Melting snow creates toxic mix
While most people welcome melting snow as a sure sign of spring, researchers at McGill University and the École de technologie supérieure have discovered the process contains hidden dangers.
They have discovered that as snow falls it acts as a sponge and absorbs airborne pollutants from the exhaust of cars and trucks.
It's one reason that the air seems cleaner after a snowfall but there are concerns that the snow then releases what they describe as a "toxic cocktail" into the environment as it melts.
The researchers also found that some of the pollutants absorbed by the snow undergo a chemical transformation that in some cases create additional pollutants with different toxicity and carcinogenicity which are released into the air, soil and water.
The senior author of the study says understanding the process could help reduce the hundreds of thousands of premature deaths caused by air pollution in North America every year.