By Yun Suh-young



The residue from the calcium chloride used to de-ice roads so far this winter could possibly pose an environmental danger.



The country was hit by heavy snowfall over the past two weeks, and local governments nationwide have used more of the de-icing chemical than usual.



The amount of calcium chloride used in Seoul totaled 33,000 tons during December. The city initially planned to use about 50,000 tons for all of this winter, but due to the frequency of snowfalls, it prepared an additional 7,500 tons. This means about 60,000 tons of calcium chloride will be used, about three times the amount used last winter.



The problem is that not much is being done about its disposal.



Concerns have been raised about the chemical polluting water when it flows into the sewage system.



"Out of the 33 billion tons of water people use, 7.4 billion ton is household sewage. The level of the chemical in the water will be less than 0.1 percent," said Hong Dong-gon, a director of the Household Sewage Division at the Ministry of Environment.



"Water from factories is the most difficult to process in the sewage system as it contains hazardous substances but de-icing chemicals aren't that harmful when they are diluted. They are more harmful when they are in powder form and attached to roads, tires and buildings."



Calcium chloride can be environmentally harmful when used in very large quantities, cause steel corrosion. It can also damage the tires of vehicles.



In terms of environmental pollution, it can acidify soil which can kill trees and plants. When blown by the wind, it can cause respiratory problems.



However, calcium chloride is widely used for deicing than other "environmentally friendly chemicals" because it is cheap, fast and effective.



The chemical prevents ice formation and de-ices the road surfaces by depressing the freezing point. It can prevent freezing at temperature as low as minus 52 degrees below Celsius.



The price of a kilogram of calcium chloride ranges between 170 won to 220 won which is much cheaper than the eco-friendly chemicals which cost between 350 won to 450 won per kilogram.



There are, however, efforts being made to use the latter. The Public Procurement Service, which distributes de-icing chemicals to local municipalities nationwide, said it will only distribute certified environmentally friendly chemicals to local governments starting next winter.



