Aiming at a letup in acid rain

Next month the federal government's Environmental Protection Agency is expected to give its response to recent studies which throw more light on the complicated acid rain problem. It is hoped that the agency will propose a carefully measured action to reduce this byproduct of air pollution.

Also very much needed is further study to:

- pinpoint the most cost-effective ways to attack the problem;

- learn whether known environmental effects of the phenomenon are widespread or rather isolated;

- discover whether forest damage in the northeast is a result of acid rain, stems from past drought or insect invasion, or from a combination;

- and examine the relatively new question of whether acid rain may pose some long-term health concern through its entry into drinking water.

Acid rain stems from the polluting of the air with very small particles of metals and acids; these then fall to earth during rain or snow storms.

For the first time, a panel now has said that a percentage of reduction in industrial pollution would reduce acid rain by the same percentage. That was a central finding of a report by a committee of the National Academy of Science.

But the panel was unable to say precisely in which industries - and in which locations - such action would produce the greatest gain in reducing acid rain, which has its most visible current impact in New England and eastern Canada. As a practical matter this knowledge is extremely important. Multiple urgent demands now exist for significantly higher expenditures in several fields: education, bridges and other parts of the American infrastructure, the military, and the acid rain problem. Choices need to be made, and specific knowledge is imperative about those actions which would produce the desired results - and do so most efficiently.

The eastern United States often points the finger of guilt at emissions from coal-burning electric-power plants in the American Midwest. If the EPA should decide a first step is to reduce their emissions, it does not seem appropriate suddenly to hit Midwestern energy users with the total cost of expensive antipollution devices, through higher electricity rates - especially since the recent studies cannot pinpoint them as at the root of the problem.

One possible approach would be for a limited reduction in emissions, which would likely be less costly. Another would be to share the cost between the Midwest, where some pollution emanates, and New England, where concern about acid rain's effect is so strong. Last month New England governors approved the idea of sharing the cost.