Salt pollution has been on the increase since the evolution of the automobile. With more pressure on government agencies to keep the highway clear and safe, an increase in the use of salt has developed. It is important to understand why salt is used and how it work as well as the environmental effects to understand the salt pollution problem. Salt is a necessary and accepted part of the winter environment. It provides safety and mobility for motorists, commercial vehicles and emergency vehicles.
Salt is used as the principal deicer because it is the most available and cost-effective deicer.
Rock salt is preferred because it is cheap and effective. It costs 20 dollars a ton where as an alternative like calcium magnesium cost around 700 dollars a ton. Some 10 million tons of deicing salt is used each year in the U.S. and about 3 million in Canada. Salt is used to keep snow and ice from bonding to the pavement and to allow snowplows to remove. When salt is applied to ice and snow it creates a brine that has a lower freezing temperature than the surrounding ice or snow.