Protecting Workers in Cold Environments


When the weather becomes “frightful” during winter months, workers who have to brave the outdoor conditions face the occupational hazard of exposure to the cold. Prolonged exposure to freezing temperatures can result in health problems as serious as trench foot, frostbite, and hypothermia. Workers in such industries as construction, utilities, commercial fishing, and agriculture need to be especially mindful of the weather, its effects on the body, proper prevention techniques, and how to treat 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 its normal temperature of 98.6°F(37°C), the blood vessels constrict. Constricted vessels decrease peripheral blood flow to the skin surface, thus reducing heat loss. Shivering generates heat by increasing the body’s metabolic rate.

The four environmental conditions that cause cold-related stress are:
  1. Low temperatures,
  2. High/cool winds,
  3. Dampness, and
  4. Cold water.
Wind chill, a combination of temperature and velocity, is a crucial factor to evaluate when working outside. For example, when the actual air temperature of the wind is 40°F(4°C) and its velocity is 35 mph, the exposed skin receives conditions equivalent to the still-air temperature being 11°F (-11°C). A dangerous situation of rapid heat loss may arise for any individual exposed to high winds and cold temperatures.

Major risk factors for increasing cold-related stresses

  • Wearing inadequate or wet clothing increases the effects of cold on the body.

  • Taking certain drugs or medications such as alcohol, nicotine, caffeine, and medication that inhibits the body’s response to the cold or impairs judgment.

  • Having a cold or certain diseases, such as diabetes, heart, vascular, and thyroid problems, may make a person more susceptible to the winter elements.

  • Being a male increases a person’s risk to cold-related stresses. Men experience far greater death rates due to cold exposure than women, perhaps due to inherent risk-taking activities, body-fat composition, or other physiological differences.

  • Becoming exhausted or immobilized, especially due to injury or entrapment, may speed up the effects of cold weather.

  • Aging — the elderly are more vulnerable to the effects of harsh winter weather.

Effects of cold on the body

Trench foot is caused by long, continuous exposure to a wet, cold environment or actual immersion in water. Workers, such as commercial fisherman who experience these types of cold, wet environments daily, need to be especially cautious. Symptoms include:
  • Tingling and/or itching sensation,
  • Burning, pain, and
  • Swelling, sometimes forming blisters in more extreme cases.
Treatment includes moving individuals with trench foot to a warm, dry area where the affected tissue can be treated. Carefully wash and dry the area, rewarm, and slightly elevate. 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. This leads to cellular dehydration. Although frostbite typically occurs at temperatures below 30°F (1°C), wind chill effects can cause frostbite at above-freezing temperatures. Ears, fingers, toes, cheeks, and noses are primarily affected. Symptoms of the exposed area include:
  • Uncomfortable sensations of coldness;
  • Tingling, stinging, or aching feeling followed by numbness; and
  • Skin appears white and cold to the touch (varies depending on whether rewarming has occurred).
Deeper frostbite involves freezing of deeper tissues, such as muscles and tendons, causing exposed areas to become numb, painless, hard to the touch.

To treat frostbitten parts, cover with dry, sterile gauze or soft, clean cloth bandages. Do not massage frost-bitten tissue because this sometimes causes greater injury. Severe cases may require hospitalization and even amputation of affected tissue. Take measures to prevent further cold injury.

If you suspect frostbite, seek medical assistance immediately. However, if hypothermia exists, it should be treated first.

General hypothermia occurs when body temperature falls to a level where normal muscular and cerebral functions are impaired. While hypothermia is generally associated with freezing temperatures, it may occur in any climate where a person’s body temperature falls below normal. Symptoms include:
  • Shivering,
  • Inability to do complex motor functions,
  • Lethargy, and
  • Mild confusion.
These initial symptoms occur as the core body temperature decreases to around 95°F (35°C). As body temperature continue to fall, hypothermia becomes more severe. The individual:
  • Falls into a state of dazed consciousness;
  • Fails to complete even simple motor functions;
  • Speech becomes slurred; and
  • Behavior may become irrational.
The most severe state of hypothermia occurs when body temperature falls below 90°F (32°C). At this point, the body moves into a state of hibernation, slowing the heart rate, blood flow, and breathing. Unconsciousness and full heart failure can occur in the severely hypothermic state.

Treatment of hypothermia involves conserving the victim’s remaining body heat and providing additional heat sources. Specific measures will vary depending upon the severity and setting (field or hospital). Handle hypothermic people very carefully because of the increased irritability of the cold heart. Seek medical assistance for persons suspected of being moderately or severely hypothermic.

Assume that a person is suffering from severe hypothermia when he is unresponsive and not shivering. Stop heat loss by:
  • Finding shelter,
  • Removing wet clothing,
  • Adding layers of dry clothing or blankets, or
  • Using a pre-warmed sleeping bag.
For mildly hypothermic cases or those more severe cases where medical treatment will be significantly delayed, apply external rewarming techniques. These include:
  • Body-to-body contact (e.g., placing the person in a prewarmed sleeping bag with a person of normal body temperature);
  • Chemical heat packs; or
  • Insulated hot water bottles.
Good areas to place these packs are the armpits, neck, chest, and groin. It is best to have the person lying down when applying external rewarming. You also may give mildly hypothermic people warm fluids orally, but avoid beverages containing alcohol or caffeine.

Preventing cold-related disorders

Personal protective clothing — perhaps the most important step in fighting the elements. Provide adequate layers of insulation, usually at least three layers of clothing:
  • An outer layer to break the wind and allow some ventilation (like Gore-Tex® or nylon).
  • 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.
  • 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 to protect against cold and dampness. Keep a change of clothing available in case work garments become wet.

Engineering controls in the workplace through a variety of practices help reduce the risk of cold-related injuries. Consider using an onsite source of heat, such as air jets, radiant heaters, or contact warm plates or shielding work areas from drafty or windy conditions.

Provide a heated shelter for employees who experience prolonged exposure to equivalent wind-chill temperatures of 20°F (6°C) or less and use thermal insulating material on equipment handles when temperatures drop below 30°F (1°C).

Safe work practices are necessary to combat the effects of exceedingly cold weather. Implement changes in work schedules and practices that:
  • Allow a period of adjustment to the cold before embarking on a full work schedule.
  • Permit employees to set their own pace and take extra “warm-up” work breaks when needed.
  • Reduce, as much as possible, the number of activities performed outdoors. When employees have to 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.
  • Provide training on 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 outdoor workers stay safe and healthy.

Frost bite and hypothermia

When your body is unable to warm itself, serious cold-related illnesses and injuries can occur and permanent tissue damage and death may result. Hypothermia occurs when land temperatures are above freezing or water temperatures are below 98.6°F. Cold-related illnesses slowly overcome a person who has been chilled by low temperatures, brisk winds, or wet clothing. The most common cold related illnesses are frostbite, and hypothermia.

Frost bite

What happens to the body?
  • Freezing in deep layers of skin and tissue.
  • Pale, waxy-white skin color.
  • Skin becomes hard and numb.
  • Usually affects the fingers, hands, toes, feet, ears, and nose.
What should be done?
  • Move the victim to a warm dry area. Do not leave the individual alone.
  • Remove wet or tight clothes that may cut off blood flow to the affected area.
  • DO NOT rub the affected area. Rubbing causes damage to the skin and tissue.
  • Gently place the affected area in a warm (105°F) water bath and monitor the temperature to slowly warm the tissue. Don’t pour warm water directly on the affected area because it will warm the tissue too fast causing tissue damage. Warming takes about 25–40 minutes.
  • After the affected area has been warmed, it may become puffy and blister. The area may have a burning feeling or numbness. When normal feeling, movement, and skin color have returned, dry and wrap the affected area to keep it warm.
    Note:If there is a chance the affected area may get cold again, do not warm the skin. If the skin is warmed and then becomes cold again, it will cause severe tissue damage
  • Seek medical attention as soon as possible.

Hypothermia — A medical emergency

What happens to the body?
  • Normal body temperature (98.6°F) drops to or below 95°F.
  • Fatigue or drowsiness occurs.
  • Uncontrolled shivering.
  • Cool bluish skin.
  • Slurred speech.
  • Clumsy movements.
  • Irritable, irrational, or confused behavior.
What should be done?
  • Call for emergency medical help.
  • Move the victim to a warm, dry area. Don’t leave the individual alone.
  • Remove any wet clothing and replace with warm, dry clothing or wrap the victim in blankets.
  • Provide warm, sweet drinks (sugar water or sports-type drinks) if the victim is alert. Avoid drinks with caffeine (coffee, tea, or hot chocolate) or alcohol.
  • Have the victim move his/her arms and legs to create muscle heat. If unable to do this, place warm bottles or hot packs in the arm pits, groin, neck, and head areas. DO NOT rub the victim’s body or place the individual in a warm water bath. This may cause cardiac arrest.

How to protect your employees

Do not allow employees who have predisposing health conditions such as cardiovascular disease, diabetes, and hypertension to work long hours outdoors in winter weather. Also, remember that individuals who are in poor physical condition, have a poor diet, or are older are more susceptible to extreme temperatures. To ensure that employees are protected from the cold elements, provide instructions to:
  • Recognize the environmental and worksite conditions that lead to potential cold-induced illnesses and injuries.

  • Recognize the signs and symptoms of cold-induced illnesses/injuries and what to do to help a fellow employee.

  • Select proper clothing for cold, wet, and windy conditions.

  • Layer clothing to adjust to changing environmental temperatures. Wear a hat and gloves, in addition to underwear that will keep water away from the skin (polypropylene).

  • Avoid exhaustion or fatigue. Energy is needed to keep muscles warm.

  • Use the buddy system (work in pairs).

  • Drink warm, sweet beverages (sugar water, sports-type drinks). Avoid drinks with caffeine (coffee, tea, or hot chocolate) or alcohol.

  • Eat warm, high-calorie foods like hot pasta dishes.
Allow your employees to:
  • Take frequent short breaks in warm dry shelters to allow the body to warm up.

  • Work during the warmest part of the day.
Keeping one step ahead of the weather pays off for employee safety and health.

1 comment:

Anita said...

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