Hazy Days In Our Parks | Science | Smithsonian
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Hazy Days In Our Parks

The air in many national wilderness wonderlands is getting worse. As officials debate controversial new rules to curb pollution, scientists find the sources are surprisingly far-flung

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Big bend national park’s superintendent, John King, calls the 801,163-acre reserve on the West Texas border with Mexico a “destination park,” meaning for most folks there’s little other reason to venture into the area at all. Reaching it takes four hours on a two-lane road from Midland, the nearest major airport. In between is the flat, scraggly PermianBasin, the state’s historic oil patch, dotted with dying and dead “horsehead” walking-beam pumps and filled with the pungent odor of black gold wafting from those still in production. But even in scorching summer heat, when temperatures average more than 90 degrees, the trip is worth it. Mesas and buttes pop up as one nears the oversize oxbow in the Rio Grande that gives the region its name, and the terrain turns to the classic ChihuahuanDesert of purple-tinged prickly pear, spiny ocotillo, sharp-barbed lechuguilla, and yuccas spikier on top than any punk rocker.

Since the late 1980s, the remote park has been plagued by an unexpected problem: haze. “I’ve had people come out, take a look around, and tell me they had to get going back to Houston for some clean air,” says Big Bend’s air quality technician, John Forsythe. Hall Hammond, a San Antonio jewelry sales consultant who has visited the park 60 times since 1969, is an activist with the private Friends of Big Bend National Park, a group that supports the Texas park. He remembers when he used to ask friends to float down the river with him and stare up from the canyon at what he called Big Bend blue. “The sky would just be cobalt,” he recalls. But lately that hue is rarer and rarer. In 1998, Hammond hiked up EmoryPeak in the ChisosMountains, looked down from its 7,825-foot height and saw “this yellow layer sitting down on the desert to the north and east. It just completely threw me.”

The air has been going bad in many parks for decades, affecting views and endangering the health of visitors, plants and wildlife. Last year, the National Parks Conservation Association (NPCA), a nonpartisan watchdog group based in Washington, D.C., listed the five most polluted national parks. Relying almost entirely on data from the National Park Service and the EPA, the group says the parks with the worst visibility and most severe ozone and acid rain levels are the Great Smoky Mountains Park on the Tennessee-North Carolina border, followed by Mammoth Cave in Kentucky, Shenandoah in Virginia, Acadia on the Maine coast, and the jointly operated Sequoia and Kings Canyon National Parks in California’s Sierra Nevada. Many parks have been hard hit by sulfur dioxide and nitrogen oxide from coal-fired power plants, which are responsible for nearly 70 percent of sulfur dioxide and 22 percent of nitrogen oxide emissions nationwide. The park service, while it disagrees with the way the NPCA assessed some of the pollution data, has little quarrel with the report’s general tenor.

Eastern parks, many downwind from huge coal-fired power plants in the Ohio RiverValley and elsewhere, are the worst hit, in keeping with national pollution patterns. Over the past century or so, man-made haze has cut average visibility in the eastern half of the country from 90 miles to between 15 and 25 miles. In the arid and naturally clearer western states, visibility has dropped from 140 miles to 35 to 90 miles. Parks famed for their views—Grand Canyon in Arizona, Yellowstone in Wyoming, Montana and Idaho, Yosemite in California, Colorado’s RockyMountain, and Big Bend—have long bouts of murky, polluted air each year.

Because federal rules have long mandated that national parks and other wilderness areas should have the cleanest air in America, regulators have been authorized to take action against known polluters, typically by suing them for noncompliance. But as pollution-control laws have become increasingly complex, companies accused of violating park airquality standards have gone to court to delay enforcement, stalling cleanup efforts. The Bush administration has proposed overhauling air pollution regulations, replacing the current, plant-specific air quality standards with a barter system; power plants would buy or trade pollution credits, allowing them to exceed pollutant limits in some places. Proponents say the administration’s Clear Skies Initiative will ultimately improve air quality by lowering emissions. But critics say that the changes will reverse progress against dirty air—and allow egregious polluters to stay in operation.

The political debate over air pollution laws underscores the plight of the parks. “There is still that vision that you can go out to the parks and breathe fresh mountain air, and get away from the urban problems that we all see, and stand in that pristine natural world,” says NPCA president Tom Kiernan, who worked from 1989 to 1992 as an EPA official in the first Bush administration. “Yet we see, by god, that we have some of the worst air in the country in the national parks.”

Why? An extraordinary scientific study conducted in an isolated stretch of Texas is yielding some answers. The implications—for the regulatory debate, for the health of the parks, even for the health of parkgoers—give new meaning to the idea of far-reaching.

Big bend is a historic place. Comanche, Apache and other tribes defied 300 years of Spanish and Mexican rule in the rugged badlands. It was the last redoubt of Indian warrior Victorio and his Mescalero Apache, finally scattered in 1880 by U.S. Army troops. The park’s center is crowned by the rugged escarpments of the ChisosMountains massif, giving it the look of a fortress.

In the 1990s, Big Bend’s growing haze spurred wide suspicion that the pollution originated across the river, 140 miles to the southeast. By 1995, two big coal-fired Mexican power plants, Carbón I and II, were generating 2,600 megawatts of electricity without significant emission controls.

In a joint effort, the EPA, the park service, the Texas Commission on Environmental Quality, the U.S. utility industry’s Electric Power Research Institute and the National Oceanic and Atmospheric Administration launched the Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study. From July through October 1999, a small tent and trailer city sprang up in a scrubby corner of the park. Instruments sprouted at dozens of locations in or near Texas. Scientists around the state injected different perfluorocarbon chemicals into the sky, and monitors in the park recorded the tracers as they arrived. Mexican officials, apparently afraid they were being set up to take the blame for Big Bend’s bad air, had backed out of the study; so U.S. scientists, unable to put tracers directly into the Carbón plants’ plumes as hoped, released them from a tower in the Texas border town of Eagle Pass, 20 miles from the plants.

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