temperature in the Arctic stratosphere ever falls low enough, comparable to that of the Antarctic.

One of the regrettable effects of panicky decision-making based on press releases is that it generally has severe economic consequences. Members of Congress are beginning to ask if those two weeks between the peak observation and the NASA announcement allowed enough time for independent scientific scrutiny, and for coordination of an accelerated CFC phase-out with all of the affected industries and government agencies. Has the White House fully considered whether CFC substitutes will be readily available after the unilateral phase-out in 1995? Will the substitutes be as non-toxic, non-carcinogenic, non-flammable, non-corrosive, and efficient as CFCs?

Some of the substitutes now being tested have produced tumors in rats; others have proven to be flammable in kitchen refrigerators. Many of them will require that existing equipment, currently worth over $135 billion in the US alone, be modified or replaced. And how will all of this impact on competitiveness, relative to countries that are not accelerating their CFC phase- out?

In any case, don't look to CFC phase-out as the solution to the putative ozone problem. Environmental activists are already clamoring for the early elimination of CFC substitutes--because they are not sufficiently "ozone-friendly."

One last item--a scientific nugget. A research paper by two Belgian scientists, now in press in the prestigious Journal of Geophysical Research, appears to demonstrate that the frequently claimed ozone depletion, based on global data from surface stations over the last 30 years, disappears completely when one corrects for the interfering effects on the measurements by atmospheric sulfur dioxide. (Such a finding would be consistent with studies that have shown a decreasing trend in UV radiation at the earth's surface.)

If confirmed by other experimenters, this discovery would throw all of our fears about ozone depletion into a cocked hat. As they say in the Alar business, how do you like them apples?