Evaluating Effects of Heat Stress on Cognitive Function among Workers in a Hot Industry

Heat stress, as one of the most common occupational health problems, can impair operator's cognitive processes. The aim of this study was to evaluate the impact of thermal stress on cognitive function among workers in a hot industry. In this cross-sectional study conducted in Malibel Saipa Company in 2013, workers were assigned into two groups: one group were exposed to heat stress (n=35), working in casting unit and the other group working in machin­ing unit (n=35) with a normal air conditioning. Wet Bulb Globe Temperature was measured at three heights of ankle, abdomen, and head. In order to evalu­ate the effects of heat stress on attention and reaction time, Stroop tests 1, 2, and 3 were conducted before starting the work and during the work. A significant positive correlation was observed between WBGT and test duration (P=0.01) and reaction time of Stroop test 3 (P=0.047), and be­tween number of errors in Stroop tests 1, 2, and 3, during the work (P= 0.001). Moreover, Stroop test 3 showed a significant higher score for both test dura­tion and reaction time of workers in case group. Results of the present study, conducted in a real work environ­ment, confirmed the impairment of cognitive functions, including selective at­tention and reaction time, under heat stress conditions.