Photos courtesy of U.S. Fish and Wildlife Service
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.
Types of Cold Stress
Hypothermia | Frostbite | Trench Foot | Chilblains
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 of hypothermia can vary depending on how long you have been exposed to the cold temperatures.
- Loss of coordination
- Confusion and disorientation
- No shivering
- Blue skin
- Dilated pupils
- Slowed pulse and breathing
- Loss of consciousness
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).
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 of frostbite include:
- Reduced blood flow to hands and feet (fingers or toes can freeze)
- Tingling or stinging
- Bluish or pail, waxy skin
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, 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 of trench foot include:
- Reddening of the skin
- Leg cramps
- Tingling pain
- Blisters or ulcers
- Bleeding under the skin
- Gangrene (the foot may turn dark purple, blue, or gray)
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 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 of chilblains include:
- Possible blistering
- Possible ulceration in severe cases
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
- The importance of monitoring yourself and coworkers for symptoms
- 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: Extreme Cold - A Prevention Guide to Promote Your Personal Health and Safety
Information on how to prepare indoors and outdoors fore extreme cold.
3.45 MB (15 pages)
Other Government Resources
Occupational Safety & Health Administration (OSHA): Tips to Protect Workers in Cold Environments
External link: http://www.osha.gov/html/cold_protection_2004.html
OSHA: Sawmill eTool: Cold Stresses
Cold stress hazards, solutions, and controls.
External link: http://www.osha.gov/SLTC/etools/sawmills/cold.html
OSHA: The Cold Stress Equation
Information on frostbite and hypothermia.
External link: http://www.osha.gov/Publications/coldcard/coldcard.html
National Oceanic and Atmospheric Administration (NOAA): Winter Storms - A Preparedness Guide
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.
2.15 MB (12 pages)
NOAA: National Weather Service Wind Chill Chart
External link: http://www.weather.gov/om/windchill/index.shtml
American Conference of Governmental Industrial Hygienists: Product Store - Threshold Limit Values and Biological Exposure Indices
This document is available for purchase at: http://www.acgih.org/store/ProductDetail.cfm?id=1360
American National Standards Institute - Ergonomics of the Thermal Environment: Medical Supervision of Individuals Exposed to Extreme Hot or Cold Environments
This International Standard provides advice to those concerned with the safety of human exposures to extreme hot or cold thermal environments.
This document is available for purchase at: http://webstore.ansi.org/RecordDetail.aspx?sku=ISO+12894%3a2001
Alaska Department of Labor and Workforce Development: Labor Standards and Safety - Cold Stress
Physical agent data sheets on hypothermia and frostbite.
149.34 KB (7 pages)
Occupational Hazards.com: Don't Leave Safety Out in the Cold
Information on cold stress symptoms and PPE.
External link: http://www.occupationalhazards.com/Issue/Article/76091/Dont_Leave_Safety_Out_in_the_Cold.aspx
Canadian Centre for Occupational Health & Safety: Cold Weather Workers Safety Guide
Cold weather safety, including PPE.
123.65 KB (8 pages)
Page last updated: October 22, 2008
Page last reviewed: October 22, 2008
Content Source: National Institute for Occupational Safety and Health (NIOSH)