Standing atop Moro Rock, one of this park's signature 360-degree vistas, chief resource interpreter William Tweed takes a short breath and a long sigh.
"You should be able to see 100 miles across California's agricultural Central Valley to the Coastal range mountains," he says, pointing due west. But a milky-gray gauze hangs over several peaks, rolling out like a jagged green carpet below, and no agricultural fields or orchards are visible in the distance. "When the hot summer air here rises," he says, "it sucks in air from the coast, and that means the urban coast from San Francisco to San Jose."
Vistas obscured by soot-tinged air are not unique to Sequoia National Park. Because of growing city and rural populations, an expanding highway system, and increased travel, the air above national parks coast to coast is sullied.
From park to park, the main culprits vary. Coal-fired power plants can be among the worst haze-producers. But key pollutants also include vehicle exhaust, dusty particulates thrown up from the road by speeding semi trailers, and pollution drifting from smelters and refineries.
"We are having visibility problems across the entire national park system due to pollution," says John Bunyak of the National Park Service's air resources division.
Park officials say rising pollution is not only taking the visual edge off finely etched escarpments, gliding hawks, and other sights. It also threatens the health of plants and ecosystems.
Here at Sequoia, pollution from oil-drilling and refining in nearby Bakersfield carries toxins from mercury to ozone - helped along by the baking of car exhaust in summer sun - which are bad for plants, animals, and humans.
"When it rains, that problem translates into acid deposition problems - sinking air-born toxins into streams, soils, and trees," Bunyak says.
A mountaintop sermon
All this translates into a growing chorus of disgruntled park users, who feel the system should be a shining example of unspoiled natural splendor, not a tarnished tribute to man's despoilment.
"It is disturbing, it really is, because I was just telling the boys how clean-smelling the air was going to be," says Wendy Sherman, who just drove five hours from Santa Monica to the park entrance, spent another 45 minutes winding the circuitous 17-mile road from the entrance to Moro Rock at 20 to 25 miles per hour, then hiked another 15 minutes to the peak. Instead of the sublime grander of pristine wilderness she hoped to show her two sons, she instead gives them a lecture on man-made pollution.
"When I went to national parks as a kid, the signs talked about what trees, birds, and mountain ranges you were looking at," Ms. Sherman says.
Now, the signs atop Moro Point explain how the nearby San Joaquin Valley is inhabited by several million people and how, under certain weather conditions, pollution is trapped in the valley for weeks at a time.
According to Park Service records, Sequoia has the worst air conditions of 156 national parks. At one vista, called "Eleven-Ridge Outlook," only four ridges were visible on a recent day.
But other key parks have reported growing visibility problems in recent years.
Shenandoah National Park, where views from the highest point of Hawksbill Peak should peak into West Virginia 30 miles away, has its own vanishing-ridge problem. And Great Smoky Mountains National Park, which pulls 10 million visitors a year, has logged 135 unhealthy air days in the past two years.
In fact, Great Smoky Mountains National Park and Big Bend National Park in Texas each recently made an annual list of the nation's 10 most "endangered" parks, based in good measure on their air-quality problems. The National Parks Conservation Association, a Washington-based nonprofit organization (NPCA), released the list earlier this month.
While scientists say visibility once averaged about 90 miles in Eastern parks and 140 miles in the West, the averages have now dropped to 18 to 40 miles and 35 to 90 miles, respectively.
The problem, persisting even at a time when some industrial pollutants have been declining for a decade, poses some puzzles for researchers.
In February, scientists at the University of California, Riverside got a federal grant to track smog across the 12 Western states. They hope to develop the first comprehensive model explaining how car exhaust and other pollutants find their way to national parks.
Coal, wind, and automobiles
Acadia National Park in Maine, has seen rising mercury levels from coal-fired power plants. At the Grand Canyon, one recent survey estimated that 21 percent of the smog originates in Los Angeles.
But if much of the haze over US wilderness comes from industrial pollutants, park visitors pack some responsibility into the parks as well - thanks to their cars.
In recent weeks, falling gasoline prices - while welcome to consumers - are spawning thousands more park visitors.
The steady growth of bad air days - Sequoia this week was listed "unhealthy for sensitive groups" - is also spotlighting individual battles between some parks and surrounding polluters.
In February, for instance, the NPCA and the Sierra Club sued the nation's largest utility, the Tennessee Valley Authority, to curb emissions from 11 coal-burning power plants they say affect vistas at Great Smoky Mountains National Park. The TVA says it has begun an $800 million effort to reduce emissions.
Meanwhile, the park should also benefit from a move by the utility Enviro-Power to reduce emissions at a new power project it is building in Kentucky. Observers say protests by residents were in part responsible for the company's move to reduce sulfur dioxide emissions.
The NPCA is also urging Congress to eliminate a provision in the Clean Air Act that exempts power plants built before 1985 from complying with the law.
New rules for old plants
Because pollution does not acknowledge state boundaries, the Environmental Protection Agency is developing regional solutions, relying on five multistate bodies.
Just last week, EPA administrator Christine Whitman signed off on the idea, beginning a 60-day public comment period. The Bush administration will require older facilities to install so-called BART (best available retrofit technology) to lower emissions. Facilities built between 1962 and 1977, from smelters to pulp plants, would be affected.
"This has been a giant step forward," says Bunyak, "because most of the haze problem we see in parks comes from large, coal-fired utilities."
(c) Copyright 2001. The Christian Science Monitor