Heat stress measurement according to WBGT index in smelters

Thermal stress is one of disturbing physical polluting factors of work environment. A wide spectrum of complications and diseases from mild disorders such as burn sensation to lethal conditions such as thermal shock may occur, due to uncontrolled thermal stress. This study was performed to evaluate thermal stress in one of Tehran's smelteries according to WBGT index and to present control methods. In this descriptive cross-sectional study, four stations were selected in one of Tehran's smelteries which its staff was exposed to heat directly and indirectly and stages of evaluation and measuring thermal stress were performed on four successive days of mid-August, in year 2006. Glass thermometer, wet bulb thermometer, standard globe thermometer and silvered Kata thermometer with K=420 and range of 52-55C° were used respectively for measuring dry, natural wet and radiant temperature and air velocity. Data were manually analyzed using descriptive statistics. WBGT was less than threshold limit value in forging strain and cutting stations in summer of 2006. WBGTTWA was estimated 27.49C° in foundry platform, which showed that its workers were exposed to higher thermal stress than allowed, compared to threshold limit value for heat exposure according to ACGIH suggestion. Atmospheric conditions are not favorable for work in foundry platform in summer season and measures should be taken in order to control radiant heat.