High humidity, however, reduces or eliminates the cooling effect of perspiration and respiration. The public should avoid the use of fans without refrigerated air during excessive heat since the movement of hot humid air will accelerate the body heating and raise the internal body temperature. Heat-related illness may begin with heat exhaustion which is characterized by fever, headache, nausea and weakness. Heat exhaustion should be treated with shade and cool water. If the body is not cooled at this point, heat stroke may follow.
Heat stroke causes blood clots and heart failure.
Without proper treatment, heat stroke is fatal 80 percent of the time. To avoid the ill effects of high heat, increase water consumption well before the onset of thirst. Alcoholic beverages are discouraged in high heat conditions because they cause dehydration. Fruit juices are a good substitute for water, and if exercising, sports drinks are encouraged.