Workplace Safety and Health Topics

NIOSH

COLD STRESS

worker in cab of truck snow in the woods unloading a truck in the winter Photos courtesy of U.S. Fish and Wildlife Service

Overview

Workers who are exposed to extreme cold or work in cold environments may be at risk of cold stress. Extreme cold weather is a dangerous situation that can bring on health emergencies in susceptible people, such as those without shelter, outdoor workers, and those who work in an area that is poorly insulated or without heat. What constitutes cold stress and its effects can vary across different areas of the country. In regions relatively unaccustomed to winter weather, near freezing temperatures are considered factors for "cold stress." Whenever temperatures drop decidedly below normal and as wind speed increases, heat can more rapidly leave your body. These weather-related conditions may lead to serious health problems.

NIOSH Fast Facts

Fast Facts: Protecting yourself from Cold Stress Protecting Yourself from Cold Stress Print or order this free card for easy access to important safety information.

Types of Cold Stress

Hypothermia | Cold Water Immersion | Frostbite | Trench Foot | Chilblains

Hypothermia

When exposed to cold temperatures, your body begins to lose heat faster than it can be produced. Prolonged exposure to cold will eventually use up your body's stored energy. The result is hypothermia, or abnormally low body temperature. A body temperature that is too low affects the brain, making the victim unable to think clearly or move well. This makes hypothermia particularly dangerous because a person may not know it is happening and will not be able to do anything about it.

Symptoms

Symptoms of hypothermia can vary depending on how long you have been exposed to the cold temperatures.

Early Symptoms

Shivering
Fatigue
Loss of coordination
Confusion and disorientation

Late Symptoms

No shivering
Blue skin
Dilated pupils
Slowed pulse and breathing
Loss of consciousness

First Aid

Take the following steps to treat a worker with hypothermia:

Alert the supervisor and request medical assistance.
Move the victim into a warm room or shelter.
Remove their wet clothing.
Warm the center of their body first-chest, neck, head, and groin-using an electric blanket, if available; or use skin-to-skin contact under loose, dry layers of blankets, clothing, towels, or sheets.
Warm beverages may help increase the body temperature, but do not give alcoholic beverages. Do not try to give beverages to an unconscious person.
After their body temperature has increased, keep the victim dry and wrapped in a warm blanket, including the head and neck.
If victim has no pulse, begin cardiopulmonary resuscitation (CPR).

Cold Water Immersion

Cold water immersion creates a specific condition known as immersion hypothermia. It develops much more quickly than standard hypothermia because water conducts heat away from the body 25 times faster than air. Typically people in temperate climates don’t consider themselves at risk from hypothermia in the water, but hypothermia can occur in any water temperature below 70°F. Survival times can be lengthened by wearing proper clothing (wool and synthetics and not cotton), using a personal flotation device (PFD, life vest, immersion suit, dry suit), and having a means of both signaling rescuers (strobe lights, personal locator beacon, whistles, flares, waterproof radio) and having a means of being retrieved from the water. Below you will find links with information about cold water survival and cold water rescue.

Frostbite

Frostbite is an injury to the body that is caused by freezing. Frostbite causes a loss of feeling and color in the affected areas. It most often affects the nose, ears, cheeks, chin, fingers, or toes. Frostbite can permanently damage body tissues, and severe cases can lead to amputation. In extremely cold temperatures, the risk of frostbite is increased in workers with reduced blood circulation and among workers who are not dressed properly.

Symptoms

Symptoms of frostbite include:

Reduced blood flow to hands and feet (fingers or toes can freeze)
Numbness
Tingling or stinging
Aching
Bluish or pail, waxy skin

First Aid

Workers suffering from frostbite should:

Get into a warm room as soon as possible.
Unless absolutely necessary, do not walk on frostbitten feet or toes-this increases the damage.
Immerse the affected area in warm-not hot-water (the temperature should be comfortable to the touch for unaffected parts of the body).
Warm the affected area using body heat; for example, the heat of an armpit can be used to warm frostbitten fingers.
Do not rub or massage the frostbitten area; doing so may cause more damage.
Do not use a heating pad, heat lamp, or the heat of a stove, fireplace, or radiator for warming. Affected areas are numb and can be easily burned.

Trench Foot

Trench foot, also known as immersion foot, is an injury of the feet resulting from prolonged exposure to wet and cold conditions. Trench foot can occur at temperatures as high as 60 degrees F if the feet are constantly wet. Injury occurs because wet feet lose heat 25-times faster than dry feet. Therefore, to prevent heat loss, the body constricts blood vessels to shut down circulation in the feet. Skin tissue begins to die because of lack of oxygen and nutrients and due to the buildup of toxic products.

Symptoms

Symptoms of trench foot include:

Reddening of the skin
Numbness
Leg cramps
Swelling
Tingling pain
Blisters or ulcers
Bleeding under the skin
Gangrene (the foot may turn dark purple, blue, or gray)

First Aid

Workers suffering from trench foot should:

Remove shoes/boots and wet socks.
Dry their feet.
Avoid walking on feet, as this may cause tissue damage.

Chilblains

Chilblains are caused by the repeated exposure of skin to temperatures just above freezing to as high as 60 degrees F. The cold exposure causes damage to the capillary beds (groups of small blood vessels) in the skin. This damage is permanent and the redness and itching will return with additional exposure. The redness and itching typically occurs on cheeks, ears, fingers, and toes.

Symptoms

Symptoms of chilblains include:

Redness
Itching
Possible blistering
Inflammation
Possible ulceration in severe cases

First Aid

Workers suffering from chilblains should:

Avoid scratching
Slowly warm the skin
Use corticosteroid creams to relieve itching and swelling
Keep blisters and ulcers clean and covered

Recommendations for Employers

Employers should take the following steps to protect workers from cold stress:

Schedule maintenance and repair jobs in cold areas for warmer months.
Schedule cold jobs for the warmer part of the day.
Reduce the physical demands of workers.
Use relief workers or assign extra workers for long, demanding jobs.
Provide warm liquids to workers.
Provide warm areas for use during break periods.
Monitor workers who are at risk of cold stress.
Provide cold stress training that includes information about:
- Worker risk
- Prevention
- Symptoms
- The importance of monitoring yourself and coworkers for symptoms
- Treatment
- Personal protective equipment

Recommendations for Workers

Workers should avoid exposure to extremely cold temperatures when possible. When cold environments or temperatures can not be avoided, workers should follow these recommendations to protect themselves from cold stress:

Wear appropriate clothing.

Wear several layers of loose clothing. Layering provides better insulation.
Tight clothing reduces blood circulation. Warm blood needs to be circulated to the extremities.
When choosing clothing, be aware that some clothing may restrict movement resulting in a hazardous situation.

Make sure to protect the ears, face, hands and feet in extremely cold weather.

Boots should be waterproof and insulated.
Wear a hat; it will keep your whole body warmer. (Hats reduce the amount of body heat that escapes from your head.)

Move into warm locations during work breaks; limit the amount of time outside on extremely cold days.
Carry cold weather gear, such as extra socks, gloves, hats, jacket, blankets, a change of clothes and a thermos of hot liquid.
Include a thermometer and chemical hot packs in your first aid kit.
Avoid touching cold metal surfaces with bare skin.
Monitor your physical condition and that of your coworkers.

CDC Resources

CDC: Extreme Cold - A Prevention Guide to Promote Your Personal Health and Safety [PDF - 3.45 MB]
Information on how to prepare indoors and outdoors fore extreme cold.

CDC: Winter Weather

Other Government Resources

Occupational Safety & Health Administration (OSHA): Tips to Protect Workers in Cold Environments

OSHA: Sawmill eTool: Cold Stresses
Cold stress hazards, solutions, and controls.

OSHA: The Cold Stress Equation
Information on frostbite and hypothermia.

eLCOSH

Electronic Library of Construction Occupational Safety & Health (eLCOSH) - Cold Stress
Cold stress or hypothermia can affect construction workers who are not protected against cold. The cold may result naturally from weather conditions or be created artificially, as in refrigerated environments.
eLCOSH - Cold Stress from Cold Conditions
Cold stress factors, safety, and hazards.

NASD

National Ag Safety Database (NASD): Princeton University Outdoor Action Guide to Hypothermia and Cold Weather Injuries
Information on cold stress disorders.
NASD: Farm Bureau Safety Program - Working Outside in Winter
Information on hypothermia.
NASD: Cold Weather Exposure
The objectives of this flyer are to recognize the symptoms and to know the results of overexposure to the cold, and to take precautions to prevent overexposure.
En Español

National Oceanic and Atmospheric Administration (NOAA): Winter Storms - A Preparedness Guide [PDF - 2.15 MB]
This preparedness guide explains the dangers of winter weather and suggests life-saving action you can take. With this information, you can recognize winter weather threats, develop an action plan and be ready when severe winter weather threatens.

NOAA: National Weather Service Wind Chill Chart