US EPA to cut off-road emissions

Viewed by many US environmentalists as the scourge of national parks, snowmobiles are to become the subject of new emissions limits being proposed by the US Environmental Protection Agency, together with off-road motorcycles, all-terrain vehicles and diesel-powered boats.

Snowmobiles present a common dilemma for national park authorities. Their growing popularity – about 2.5 million are currently in use in the US, provide a considerable tourist business for rural areas and national parks in particular. The cost to the environment is however too high for many campaigning environmental groups, which have quoted hydrocarbon emissions for one hour’s operation of a snowmobile being equivalent to those of a modern car, driven for a year. At Yellowstone national park where more than 70,000 units enter the park annually, the highest carbon monoxide levels nationwide were recorded at a park entrance, with reports that it was necessary to pump fresh air into Park offices to overcome side effects from the pollution.

The EPA says that the group of vehicles to be affected by the new proposals account for about 13% of hydrocarbon (HC) emissions; 6% of carbon monoxide (CO) emissions; and 3% of total emissions of nitrogen oxides (Nox) from mobile sources nationwide. Once introduced, the controls are expected to reduce CO emissions by up to 56%; and, HC and NOx emissions by up to nearly 80%.

For snowmobiles, HC and CO emissions are expected to drop 30% by 2006 and 50% by 2010. Heavy, non-road machinery engines will be scheduled to adopt standards set by California in 1998, effective nationwide by 2004, with stricter requirements after 2007. Recreational diesel-powered boats will be given a two year lead time to meet the requirements already in place for commercial marine engines.

For both off-road motorcycles and all-terrain vehicles, the EPA is pushing for an emissions standard that would encourage manufacturers to switch from two-stroke engines to four-stroke ones, from 2006. A second more stringent control for all-terrain vehicles would begin in 2009. Competition vehicles would be exempt.

“If left unregulated, pollution from these sources will continue to increase, becoming a larger part of the overall mobile source pollution,” commented EPA Administrator Christie Whitman, announcing the proposals on 19 September. “When fully implemented, this action will not only protect public health, but will help to restore the view of our nation’s treasured scenic parks and wilderness areas.”

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