Throughout the winter and spring we Canadians look forward to the longer days, beaming sunshine, and relative heat that define the summer months. But for outdoor workers in Canada, summer can bring with it some significant challenges. When working outdoors during the warmers months the sometimes extreme heat can become a threat to individual health and safety. Bodies, when extremely overheated, can be driven to a state where their basic functions are threatened and survival mode is induced. By definition, hyperthermia is the increase in core temperature above the essential for normal metabolic and bodily functions.

When preparing for outdoor work this summer, there are a few key factors to take into consideration to ensure that you and your workforce are protected against the dangers of hyperthermia at work.

Understanding body temperature regulation

The Integumentary System (skin) is the largest organ of the human body and is the primary location for heat transfer to/from the human body.  The mechanisms of human thermoregulation are the ways by which the surface of the skin dissipates\retains heat.  The mechanisms include:

• Evaporation: The transition of liquid to gas - sweating.
  
  
• Radiation: The emission of heat from the body.
  
  
• Convection: The movement of temperature currents through fluids.
  
  
• Conduction: The transfer of heat from one region to another.

At its core, heat regulation in the body is only as effective as the skins control of the blood flow through its tissues. At rest, blood flow through the skin is enough to facilitate the dissipation of heat that’s generated from basic bodily functions.  Blood vessels within the skin have the ability to increase and/or decrease their diameter which reduces or increases blood flow, respectively.  

Keeping it cool – heat loss through the skin

When the body experiences an increase in core temperature, blood flow to the skin will significantly increase through vasodilation.  Specifically, skin blood vessels will increase in diameter allowing for more blood to be exposed to the environment because the larger the amount of blood exposed to the environment, the higher the amount of heat loss.  Other temperature regulation mechanisms like evaporation (sweating) will also help to reduce body temperature.  These and other heat loss mechanisms are especially important during bouts of physical activity.  As internal heat production increases during physical exertion it must be dissipated to ensure both muscle and core temperatures stay within their safe functioning limits. Simply put, if excessive heat gain is not appropriately regulated it will result in significant mental and physical impairment. 

Work environments and danger of hyperthermia

Wet hot environments are the most dangerous work conditions when it comes to heat regulation in the body. The high relative humidity of these environments makes it very difficult for the body to properly dissipate heat during physically demanding work. In a hot wet environment, evaporation (sweating) will be significantly blunted.

Very often its work clothing that can be the most detrimental to bodily temperature regulation. The best example is with firefighters. Their clothing is built to reduce the exposure to heat, but it also significantly reduces heat loss.  The buildup of moist warm air within a suit reduces convection and evaporation (sweating) and the heat protective qualities of a suit will reduce conduction and radiation.  Therefore, independent of the work environment, employee clothing and equipment must also be evaluated for inefficiencies in heat loss during physical demanding work.

Impacts of hyperthermia on safety and work performance

Hyperthermia has a significant negative effect on both the physical and mental abilities of an individual. Specifically, as muscle tissue becomes hot the optimal function of proteins becomes compromised.  Additionally, muscles become more prone to fatigue. The inability to properly dissipate heat will not only result in localized muscle fatigue, but it will also significantly affect mental faculties. Safety sensitive occupations which require special rescue or safety clothing and equipment will more often experience the consequences of hyperthermia.

What can employers do to mitigate risk to employee health and safety?

The best course of action to avoid the risks associated with hyperthermia in potentially high risk environments is the development of Job Demands Analysis (JDAs). By having a clear and defined understanding of the job demands based on the specific job role, the employer is enabled to address potential risk.

Here are some tips that employers can use to help mitigate risk of hyperthermia in the workplace in the short term:

• Provide employees with education and resources about health and safety practices and procedures specific to each job role
• Provide clothing and equipment that’s been proven safe for the specific job role and environment
• Encourage regular breaks for rest and recuperation during shifts
• Encourage regular hydrate at levels appropriate for the environment, the work being completed, and the individual

To learn more about hyperthermia or hypothermia as it relates to workplace health and safety, email us at marketing@horizonohs.com.