The military community responds to cold trauma according to accepted epidemiologic principles. The specific causative agent is cold. Moisture is closely related because it speeds the loss of body heat although it alone cannot cause cold injury. Cold produces injury by increasing the rate of body-heat loss. This rate is determined not only by the ambient temperature, but also by other factors such as moisture and wind.
Moisture increases the rate of heat loss by conduction and evaporation, wind by convection.
A variety of environmental and host factors combines in the total causation of cold injury and influences the incidence, prevalence, type, and severity of the injury, though these influences vary from situation to situation. The most important environmental factors in cold injury are weather, clothing, and type of combat action. Weather is a predominant influence in the causation of cold injury. Temperature, humidity, precipitation, and wind modify the rate of loss of body heat. Low temperatures and low relative humidity favor the development of trenchfoot.