The Cold Stress Equation-November 2011

Monthly Round Up of Important Ideas and Standards in
Industrial Hygiene and Safety 

November 2011


IN THIS ISSUE: The Cold Stress Equation

The hot summer months are over, and many parts of the country are anticipating cold weather in the coming weeks. Precautions should be taken to avoid the dangers of cold stress. 

What is the cold stress equation?

Low Temperature + Wind Speed + Wetness = Injuries & Illness.

OSHA developed this cold stress equation based on the guidelines from the American Conference of Governmental Industrial Hygienists. It factors in temperature, wind, and wetness. As indicated by the chart provided here, a shorter time of exposure is needed to cause injury as these factors increase. Work times should be adjusted accordingly.

What is cold stress?

Cold stress occurs when the body is unable to warm itself. This may lead to illness, injury or death. Frostbite and hypothermia are examples of cold stress.

  • HYPOTHERMIA. This medical emergency occurs when the body loses heat faster than it produces heat, causing a dangerously low body temperature.  In mild cases, workers may shiver, massage cold areas, or stomp their feet.
  • FROSTBITE. This type of cold stress typically affects fingers, hands, nose, and ears. Early signs may consist of tingling, itching or a burning sensation. As it progresses, the affected body part will be cold, tingling, stinging or aching followed by numbness. Skin color turns red, then purple, then white, and is cold to the touch and there may be blisters in severe cases.  In cases of frostbite, soak feet in warm water, then wrap with dry cloth bandages.

What should be done about cold stress?

  1. TRAINING.  Employees should be made aware of the signs and symptoms of cold stress. Management should provide protective equipment and training.  In cases of severe hypothermia, employees may also be fatigued, have loss of coordination, drowsiness, apathy, hallucinations, and resistance to help. This is a dangerous situation and requires immediate medical help.
  2. PROTECTION.  In cold weather provide adequate insulating clothing. Multiple layers should be worn, so they can be added or removed as needed. Use inner layers of clothes that can absorb moisture and transport it away from body’s surface. An outer layer should be used that is waterproof, windproof, and durable. Have a change of clothing ready. Wear a hat or hood because most heat loss comes from the head. Wear insulated and water proof boots.
  3. MONITORING.  The factors of the cold stress equation (temperature, humidity, and wind) should be closely monitored. For workers who regularly work in cold environments, consult the ACGIH “Threshold Limit Values for Chemical Substances and Physical Agents” for detailed guidelines.
  4. EMERGENCIES.  Plan ahead for potential emergencies.  If cold stress is evident, move the employee to a warm area, remove wet clothing and replace with dry clothing, cover with blankets, and cover the head. Provide the employee with a warm sugary drink.

 For more information on this topic and to discuss your company’s safety and industrial hygiene needs call OccuSafe at (214) 662-6005 or (303) 219-6973 or visit us at

OccuSafe Industrial Hygiene & Safety, Inc. provides skills and expertise to recognize, evaluate andcontrol hazards and injuries in the areas of industrial hygiene, occupational safety andhealth. OccuSafe services companies of all sizes in a range of industries.

This newsletter is published monthly by OccuSafe Industrial Hygiene & Safety, Inc. Feel free to forward it to friends and colleagues.

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