With winter fast approaching and climate change causing increased temperature extremes, the importance of cold injury awareness becomes more relevant. The CDC reports that exposure to excessive natural cold has claimed the lives of over 250 people per year on average from 2006-2010. Individuals at greatest risk include the elderly, infants, people with chronic diseases such as diabetes, and individuals whose economic status prevents them from adequately heating their homes. Workers in outdoor occupations such as agriculture and fishing are also at greater risk due to their extended time spent in the cold. Especially during this transition of fall to winter, we must be vigilant for cold-related injuries in both ourselves and others.
What are cold-related injuries?
Excessive cooling of the body can result in both freezing and non-freezing injuries. Non-freezing cold injuries are caused by heat loss, decreased blood supply to the affected limb, and capillary injury. Freezing injuries are primarily caused by damage from microscopic ice crystal accumulation in the skin and tissues. Toes, fingers, ears, and the nose are at greatest risk because these areas have a large surface area-to-volume ratio and also lack nearby muscles to produce heat.
Here is a description of non-freezing cold-related injuries:
• Perniosis, also known as “chilblains,” occurs when excessive cold damages capillaries in the skin resulting in redness, inflammation, and blisters. Symptoms can vary from itching to pain and ulceration. Chilblains can be prevented by wearing warm socks, gloves, and exercising weekly to improve circulation.
• Trench foot results from prolonged exposure to damp, cold conditions near freezing. The primary injury is to nerves and muscles, causing numbness, swelling, ulceration and sometimes tissue death. Prevention includes keeping the feet clean, dry, and warm.
Here are the freezing cold-related injuries:
• Frostnip is the mildest level of frostbite. It usually affects body parts at the end of the circulatory line such as the fingers, toes, ears, and nose. Superficial skin will look pale and feel numb, but the underlying tissue remains warm and flexible. Never rub the affected body part to warm it up, since friction to the ice crystals in the tissue can cause additional damage.
• Frostbite occurs when skin and tissue temperature falls below freezing. Blood flow becomes obstructed by ice crystals or by artery constriction. Lack of blood supply can cause tissue death requiring amputation.
What about hypothermia?
Hypothermia is defined as a body core temperature below 35ºC (about 95ºF). Usually, the body’s internal core temperature stays fairly constant at 37ºC (98.6ºF) . However, in extreme cold the body’s temperature regulation can become overwhelmed. During mild hypothermia (body temp 35-37ºC) normal shivering occurs, as well as increased heart rate. Moderate hypothermia (body temp 32-35ºC) causes more violent shivering as well as confusion and increasingly uncoordinated movement. Severe hypothermia (body temp 24-32ºC) results in slow heart rate and difficulty speaking and thinking. Shivering stops. Victims of severe hypothermia may exhibit irrational behavior such as paradoxically undressing themselves. Death occurs from cardiac and respiratory failure.
What do I do to help someone who develops a cold-related injury?
It is important to seek immediate medical attention and move the person to a warm area. Loosely cover the area with sterile gauze to absorb moisture and as with all cold-related injuries, do not attempt to rub frozen areas. Do not try to heat up frozen limbs unless you are sure they will stay warm, since more tissue damage will occur if the thawed tissue refreezes. If an individual stops breathing and appears dead, provide CPR anyway because in some cases hypothermia can preserve organ function long enough for successful hospital resuscitation.
What can I do to prevent cold injuries from happening to me?
The saying, “an ounce of prevention is worth a pound of cure” applies here, and preparation for winter includes maintenance of heaters, water pipes, and housing insulation. Stocking additional food, water, medicine, and a carbon monoxide detector is prudent especially in areas prone to heating or electricity interruptions. Indoor air should be heated to at least 64ºF. Engage in regular physical exercise and avoid alcohol and tobacco when in the cold. Remember to dress in layers, as inappropriate clothing is a major risk factor for cold-related injury. If going outdoors, remember to cover your hands, feet, and head.
• OSH Answers Fact Sheets. (2008, October 2). Retrieved October 30, 2015, from http://www.ccohs.ca/oshanswers/phys_agents/cold_health.html
• How cold weather affects health. (2013, February 15). Retrieved October 30, 2015, from http://www.euro.who.int/en/health-topics/environment-and-health/Climate-change/news/news/2013/02/how-cold-weather-affects-health
• Berko J, Ingram DD, Saha S, Parker JD. Deaths attributed to heat, cold, and other weather events in the United States, 2006-2010. Natl Health Stat Report. 2014;(76):1-15.
• Zhou MG, Wang LJ, Liu T, et al. Health impact of the 2008 cold spell on mortality in subtropical China: the climate and health impact national assessment study (CHINAs). Environ Health. 2014;13:60.
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November 2015. This post was authored by Alan Luo, University of Illinois at Chicago medical student and edited by Susan Buchanan, MD, MPH, Director of the Great Lakes Center for Children’s Environmental Health – Region 5 Pediatric Environmental Health Specialty Unit (PEHSU).