As Congress deliberates on revising the Clean Air Act, a prominent environmental group has launched an 11th-hour attack with a report that concludes human health will be endangered if air quality standards are relaxed.
The report, issued by the National Audubon Society June 4 and titled ''Implications for Mortality of Weakening the Clean Air Act,'' is furiously opposed by the administration and viewed with some skepticism by independent researchers.
In a lengthy analysis, Audubon researchers conclude that if Congress emasculates the 1977 amendments to the Clean Air Act during the reauthorization process now under way, ''several thousand premature deaths per year may occur West of the Mississippi by the year 2000. . . .''
The Audubon allegation has opened a major new front in the political skirmishing over the Clean Air Act.
The debate until now has not centered on health issues. The 1977 amendments generally address preventing or controlling the deterioration of air quality in areas - mostly in the West - where air quality is much better than required by the air quality standards. As a result, the political wrangling to date has pitted the costs of air pollution control against matters such as reduced visibility at national parks and environmental destruction from acid rain.
''Until now, the health-effects issue has not been raised,'' acknowledges Jan Beyea, Audubon's senior energy scientist and co-author of the study. But with this study, the group is attacking what Dr. Beyea regards as a highly questionable assumption held by both industry spokesmen and the Environmental Protection Agency (EPA): that incremental increases in air pollution in pristine areas do not have any measurable effect on human health.
In a counterattack, the administration has questioned some assumptions in the Audubon study. Kathleen M. Bennett, an assistant administrator for the EPA, says , ''This Audubon study reaches an unsupportable result which is absurd on its face. The thought that either Congress or this administration would accept changes to the Clean Air Act which would result in an increase of 2,000 deaths per year is simply ridiculous.'' The number of ''unsupportable assumptions'' in the study make it ''unusable,'' she continues. ''We are disappointed that (Audubon) president (Russell) Peterson would move the Audubon Society, with its long history of responsible contribution to environmental policymaking in this country, to this kind of politically motivated rhetoric.''
While not absolutely certain that adverse health effects will result from chronic exposure to small amounts of certain air pollutants, Beyea cites ''pretty strong evidence'' to back his argument that Congress should support public health and not weaken the '77 amendments at all.
The study concentrates on one family of pollutants, sulfur compounds, and is limited to 22 Western states. ''Four out of five recent studies have found a positive statistical correlation between chronic exposure to sulfates (sulfur compounds) and excess deaths,'' Beyea reports.
In their report, Audubon researchers admit the uncertainties of the analysis by estimating that the mortality figure might vary by a factor of five. That is, the 2,200 excess deaths that could result if the 1977 amendments are voted down might actually number anywhere from 980 to 5,000. But Beyea maintains that the assumptions are ''conservative'' so, if anything, the adverse effects have been understated.
However, the EPA's criticisms are reinforced by David Streets of Argonne National Laboratory, one of three independent specialists who reviewed the study for National Audubon. Although the report was revised after Dr. Streets offered some comments, he says he is not comfortable with the study's conclusion.
''They tried to do something which is difficult even for a major study with resources like computers, which they didn't have. As a result, they estimated all over the place and the study is not very scientifically accurate,'' Streets says.
He and the administration also question the Audubon effort on a more philosophical ground. A portion of the Clean Air Act which Congress is leaving untouched sets the primary air quality standards for pollutants such as sulfates. This orders the EPA to set 24-hour and annual average permissible-exposure levels to ensure that people do not suffer acute or chronic health effects, and to review these standards periodically.