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The Environmental Downside of Dry Sidewalks

We spread hundreds of thousands of pounds of calcium chloride onto New York City sidewalks each year to melt snow. What's the downside of this product and what alternatives are there?

The concerns about de-icing and anti-icing substances is toxicity -- both to humans applying it and to waterways that receive the runoff. The benefits include safety (less slippery roads and walkways), as well as speed and economy of application.

Calcium chloride is considered less problematic than common rock salt (sodium chloride), according to FacilitiesNet, though can be hardest to clean up when tracked indoors.

According to its Material Safety Data Sheet (MSDS), calcium chloride is not considered a hazardous or toxic substance, but it may cause:
  • Severe respiratory and digestive tract irritation with possible burns
  • Severe eye and skin irritation with possible burns
  • Cardiac disturbances.
So it needs to be handled and applied with care.

FacilitiesNet also notes that:
Sodium acetate and calcium magnesium acetate (CMA) ... are considered non-corrosive and are biodegradable, creating no problems in runoff water. [But they produce] a slushy texture, making them less desirable for use on walkways.
But more to the point:
Different areas have different priorities. Bridges or areas near exposed steel might require non-corrosive materials. Areas around environmentally sensitive sites deserve non-chloride and biodegradable products. Near building entrances, fast acting-chemicals and easy cleanup might be priorities.
Bottom line: you can't get a bottom line from a column like this. De-icing, like so many sustainability issues, requires a place-based, context-appropriate solution.

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Gil Friend, systems ecologist and business strategist, is president and CEO of Natural Logic, Inc. -- offering advisory services and tools that help companies and communities prosper by embedding the laws of nature at the heart of enterprise. Sign up online to receive his monthly column via email. Read Gil's blog here.

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