How Does Heat Exhaustion Occur?
by Contributing Writer
About Heat Exhaustion
Heat exhaustion is the most common heat-related illness. While it is normally the result of overexposure to high temperatures, it can also be caused by prolonged exercise in higher heat environments, or the impact of medications or illicit drugs on the body's thermoregulatory system. Heat exhaustion can quickly progress to heatstroke, which is a serious medical emergency.
The body has several ways of cooling itself, notably through thermal radiation and perspiration. Thermal radiation is the transfer of body heat into the air through electromagnetic waves, and this normally accounts for 65 percent of the body's heat loss. However, when the air temperature is 95 degrees or higher, radiation heat loss ceases, as the difference between air temperature and body temperature is no longer significant.
The body can now only cool itself through perspiration, or the evaporation of sweat off the body. Evaporation accounts for 30 percent of the body's heat loss, and is normally sufficient to keep the body cool in high temperatures. But this can change rapidly once a person becomes dehydrated, which can happen quickly in hot conditions, especially if the person is engaging in physical activity. Dehydration causes perspiration to slow and then stop. Body temperature now begins to rise, causing hyperthermia.
Heat Exhaustion and Heatstroke
Heat exhuastion has symptoms similar to a viral illness, including fatigue, dizziness, fainting, nausea and a temperature of 100 degrees or more. If heat exhaustion is not treated, body temperature continues to rise, and the condition progresses to heatstroke. Heatstroke is when the body reaches a dangerously high temperature of 106 degrees or more, which causes brain and organ damage, and will result in death if untreated.