Is Yellowstone's Latest Snowmobile Study Already Obscured by Haze?

The scoping period for input on what Yellowstone National Park's latest environmental impact statement on snowmobiles in the park should cover comes to an end September 1. That leaves the Park Service with three or four days left to tell us all what the monitoring of last winter's snowmobile traffic indicated in terms of the snowmobiles' noise, air and water pollution.
Last week the New York Times editorialized about the latest round of snowmobile studies, casting doubt on how objective the Park Service is being in measuring pollution outputs from snowmobiles and snowcoaches, the alternative mode of winter travel in Yellowstone. Additionally, the editorial pointed out that one of the alternatives the Park Service will study in the coming months is allowing unguided snowmobile travel in the park, a move that would roll back past efforts to minimize their impact on Yellowstone's landscape.

While Yellowstone officials told me Friday that they were still reviewing last winter's monitoring data and didn't know when the reports would be ready for the public to digest --some reports indicate the data won't be available until after the scoping period closes -- I've come across some of the data, and it's pretty clear in portraying snowmobiles as much dirtier than snowcoaches.
For instance, according to the agency's studies modern snowcoach engines -- those put into service since 2000, not those 25-year-old Bombardier coaches -- are up to 100 times cleaner than the older snowcoach engines when it comes to carbon monoxide outputs. As for snowmobiles, those four-strokers dubbed "Best Available Technology" did not meet the BAT standard that they supposedly had been certified as meeting.
In fact, the four-stroke machines built by Ski Doo spewed nearly as much carbon monoxide as the average 1999 two-stroke snowmobile, according to the monitoring data I've seen.
Want some side-by-side numbers? OK. While the four-stroke 'biles in the Arctic Cat fleet --which demonstrated to have the lowest emissions of the snowmobiles out there -- emitted 25 grams of carbon monoxide per mile per person, 3.1 grams of hydrocarbons, and 2.8 grams of nitrogen oxides, the snowcoaches with the lowest emissions put off 0.79 grams per mile per person of carbon monoxide, 0.14 grams of hydrocarbons, and 0.19 grams of nitrogen oxides.