We’ve all stood outside on a wintry day, trying to catch snowflakes on our tongues. Heck, some people even make snow ice cream.
But scientists in Canada have found that snow absorbs nanosized particles and certain organic components of car exhausts. 
Maybe you should avoid the white snow as much as the yellow kind.
Research has shown that tiny particles spit out by exhaust fumes negatively impact both the environment and human health. This type of pollution is especially bad for people with asthma and can cause cancer. One in 8 deaths worldwide can be attributed to air pollution, according to the World Health Organization (WHO).
Using an artificial snow chamber, researchers at McGill University in the U.K. demonstrated the impact of snow on these pollutions.
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The presence of snow changed shifted the distribution of the aerosols of benzene, toluene, ethylbenzene and other organic compounds, as well as particles produced when gasoline and oil are burned. This is because when particles exit an exhaust’s cooler system into a colder environment, the temperature gradient means that aerosols are removed by the colder surface, Chemistry World explains.
It’s possible that people may be exposed to even more pollutants when snow melts.
Over the course of an hour, the level of pollutants in the snow more than doubled. The researchers aren’t sure whether the snow acts as a temporary “sink,” or if this effect lasts longer.
A temporary sink means that pollutants could spread quickly in industrialized areas where snow melts.
Parisa Ariya, a professor at McGill University, explained:
“We demonstrated that during the experimental time, snowpack does remove certain air pollutants emitted with car exhaust.
“Other studies, including studies by our group, previously showed that snowpack accumulates air pollutants over a longer period of them, and they are immobilized when the snow melts contaminating soil and entering groundwater.”
“As the snowpack warms up and melts, the emission of certain pollutants into the atmosphere can occur…emission of pollutants from the snowpack into the atmosphere is therefore a phenomenon of potentially high importance in the environmental and public health context, and needs to be investigated.” 
A 2010 report issued by the nonprofit Health Effects Institute analyzed 700 peer-reviewed studies around the globe on the ways in which motor vehicle emissions impact health. It found “evidence of a causal relationship” between pollution from vehicles and decreased lung function and hastened hardening of the arteries.
The analysis also showed “strong evidence” that exposure to traffic caused variations in heart rate and other ailments that result in deaths. 
 Chemistry World
 Daily Mail