Learning a lesson from the spray-can bogey
When experts confront an environmental hazard, some of them call for ''more research.'' That can look like a cop-out. Certainly, it's anathema to activists thirsting to ''do something now.'' But there can be wisdom in such caution.
This has become abundantly evident as ''more research'' deflates the great spray-can/ozone scare. Unfounded fear made the chlorofluorocarbons, which propel aerosols and cool refrigerators, an eco-enemy in the 1970s. Those who condemn President Reagan for wanting more understanding of acid rain complexities before slapping stringent new controls on smokestack America could profit from the spray-can example.
Ozone - a tri-atomic form of oxygen - forms naturally in the stratosphere, where it absorbs harmful ultraviolet (UV) radiation from the sun. Its concentration normally varies. About a decade ago, however, F. Sherwood Rowland of the University of California (Irvine) and Mario J. Molina of the NASA-Jet Propulsion Laboratory suggested that chlorofluorocarbons (CFCs) leaking into the environment make their way into the stratosphere, where they enhance destruction of the ozone UV shield.
The evidence was sketchy. The complex chemical interactions were poorly understood. Yet those who called for ''more research'' were figuratively shouted down. It was better to be hasty and safe than cautious and sorry, the argument went. The US government banned most uses of CFCs as aerosol propellants in 1978. It has been eyeing their use as refrigerants as well.
Yet the CFCs are excellent materials for such uses. They do the job well and are neither poisonous nor explosive. Thus other countries have been reluctant to ban them, even in spray cans, despite US pressure to do so. They consider the US action to have been too hasty. And several scientific studies reported this year show that they are right.
Last February the US National Academy of Sciences, for the second time in five years, significantly reduced its alarming 1977 estimate that continued use of CFCs at what was then the world rate would destroy 15 to 18 percent of the ozone shield by late in the next century. Now it says that ''more thorough understanding of the complexities of atmospheric processes'' suggests there might even be a 1 percent increase in total stratospheric ozone over that time span. It warned, however, that the scientific uncertainties in the computer models are such that ''the result could range between an increase of a few percent to a decrease of as much as 10 percent,'' according to the March issue of the academy's News Report.
The academy also noted that detailed analyses show there had been ''no discernible trend'' in the total amount of stratospheric ozone from 1970 to 1980 . Yet that was the period during which the alarm began ringing.
Public fear had been generated by conclusions grounded in scientific ignorance and inadequate computer modeling. The early studies focused on the effects of CFCs. The academy explained that the computer predictions change drastically when they include the simultaneous effects of other stratospheric gases such as nitrous oxide, methane, and carbon dioxide.
In June, P. M. Solomon and colleagues at the State University of New York (Stony Brook) noted in Science that, even considering CFCs alone, better knowledge of how CFCs act in the stratosphere shows the early predictions were needlessly alarming. They should have projected 3 to 5 percent ozone destruction , not 15 to 18 percent. Other neglected factors are also important. In July, John C. Gille and Charles M. Smythe of the National Center for Atmospheric Research (NCAR) and Donald F. Heath of the NASA-Goddard Space Flight Center reported in Science that natural ozone variations tied to solar activity must be monitored and included in any assessment of human impact on the ozone layer.
A few weeks ago, William G. Mankin and M.T. Coffey of NCAR, also reporting their research in Science, showed that Mexican volcano El Chichon had injected massive amounts of hydrogen chloride into the atmosphere when it erupted in 1982 . They said the fact that a single volcano could raise the stratosphere's chloride content ''by 40 percent over a large part of the globe'' should lead scientists to consider natural, as well as human, sources for ozone-threatening chlorine compounds.
None of this implies that we can relax ozone layer monitoring or ignore the possibility of ozone destruction through pollution. It does show that experts who called for more research before regulation had a point.
Proponents of acid rain regulations should heed this lesson. They urge that costly control measures be imposed on some Midwestern states to reduce sulfur emissions, which are considered the main culprit in acid rain. But many experts point out that other pollutants such as oxides of nitrogen and hydrocarbons may be just as important, if not more so. And these come largely from autos, not smokestacks. Also, the relation between acid precipitation and acid lakes and soils is unclear.
Those experts calling for more research before we make scapegoats of Midwestern states see genuine uncertainties, just as did their counterparts when the spray-can controversy arose. President Reagan may not be so lax in listening to them after all.