check this out. you learn something every day (my sister teaches me something every day...thanks heath!!)
this is a letter she wrote to Andy Barrie on CBC after he was encouraging salt use!
Using salt (NaCl) to clear your sidewalk has many problems including:
-environmental: it gets into the storm sewers and causes problems for aquatic life
-damage to your garden, lawn, shrubs
-corrosion to cars
I encourage you to clear your sidewalks using other friendlier methods including:
-Use calcium magnesium acetate (CMA) which is considered the most environmentally friendly method of melting the salt, calcium chloride is also preferred to NaCl. These are both easily available at Canadian Tire
-Use sand to reduce the slip factor
-Be proactive. Clear the snow as soon as it falls and regularily shovel the sidewalk during the day when the temperature is warmer and the ice is more likely to be slush.