One of the major problems of winter weather is ICE. It is common to apply materials after the storm is over to address the problem. The most widely materials are blends with combinations of various salts: Sodium chloride, Potassium chloride, calcium chloride or magnesium chloride. Sodium chloride (rock salt) is the cheapest, but it is effective only to 15 oF, is damaging to concrete and plants, and is unhealthy for pets. Potassium chloride is less toxic, but is also less effective at colder temperatures. Calcium chloride is effective to -20 oF, but still has the problems of toxicity. Magnesium chloride has similar properties to calcium chloride, but is effective only to about 5 oF. There ARE a few non-chloride based deicers. One is an amide-glycol blend called Safe Paw that is marketed as salt-free and safe for pets. Another is calcium magnesium acetate (CMA) which is a combination of limestone and acetic acid. It also has fewer negative environmental impacts than chloride-based products. In any case, remove as much snow and ice first, and use as little product as possible.
Mary Knapp, Weather Data Library