Real-time Remote Sensing of Snowmobiles Emissions at Yellowstone National Park: An Oxygenated Fuel Study, 1999

In the winter of 1999, the University of Denver conducted a remote sensing study at Yellowstone National Park. The objective of the study was to identify the effect of oxygenated fuels on the exhaust emissions from snowmobiles. Ratios of CO, HC and toluene to CO 2 were measured and used to calculate %CO, %HC and parts per million of toluene. From the measured ratios we also calculated the grams per gallon of fuel, grams per mile and grams per kilogram of fuel for CO and HC. The ambient air temperature was collected and correlated to the remote sensing measurement to account for temperature effects. Measurements of CO and HC were made at the West Entrance, South Entrance and west exit of Yellowstone where there were 974, 376 and 163 valid readings respectively. The mean CO exhaust emissions in percent were 6.0, 6.4 and 7.1 respectively and the medians were 6.1, 6.5 and 7.4. For CO emissions of snowmobiles the observed distribution looks normal compared to the observations from automobiles where their distribution is very skewed with most measurements low and very few high emitters. At the West Entrance where an ethanol blend was used in the snowmobiles there was a 7 ± 4% decrease, corrected for temperature, in CO emission compared to the South Entrance where non-oxygenated fuels were used. The mean HC emissions measurements in percent were 2.5 for the West Entrance, 2.2 for the South Entrance, and 2.0 at the West Exit and the medians were 2.5, 2.1 and 1.9 respectively. Since HC emissions from snowmobiles are variable with many different parameters that could not be controlled, an ethanol effect could not be clearly identified and an ethanol penalty can not be discounted. The first ever measurement of aromatics from mobile sources in realistic operation was made at the West Entrance of Yellowstone. There were 470 valid measurements made for toluene. The mean was 1976ppm and the median was 1734ppm. The data show, on average, a correlation between higher HC emissions and higher reported toluene measurements with r 2 = 0.93 with an equation ppm toluene = 0.105 * ppm HC-619.