What are Cold Injuries?
When the body or a certain area of body tissue is not able to maintain necessary temperatures for proper functioning, serious injuries may occur, and permanent tissue damage and death may result.
Cold injuries are sometimes referred to as cold weather injuries (CWI) because they are most frequently attributed to exposure to cold temperatures. Primary CWI monitored by the military include hypothermia, frostbite, chilblains and immersion foot. These diagnoses are military Reportable Medical Events (RMEs).
In addition to below- or near-freezing temperatures, increased wind speed also causes heat to leave the body more rapidly (wind chill effect). Wetness or dampness, even from body sweat, also facilitates heat loss from the body. Because of this, some CWI (e.g., trench foot or immersion foot) can also occur in warmer ambient temperatures if an individual is wet for extended periods due to rain or water immersion.
Other medical conditions that can be caused by a variety of circumstances may be cold weather-related if caused by cold weather, snow, or an ice condition or hazard. Examples include: snow blindness; dehydration; contusions, sprains, strain and bone fractures from slips or falls; other accidents due to impaired physical and/or mental function that result from cold stress, and burns, electric shock or carbon monoxide poisoning from heaters.
Who is at Risk of CWI?
Environmental cold can affect any worker exposed to cold air temperatures – even in an indoor environment if handling cold or wet objects for extended periods. Those who work outdoors (e.g., snow cleanup crews, construction workers, police officers and firefighters) are at higher risk of exposure.
Military personnel also have an increased likelihood of exposure to cold temperatures and wet conditions during various training and operational activities. Each year hundreds of active-duty Service members are diagnosed with a CWI.
The 2022 Health of the Force estimated that Service members with a CWI will experience 5 days of lost duty time to recover. In addition to the immediate impact on unit readiness, some cold injuries may result in long-term health problems, and some Veterans may have been exposed to extreme cold without adequate protection during past operations.
Military health surveillance analysis from November 2022 found that rates of CWI among active duty members are higher among men, non-Hispanic Blacks, and the youngest (under 20 years). Higher rates were reported by the Army and Marines.
Despite these statistics, anyone can become a CWI casualty in the right conditions.
What Factors Can Increase Risk of a CWI?
Primary environmental factors are external temperatures, wind speed (as it increases, it causes the cold air temperature to feel even colder, increasing the risk), and wetness/dampness.
Other factors unique to the individual include:
- Prior Cold Injury or Certain Medical Conditions: Persons who have had a CWI in the past, or who have certain existing medical conditions, are much more likely to develop a CWI within a shorter period of time or more severe CWIs. For example, Raynaud’s Disease causes blood vessel constriction in cold temperatures, resulting in reduced blood flow to the extremities (e.g., fingers and toes) and increasing risk of frostbite. Some evidence suggests experiencing frostbite may also increase chance of developing Raynaud's. Other diseases that may also increase susceptibility to frostbite and other CWIs include: anemia, diabetes, sickle cell disease, hypotension, hypothyroidism, and atherosclerosis.
- Medications: Some medications impair blood vessel constriction increasing risk of CWI. These include but are not limited to: benzodiazepines, tricyclic antidepressants, barbiturates, and general anesthetics.
- Alcohol and Nicotine: Alcohol imparts a sense of warmth, causes dilation of skin blood vessels, and increases heat loss to the environment. It may also impair the senses and judgment, making it difficult for individuals to detect signs and symptoms of a CWI. Nicotine (which includes smoking, chewing, vaping) can cause increased constriction of skin blood vessels, which increases the risk for frostbite.
- Over- and Under-Activity: Vigorous exercise and activity induces sweating, which leads to wet clothing
and subsequent increased heat loss. Conversely, under-activity results in low
heat production, which may lower the body’s core temperature.
- Clothing: Close-fitting clothing reduces insulation and may restrict movement, resulting in heat loss. Clothing should be worn loosely and layered to allow adjustments as physical activity levels and environmental conditions change.
- Dehydration: Inadequate fluid intake affects the body’s ability to sustain physical activity, which affects thermoregulation (i.e., the balance between heat production and loss). In cold environments, sensitivity to thirst declines, which can increase the risk of dehydration during strenuous activity where fluid loss often exceeds intake.
- Inadequate Nutrition: Undereating, restricting calories and/or skipping meals can cause low blood sugar (hypoglycemia) which impairs shivering, thus making it difficult to generate body heat. Low carbohydrates stores also limit the ability to maintain optimal physical activity.
- General Physical Conditioning: In addition to inadequate nutrition/calories and dehydration, evidence suggests poor fitness (such as being overweight, having poor aerobic conditioning/run times, and inadequate sleep) may increase a person’s susceptibility to cold stress and CWI.
What Are Some General Prevention Tactics?
- Be aware of Service members in their units who are at higher risk due to prior CWI, medical condition(s) or medication(s).
- Ensure Service members are properly hydrated, have necessary nutritious caloric intake, wear proper clothing (including clothing for changing), and have equipment suited for cold and wet conditions.
- Ensure Service members take adequate breaks from the cold/wet environment to warm up and/or change to dry clothing.
- Increase resilience to cold weather by:
- Consuming a healthy diet
- Staying hydrated (drink plenty of fluids, drink warm liquids)
- Maintaining fitness levels
- Getting quality sleep each night
- Dress properly:
- Dress in a way to easily adjust (loose layers)
- Ensure skin is kept dry (trench foot from prolonged wet skin can occur in any temperature)
- Protect skin with sunscreen and lip balm
- Wear dark (polarized) UV protective glasses to prevent snow blindness
- Use gloves to handle all equipment and fuel products
- Do not use face camouflage at temperatures below 32°F
- Balance the time spent in cold weather conditions - especially if you are at-risk with prior CWI, medical condition(s), or medication(s).