An investigation of driver exposure to carbon monoxide while traveling in the wake of a snowmobile

A dramatic increase in the popularity of snowmobiling across the nation raises new concerns regarding exposure to pollution from snowmobiles. Because many tourists choose to snowmobile in large groups along fixed trails, this study investigates exposure to carbon monoxide (CO) while traveling in the wake of a snowmobile. Steady-state measurements of engine-out CO concentrations were taken at four different speeds while traveling on level ground. Values ranged from 9.9 grams per mile (g/mile) at 10 miles per hour (mph) to 19.9 g/mile at 40 mph. At these same speeds, bag samples were taken on a second snowmobile while traveling at fixed distances behind the first snowmobile. A maximum centerline exposure of 25.7 parts per million (ppm) occurred at 10 mph and 25 ft behind the lead snowmobile. Off-centerline exposure data as well as exposure data without the lead snowmobile were also taken at the same speeds and distances. This information was then used to develop a model to predict exposure to CO while traveling behind another snowmobile as a function of both the vehicle speed and the distance between the snowmobiles. This model can also be used to predict exposure to pollutants other than CO (if emission factors are known). The results are of interest to snowmobilers, snowmobile manufacturers, environmentalists, park managers, and regulatory agencies. Recommendations for further study are made.