Cold injury classified as either localized, as frostbite, frostnip or chilblain or generalized as in hypothermia. The main factors contributing to cold injury are exposure to humidity and high winds, contact with wetness and inadequate clothing.
The likelihood of developing frostbite is increased when the face or extremities are exposed to cold wind in addition to cold temperatures.
The freezing point of the skin is about 300 F. The fluids around the cells of the body tissue freeze, causing the skin to turn white. This freezing is due to exposure to extremely low temperatures. As wind velocity increases heat loss is greater and frostbite will occur more rapidly. The first symptom of frostbite is usually an uncomfortable sensation of coldness, followed by numbness. There may be tingling, stinging or aching feeling in the effected area. The most vulnerable parts of the body are the nose, cheeks, ears, fingers and toes. Symptoms of hypothermia, a condition of abnormally low body temperature include uncontrollable shivering and sensations of cold. The heartbeat slows and may become irregular, the pulse weakens and the blood pressure changes. Pain in the extremities and severe shivering can be the first warning of dangerous exposure to cold.
When the ambient temperature or wind chill equivalent falls below 400 F (American Conference of Governmental Industrial Hygienists (ACGIH) recommendation) site personnel should wear insulated coveralls, insulated boot liners, hard hat helmet liners and insulated hand protection. Keeping the head covered is very important, since 40% of body heat can be lost when the head is exposed. If it is not necessary to wear a hard hat, a wool knit cap provides the best head protection.
Persons should dress in several layers rather than one single heavy outer garment. The outer garment should ideally be wind and waterproof. Clothing made of thin cotton fabric or synthetic fabrics such as a polypropylene is ideal since it helps evaporate sweat. Loosely fitting clothing aid in sweat evaporation. Denim is not a good protective fabric since it is loosely woven which allows moisture to penetrate. Socks of high wool content are best.
Have extra sets of warm clothing with you on cold days. If clothing becomes wet, it should be taken off immediately and a dry set of clothing put on.
Dehydration occurs in the cold environment and may cause susceptibility of the worker to cold injury due to significant change in blood flow to the extremities. Limit the intake of caffeine.
