As anyone who's lived or worked in it knows, a cold environment just makes everything harder. You fumble with numb fingers under bulky gloves, slip on the ice, shiver at the sight of your breath hitting the icy air. Working under extremely cold conditions, however, is not only inconvenient and uncomfortable; if you don't take some basic precautions, it can pose serious threats to your health. What's more, the symptoms of cold-related ailments are easy to overlook -- even though they can cause irreversible tissue damage and in extreme cases even kill. So whether you're working in the fishing industry, laboring outdoors in the winter, or working in refrigerated warehouses, you should be aware of the health risks that come with your job -- and how to protect yourself against them.
How cold is too cold?
No matter what the temperature is around your body, it continuously strives to maintain its normal internal temperature of 98.6. (A drop of just a few degrees can be life-threatening.) For most of us, that means we're most comfortable working in an environment of about 73 degrees (with 45 percent humidity). If your work is extremely labor-intensive (and thus heat-generating), however, the ideal working temperature could be as low as 55 degrees -- without special clothing to ward off the cold.
When you're calculating safety, don't forget to include the wind chill factor -- a reading that combines air temperature with wind velocity. On a 40-degree day with 35-mile-per-hour winds, for example, the temperature your exposed skin is experiencing is not 40 degrees: it's 11 degrees.
What happens to the body under extreme cold conditions?
While the body has some very effective mechanisms to adjust to extreme heat conditions, it has very few tricks to deal with the cold. Its first line of defense is to constrict blood vessels and limit blood flow to the extremities (primarily hands and feet) and to the skin's surface. That way, less body heat from the blood is lost through the skin into the environment. The body's only other defense against the cold is shivering, which generates heat by increasing the body's metabolism.
What are the health problems associated with working in an extremely cold environment?
Frostbite. This occurs when your skin and sometimes muscle tissue freeze due to exposure. It usually affects the hands and feet -- which your body has kept colder in order to save heat in the rest of the body -- or the exposed skin on ears, cheeks and noses. One is at risk for frostbite at temperatures below 30 degrees, although wind chill effects can also cause frostbite at above-freezing temperatures. The tissue damage can be irreversible, and in rare cases amputation is sometimes necessary. Early symptoms of frostbite include a tingling, stinging, or aching feeling in exposed area followed by numbness. If the victim is suffering from hypothermia (see below), treat hypothermia first. Then treat frostbite by covering affected areas with dry, sterile gauze or soft, clean cloth bandages. Do not massage the area; it can worsen the injury. Severe cases require hospitalization.
Hypothermia. In this potentially fatal condition, the body temperature falls, impairing normal muscular and brain functions. Initial symptoms -- which occur if the body temperature drops to 95 degrees from the normal 98.6 -- include shivering, the inability to perform complex motor functions, mild confusion, and lethargy. If body temperature continues to fall, hypothermia becomes more severe until victims cannot perform even simple motor functions. They may also fall into a semi-conscious state, exhibiting slurred speech and irrational behavior; campers caught in a blizzard and suffering from hypothermia, for example, have been known to tear off their clothes and run in the snow. The most severe state of hypothermia occurs when body temperature falls to 90 degrees. This causes the body to move into a state of hibernation: the heart rate and breathing slow and the victim may lose consciousness; full heart failure can occur.
Naturally, victims need immediate medical treatment. If you can't get a hypothermia victim to the hospital, try conserving her body heat by warming her. Find shelter if possible, remove the worker's wet clothing, add layers of dry clothing, and cover her with blankets. Do not apply direct heat: Do not use hot water, a heating pad, or a heat lamp to warm the victim. If medical treatment will be delayed, try warming the victim's body with your own. If possible, use warm compresses on the neck, chest, and groin. Do not warm arms and legs -- this forces cold blood back toward the heart, lungs, and brain, which can be fatal. Give the victims liquids as well (but no alcohol or caffeine).
Trench foot. Common among fisherman, this condition is caused by continuous exposure to wet, cold environments, especially when the feet are immersed in water. Spasms in the blood vessels stop the blood's circulation to the foot, which can cause muscular damage. Symptoms include a tingling or itching sensation, burning, pain, swelling, and sometimes blisters. Move the worker to a warm, dry area, then wash and dry the affected skin. Rewarm the foot and elevate it slightly, and get medical help as soon as possible.
What can I do to protect myself?
Wear protective clothing. The first line of protection against the cold is dressing correctly. You should wear at least three layers of clothing, beginning with an inner layer of cotton or synthetic weave to allow your skin to breathe. The middle layer should be a fabric like wool or synthetic fabric (such as Qualofil or Pile) to absorb sweat and retain insulation (down is also a good lightweight insulator but useless if it gets wet). The third, outer layer -- a fabric like Gore-Tex or nylon -- should break the wind and allow some ventilation. Special care should be taken to properly cover the head (where 40 percent of body heat can be lost), as well as the feet, hands and face, which are most prone to frostbite. Make sure your foot and hand gear is thoroughly waterproof. Also, keep a change of clothes at work in case your clothes get wet.
Get your engineers involved. Your workplace should reduce exposure to cold by installing on-site heating devices, erecting shields or walls, and putting thermal insulating covers on equipment handles when temperatures are below 30 degrees.
Adopt safe work practices. Your employer should allow you time to adjust to new cold conditions before requiring you to work at full capacity.
Reduce exposure. Try to reduce the time you're required to work in the cold as much as possible (by working during the warmest hours of the day, for example).
Get advice. Talk with a safety specialist about the potential for accidents while wearing thick gloves or bulky clothing.
Take breaks. Work at your own pace and take more frequent breaks if needed.
Liquids help. Ask your employer to provide liquids to keep you from dehydrating, if that isn't already being done.
Buddy system. Implement a buddy system under which you and other employees can look after each other during outdoor work.
Warning signs. Most importantly, ask for on-the-job training about the risks of working in extreme cold environments and how to recognize symptoms of cold-related ailments.
National Institute for Occupational Safety and Health (NIOSH) http://www.cdc.gov/niosh
Occupational Safety and Health Administration (OSHA) http://www.osha.gov
Mayo Clinic. Hypothermia: First aid. January 2008. http://www.mayoclinic.com/health/first-aid-hypothermia/FA00017
OSHA Fact Sheets. Protecting workers in cold environments. U.S. Department of Labor. December 22, 1998. USDL 98-55.
American Heart Association. Cold Weather: AHA Recommendations: 2000.