Heat Stress negatively affects productivity and can lead to accidents, illness and even death. Prolonged exposure to high temperatures provokes fluid loss, muscular cramps, shock or heat stroke; it increases human error, reduces mental and physical activities. Monitoring heat stress in workplaces (thanks to WBGT and PHS indexes), to evaluate operative thermal conditions and define working exposure/rest times, is of primary importance to organize the work. Evaluation of heat stress in workers exposed to hot/dry conditions of industry is imperative for the management of heat stress.

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​A variety of indices were introduced for the evaluation of heat stress in hot environments. WBGT index (Wet Bulb Globe Temperature) is one of the best known and most widely used. It contains important environmental factors such as dry bulb temperature, wet bulb temperature and globe temperature. In the calculation of this index, factors such as clothing, level of metabolism and acclimatization are used.