Dear EarthTalk: Are there environmentally friendlier ways to de-ice pavement besides using salt?
—Heidi David, Concord, NH
Although salt and various salt derivatives melt ice effectively and make both walkways and roads safer, they can be damaging to the environment. After salt is applied, it washes off paved surfaces into storm drains or onto adjacent ground, and can then be carried into nearby bodies of water. According to The New York Times, this salty runoff poisons fish and wilts vegetation. It also corrodes metals, damages concrete and poses health risks to people with high blood pressure.
Some studies have also shown that salt applied to road surfaces increases automobile collisions with wildlife, especially white-tailed deer that are attracted to natural and artificial salt deposits in their normal course of feeding.
Despite these facts, salt remains the cheapest and most effective way to keep pavement free of ice. According to materials consultant Henry Kirchner, individuals can effectively use salt with minimum impact: "Do not use a chemical deicer to melt every bit of ice," says Kirchner. "Use only enough to break the ice/pavement bond, then remove the remaining slush by plowing or shoveling." All snow should be cleared away first, and the ice should be chipped off and moved away from water supplies and vegetation.
For small jobs, it may be feasible to use more potent, less environmentally toxic de-icers like magnesium chloride or calcium magnesium acetate instead of rock salt. These stronger, though more expensive, compounds can be strategically applied before a storm to block ice from forming. Sand and cat litter can be used to provide temporary traction, but these materials may dog surface water and bury plants. Although many researchers are experimenting with even more benign de-icers, including by-products of corn and cheese processing, none of these compounds is currently available to consumers.
Perhaps the larger issue is how municipalities store and use large amounts of road salt. Many of the most severe cases of environmental contamination have been caused by improper storage. When salt is stored outside uncovered, rain and snow can carry large quantities to surrounding soil and water.
As to reducing salt use, many cities and towns simply don’t de-ice in flat residential areas, except during ice storms. Some use a mix of sand and salt, instead of pure salt. Also, salt spreading equipment that is well maintained will distribute salt more accurately and, as a result, use less. Additionally, salt that is wetted before being spread sticks better to the road.
According to the trade magazine, Better Roads, a product called Verglimit, a mixture of de-icing salts and caustic soda, can be mixed with asphalt roadway during paving. Its installation doubles the cost of surfacing a road, but helps reduce the amount of salt needed for de-icing roadways and, according to the magazine, "in certain conditions can eliminate the need for salting entirely."
CONTACTS: The Salt Institute, (703) 549-4648, www.saltinstitute.org ; Better Roads, "Materials for Deicing and Anti-icing," www.betterroads.com/articles/NewProds/Apr03bid.htm.
Dear EarthTalk: I have developed asthma from the fiberglass insulation in our home. How can I find insulation that won’t make me sick?
—Cynthia Bacon, Orlando, FL
Fiberglass, a common home insulator that grew popular after the dangers of asbestos became more widely known, is itself now associated with a range of health issues. Microscopic slivers of fiberglass can break loose during handling and be inhaled, irritating the lining of the respiratory tract and becoming lodged in lung tissue. This can cause a fibrous buildup that reduces lung capacity, or cause DNA mutations that can lead to lung cancer. In fact, cancer warnings appear on all fiberglass insulation sold in the United States.
Although wearing a respirator or dust mask can prevent inhalation of fibers during installation, all three principal U.S. manufacturers of fiberglass insulation now seal their batts in a perforated polyethylene or polypropylene sheeting so as to prevent airborne exposure. Nevertheless, for those suffering from aggravated respiratory problems, replacing fiberglass insulation with a more environmentally friendly alternative may be the best option. Luckily there are many such options available.
A favorite of environmental advocates is cellulose, which is made from recycled, shredded newspaper. In his book, The Solar House, author Dan Chiras calls cellulose "one of the most environmentally friendly insulation choices." It is also highly efficient, readily available and economically priced, he says, and thus competes well with fiberglass.
Chiras also recommends cotton insulation, calling it "a natural product and safe from a human health standpoint," while acknowledging that it is twice the price of fiberglass and "one of the most chemically intensive crops grown in the United States." It contains no formaldehyde binders, however, a health and environmental plus, and usually contains a fire retardant, an important safety consideration.
Radiant barriers are another option, says the Fiberglass Information Network. Ideal for hot climates, they are made from metal foil and either Kraft paper or bubble wrap. The Network also recommends insulation batts made from recycled #1 plastic, known as PET, the same material used to make some soda bottles and carpeting. Made by RTICA, based in Stony Creek, Ontario, the batts are installed just like fiberglass and make for an excellent fiberglass replacement choice.
But before ripping out that old fiberglass, it may be worth getting a professional to evaluate the integrity of your home"s ductwork. With properly sealed ducts, any stray fiberglass slivers inside your walls should not be able to get out. In the case of duct contamination, your best bet is to replace the entire system. Duct cleaning is also an option, but the U.S. Environmental Protection Agency does not recommend it. If you do decide to opt for cleaning, the National Air Duct Cleaners Association offers a list of companies that can do the work.