Investigating the acute effects of combined exposure to heat and noise on human brain waves and perceived workload

The prevalence of multiple health hazards in various industries is on the rise, with noise and heat being common harmful factors in industrial environments in Iran. This study aimed to examine the immediate effects of simultaneous exposure to thermal stress and noise on human brain waves and perceived workload. Seventy-two students (36 men and 36 women) participated voluntarily in this study. Participants were subjected to varying levels of noise exposure, including four noise levels and heat stress (three levels of Wet Bulb Globe Temperature) for 30 minutes each. EEG recordings were conducted for 10 minutes, with participants allowed a 30-minute rest period between each test condition. The combined exposure to noise and heat at two high levels (SPL95+WBGT34 and SPL95+WBGT29) resulted in a significant increase in perceived mental workload compared to the baseline state (P<0.05). EEG analysis indicated a decrease in absolute alpha power in the two high-level conditions compared to the baseline (t<0), while absolute beta power showed a significant increase in the two high-level conditions compared to the baseline mode (SPL45+WBGT22). The study demonstrated that simultaneous exposure to noise and heat, leading to an elevated perceived mental workload, was associated with decreased absolute alpha power and increased absolute beta power in the frontal and occipital regions. These findings suggest that these changes serve as reliable indicators of cognitive and physiological performance.