This past weekend the Northeast was hit by a snowstorm, making travel and transportation near impossible. Though the roads and sidewalks have since been cleared (mostly) travel is still dicey because of the risk of falling and sliding on ice. Luckily citizens and municipalities have a “natural” tool to protect us from accidents. But is road salt healthy for the environment?
Granulated sodium chloride was first used in New Hampshire as an experimental deicing agent in 1938. By World War II salt use had spread to highways nationwide. Now, 22 million tons of salt are used for de-icing a year and road salt equals 65% of salt sales in the country.
Many people assume that because road salt is natural (it is the same salt as you find on your dining room table) that it is healthy for the environment, but the addition of any outside substance to the environment can be unhealthy.
Pets and wildlife can get sick from accidentally ingesting high quantities of salt. Salt attracts deer to roadways, increasing the risk of accidents. Salt can also irritate animals paws, making them prone to infection.
Another issue caused by the mass use of salt is the gradually increasing salt concentrations in our waterways and groundwater. The EPA suggests that 20 mg/l is a safe level for sodium in drinking water but salt in water runoff puts these levels at risk. Higher concentrations of salt are more likely to occur in shallow wells in proximity to highly salted roads or storage facilities.
Chloride ions can dehydrate plants, kill small wildlife, and reduce water circulation in lakes, reducing aeration. The substance potassium acetate can melt ice without introducing chloride into the environment but unfortunately it is much more expensive than salt.
For now the best way to address the salt problem is to improve the effectiveness of road salting programs. Road design that reduces runoff is helpful. Other strategies to keep the salt from finding its way into the environment include spraying wet salt, which keeps the salt from slipping off the road, and pre spraying before a storm.
Municipalities (and individuals) also need to be conscious of how much salt they use. This will not only save money but it will also reduce the salt that’s introduced into nature. The use of GPS, thermal mapping, and sensitized salt distribution can help municipalities accurately spread salt.
Salt may be natural (sodium is the 6th most common element), but we need to be more conscious of how we use it because even natural substances can shift the environment and get us (and animals) sick.
Salt piles via Shutterstock