Now that winter has arrived in the northern hemisphere, workers are at risk for health emergencies. Cold weather can lead to danger for workers outside or in poorly insulated or unheated areas, particularly in fields such as sanitation, construction, emergency response, delivery, or transportation. Weather-related conditions can also pose a risk for drivers on slippery roads and for those responsible for snow removal. What happens in the cold, and how can employers keep workers safe in the cold?
What is cold stress?
According to the Occupational Safety and Health Administration (OSHA), cold stress occurs by driving down the skin temperature and eventually, the internal body temperature. As the body is unable to warm itself, serious illness and injuries, permanent tissue damage, and death could result. Types of cold stress include hypothermia, cold water immersion, trench foot, frostbite, and chilblains.
The temperature threshold for cold stress and its associated effects are different across the country. For regions that are not used to winter weather, temperatures close to freezing are considered risk factors for cold stress. In other areas, risk factors for cold stress can be:
- wetness/dampness, improper dress, and exhaustion;
- predisposing health conditions such as hypertension, hypothyroidism, and diabetes; and
- poor physical conditioning.
Hypothermia—abnormally low core body temperature—occurs when cold temperatures cause the body to lose heat faster than it can be produced. Prolonged exposure to cold will eventually use up the body’s stored energy. Hypothermia begins to occur at a body temperature of 95° or about three degrees lower than a typical body temperature around 98.6°. A body temperature that is too low affects the brain, making the victim unable to think clearly or move well.
Early symptoms of hypothermia include:
- Loss of coordination
- Confusion and disorientation
Late symptoms include:
- No shivering
- Blue skin
- Dilated pupils
- Slowed pulse and breathing
- Loss of consciousness
Anyone suffering from hypothermia should be evaluated by a health professional. In most cases, early symptoms of hypothermia can be treated by moving the person to a warmer environment, removing wet clothing, and providing warm, non-alcoholic and non-caffeinated beverages. Moderate or severe hypothermia requires immediate emergency assistance.
Cold Water Immersion/ Trench Foot
Cold water immersion creates a specific condition known as immersion hypothermia. Cold water immersion develops much more quickly than standard hypothermia because water conducts heat away from the body 25 times faster than air. For example, hypothermia can occur in any water temperature below 70°F. Anyone who has been immersed in cold water for any period of time should be dried, warmed, and evaluated for hypothermia.
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 air temperatures as high as 60°F and in as little as 13 hours if the feet are constantly wet. To prevent heat loss, the body constricts blood vessels to shut down circulation in the feet. As a result, skin tissues begin to die because of the lack of oxygen and nutrients and due to the buildup of toxic products. Workers at risk of trench foot should wear water-resistant footwear and take care to keep feet warm, clean, and dry. A medical professional should evaluate any potential instance of trench foot.
Symptoms of trench foot include:
- Reddening of the skin
- Leg cramps
- Tingling pain
- Blisters or ulcers
- Bleeding of the skin
Frostbite results from skin tissue freezing. It can cause permanent damage to the body, infection, and nerve damage, and in severe cases lead to amputation. Exposed skin in cold, windy conditions is at the highest risk, but even covered skin can suffer frostbite in extreme temperatures. Those with reduced blood circulation and those not wearing proper clothing (including personal protective equipment) have an increased risk of frostbite. Before frostbite develops, cold skin can be rewarmed. Once frostbite is established, the patient requires professional medical care.
Symptoms of frostbite include:
- Reduced blood flow to hands and feet
- Tingling or stinging
- Bluish or pail, waxy skin
Chilblains are the painful, itchy inflammation of capillaries in the skin due to sudden warming from cold temperatures just above freezing to as high as 60°F. The repeated cold exposure causes damage to the capillary beds in the skin. This damage is permanent and the redness and itching may return for years with additional exposure. Chilblains most often develop on the extremities, such as ears, nose, fingers, and toes. In general, chilblains will resolve on their own within a few weeks, although they can lead to infection and severe skin damage if the skin blisters. Treatment may include corticosteroid creams to help relieve itching, prescription medication to increase blood flow, and infection prevention or antibiotics if necessary.
Symptoms of chilblains include:
- Possible blistering
- Possible ulceration in severe cases
Prevention of Cold Stress
Although there is no specific OSHA standard for cold stress, under section 5(a)(1) of the OSH Act of 1970 (the general duty clause) each employer:
- “Shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees.”
This portion of the standard covers workers and employers’ duties to keep those workers safe. Employers should train workers on working safely, provide engineering controls, and use safe work practices when dealing with cold, dangerous conditions. Employers should provide cold stress training that includes:
- How to recognize the environmental and workplace conditions that can lead to cold stress.
- The symptoms of cold stress, how to prevent cold stress, and what to do to help those who are affected.
- How to select proper clothing for cold, wet, and/or windy conditions.
Employers should also:
- Monitor workers’ physical condition.
- Schedule frequent short breaks in warm, dry areas to allow the body to warm up.
- Schedule cold jobs for the warmest part of the day.
- Provide warm, sweet beverages that do not include alcohol.
- Provide engineering controls such as radiant heaters.