Many snowmobiles permitted in national parks are near noise, pollution limits

CODY, Wyo. — Many snowmobile models recently approved for use in Yellowstone and Grand Teton national parks approach the limits set for noise and carbon monoxide emissions.

The National Park Service this week released a list of 41 models less than five years old that will be allowed into the parks. The list is part of a rule permitting in the parks only models that make use of the best available technology to limit noise and pollution.

More than half of those models exceed the parks' 73-decibel noise limit at full throttle. But those models are permitted because of a 2-decibel variance to account for differences in conditions when the models were tested.

As for carbon monoxide, snowmobiles may emit up to 120 grams of carbon monoxide per kilowatt-hour of power produced. Of 24 certified models from 2006 to 2008, 13 emit 120 grams.

Eight models that exceed the noise or carbon monoxide limits will be allowed into the parks, but only with modifications to prevent operation at full throttle.

The requirements are part of a temporary plan in place since 2004 allowing up to 720 snowmobiles a day into Yellowstone. A new long-term plan that begins with the winter of 2008-09 will allow up to 540 snowmobiles a day.

Commercial guides must accompany all riders.

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