Little snowmobiles can be big polluters in the Arctic.

What did they do?

Scientists measured levels of  aromatic hyrocarbons in the air to determine the contribution of local emissions from snowmobiles, passenger cars and heavy-duty vehicles from a nearby coal mine.

The scientists set up an air monitor at a location near both a main road and a snowmobile track. They collected air samples from mid-April to mid-June, 2007.

Samples were analyzed for benzene, ethyl benzene, toluene and xylene. Results of early spring samples – during the height of snowmobile season – were compared with samples from early summer – after the snow melted – when cars and heavy-duty coal trucks dominate the roads.

Registration records of snowmobiles, cars and high density vehicles were examined to determine how many of each type of vehicle were in the area. Based on the amounts of exhaust emissions each type of vehicle produces, the researchers calculated and compared the contribution of each type of vehicle to the total amount of pollutants measured.

What did they find?

In the spring, when snowmobile season is in full swing, the levels of the chemicals measured near the road are 100 times higher than during the summer, when only cars and vehicles from the coal mine are in use.

An interesting daily pattern was noted in the spring, with sharp peaks in aromatic hydrocarbon levels occurring around 9 a.m. and then again in the afternoon. These peaks correspond with daily snowmobile tours all leaving the town during the morning “rush hour” and then returning later in the afternoon.

Based on knowledge of the amounts of exhaust emissions each type of vehicle produces, the scientists estimate that snowmobiles contribute close to 90 percent of the total aromatic hydrocarbons produced by vehicles in Longyearbyen each year.

More surprisingly, the researchers estimate that snowmobiles with older, less efficient, 2-stroke engines produce more than 90 percent of the total aromatic hydrocarbons snowmobiles generate each year. These older models comprise only 30 percent of the total number of snowmobiles in the community. Basically, the snowmobiles with 2-stroke engines are producing 4 times as much of these pollutants than all other vehicles combined.

What does it mean?

Snowmobiles are a major source of air pollutants called aromatic hydrocarbons in a community in Svalbard located in the Arctic Circle. Older machines produce the majority of the chemicals, which are known to affect human health, during the spring tourist season.

The peak levels of aromatic hydrocarbons in Longyearbyen in the spring are so high that they are close to levels of the same pollutants in Zurich, Switzerland – a major city with close to 400,000 people. As there are only 540 snowmobiles with 2-stroke engines registered in Longyearbyen, it is clear that a small number of snowmobiles can have a big impact on the amount of airborne pollutants.

Although this is startling, it should be noted that the levels of these chemicals in Longyearbyen are well below the federal safety limits as established in the United States. However, vehicular emissions are but one source of exposure to benzene and the other chemicals. Any efforts to lessen exposure to aromatic hydrocarbons can carry potential health benefits.

The good news is that if snowmobiles with 2-stroke engines are targeted for replacement with snowmobiles that have more efficient 4-stroke engines, then levels of aromatic hydrocarbons emitted from vehicles should dramatically decrease during the spring. This may be an attainable goal given the small number of snowmobiles with 2-stroke engines registered in the community.