Heat and Human Performance: Illness and Risk Factors

Types of heat-related illness:
  • Heat Rash. Heat rash is a series of red, blister-like marks with a burning or prickling sensation.
  • Heat Cramps. A heat cramp is an involuntarily and forcibly contracted muscle. It can also manifest itself as fibers of a muscle that don’t relax. Heat cramps are often caused by heavy sweating and large electrolyte losses.
  • Heat Exhaustion. Heat exhaustion is primarily caused by the failure to self-regulate body core temperature. Heat exhaustion is a more serious and advanced stage of heat-related illness. Untreated heat exhaustion can quickly progress to heat stroke.
  • Heat Stroke. In heat stroke, the body becomes so stressed that it can no longer regulate its own temperature. As a result, the body rapidly overheats.
Risk factors:
  • Direct Sun. The more direct sun you are working in, the hotter the environment.
  • Humidity.  Humidity (moisture in the air) interferes with sweat evaporating from the skin, thus interfering with the cooling of the body. The more humid it is, the less sweat can evaporate, and the less body cooling occurs. That’s why increased humidity increases the risk of heat-related illness.
  • Radiant Heat. Radiant heat is the transfer of heat energy through the air from sun and other sources such as asphalt, engines and dark surfaces. Heat can be reflected by these sources, increasing temperature.
  • Conductive Heat. Conductive heat transfers heat to the body by direct contact with heat sources such as tools, equipment and machinery.
  • Limited Air Movement. Limited air movement, such as when there is little or no wind, creates a hotter environment. Because less air is moving, less cooling of the body can occur.
  • Physical Exertion. The harder and longer you work, the hotter you become.
  • Protective Clothing. Wearing PPE such as rubber sleeves, gloves, switching suits, rain gear or respirators can hold heat to the body and inhibit cooling.
  • Personal Factors. Age, physical fitness, weight and overall health can impact the amount of heat your body can tolerate.
  • Medications. Some medications can make a person more sensitive to the effects of heat and many contribute to dehydration.
Posted: 6/6/2016 3:00:00 PM by Townsend Editor