Managing 24/7

Working When the Temperature is Dropping

 

It’s February which means in much of the world – it’s pretty cold. Many shiftworkers routinely work in cold conditions to keep our 24-hour society running. To do this job properly, shiftworkers, and their managers, should be aware of cold temperature’s effect on the body and proper prevention strategies for dealing with cold conditions.

Failure to educate shiftworkers who work in cold conditions can lead to adverse effects on human performance and health. Cold can interfere with other factors in the workplace, aggravate the risk of common hazards and increase the risk of injuries. Prolonged exposure to freezing temperatures can result in serious health problems, such as frostbite and hypothermia. Cold can also increase the incidence of fatigue related accidents and errors.

Why is working in the cold challenging?

Just like working the night shift feels unnatural for many people, working in cold environments can be a challenge for many employees. The human body is designed to work best at a constant core temperature of 98.6ºF (37ºC). The body maintains this temperature constant by producing heat (from food and muscular work) and by losing heat through:

  • Radiation - the loss of heat to the environment due to the difference between the temperature of the air and the temperature of the body;
  • Conduction - the loss of heat through direct contact with a cooler object;
  • Convection - the loss of heat from the body to the surrounding air as the air moves across the surface of the body;
  • Evaporation - the loss of heat due to the conversion of water from a liquid to a gas, by perspiration/sweating and respiration.

It is important to recognize the strong connection between fluid levels, fluid loss, and heat loss. As body moisture is lost through the various processes, the overall circulating volume is reduced which can lead to dehydration. This decrease in fluid level makes the body more susceptible to hypothermia and other cold injuries.

How the body responds to the cold

In a cold environment, the body uses most of its energy to maintain its core temperature. Under cold conditions, blood vessels in skin, arms and legs constrict, to reduce blood flow to extremities, in order to  conserve heat (minimizing cooling of the blood) and keep critical internal organs warm.  At very low temperatures, when blood flow to exposed skin and extremities is reduced, they can cool rapidly, which increases the risk of frostbite and hypothermia. When the body can not maintain temperature by vasoconstriction, it starts shivering to increase metabolic rate and generate heat.

In general, people in good physical health can handle cold better and are less susceptible to cold injury. The following factors increase the risk of cold injuries:

  • Age: older adults are more susceptible
  • Gender: women are generally at greater risk of cold injuries
  • Certain diseases such as diabetes and cardiovascular disease
  • Consumption of alcohol, nicotine and caffeine
  • Certain medications
  • Fatigue
  • Inadequate clothing

Work-related factors that can lead to cold injuries:

  • Handling evaporative liquids (such as gasoline) presents an additional risk, due to evaporative cooling. Workers should take precautions to avoid soaking of clothing or contact with skin. Liquid oxygen and nitrogen present particularly acute splash hazards in cold weather.
  • Vibration from tools and equipment also presents increased risk. As air temperature drops, risk arising from tools that cause significant hand-transmitted or whole body vibration may be increased.
  • Work/rest schedule: The "work warm-up schedule," as developed by the Saskatchewan Department of Labour, has been adopted by the American Conference of Governmental Industrial Hygienists (ACGIH) as Threshold Limit Values (TLVs) for cold stress. These guidelines describe exposure conditions and techniques for working in cold conditions under which it is believed that nearly all workers can be repeatedly exposed without any adverse health effects. The TLV objective is to maintain core body temperature from falling below 96.8F

Cold stress related injuries

Prolonged exposure to cold can lead to fatigue, lowered concentration, slowed reflexes and loss of physical coordination. Manual tasks are impaired because the sensitivity and dexterity of fingers are reduced in the cold. At even lower temperatures, the cold affects the deeper muscles resulting in reduced muscular strength, stiffened joints and musculoskeletal injuries. Mental alertness is reduced due to cold-related discomfort. Exposure to cold could impair decision-making and affect the ability to follow safe working procedures. All of these can increase the risk of injuries.

What are the early-warning signs of cold-related illnesses?

  • Hands become numb
  • Involuntary shivering
  • Loss of fine motor coordination (particularly in hands, i.e., having trouble with buttons, zips, laces)
  • Slurred speech
  • Difficulty in thinking clearly

Once two or more signs have been experienced or observed, the worker should stop working and take steps to safeguard health, or they risk experiencing musculoskeletal strains, sprains, or tears, frostbite, or even hypothermia. 

What can be done to help prevent the adverse effects of cold?

The risk of injury due to prolonged exposure to cold can be minimized by proper equipment design, safe work practices and appropriate clothing. The following is a summary of actions including some from recommendations from the ACGIH (American Conference of Governmental Industrial Hygienists).

Try to limit exposure to cold environment: Where possible, try to limited prolonged exposure to a very cold environment. Make sure tasks are varied and often rotated, and avoid activities which minimize blood circulation, such as remaining in static or cramped positions for long periods of time.

Equipment Design: For work below the freezing point, metal handles and bars should be covered by thermal insulating material. Also, machines and tools should be designed so that they can be operated without having to remove mittens or gloves.

Emergency Procedures: Procedures for providing first aid and obtaining medical care should be clearly outlined. For each shift, at least one trained person should be assigned the responsibility of attending to emergencies.

Education: Workers and supervisors involved with work in cold environments should be informed about symptoms of adverse effect exposure to cold, proper clothing habits, safe work practices, physical fitness requirements for work in cold, and emergency procedures in case of cold injury.

Buddy system: Individuals may not recognize their own symptoms. Try setting up a buddy system approach, where workers watch out for one another, which would allow for earlier recognition of signs of frostbite and hypothermia and mitigate risks.

Diet: Balanced meals and adequate liquid intake are essential to maintain body heat and prevent dehydration. Working in the cold requires more energy than in warm weather because the body is working to keep itself warm. It also requires more effort to work when wearing bulky clothing and winter boots, especially when walking through snow.

Workers should drink fluids often especially when doing strenuous work (e.g., 3-5 liters/day, including liquids from food). For warming purposes, hot non-alcoholic beverages or soup are best. Caffeinated drinks are not recommended because they increase urine production and contribute to dehydration. Caffeine also increases the blood flow at the skin surface which can increase the loss of body heat. Alcohol should not be consumed as it causes expansion of blood vessels in the skin and impairs the body's ability to regulate temperature (it affects shivering). These effects cause the body to lose heat and thus increase the risk of hypothermia.

 


Working in cold environments is necessary for many 24/7 operations, but can carry serious risks both for the company, and the individual worker. By implementing some of these simple tips, a bitter cold work environment may not end up feeling warm and cozy, but it can be made as safe as possible.

 

APPENDIX

Extreme Hot or Cold Temperature Conditions. Canada’s National Occupational Health & Safety Resource. http://www.ccohs.ca

Cold Environments-General. Canada’s National Occupational Health & Safety Resource. http://www.ccohs.ca

Cold Environments-Working in the Cold. Canada’s National Occupational Health & Safety Resource. http://www.ccohs.ca

Work in Hot or Cold Environments. Code of Practice 2001. WorkCover NSW Health and Safety Code of Practice. http://www.workcover.nsw.gov.au

Cold Stress. Electronic Library of Construction. Occupational Safety and Health. http://www.cdc.gov

Cold Stress Policy. City of Toronto-Human Resources-Guidelines. http://wi.toronto.ca

Cold Stress. Occupational Safety and Health Administration. http://www.osha.gov

Protecting Workers in Cold Environments. U.S. Department of Labor. Occupational Safety and Health Administration. http://www.osha.gov

Working in a Cold Environment. Cambridge Integrated Services Australia Pty.Ltd.

Threshold Limit Values (TLVTM) and Biological Exposure Indices (BEITM) booklet. ACGIH, Cincinnati, OH. 2008. 

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