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Clean Snowmobiles: Background and Overview
Table of Contents
Background and Overview
Reasons for Change
Preventing Pollution
Where To Go for Help
Complete List of Links

Essential Links:

Clean Snowmobile Facts
Presents objective and balanced information about all aspects of the debate over snowmobile emission...

How Two-Stroke Engines Work
Explains how two-stroke engines operate and their advantages and disadvantages.

Snowmobiling is a popular winter sport and basic mode of transportation in remote areas. The economic impact of the industry is $20 billion per year. In 2004, there were 109,750 snowmobiles sold in the U.S. The average suggested retail price of a new snowmobile sold in 2004 was $6,550. There are more than 1.7 million registered snowmobiles in the U.S. and more than 225,000 miles of groomed and marked snowmobile trails. The average snomobiler rides 990 miles per year. Source: International Snowmobile Manufacturer's Association

Twenty-six states in the U.S. have active state snowmobile associations: Alaska, Arizona, California, Colorado, Idaho, Illinois, Indiana, Iowa, Massachusetts, Michigan, Minnesota, Montana, Nebraska, New Hampshire, New York, North Dakota, Ohio, Oregon, Pennsylvania, South Dakota, Utah, Vermont, Virginia, Washington, Wisconsin, and Wyoming. Source: American Council of Snowmobile Associations

Do snowmobiles emit significant amounts of pollution?
Some Do, and Some Do Not!

A final EPA regulation of snowmobiles was published in September 2002, utilizing 2000 baseline data developed from 23 different snowmobile machines. Starting in model year 2004, these regulations will reduce fleet-wide hydrocarbons (HC) and carbon monoxide (CO) snowmobile emissions by 30 percent by 2006, by 50 percent by 2010, and by 70 percent by 2012. The reduction is a fleet average for each manufacturer depending on the number and type of engines used each year. The regulations have allowances for minor producers and special use (racing) snowmobiles. The first regulation deadline incorporates some emissions credits for manufacturers fielding cleaner 4-stroke snowmobiles used in Yellowstone and other environmentally sensitive areas. These cleaner, quieter snowmobiles have reduced audible noise by about half, reduced CO and HC by more than 80 percent, as measured using the EPA 5-mode emissions test protocol. The emissions are similar to those of small engine requirements in California on a mass of pollutant per unit of power basis.

The EPA regulation does not cover particulate matter, although the 2012 emissions level will require a change of technology such as the use of 4-strokes or direct-fuel-injection two-stroke engines. This type of two-stroke engine was measured as emitting less HC and CO than four-stroke equivalents.

  • Current (2004) production snowmobiles use cleaner versions of two-stroke engines or four-stroke engines. The two-stroke engines produce amounts of unburned HC and CO similar to that produced by automobiles before the 1970 Clean Air Act. These two-stroke engines still produce significant amounts of fine (PM-2.5) particulate matter emissions due to the method of scavenging, leaving the exhaust and fuel inport ports open at the same time.
  • The best estimates available comparing snowmobile emissions to average automobile emissions conclude that a traditional snowmobile produces ten to 70 times more CO and between 45 and 89 times more unburned HC than an average car (see the National Park Service revised 2001 report on Impacts of Snowmobiles in National Parks.)
Two-stroke engines used in snowmobiles are sometimes the same engines used in personal water craft (PWC) like jet skis, with modified air and exhaust systems to adapt for water use. However, the way these engines are used in PWC is considerably different, and these operational differences change the emissions and emission content. Temperature difference is one large variable. PWC seldom operate at temperatures below freezing (0° C) where snowmobiles typically operate at colder temperatures when all engines want to run rich. Colder temperatures favor the production of carbon monoxide and warmer temperatures favor the production of unburned hydrocarbons.


The Topic Hub™ is a product of the Pollution Prevention Resource Exchange (P2Rx)

The Clean Snowmobiles Topic Hub™ was developed by:

Peaks to Prairies Pollution Prevention Center
Peaks to Prairies Pollution Prevention Center
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Hub Last Updated: 11/26/2012