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Health Promot Perspect. 2014 Dec 30;4(2):240-6. doi: 10.5681/hpp.2014.031. eCollection 2014.

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

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Department of Occupational Health Engineering, Tehran University of Medical Sciences, Tehran, Iran.
Department of Epidemiology and Biostatistics, Tehran University of Medical Sciences, Tehran, Iran.



Heat stress, as one of the most common occupational health problems, can impair operators' 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.


Attention; Reaction Time; Stroop Test; Thermal Stress; Wet Bulb Globe Temperature

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