Congress debates depletion of ozone in the stratosphere

Along with the agonies of further budget cuts and the trade-offs of foreign policy, Congress must once again face the perplexities of stratospheric ozone. Both Senate and House have bills that would hold back further Environmental Protection Agency (EPA) restrictions on manufacture and use of chlorofluorocarbons (CFCs) unless there was much clearer evidence that these useful chemicals do indeed significantly endanger the ozone, which absorbs solar ultraviolet (UV) radiation. The legislation would amend the Clean Air Act, a law that is itself up for reconsideration and renewal.

Concern over CFCs is based on the admittedly uncertain possibility that these chemicals, migrating to the stratosphere, can destroy enough ozone to weaken the UV shield permanently. It is also uncertain what danger the increased UV might involve.

Acting on suspicion rather than fact, EPA banned CFCs in aerosol sprays three years ago, a use for which substitutes were readily found. However, in spite of extensive research, no substitutes have been found for CFCs as refrigerants or in other major industrial applications. CFC makers and users, concerned that such uses might be restricted out of fear, formed the Alliance for Responsible CFC Policy. This lobby group drafted the bills that would restrain the EPA and which Lloyd M. Bensten (D) of Texas has introduced in the Senate and Thomas A. Luken (D) of Ohio has presented in the House.

One of the strong points in arguing for such restraint has been the lack of direct scientific proof that CFCs seriously endanger the ozone. While that is still the case, the debate has been sharpened by a National Aeronautics and Space Administration study suggesting that, over the past eight years, "someone has taken a bite out of the ozone," to quote Donald F. Heath of NASA's Goddard Space Flight Center which conducted the study. This was revealed in August in what Heath called a "most unfortunate" premature announcement during congressional testimony by Mario Molina of the University of California, one of the originators of the ozone depletion theory.

Heath considered the announcement unfortunate because the findings had not yet been presented to the scientific community for comment and criticism. Also, the "bite" is rather small. Satellite data indicate an average decline in ozone concentration of 0.5 percent a year at 40 km. Whether this amounts to a significant overall decline in the ozone layer, which extends from 25 to 54 km, is not known. It also is unknown whether or not CFCs are to blame.

Heath claims only that he has good evidence that something is depleting ozone and that this is unlikely to be a natural effect. "It's not the proof [of the CFC-ozone depletion hypothesis] . . . But at least [we know] we're not just chasing our tails," he says.

Better data may come from balloon measurements now planned for the spring. MEanwhile, the debate in Congress could be lively.