Through a mist darkly: Will air pollution dim beauty of US national parks?

On a clear day, standing on the rim of the Grand Canyon, it seems as if you can see forever. But over the last few decades clear days have come less and less frequently to the Grand Canyon and a number of other national parks and scenic areas throughout the nation.

The problem of the gradual obscuration of scenic vistas has National Park Service officials worried. "If I were to rank threats to the parks, air pollution and visibility degradation would be No. 1," Park Service director William Wellan told members of the National Audubon Society last summer.

Adding to this concern are the proposed energy developments near Bryce Canyon , Zion, Arches, Canyonlands, and Capitol Reef national parks, all in Utah, and Acadia National Park in Maine, as well as numerous national monuments and wilderness areas, particularly in the Rocky Mountain states. Although studies that have been done generally conclude that energy development can be accomplished without major air quality degradation, many observers are not reassured.

Air quality at 15 parks currently does not meet federal Class 1 air-quality standards. This is the most stringent classification and allows minimal degradation.

There are 158 Class 1 areas in the United States. These include parks, monuments, wilderness areas, and some Indian reservations. According to a recent survey of the federal managers of these areas, fully one-third are experiencing periods of reduced visibility due to man-made air pollution or need to be evaluated for such impact. Although two-thirds report acceptably clean air, few if any are totally free from visibility-reducing air pollutants, the Environmental Protection Agency (EPA) reported to Congress last fall.

Environmentalists have been aware of this problem for many years. Their lobbying efforts led to a provision for the control of haze- causing pollutants in Class 1 areas in the 1977 amendments to the Clean Air Act. The acts instructed the EPA to come up with a plan to control these pollutants last August.Once formulated, the plan then would be implemented by the states. But the agency missed its deadline, a failure which led to charges from environmentalists of "gross negligence."

"Congress fired the gun on visibility regulations in 1977 and the EPA has barely gotten out of the starting blocks," charges Ron Rudolph of Friends of the Earth. FOE brought and recently won a lawsuit against the EPA which impels the agency to come up with the required regulations by next May.

"Visibility turned out to be quite a bit more complicated than people thought ," explains Terry Phoem of the EPA in justifying the agency's failure to meet the congressional timetable.

There was a misconception that visibility problems at sites such as the Grand Canyon were due soley to emissions from nearby power plants, he explains. Instead, the EPA has found that visibility tends to be a regional rather than single-source phenomenon maring control efforts more complicated.

The relative contributions of various pollutants have yet to be determined. According to current wisdom, sulfates are the major culprit. These lend a flat, grayish cast to the sky and distant objects. sulfates are produced by power plants, smelters, and similar operations. Nitric oxides, in automobile pollution, are considered the second most serious contributor. Nitric oxides tint the air reddish brown.Extremely fine dust particles and smoke from controlled burning of agricultural lands are other, lesser visability reducers.

"I'm optimistic that we can control this problem, provided our present understanding of the relative contributions of the various pollutants is correct ," says Mr. Phoem. the technology exists for controlling sulfates but not for nitric oxide.

However, the scientific basis for assigning a major role to sulfates is slim. "I don't think the evidence is in at all," comments Glen Hirst of the Electric Power Research Institute. It will be at least five years until the complicated scientific issues involved will be settled, the utility scientist believes.

The EPA appears to share this view. The strategy which it will propose is two-phased: In the first phase, the most obvious sources of pollutants will be required to install the best available control technology. The second phase, to be implemented when better scientific information is available, will involve regionwide efforts to control man-made haze.

This latter phase in particular is likely to pit environmentalists and energy developers against each other.