The particles leave the exhaust cooler system - and when they hit the colder snow environment, the colder temperatures essentially suck out certain sizes of the particulate matter, like a sponge, according to an analysis by the Royal Society of Chemistry.
That is, the study team found that urban snow can absorb the carcinogenic and otherwise toxic pollutants from auto exhaust.
Led by Dr. Parisa Ariya of McGill University, the team looked at how snow interacts with pollutant chemicals, particularly pollutants found in vehicle exhausts.
By the end of an hour, the level of pollutants in snow had increased enough to allow them to conclude that snow had absorbed the pollutants. However, she added, "I do not wish to be alarmist". After examining the chemical reactions that took place, the researchers discovered that snow was efficient at removing pollutant particles from the air.
These pollutants included benzene, ethylbenzene, toluene, and xylenes, and were found in unusually high amounts.
For the latter reason, the scientists said in their findings that snow's interaction with freezing temperatures and exhaust fumes may be resulting in a threat to public health. They suggest including this topic in discussions about climate change.
"Without considering snow and ice, one will not be able to properly evaluate the effect of exhaust emission, and subsequently health and climate impacts, for the cities which receive snow", Ariya said in the Huffington Post article.
Air pollution particles are carried and stored in the snowflakes, meaning that ingesting the white stuff could be bad stuff, according to a study published last month in the journal Environmental Science: Processes and Impacts.
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