YELLOWSTONE NATIONAL PARK, Wyo. - Wendy Ross traveled the globe before settling into a job at Yellowstone National Park. Now she suffers from what she calls "the worst air I've ever breathed."


She and her co-workers at the park's west entrance depend on air pumped into their glass booths from a port about 75 feet off the road, but they still get hit hard when they work the outdoor shift checking pre-paid park passes.


"If I were in L.A. or Denver or even Salt Lake City, I'd be expecting it," says the 26-year-old. "But you just don't expect it coming to the most beautiful place in the world."


But it's true. The nation's highest carbon monoxide levels are to be found in Yellowstone, according to the National Park Service. The world's oldest national park has flunked three tests for federal carbon monoxide standards during the past 14 months, and the Park Service says the most recent, conducted March 2, confirms that the air is dangerous on busy winter days.


The culprit: snowmobiles.


Yellowstone officials say the snowmobiles' "deplorably dirty" engines are making park gatekeepers complain of dizziness, headaches and nausea. They say engine fumes make workers so dopey they sometimes can't count change.


"There is no doubt in our minds ... that this is an extremely unhealthy place to have people working," said Bob Seibert, the park's west-district ranger.


In last month's test, researchers riding a snowmobile rigged with an air-monitoring device recorded carbon monoxide levels at 36 parts per million along the well-traveled 14-mile stretch between West Yellowstone and Madison Junction, Seibert said.


The federal limit is 35 parts per million, and Park Service figures show the highest level recorded anywhere in the nation during 1995 was 32 parts per million in Southern California's Imperial County.


The day of the last Yellowstone test, 2,304 visitors toured the park, about an average number for a winter Saturday. Because nearly all park roads are closed to automobiles in winter, the vast majority of 150,000 annual winter visitors see the park via snowmobile along narrow strips of groomed roadway.


The Park Service reported high carbon monoxide levels at the park's west entrance last winter, but this year's study has officials most concerned because it shows that visitors are breathing bad air inside the park as well as at the gate. Environmental concerns aren't that big a deal: only 80 feet from the roadways, carbon monoxide levels drop tenfold.


"This is a very localized phenomenon, but ... it's where the public is traveling and it's where we have our employees working long hours," Seibert said.


The test results don't wash with everyone. Bob Jeffrey, an air quality specialist with the Montana Department of Environmental Quality, said hooking up an air monitor to a snowmobile and driving it around the park is not acceptable protocol for state and federal testing. The federal government has numerous regulations regarding how samples should be taken, and they don't use mobile test stations.


Park Service air quality specialist Miguel Flores acknowledged the testing didn't meet federal standards and said more studies are needed. But he maintained the early results are scientifically valid.


The air quality issue bolsters the Park Service's push to set limits on the number of Yellowstone visitors. Complaints based on aesthetics, crowds, lines and a lack of solitude are now compounded by a public-health threat. Skier and snowshoer numbers could be affected, but it's snowmobile restrictions that would likely prove the most contentious: Snowmobile rentals have become a huge industry in the past 20 years for the park's border towns, particularly West Yellowstone, Mont.


On the busiest days, more than 1,000 of the two-stroke engine-driven sleds zip in and out of the park gate at the edge of the city. Most of those machines are rented from the business community's 1,400-strong fleet, and out-of-state riders at West Yellowstone pump an estimated $30 million into Montana's economy each year.


But the Park Service says a winter survey backs its argument that growing numbers of people and snowmobiles are ruining the trip for some who come to the park to see its world-famous geysers, winter wildlife, and snow-blanketed mountains.


"I am disappointed, definitely," said Boulder, Colo., attorney Pam Cole, standing on her touring skis near Old Faithful and speaking above the din of dozens of snowmobiles. The exhaust hung so thick in places you could taste it.


Snowmobile backers see things differently: "It's a public place, just like Niagara Falls," said Adena Cook of the Blue Ribbon Coalition, an off-road vehicle advocacy group. "It's a natural phenomenon, but natural doesn't equate to wild."


Cook pointed out that snowmobiles are only allowed on roadways, and quiet solitude inside the 2.2 million-acre park is only as far away as the far side of the nearest ridge. That can take a skier or snowshoer with enough muscles and gumption as little as 20 minutes.


But most visitors never leave the crowds, noise and smoke.


"They won't let cars in, so they ought to let snowmobiles in," said Mike Pine, who moved recently from Atlanta to Bozeman, as he sat in front of Old Faithful waiting for it to blow. He was bewildered that anyone would want to limit the snowmobiles.


Most who who were asked about the snowmobile issue had a similar answer.


"If at certain times things are a little crowded, that means you're doing something right," Cook said. "I really resist people telling us something is for our own good, especially when it's the federal government."


Viki Eggers, director of the West Yellowstone Chamber of Commerce, said the smiling faces and rave reviews day in, day out, prove the park is still a fun place to visit. She pointed to the Park Service's own survey as further evidence the public still loves the winter trip into Wonderland. More than 60 percent of those surveyed in 1995 said there should be no limits on winter visitor numbers.


Meanwhile, gatekeepers like Wendy Ross continue to breathe the plumes of blue smoke riders leave behind as they roar into the park.


"You go home and your ears are ringing and you have a headache," she said. "You feel really disoriented."


Yellowstone superintendent Mike Finley said something will have to change.


"It's not only a matter of law that they shouldn't have to work in that environment, it's a matter of conscience."


* Dan Egan





Dan Egan writes for the Post-Register from Idaho Falls, Idaho.