As the weather becomes frightful, workers who must brave outdoor conditions face the occupational hazard of exposure to the cold. Prolonged exposure to freezing
temperatures can result in serious health problems such as trench foot, frostbite and hypothermia. Workers need to be mindful of the weather, its effects on the body, proper prevention techniques and treatment of cold-related disorders.
The Cold Environment
An individual gains body heat from food and muscular activity and loses it through convection, conduction, radiation and sweating to maintain a constant body temperature. When body temperature drops even a few degrees below the normal of 98.6 degrees F, blood vessels constrict, decreasing peripheral blood flow to reduce heat loss from the surface of the skin. Shivering generates heat by increasing the body's metabolic rate.
The four environmental conditions that cause cold-related stress are low temperatures, high/cold winds, dampness and cold water. Wind chill is a crucial factor to evaluate when working outside. For example, when the actual air temperature of the wind is 40 degrees and its velocity is 35 mph, the exposed skin receives conditions equivalent to a still-air temperature of 11 degrees. Dangerous heat loss may occur for any individual exposed to high winds and cold temperatures.
Major Risk Factors for Cold-Related Stresses
- Wearing inadequate or wet clothing increases the effects of cold on the body.
- Taking drugs or medications can inhibit the body's response to the cold or impair judgment. This includes alcohol, nicotine, caffeine and prescription medication.
- Having a cold or certain diseases, such as diabetes, heart, vascular and thyroid problems, may make a person more susceptible to the winter elements.
- Becoming exhausted or immobilized, especially due to injury or entrapment, may speed up the effects of cold weather.
Harmful Effects of Cold
Trench Foot is caused by, continuous exposure to a wet, cold environment, or actual immersion in water. Symptoms include tingling and/or itching, burning, pain, and swelling, and the forming of blisters in more extreme cases. Move individuals with trench foot to a warm, dry area, where the affected tissue can be treated with careful washing and drying, re-warming and slight elevation. Seek medical assistance as soon as possible.
Frostbite occurs when the skin tissue actually freezes, causing ice crystals to form between cells and draw water from them, which leads to cellular dehydration. Although this typically occurs at temperatures below 30 degrees F, wind chill effects can cause frostbite at above-freezing temperatures.
Initial effects of frostbite include uncomfortable sensations of coldness; tingling, stinging or aching in the exposed area followed by numbness. Ears, fingers, toes, cheeks, and noses are primarily affected. Frostbitten areas appear white and are cold to the touch. The appearance of frostbite varies depending on whether re-warming has occurred.
Deeper frostbite involves freezing of deeper tissues (muscles, tendons, etc.) causing exposed areas to become numb, painless and hard to the touch.
If you suspect frostbite, seek medical assistance immediately. Any existing hypothermia should be treated first. Frostbitten parts should be covered with dry, sterile gauze or soft, clean cloth bandages. Do not massage frostbitten tissue because this sometimes causes greater injury. Severe cases may require hospitalization and even amputation of affected tissue.
General Hypothermia occurs when body temperature falls to a level where normal muscular and cerebral functions are impaired.
The first symptoms of hypothermia - shivering, inability to perform complex motor functions, lethargy and mild confusion - occur as the core body temperature decreases to about 95 degrees.
As body temperature continues to fall, hypothermia becomes more severe. The individual falls into a state of dazed consciousness, unable to complete even simple motor functions. The victim's speech becomes slurred and his or her behavior may become irrational.
The most severe state of hypothermia occurs when body temperature falls below 90 degrees. As a result, the body moves into a state of hibernation, slowing the heart rate, blood flow and breathing. Unconsciousness and full heart failure can occur.
Treatment of hypothermia involves conserving the victim's remaining body heat and providing additional heat sources. Handle hypothermic people carefully because of the increased sensitivity of the cold heart and seek medical assistance.
If the person is unresponsive and not shivering, assume they are suffering from severe hypothermia. Reduction of heat loss can be accomplished by various means: obtaining shelter, removal of wet clothing, adding layers of dry clothing, blankets, or using a pre-warmed sleeping bag.
For mildly hypothermic cases or more severe cases where medical treatment will be significantly delayed, external re-warming techniques may be applied. This includes body-to-body contact (e.g., placing the person in a pre-warmed sleeping bag with a person of normal body temperature), chemical heat packs or insulated hot water bottles. It is best to have the person lying down when applying external re-warming. You also may give mildly hypothermic people warm fluids orally, but avoid beverages containing alcohol or caffeine.
Preventing Cold-Related Disorders
Perhaps the most important step in fighting the elements is adequate insulation. Wear at least three layers of clothing:
1. An outer layer to break the wind and allow some ventilation (like Gore-Tex or nylon);
2. A middle layer of wool or synthetic fabric (Qualofil or pile) to absorb sweat and retain insulation in a damp environment. Down is a useful lightweight insulator; however, it is ineffective once it becomes wet.
3. An inner layer of cotton or synthetic weave to allow ventilation.
Pay special attention to protecting feet, hands, face and head. Up to 40 percent of body heat can be lost when the head is exposed. Footgear should be insulated, and keep a change of clothing available in case garments become wet.
Environmental Controls
A variety of practices in the workplace help reduce the risk of cold-related injuries:
- Use an on-site source of heat, such as air jets or radiant heaters
- Shield work areas from wind.
- Provide a heated shelter for employees who experience prolonged exposure to equivalent wind-chill temperatures of 20 degrees or less.
- Use thermal insulating material on equipment handles when temperatures drop below 30 degrees.
Safe Work Practices
Changes in work schedules and practices are necessary to combat the effects of exceedingly cold weather.
- Allow a period of adjustment to the cold before embarking on a full work schedule.
- Always permit employees to set their own pace and take work breaks when needed.
- Reduce, as much as possible, the number of activities performed outdoors. When employees must brave the cold, select the warmest hours of the day and minimize activities that reduce circulation.
- Ensure that employees remain hydrated.
- Establish a buddy system for working outdoors.
- Educate employees to the symptoms of cold-related stresses - heavy shivering, uncomfortable coldness, severe fatigue, drowsiness or euphoria.
The quiet symptoms of potentially deadly cold-related ailments often go undetected until the victim's health is endangered. Knowing the facts on cold exposure and following a few simple guidelines can ensure that this season is a safe and healthy one.