By: Green Venture^*

With more than five million tonnes of road salts used in Canada each year, we all know the damage they can do: they eat the metal in our cars, corrode body work and brake lines, contaminate roadside streams where we fish, and damage concrete bridges and parking garages.

What are the environmental concerns associated with road salts?

Image distributed under Creative Commons license, courtesy Flickr user jdj150

In August 2000 Environment Canada completed a five-year study of the effects of road salt on the environment. They concluded that road salts are toxic to the environment, particularly in large concentrations.

The heavy use of road salts can lead to damage to vegetation, to organisms in soil, to birds, and to other wildlife. Almost all chloride ions from road salts eventually find their way into waterways, whether by direct run-off into surface water or by moving through the soil and groundwater. In surface water, road salts can harm freshwater plants, fish, and other organisms that are not adapted to living in saline waters.

Because most ice melters contain salt, they can also injure pets and children. Doctors and veterinarians routinely treat cases of poisoning and painful skin and jaw lesions that are caused by these salt deicers. Animals can be poisoned when they lick ice-melting products off their feet, so be sure to use a damp towel to wipe your pet's paws and underside after being outside.

De-icing Alternatives

Keeping ice and snow off your driveway and sidewalks is important for safety. Consider using a product that is less damaging to the environment on your driveway, walkway, and sidewalks. The following tips from Envirocast can help you choose the best deicing product for your home and the environment:

1. Buy Early: Make sure to buy your deicing product well before the big storm hits; otherwise, you could be looking at empty shelves and have few, if any, environmental choices to make at the store.
2. Check the Label: The table below provides a summary of the pros and cons of the various main ingredients of common deicing products. Check the package label closely to see what you are buying. Experts recommend using calcium chloride over sodium chloride (rock salt).

Check the label for:	Works down to:	Cost is:	Environmental Impacts:
Calcium Magnesium Acetate (CMA)	-3°C to -5°C	20x more rock than salt	(+) Less toxic — if used sparingly
Potassium Acetate (KAc)	-30°C to -60°C	8x more rock than salt	(+) Less toxic — biodegrades, but lowers oxygen levels in bodies of water
Calcium Chloride (CaCl)	-31°C	3x more rock than salt	(+) Lowers rate of application; (+) No cyanide; (-) Chloride impact
Magnesium Chloride (MgCl)	-15°C	5x more rock than salt	(+) No cyanide; (-) Chloride impact
Potassium Chloride (KCl)	-11°C	2.5x more rock than salt	(+) No cyanide; (-) Slightly higher rate of application; (-) Chloride impact — contains 17-56% more chloride ions than other "salt"-type deicers
Urea	-4°C to -7°C	5x more rock than salt	(+) Less corrosive; (-) Slightly higher rate of application; (-) Adds needless nutrients - can be harmful to plants & waterbodies
Sand	Minimal melting effect	$3 for a 20kg bag	(+) Improves traction; (-) Accumulates in streets and streams
Sodium Chloride (NaCl) aka rock salt	-10°C	$5 for a 20kg bag	(-) Contains cyanide; (-) Chloride impact

3. Avoid Kitty Litter and Ashes: Although these products are environmentally friendly, they aren't very effective. While they provide some traction, they do not melt snow and ice. Also, they tend to get real gooey and messy when it warms up, which often tracks in onto the floors of your home. If traction is what you want, then stick with sand, which is much cheaper and easier to sweep up.
4. Shovel Early and Often: When it comes to snow removal, there is no substitute for muscle and elbow grease. Deicers work best when there is only a thin layer of snow or ice that must be melted. Get out the snow shovel and move as much snow as you can during the storm. A flat hoe can also help to scrape ice off the surface before any deicers are applied.
5. Know Your Salt Risk Zone: You wouldn't want to kill your favorite tree, shrub or grass, so check out the plants that grow within five or ten feet of your driveway and sidewalk. If you have salt-sensitive plants in this zone, you should avoid any deicing product that contains chlorides or use very small doses. You may want to use Calcium magnesium acetate as a safer alternative, or stick with sand.

Landscaping Areas	Species at risk from salting
Deciduous Trees	Tulip Polar, Green Ash, Hickory, Red Maple, Sugar Maple
Conifers	Balsam Fir, White Pine, Hemlock, Norway Spruce
Shrubs	Dogwood, Redbud, Hawthorn, Rose, Spirea
Grasses	Kentucky Bluegrass, Red Fescue

6. Avoid Products that Contain Urea: Urea is fairly expensive and performs poorly when temperatures drop below -6°C. Given that nitrogen is a major problem in our waterways, it doesn't make sense to use nitrogen-based products, such as those containing urea, for deicing.
7. If You Must Use Salt: Apply it Early, but Sparingly Remember what your Mom may have told you at the dinner table: "A little salt goes a long way." The recommended application rate for rock salt is about a handful per square meter treated (after you have scraped as much ice and snow as possible). Using more salt than this won't speed up the melting process. Even less salt is needed if you are using calcium chloride (about a handful for every three square metres treated - or about the area of a single bed). If you have a choice, pick calcium chloride over sodium chloride. Calcium chloride works at much lower temperatures and is applied at a much lower rate.

Sources:
Cryotech
Envirocast
Environment Canada
Hackensack Riverkeeper
Peace and Environment News
The Sault Star

* Green Venture is a not for profit organization in Hamilton Ontario, and a member of Green Communities Canada.  Green Venture connects ideas and people to facilitate sustainable living and realize a cleaner, healthier community.

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