Anyone working in a cold environment may be at risk of cold stress. Some workers may be required to work outdoors in cold environments and for extended periods, for example, snow cleanup crews, sanitation workers, police officers and emergency response and recovery personnel, like firefighters, and emergency medical technicians.
When the body is unable to warm itself, cold related stress may occur. Cold stress occurs by driving down the skin temperature and eventually the internal body temperature (core temperature). Over time, your body will begin to shift blood flow from your extremities (hands, feet, arms and legs) and outer skin to the core areas (chest and abdomen). This allows exposed skin and the extremities to cool rapidly and increases the risk of frostbite and hypothermia. Combine this with cold water, and trench foot may also be a problem. This may lead to serious health problems, and may cause tissue damage, and possibly death.
Risk factors that contribute to cold stress include:
Wind chill is the temperature your body feels when air temperature and wind speed are combined. The wind chill temperature is how cold people and animals feel when outside. Wind chill is based on the rate of heat loss from exposed skin caused by wind and temperature, however, research has shown that relative humidity is not a significant factor affecting wind chill.
As the wind increases, it draws heat from the body, driving down skin temperature and eventually the internal body temperature. Therefore, the wind makes it FEEL much colder. For instance, if the temperature is 0°F and the wind is blowing at 15 mph, the wind chill is -19°F. At this wind chill temperature, exposed skin can freeze in 30 minutes. See the Wind Chill Chart to learn more.
While it is obvious that below freezing conditions combined with inadequate clothing could bring about cold stress, it is also important to understand it can also be brought on by warmer temperatures (such as 50°F) combined with some rain and wind.
Hypothermia means "low-heat," which is a potentially serious health condition. This occurs when body heat is lost faster than it can be replaced. When the core body temperature drops below the normal 98.6°F to around 95°F, you will see the following symptoms:
Without early recognition and active care, hypothermia can be deadly. Here are some things you can do, if you recognize someone who is dealing with hypothermia:
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Frostbite is a severe reaction to cold exposure that causes freezing in the deep layers of skin and tissues. Frostbite can cause permanent damage and even cause amputation of the affected area. While frostbite usually occurs when temperatures are 30 degrees Fahrenheit or lower, wind chill factors can allow frostbite to occur in above freezing temperatures.
Frostbite usually affects the extremities, particularly the feet and hands. (see picture) However, frostbite can also affect the ears and nose. The affected body part will be cold, tingling, stinging or aching followed by numbness. The skin color turns red, then purple, then white, and is cold to the touch. There may also be blisters in severe cases.
Early recognition and care for a frostbitten victim can reduce or even eliminate future complications. Minor frostbite can be treated by simply re-warming the area using skin-to-skin contact, such as a warm hand. If more serious, get the person to a warmer place.
Here are some more treatment tips:
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Trench foot, or immersion foot, is caused by having feet immersed in cold water at temperatures above freezing for long periods of time. It is similar to frostbite, but considered less severe. Symptoms usually consist of tingling, itching or burning sensation. Blisters may also be present.
When possible, air-dry and elevate your feet, and exchange wet shoes and socks for dry ones to help prevent the development of trench foot. Treatment for trench foot is similar to the treatment for frostbite. Take the following steps:
If you have a foot wound, your foot may be more prone to infection. Check your feet at least once a day for infections or worsening of symptoms.
Engineering controls can be effective in reducing the risk of cold stress through the design of equipment, materials, and facilities. For example:
There are several work practice measures to protect workers in cold environments. Here are a few:
Protective clothing is the most important way to avoid cold stress. The type of fabric also makes a big difference. Cotton loses its insulation value when it becomes wet. Wool, silk and most synthetics, on the other hand, retain their insulation even when wet. Workers should wear at least three layers of clothing. There should be an inner layer of wool, silk or synthetic to pull moisture away from the body. The middle layer should include a layer of wool or synthetic to provide insulation, even when wet. Then, an outer wind and rain protection layer is needed to allow some ventilation to prevent overheating.
Here are some other protective clothing recommendations:
Training in recognition and treatment of cold stress is important. Supervisors, workers and co-workers should watch for signs of cold stress and allow workers to interrupt their work if they are extremely uncomfortable. Supervisors should also ensure work schedules allow appropriate rest periods and make sure liquids are available. They should use appropriate engineering controls, personal protective equipment and work practices to reduce the risk of cold stress.
All of these measures should be incorporated into the relevant health and safety plans.
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During the winter months, exposure to the cold is an additional occupational hazard. Health problems including frostbite, trench foot and hypothermia can result. This Builders Mutual video discusses how to prevent and respond to each.