Road salt: Leaving a bitter taste in the mouths of Canadians.

Photo by Phil Romans |

Photo by Phil Romans |

 Year after year, the miserable Canadian winter rears its ugly head, and year after year, I wonder the same thing: why on earth do we need to use so much salt?  It seems quite excessive at times, with trucks pouring tonnes upon tonnes of it on highways, and a brand new layer added after every snowfall at university campuses, mall parking lots, and skate parks alike.  I’m not questioning whether sensible amounts of salt-sprinkling is necessary during the wintertime, but rather I am questioning whether the quantity of salt we release into the environment on a yearly basis is necessary, regulated, monitored, and/or reviewed annually for adverse environmental impacts (not to mention the hideous stains on my winter boots). 

First, let’s discuss what makes salt such a desirable compound during the winter season.  As we know, salt is composed of sodium chloride (the same compound you sprinkle on your fries).  Essentially, it lowers the freezing point of water.  When applied to snow and ice, it assists in melting, mostly at relatively warm temperatures of about -10°C (relatively warm for most of Canada, that is).  The amount of salt required is dependent on temperature, such that higher temperatures require lower quantities of salt, and vice versa.   But once spring rolls around and the snow and ice begin to disappear, what happens to all of this salt? 

As expected, much of this salt makes its way to bodies of water of various sizes, whether through sewer systems or runoff.   For example, the city of Pickering, Ontario, reports using 7600 tons of salt, the majority of which ends up in either a bay or in the groundwater.  Additionally, a study conducted at the University of Minnesota discovered that 70% of road salt ended up in the local watershed.

The following is a non-exhaustive list of environmental problems caused by the release of salt into the environment, in no particular order of concern:

·      Rust.  Since salt is corrosive (just place a metal paper clip in salt water for a few weeks and observe what happens), rust will begin to form on rather important components of both our natural and built environment, the most concerning of which being bridges (because of safety and public costs), but also extending to vehicles (personal cost) over time.      

·      Toxicity in fish and aquatic ecosystems. When salt runoff from roads reaches its eventual destination – typically freshwater systems – it can be toxic to aquatic life.

·      Toxicity in soil.  An elevated salt content in soil will have a negative impact on plant growth.

·      Damage to roads.  Salt causes damage to road infrastructure, therefore requiring more frequent repairs.  This not only comes at a cost to taxpayers, but also causes its own environmental damage (from excessive paving of roads, etc.).

It’s no question that salt can have damaging effects on the environment, not just during winter, but all year long.  But the big question still remains: Are we being irresponsible with salt use in this country? Environment Canada recognizes that salt, innocent as it seems, is toxic within ecosystems, and considers the management of salt to be greatly irresponsible.  Road salt has even been recommended for addition to the List of Toxic Substances, and is the focus of various risk management tools, strategies, and assessments under the federal government.  Although Environment Canada does not intend on banning the use of road salt altogether (since this could jeopardize road safety), they do have measures in place in an attempt to enable Canadians to utilize road salt more responsibly.  Annual reports of road salt management practices are kept by Environment Canada as per Annex C of the Code of Practice for the Environmental Management of Road Salts.  It is evident that the federal government takes the matter of road salt pollution seriously and is continuously monitoring salt distribution patterns and use to ensure the resource is used more responsibly in an attempt to mitigate environmental harm. 

Many sources claim that, yes, Canadians use far too much road salt.  The solution?  Many state that people need to learn how to drive effectively in winter weather (or not drive personal vehicles altogether), and that dumping salt on the roads every time the temperature falls below zero is an ineffective band-aid solution.

(Fun fact: some other potential alternatives to road salt include cheese brine (surprisingly a relatively popular choice), garlic salt, and even beet juice.  (I won’t get into the underlying science behind these alternatives – that deserves its own article!).