Understanding Cold Stress for FR Clothing Wearers

This is the first post in a series covering cold stress and how to layer FR clothing properly during colder months. Subsequent topics will include: wicking or FR inner layers, FR outer layers for warmth and insulation, and a final, waterproof FR layer.

Now that the temperatures are cooling down, it is time to think about protecting yourself from the elements of winter. Workers who are exposed to extreme cold or work in cold environments may be at risk of cold stress. Just as heat stress poses health risks in the summer, cold stress can lead to illness or injuries on the job.

FR Clothing & Cold Stress

The best way to stay warm in the winter is to dress appropriately, including wearing layers. However, layering the correct clothing together is not always easy when your job requires you to meet certain clothing standards. With the increase in regulation surrounding the use of personal protective equipment (PPE) and FRC, comes higher risk of pairing incorrect clothing together in an effort to stay warm. If you are required to work outside in cooler temperatures, it’s important to understand the risks you face.

Just like with heat stress, there are different ways one could be affected by cold stress. The three most common types of cold stress are explained below:


Prolonged exposure to cold will eventually use up your body’s stored energy. Hypothermia, or abnormally low body temperature, occurs when your body loses heat faster than it can be produced. Someone being affected by this type of cold stress may not be able to think clearly or move well. This is particularly dangerous because a person might know they are experiencing hypothermia but may not be able to do anything about it. Here is how to identify if you or one of your coworkers has hypothermia:

Early Symptoms:

  • Shivering
  • Fatigue
  • Loss of coordination
  • Confusion/disorientation

Late Symptoms:

  • No shivering
  • Blue skin
  • Dilated pupils
  • Slow pulse and breathing
  • Loss of consciousness


Frostbite is an type of cold stress injury to the body caused by freezing. Frostbite causes a loss of feeling and color in the affected areas, mostly the nose, ears, cheeks, chin, fingers and toes. Frostbite can permanently damage body tissue with the most severe cases leading to amputation. In extremely cold climates, the risk of frostbite is increased among workers with reduced blood circulation and those who are not dressed properly.

Symptoms of frostbite include:

  • Reduced blood flow to hands and feet (when fingers and toes can freeze)
  • Numbness
  • Tingling or stinging
  • Aching
  • Bluish or pale skin

Trench Foot

Trench foot, also known as immersion foot, is an injury of the feet resulting from prolonged exposure to cold, wet conditions. However, trench foot can occur at temperatures as high as 60 degrees if the feet are constantly wet. Water conducts heat away from the body 25 times faster than air which is why trench foot injuries can occur. To prevent heat loss, the body will constrict blood vessels to shut down circulation to your extremities – your feet being first. Skin tissue begins to die because of the lack of oxygen and nutrients.

Symptoms of this type of cold stress include:

  • Reddening of the skin on the feet
  • Numbness
  • Leg cramps
  • Swelling of the feet and toes
  • Tingling pain
  • Blisters or ulcers
  • Bleeding under the skin

5 Ways to Protect Yourself from Cold Stress:

  1. Monitor your physical condition and that of your coworkers.
  2. Wear appropriate FR clothing as layers. Loose layers provide insulation whereas tight layers on top of a thermal base layer can constrict blood circulation to your extremities. It is important to make sure that top layers providing insulation allow for movement and full range of motion.
  3. Protect the ears, face, hands and feet in extremely cold or wet weather.
  4. Limit your amount of time outside and take breaks from cold temperatures by moving into warm locations.
  5. Pack or carry extra layers of FR clothing or a change of clothes for after work.

For more information on how to treat these types of cold stress or give first aid to someone affected by cold stress, please visit the CDC’s website.

Check back for more information on how to properly layer FR clothing during cold winter months to help stay compliant with company policies and industry regulations.

Information included in this post, accessed Nov 2013, is from:


Leave a Reply

Your email address will not be published. Required fields are marked *