Workers who may be required to work outdoors in cold environments for extended periods may be at risk for cold stress. What constitutes cold stress and its effects can vary across the various geographic regions of the country. For example, in regions that are not accustomed to winter weather, temperatures near freezing could be considered factors for cold stress. Increased wind speed also causes heat to leave the body more rapidly (wind chill effect). Wetness or dampness also increases heat loss from a body. Outdoor settings are not the only environment in which a worker can experience cold stress. Some examples of indoor settings where workers can experience cold stress include meat and seafood packing facilities, refrigerated trucks, and frozen food storage facilities. However, the focus of this article applies more to workers in a prolonged cold outdoor setting. If workers are exposed to cold environments, then risk assessment discussion as part of your Job Safety Analysis (JSA) or Job Hazards Analysis (JHA) would be appropriate.
The human body has to work harder to maintain its temperature when exposed to a cold environment. Because most of the body’s energy is focused on keeping the internal core temperature warm (chest and abdomen), over time the body will shift blood flow from the outer skin and extremities (arms, hands, legs, and feet) to the inner core. Eventually, the temperature of the inner core itself could be driven down. When the body is not able to sufficiently warm itself, serious cold-related injuries and illnesses may occur, and permanent tissue damage and even death may result.
Prolonged exposure to cold conditions could result in hypothermia, which is defined as a core body temperature of less than 95 degrees Fahrenheit (ºF) or 35 degrees Celsius (ºC). Data for 1999 through 2011 from the Centers for Disease Control and Prevention (CDC) shows that an average of 1,301 people die from cold conditions annually in the United States, which is more than from heat-related illnesses.
Some of the risk factors that contribute to cold stress are:
- Wetness/dampness, dressing improperly, and exhaustion.
- Pre-disposing health conditions such as hypertension, hypothyroidism, and diabetes.
- Poor physical conditioning.
Although the Occupational Safety and Health Administration (OSHA) currently does not have standards specific to cold-related illnesses, courts have interpreted OSHA's general duty clause to mean that an employer has a legal obligation to provide a workplace free of conditions or activities that either the employer or industry recognizes as hazardous and that cause, or are likely to cause, death or serious physical harm to employees when there is a feasible method to abate the hazard. This includes cold-related hazards that are likely to cause death or serious bodily harm.
When hazards related to cold are present or expected to be present at a job site, employers should plan ahead to protect workers. Employers should create a written plan to prevent cold-related symptoms. Cold conditions can change rapidly and management commitment to adjusting cold stress controls is critical to prevent cold illness. An individual at the job site should be responsible for monitoring conditions and implementing the employer's cold plan throughout the workday. This individual can be anyone with the proper training, which includes knowing how to
- identify and control cold hazards.
- recognize early symptoms of cold stress.
- administer first aid for cold-related conditions.
- activate emergency medical services quickly when needed.
The Personal Protective Equipment (PPE) standard at 29 Code of Federal Regulations (CFR) 1910.132(d) requires every employer in general industry to conduct a hazard assessment to determine the appropriate PPE to be used to protect workers from the hazards identified in the assessment. The National Institute for Occupational Safety and Health (NIOSH) has published criteria for a recommended standard for occupational cold stress. The NIOSH document "Preventing Cold-related Illness, Injury & Death among Workers" (NIOSH Publication Number 2019-113, September 2019) includes recommendations for employers about how to prevent cold-related illnesses.
The various degrees of cold-related conditions (in order of less severe to most severe) and the appropriate first aid measures to take are summarized as follows:
Hypothermia - Occurs when body heat is lost faster than it can be replaced and the normal body temperature of 98.6 ºF drops to less than 95 ºF. Hypothermia is most likely at very cold temperatures, but it can occur even at cool temperatures (above 40 ºF), if a person becomes chilled from rain, sweat, or submersion into cold water. Symptoms of hypothermia can vary depending on how long you have been exposed to the cold temperatures.Early Symptoms
- Loss of coordination.
- Confusion and disorientation.
First AidTake the following steps to treat a worker with hypothermia:
- No shivering.
- Blue skin.
- Dilated pupils.
- Slowed pulse and breathing.
- Loss of consciousness.
- 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 – 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:
First AidWorkers suffering from frostbite should:
- Reduced blood flow to hands and feet (fingers or toes can freeze).
- Tingling or stinging.
- Bluish or pail, waxy skin.
- 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 water and 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 ºF 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.
- 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 - Chilblains are caused by the repeated exposure of skin to temperatures just above freezing to as high as 60 ºF. 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:
- 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.
Outdoor workers who are exposed to cold and windy conditions are at risk of cold stress as both air temperature and wind speed affect how one feels. "Wind Chill" Is the term used to describe the rate of heat loss from the body, resulting from the combined effect of wind speed and low air temperature. The "Wind Chill Temperature" is a single value that takes wind speed and air temperature into account. For example, when the air temperature is 40 ºF and the wind speed is 35 miles per hour (mph), the wind chill temperature is 28 ºF. This temperature is the actual effect of the environmental cold on exposed skin.
The following is the "Wind Chill Chart" from the National Weather Service website (https://www.weather.gov/safety/cold-wind-chill-chart). The chart is color-coded to indicate the exposure time needed before frostbite could occur. This chart could be used as a resource by both employers and workers as work conditions are evaluated and appropriate measures can be taken to minimize exposure to cold conditions.
Recommendations that can be taken by both employers and workers to protect from cold stress are summarized as follows.
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
Workers should avoid exposure to extremely cold temperatures when possible. When cold environments or temperatures cannot 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 co-workers.
To assist in the prevention of cold stress conditions, employers and employees should prioritize the creation of a job safety analysis (JSA), also known as a job hazard analysis (JHA), for each job that involves exposure to the cold.
A list of key items that should be addressed in the Job Safety Analysis (JSA) include but are not limited to the following:
- Name(s) and contact information of designated on-site Health and Safety personnel.
- Locations and contact information of local emergency services (i.e., hospital, urgent care, ambulance, paramedics, fire, and/or police).
- Emergency contact information for personnel (spouse, parents, children, relatives, etc.).
- Review of forecast temperatures and wind speeds at the beginning of each workday.
- Update of temperatures and wind speeds at various times throughout the workday.
- Methods of measuring temperature and wind speeds throughout the workday (local weather station, weather apps, on-site monitoring equipment, etc.).
- Criteria for stopping work, and frequency and duration of breaks.
- Location(s) of designated break areas to warm up.
- Method(s) to warm up.
- Required clothing and other personal protective equipment (PPE).
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