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Cold, Wind, and Sun Exposure

Managing—and Preventing—Skin Damage

Mark Snowise, MD; William W. Dexter, MD

Sports Dermatology Series Editor:
William W. Dexter, MD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 32 - NO. 12 - DECEMBER 2004

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In Brief: Outdoor athletes, through the course of their training and competition, are constantly battling environmental effects. Cold and wind exposure can lead to frostbite, which may not be immediately apparent if the skin grows numb. Other common cold-induced conditions include Raynaud's phenomenon, cold-induced urticaria, and chilblains. Summer athletes and athletes participating at higher altitudes need to be especially vigilant for sunburn. Physicians should know when to withhold athletes from play to prevent further damage. By teaching prevention strategies, clinicians can help their patients safely enjoy outdoor sports.

Outdoor athletes encounter wind, cold, sun, and heat as a regular part of sports. Because the skin is the largest organ of the body, it is not surprising that athletes often encounter dermatologic conditions that are caused by environmental exposure. Clinicians can help active patients prevent and treat these conditions to avoid long-term sequelae.

Most cold-related injuries result from insufficient protection against the environment. Humans adapt less readily to cold than to heat. As the body cools, the shell (including the skin, subcutaneous tissue, and muscles) adapts to protect the core, many times at the expense of the shell. Whenever an athlete presents with a superficial cold injury, the evaluation should include searching for signs and symptoms consistent with hypothermia (eg, shivering, altered mental status, slurred speech, coordination difficulty). Also, windchill accelerates heat loss, with the greatest effect seen in the first 20 mph of wind speed.1

Frost Nip and Frostbite

The most common dermatologic injury caused by cold exposure is frostbite. The overall incidence in athletes is difficult to determine, because most participants do not report mild cases. Frost nip is even less severe and results from superficial freezing. Most athletes who have frost nip usually do not report it to their athletic trainer or team physician.

Reamy2 noted that frostbite is seen most commonly in 30- to 49-year-old patients, and it affects the feet and hands in 90% of cases. Foray3 reviewed 1,261 mountain frostbite cases and found that 57% occurred on the feet, 46% on the hands, and 17% on the face and ears (some patients had frostbite at more than one site).

Deeper frostbite is much less common than frost nip and occurs in four phases. The prefreeze stage occurs at temperatures of 37° to 50°F (3° to 10°C) and causes decreased cutaneous sensation with slight skin edema. The freeze-thaw stage occurs from 5° to 21°F (-15° to -6°C) and produces intracellular and extracellular crystal formation and slight tingling. As cooling continues, vascular stasis occurs, causing continued ice crystal formation, plasma leakage, vasospasm, and stasis coagulation. The final phase of frostbite is late ischemia, seen as thrombus formation, autonomic dysfunction, and tissue breakdown. Except for high-altitude climbers, severe frostbite is very rare in athletes and, when seen, is usually associated with alcohol use, poor judgment (which may occur with high-altitude-induced hypoxemia), or both.4,5

Diagnosis. Frost nip involves only the superficial layers of skin and typically causes numbness and blue-white discoloration of the affected area. The classification of frostbite initially differentiates the superficial from the deeper injuries. Mild frostbite symptoms include burning and numbness. The skin is usually grayish and pale, but the deeper tissue is soft and pliable.

Deep frostbite is usually painful initially, then stops hurting as the tissue becomes numb. At this point, the skin is cold, firm, rigid, and pale. Blisters may develop after thawing (figures 1 and 2). The ultimate severity of the frostbite, based on clinical exam, is usually not gauged until several days after the injury. First-degree frostbite involves mild numbness, erythema, and edema. Second-degree injuries have clear blisters, erythema, and edema, whereas third-degree frostbite involves hemorrhagic blisters. Fourth-degree frostbite involves injuries to bone and muscle, with necrosis and loss of tissue.2

Treatment. The mainstay of treatment is warming the skin, but this should not be started until there is no risk of re-exposure to cold. Repeated partial thawing and refreezing result in the release of increased inflammatory mediators and more severe tissue damage.6-8 The prompt administration of ibuprofen at 12 mg/kg/day limits tissue damage by inhibiting the inflammatory cascade.2

Care must be taken not to overlook the symptoms of hypothermia. Wet clothing should be removed and the extremity should be splinted and elevated if possible. Warming may be performed with body contact if frostbite is mild; for example, removing wet gloves and placing the fingers on the abdomen or in an axilla. For more severe injuries, warming in a water bath at 102° to 108°F (39° to 42°C) for 15 to 30 minutes is best. With severe frostbite, patients will usually require analgesics during rewarming.

Clear or white blisters are debrided and covered with aloe vera (gel, ointment, or cream), but hemorrhagic blisters are left intact and covered with aloe vera. With severe deep-tissue damage, antibiotic treatment with intravenous penicillin G at 500,000 U every 6 hours for 48 hours is warranted.9

The status of the patient's tetanus immunization should be determined and updated if it has not been given within 10 years. Other therapies that have been investigated for frostbite include hyperbaric oxygen, tissue plasminogen activator, alprostadil (prostaglandin E1) analogs, nifedipine, pentoxifylline, and superoxide dismutase, none of which show consistent evidence that they are beneficial.2,8,10

The prognosis for frostbite is excellent if pinprick sensation is intact, the skin color appears healthy, and the vesicles have clear fluid. Poor prognostic signs include hemorrhagic vesicles, cyanotic color, and frozen tissue. The long-term sequelae include decreased sensation, cold sensitivity, hypopigmentation, hyperhydrosis, ischemic nail abnormalities, autonomic dysfunction, premature closure of the physes, and loss of tissue.

Return to play. Any athlete with more than frost nip should be removed from competition. With frost nip, once the skin has normal color and sensation, return to play may be allowed with close observation of the area. Any signs of recurrent frost nip require removal from play with no return during that event.

With more severe frostbite, the athlete should be removed from competition that day and treated as described. Because re-exposure of a frostbitten area can worsen the injury, care must be taken to avoid another freeze-thaw cycle. In emergency situations, frostbitten feet can still be walked on, but thawed feet cannot. Return to play should be delayed until all blisters completely heal and the affected extremity has normal sensation and range of motion. The athlete should be cautioned that a twofold increased risk of recurrent frostbite exists.11

Preventing Frostbite

Because frostbite results from inadequate protection from the cold, prevention is based on protective measures. Proper protective clothing and layering can help remove moisture from the skin, preventing freezing. Because metal readily conducts cold, removal of metal jewelry is recommended. Anticipating the conditions can heighten everyone's awareness of the risk for frostbite, thus decreasing the incidence. Educating athletes about the early signs of injury can prevent more severe tissue damage.

Wet bulb globe temperatures (WBGTs) are helpful in providing guidelines for participation in the heat and cold. The WBGT index factors in temperature, humidity, wind speed, and radiant heat.11 Risk for cold injuries increases when the WBGT drops below 50°F (10°C), and outdoor events should be cancelled if temperatures fall below -4°F (-20°C).

Another way to estimate the risk for frostbite injury is to combine temperature with wind speed (table 1) to determine windchill.12 If an anemometer is not available, gross estimations of wind speed can be made by observing the natural surroundings:

  • At 10 mph (16 kph), wind is felt on the face;
  • At 20 mph (32 kph), small branches are moving or snow and dust are raised;
  • At 30 mph (48 kph), large tree branches move; and
  • At 40 mph (64 kph), an entire small tree bends.

For more about windchill, see "What to Tell Patients About Windchill."

TABLE 1. Estimated Windchill Chart
Air Temperature
in Degrees
Estimated Wind Speed
0 km/h (0 mph)   10 km/h (16 mph)   20 km/h (32 mph)   30 km/h (48 mph)
30F (-1.1C)30F (-1.1C)16F (-8.9C)4F (-15.6C)-2F (-18.9C)
20F (-6.7C)20F (-6.7C)4F (-15.6C)-10F (-23.3C)-18F (-27.8C)
10F (-12.2C)10F (-12.2C)-9F (-22.8C)-25F (-31.7C)-33F (-36.1C)
0F (-17.8C)0F (-17.8C)-24F (-31.1C)-39F (-39.4C)-48F (-44.4C)
-10F (-23.3C)-10F (-23.3C)-33F (-36.1C)-53F (-47.2C)-63F (-52.8C)
-20F (-28.9C)-20F (-28.9C)-46F (-43.3C)-67F (-55C)-79F (-61.7C)

To use the chart, find the temperature on the left and the closest wind speed at the top of the chart. The number at the intersection of the two numbers is the windchill index.

Colored areas show moderate risk (green), increased risk (orange), and high risk (red). At high risk, flesh freezes in less than one minute.

Adapted with permission from Milesko-Pytel D: Helping the frostbitten patient. Patient Care 120213;17:90-115.

Raynaud's Phenomenon

Curiosity will often lead athletes to question their physicians about Raynaud's phenomenon, an episodic spasm of digital blood vessels in response to cold exposure or an emotional challenge. The digits first become cold, pale, and numb (ischemic phase) and then turn red, throb, and swell. Raynaud's phenomenon is mostly idiopathic and is more common in women. This can be differentiated from Raynaud's syndrome, in which the vasospasm is secondary to an underlying condition, such as collagen vascular disease, occlusive arterial disease, thoracic outlet syndrome, cryoglobulinemia, or cold agglutinin disease.

Treatment involves rewarming the affected digits. Prevention methods include avoiding tobacco products, keeping the torso insulated from ambient temperatures, and using medications such as calcium channel blockers, angiotensin-converting enzyme inhibitors, or prazosin hydrochloride. An episode of Raynaud's phenomenon is no reason to preclude an athlete from competition.1,4

Cold-Induced Urticaria

A physical response that is induced by cold and manifested as urticarial lesions (hives), cold-induced urticaria can occur alone or with cold-induced angioedema. The hives usually appear during warm-up and resolve within an hour after the athlete is removed from the cold. Cold-induced urticaria may also occur with exercise-induced asthma.4

The diagnosis is easily made in the office, because symptoms can be reproduced by placing an ice cube on the arm for 4 minutes. The underlying pathophysiology is histamine release triggered by cold. Initial treatment with nonsedating histamine 1 receptor blockers once or twice daily is usually attempted, followed by the addition of histamine 2 receptor blockers, and then tricyclic antidepressants, if necessary.

Players may continue to compete as long as no significant angioedema develops.

Chilblains

Prolonged exposure to nonfreezing cold temperatures (usually in the 32° to 50°F [0° to 10°C ] range) may cause localized inflammatory lesions that lead to a chronic vasculitis called chilblains or perniones. Chilblains are more common in women than in men and, when seen in men, mostly occur in military personnel, sailors, and fishermen.

The lesions usually start as pruritic red or purple macules or papules that are occasionally painful (figure 3). In severe cases, they can progress to blisters, pustules, plaques, and, eventually, ulcers. Each lesion usually starts within 24 hours after exposure to damp cold and can last up to 3 weeks. They are mostly seen on the proximal phalanxes of the fingers and toes, the plantar surfaces of the toes, or the nose and ears. Wet shoes or boots that were worn for long periods in cold, damp environments are often implicated when chilblains develop on the plantar surface of a foot.

Warming the affected body part is the primary treatment, and applying a medium-potency topical steroid may help with itching. Nifedipine and other vasodilators reduce pain, speed resolution, and prevent new lesions. Prevention involves keeping the area dry and warm and avoiding tight clothing. Using an aluminum chlorohydrate solution to prevent sweating may help. Chilblains are not a contraindication to return to play.5,13

Sun and Heat Exposure

By far the most common dermatologic problem seen in summer athletes is sunburn. The timing of many athletic events, the limited coverage of most athletic clothing, and the difficulty of maintaining adequate sunblock application during training or competition may lead athletes to sustain varying degrees of sunburn. In one survey of cyclists,14 40% got some degree of sunburn during their long-distance ride.

Diagnosis. First-degree sunburn involves only erythema, second-degree burns have erythema and blistering, and third degree injuries have erythema, blisters, and ulcerations.

Treatment. A recent review by Han and Maibach15 examined the evidence behind various treatments for sunburn. They reviewed studies examining the effects of corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs), antihistamines, antioxidants, and emollients on acute sunburn. They concluded that the evidence for treatment effectiveness is scant, and further studies need to be conducted. Corticosteroids showed no significant benefit when compared with placebo. NSAIDs, if taken immediately, may decrease erythema after ultraviolet-B (UVB) exposure. The combination of corticosteroids and NSAIDs may improve symptoms, but antihistamines have no benefit. The role of antioxidants is uncertain, but emollients may help control pain and decrease sunburn symptoms.

Until further evidence is gathered, cold water and emollients are the preferred treatment for first-degree sunburn. Occasionally, a midpotency topical steroid applied tid and an oral NSAID can be used to ease pain. For severe burns, a 7-day prednisone taper can be prescribed. Any athlete who has severe sunburn should be evaluated for heat exhaustion and heatstroke. If any blistering is noted, a tetanus shot should be given if the patient's immunization status is not up to date.

Prevention. The easiest but least used form of treatment is prevention. Avoiding athletic activities when the sun is the highest (10 am to 2 pm) is best, because this is the peak time for sunburn.

Protective clothing should include a cap or hat with a floppy brim, if the sport allows. Athletes should wear loose-fitting, lightweight clothing that protects the body from sun and allows adequate cooling through sweating. Darker clothing may provide better UV protection than light clothing; however, dark colors may contribute to overheating by absorbing more solar radiation. Men should be encouraged to not remove their shirts during practice.

The use of sunscreen lotions is an effective way to protect against excessive sun exposure. Patients should be aware that the sun protection factor (SPF) usually refers only to UVB protection, not ultraviolet-A (UVA) protection. Most dermatologists recommend that sunscreen block both UVA and UVB, with an SPF of at least 15 for each. Water-resistant sunblock (paraaminobenzoic acid [PABA] esters) with an SPF of at least 15 should be applied liberally and regularly. Most sunscreen lotions are not as effective as complete sunblocks containing zinc oxide and titanium dioxide; however, these sunblocks may have the disadvantage of being opaque. Some are concerned that sunscreens may increase the risk for hyperthermia, especially in long-distance runners. This has yet to be evaluated completely, and runners are encouraged to continue applying sunscreen and to wear proper protective clothing.

Many teenage athletes are taking oral medications for acne (eg, doxycycline, tetracycline) that can have significant photosensitizing effects. Physicians need to caution these athletes about proper sun protection. Finally, many athletes forget that for every 5,000 ft in elevation the sun intensity increases by 20%; therefore, sunburn may occur much faster at higher altitudes than at sea level.16-18

Return to play. Mild sunburn does not necessitate removal from competition; however, athletes who have more severe sunburn should be removed from play until the affected areas can be adequately covered to prevent further damage.

Competing Safely

Athletes cannot ignore the environment or the conditions at practice or at competitions. Many injuries from cold, wind, heat, or sun are preventable. It is the physician's role to educate athletes about these injuries and their prevention. The healthcare team can monitor environmental conditions that may affect player safety, anticipate weather conditions, and counsel athletes to dress appropriately. Although not every event will have a WBGT reading, local temperatures and common sense are key to minimizing harmful exposure. Event planners should try to schedule summer events earlier in the morning or in the evening to avoid activities during peak heat and sun times. Winter events should be scheduled for midday when the temperature is usually slightly warmer.

Medical kits should include sunscreen, midpotency topical steroid cream, and a moisturizer containing aloe vera. When exposure injuries occur, most can be managed by the team physician with adherence to guidelines for return to play. When evaluating athletes who have heat or cold exposure injuries, the signs and symptoms of heat illness or hypothermia should not be overlooked.

References

  1. Bowman WD: Safe exercise in the cold and cold injuries, in Mellion MB, Walsh WM, Shelton GL: The Team Physician's Handbook, ed 2. Hanley and Belfus, Philadelphia, 1997, pp 166-174
  2. Reamy BV: Frostbite: review and current concepts. J Am Board Fam Pract 192021;11(1):34-40
  3. Foray J: Mountain frostbite: current trends in prognosis and treatment (from results concerning 1261 cases). Int J Sports Med 1992;13(suppl 1):S193-S196
  4. Sallis R, Chassay CM: Recognizing and treating common cold-induced injury in outdoor sports. Med Sci Sports Exerc 1999;31(10):1367-1373
  5. Fritz RL, Perrin DH: Cold exposure injuries: prevention and treatment. Clin Sports Med 120219;8(1):111-128
  6. Bracker MD: Environmental and thermal injury. Clin Sports Med 1992;11(2):419-436
  7. Washburn B: Frostbite: what it is—how to prevent it—emergency treatment. N Engl J Med 1962;266:974-20219
  8. Heggers JP, Phillips LG, McCauley RL, et al: Frostbite: experimental and clinical evaluations of treatment. J Wilderness Med 1990;1(1):27-32
  9. Kanzenbach TL, Dexter WW: Cold injuries: protecting your patients from the dangers of hypothermia and frostbite. Postgrad Med 1999;105(1):72-78
  10. Miller MB, Koltai PJ: Treatment of experimental frostbite with pentoxifylline and aloe vera cream. Arch Otolaryngol Head Neck Surg 1995;121(6):678-680
  11. McCauley RL, Heggers JP, Roboson MC: Frostbite: methods to minimize tissue loss. Postgrad Med 1990;88(8):67-77
  12. ACSM Position Stand: Heat and cold illness during distance running. December 1996, available at https://www.acsm.org/publications/positionStands.htm. Accessed November 9, 2004
  13. Freedberg IM, Eisen AZ, Wolff K, et al: Chilblains (or perniosis), in Freedberg IM, Fitzpatrick TB (eds): Fitzpatrick's Dermatology in General Medicine, ed 5. McGraw Hill, New York City, 1999, p 1499
  14. Helzer-Julin M: Sun, heat, and cold injuries in cyclists. Clin Sports Med 1994;13(1):219-234
  15. Han A, Maibach HI: Management of acute sunburn. Am J Clin Dermatol 2004;5(1):39-47
  16. Conklin RJ: Common cutaneous disorders in athletes. Sports Med 1990;9(2):100-119
  17. Basler RS, Garcia MA: Acing common skin problems in tennis players. Phys Sportsmed 192021;26(12):37-44
  18. Adams BB: Dermatologic disorders of the athlete. Sports Med 2002;32(5):309-321

What to Tell Patients About Windchill

Patricia D. Mees

The term "windchill factor" was coined in 1939 by Antarctic explorer Paul A. Siple. During the 1940s, Siple and Charles F. Passel conducted experiments with a water-filled plastic cylinder to see how long it took water to freeze at various temperatures. The beginning water temperature, the air temperature, and the wind speed all affected the time required to freeze the cylinder. Based on their data, they extrapolated the risk of frostbite. The theory was that exposed flesh would freeze at the same rate when the temperature was subzero—whether that was the calm air temperature or the equivalent windchill temperature. This isn't actually the case, but the notion seems to have been popularized by TV weather forecasters in the 1960s and '70s in the United States.

In 2021, the US National Weather Service developed new charts to correct some errors in the windchill factor charts and renamed them the windchill index (WCI). The WCI only measures the speed of heat loss. The body will never cool to temperatures that are less than the actual air (no wind) temperature. If the air temperature is 5°C (41°F) and the WCI is -10°C (14°F), water will not freeze. Likewise, car engines will cool to the air temperature faster on windy days, but they will never cool to less than the air temperature.1 Windchill doesn't really affect machinery, however, because windchill is a subjective measure of relative discomfort.2

Wind greatly affects body heat loss because of the evaporative cooling effect of water. Protecting the skin from the wind greatly reduces the dangers of frostbite and hypothermia. The risk of finger frostbite is minor if the air temperature is above -10°C (14°F), even on a windy day. At -25°C (-13°F) the risk is pronounced, even on a calm day.3

Winter cyclists, skiiers, snowmobilers, and other outdoor enthusiasts should remember that forward movement in calm air has the same cooling effect as standing still in a wind. The "relative wind speed" is as important as the actual wind speed. Hypothermia can be a concern if too much body heat is lost. When a person moves at 15 mph, -5°C 41°F calm air will feel like -5°C 23°F or 9° below freezing.3 Because the air temperature is above freezing, frostbite won't be a danger, but it will feel that cold.

REFERENCES

  1. The National Science Digital Library: An introduction to windchill. Available at: https://avc.comm.nsdlib.org/cgi-bin/wiki_grade_interface.pl?An_Introduction_To_Wind_Chill. Accessed September 24, 2004
  2. Icebike: windchill temperatures. Available at https://www.icebike.org/Articles/windchill.htm. Accessed December 21, 2004
  3. Danielsson U: Windchill and the risk of tissue freezing. J Appl Physiol 1996;81(6):2666-2673

Dr Snowise is a sports medicine and family practice physician at Suburban Internal Medicine in Lee, Massachusetts. Dr Dexter is the director of the sports medicine fellowship and the assistant program director of the family practice residency program at the Maine Medical Center in Portland, Maine. Address correspondence to Mark Snowise, MD, Suburban Internal Medicine, 710 Stockbridge Rd, Lee, MA 01238; e-mail to [email protected].

Disclosure information: Dr Snowise discloses no significant relationship with any manufacturer of any commercial product mentioned in this article. No drug is mentioned in this article for an unlabeled use.


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