The human body maintains a steady temperature through the balance of internal heat production and environmental heat loss. Heat exchange between the body and environment occurs via four common processes: radiation, evaporation, conduction, and convection. In extreme temperatures, the body’s thermoregulation may fail. This results in the core body temperature moving toward the temperature of the external environment. Cold and heat exposure may cause a wide spectrum of conditions that can lead to death; the severity varies considerably among individuals. Many of these conditions are preventable with appropriate education and planning. Preventive measures must be implemented on an individual and population level.
The likelihood and severity of extreme temperature-related conditions depend on physiologic and environmental factors. Physiologic risk factors include extremes of age; cognitive impairment; poor physical conditioning, sedentary lifestyle or immobility; poor acclimatization; concurrent injury; prior temperature-related injury; and numerous underlying medical conditions, especially those affecting cognition and thermoregulation. Pharmacologic risk factors include medications, holistic or alternative treatments, illicit drugs, tobacco, and alcohol. There is a subset of medications associated with a particularly high likelihood of worsening temperature-related conditions, such as those that impact sweating and the central nervous system (ie, anticholinergics, stimulants, and sedatives) and those that affect cutaneous blood flow such as peripheral vasoconstrictors or vasodilators. Environmental risk factors include changing weather conditions (eg, humidity, wind, rain, snow), inadequate clothing or housing (homelessness, or housing with inadequate temperature control), and occupational or recreational exposure.