The US had considerable experience with cold injury during World War II. In the US
Army, there was a total incidence of 90,535 time--lost injuries that included trench foot
and frostbite in ground troops and high altitude in aircrews. More recently, in Korea, US
troops experienced more than 9,000 cases of cold injury, chiefly frostbite, in ground
troops. Over 8,000 of these cases occurred in the winter of 1950-1951.
Cold injury, as it involves a military population, behaves in general according to
accepted epidemiologic principles. A specific agent is present and a variety of
environmental and host factors influence the incidence, prevalence, type, and severity
of the injury. These factors combine in the total causation of cold injury, and the
influence of each may vary in every situation. Careful evaluation of these factors and
their relative effects serves to guide preventative and control activities.
a. The Agent. Cold is the specific agent in cold injury and is the immediate
cause of tissue damage. If, however, the effect of cold is considered to be loss of body
heat, an agent relationship with modes of heat conduction and heat production is
apparent, and the ways in which various host and environmental factors modify cold
injury become clear. Therefore, the effect of cold cannot be evaluated by ambient (air)
b. Weather. Weather is a predominant influence in causing cold injury.
Temperature, humidity, precipitation, and wind modify the rate of body heat loss. Low
temperatures favor frostbite, whereas higher temperatures together with ground
moisture are usually associated with trench foot. Wind velocity accelerates body heat
loss under both wet and cold conditions. The wind chill effect is shown in table 4-1, and
this effect must be thoroughly understood by all personnel in areas where cold injury is
possible. It must be recognized also that the equivalent temperature depicted on the
wind chill chart relates to the cooling effect on exposed skin and clothing. The specific
implications of the wind-chill phenomenon then relate to a freezing hazard of
unprotected body surfaces--face or ears. It is important also when considering host
factors in general that increasing wind should be recognized as a significant factor in
total body heat loss.
c. Type of Combat Action. The incidence of cold injury varies greatly
according to type of combat action. Units in reserve or in rest areas have few cases; on
holding missions or on static defense, exposure is greater and a moderate increase in
incidence is expected; on active defense or offense, marked increases usually occur.
Immobility under fire, prolonged exposure, lack of opportunity to rewarm and change
clothing or carry out personal hygienic measures, fatigue, and state of nutrition may all