Course 602 - Heat and Cold Stress Safety

Safety guides and audits to make your job as a safety professional easier

Cold Stress and Safety



During emergency response activities or recovery operations, workers may be required to work in cold environments, and sometimes for extended periods of time. Cold stress is a common problem encountered in these types of situations. When the body is unable to warm itself, cold related stress may occur. This may include tissue damage and possibly death.

Cold Stress Factors

Four factors contribute to cold stress:

  • Cold air temperatures,
  • high velocity air movement,
  • dampness of the air, and
  • contact with cold water or surfaces.
Wind chill is the combination of air temperature and wind speed.

Cold-related illnesses can slowly overcome a person who has been chilled by low temperatures, brisk winds, or wet clothing. A cold environment forces the body to work harder to maintain its temperature. Cold air, water, and snow all draw heat from the body.

Wind Chill

Wind chill is the combination of air temperature and wind speed. For example, when the air temperature is 35 degrees Fahrenheit, and the wind speed is 30 miles-per-hour, your exposed skin receives conditions equivalent to the air temperature being a mere 22 degrees Fahrenheit.

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 degrees Fahrenheit) combined with some rain and wind.

Reactions to Cold Temperatures

When in a cold environment, most of your body’s energy is used to keep your internal temperature warm. Over time, your body will begin to shift blood flow from your extremities (hands, feet, arms and legs) and outer skin to the core (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.

Common Cold-Induced Problems

If you are not careful while working in cold temperatures, hypothermia could be the result.


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 degrees Fahrenheit to around 95 degrees Fahrenheit, you will see the following symptoms:

  • Uncontrollable shivering
  • Slow speech
  • Memory lapses
  • Frequent stumbling
  • Drowsiness
  • Exhaustion


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:

  • Gently move the victim to a warmer place
  • Remove wet clothing
  • Cover the victim with something dry and warm
  • If available, contact Emergency Medical Services. If you are far from professional medical care, start re-warming the person. Place him near a heat source and put containers of warm water in contact with the skin.

Fact: Drinking alcohol increases your risk of becoming hypothermic: Although it may give your face a warm flush, drinking alcohol on a cold day does not warm you up. It can actually lower your body's core temperature.

Real-Life Scenario

On January 4th, 2008, an employee and co-worker were securing a large tug boat that broke loose during a storm and was drifting towards waterfront homes. The two employees off-boarded the work boat and boarded the tug boat. At some point, the work boat became detached from the tug boat and drifted away. One of the employees dove into the frigid water to catch the work boat. However, he couldn’t reach it and re-boarded the tug boat. He found another smaller vessel on board the tug boat and boarded it. He was going to float out to get the work boat. The small boat capsized and the employee was hanging onto the boat, waiting for rescue workers. The rescue took about 45 minutes. He was transferred to a hospital and later died from complications related to hypothermia.

Common Cold-Induced Problems (Continued)


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.

Frostbite is a reaction to cold exposure - U.S. Army.


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:

  • Remove any jewelry from the affected areas.
  • Place clean pads between frostbitten fingers and toes.
  • Wrap the affected part with a clean towel or pad.
  • Do not rub or massage the affected area or disturb blisters on frostbitten skin.

Real-Life Scenario

On August 4th, 2004, a worker was wearing a thermo-insulated jacket, overalls, and gloves and began work in the freezer department of a supermarket chain warehouse. His work consisted of selecting produce off warehouse shelves and delivering the product to the designated freezer truck. At the completion of the eight-hour work shift, he went home and soon realized that he was in unbearable pain and the toes on both his feet were black and blistering. He immediately left the house and went to the hospital where his feet were treated for frostbite and he was hospitalized.

Common Cold-Induced Problems (Continued)

Trench Foot

trench foot
Trench foot is caused by having feet immersed in cold water at temperatures above freezing.

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:

  • Thoroughly clean and dry your feet.
  • Put on clean, dry socks daily.
  • Treat the affected part by applying warm packs or soaking in warm water (102° to 110° F) for approximately 5 minutes.
  • When sleeping or resting, do not wear socks.
  • Obtain medical assistance as soon as possible.

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.

Protective Clothing

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:

  • Wear a hat or hood. Up to 40% of body heat can be lost when the head is left exposed.
  • Wear insulated boots or other footwear.
  • Keep a change of dry clothing available in case work clothes become wet.
protective clothing
Protective clothing, such as these boots, is the most important way to avoid cold stress.
protective clothing
Protective clothing, such as this warm jacket, is the most important way to avoid cold stress.

Work Practice Measures

There are several work practice measures to protect workers in cold environments. Here are a few:

  • Recognize the environmental and workplace conditions that may be dangerous.
  • Learn the signs and symptoms of cold-induced illnesses and injuries and what to do to help workers.
  • Train workers about cold-induced illness and injuries.
  • Encourage workers to wear proper clothing for cold, wet and windy conditions, including layers that can be adjusted to changing conditions.
  • Be sure workers in extreme conditions take a frequent short break in warm, dry shelters to allow their bodies to warm up.
  • Try to schedule work for the warmest part of the day.
  • Use the buddy system-work in pairs so that one worker can recognize danger signs.
  • Avoid exhaustion or fatigue because energy is needed to keep muscles warm.

Engineering Controls

Engineering controls can be effective in reducing the risk of cold stress. Radiant heaters may be used to warm workers. Shielding work areas from drafts or wind will reduce the wind chill. Use insulating materials on equipment handles, especially metal handles, when temperatures drop below 30 degrees Fahrenheit.

Employee Training

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.

Last Words

That is a lot of information! It's now time for your module quiz. Good luck!


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. Wind chill is the combination of _______ and ______________.

2. Hypothermia occurs when body heat is lost faster than it can be replaced.

3. According to the text, which of the following is NOT a treatment for SEVERE frostbite?

4. Which of the following are symptoms of frostbite?

5. Blisters may be present in trenchfoot.

Have a great day!

Important! You will receive an "error" message unless all questions are answered.