Fatigue induced by combined exposure to noise and whole-body vibration under simulated off-road heavy equipment driving conditions.

BackgroundFatigue, a complex state of lack of alertness, contributes to accidents, injuries, and death in different conditions. Previous research has studied the effects of noise and whole-body vibration (WBV) exposure on fatigue separately; however, there is little information about fatigue induced by combined exposure.ObjectiveThis experimental study aimed to investigate the combined effects of exposure to noise and WBV on fatigue.MethodsThirty young male participants were assessed for fatigue resulting from combined exposure to noise (85 dB) and WBV (0.87 and 1.3 m/s2) during five scenarios under simulated off-road heavy equipment driving conditions. Fatigue level was measured based on brain electrical activities as objective fatigue indicator and self-reported perceptions as subjective feeling of fatigue.ResultsThe results showed significant differences in the participants' objective and subjective fatigue after exposure to noise and/or WBV (p < 0.05). Single noise exposure affected the participants' objective fatigue the least while combined exposure to noise and WBV affected the participants' fatigue the most with effect sizes 0.465 and 0.868, respectively. There was a high correlation between objective and subjective fatigue measures (r = 0.826, p < 0.05). The findings demonstrated that subjective fatigue increased more in combined exposure to noise and WBV compared to separate exposure to the agents (p < 0.05).ConclusionsIt can be concluded that some interaction effects can occur in fatigue level in co-exposure to noise and WBV. It is verified that combined or even multiple exposures of drivers to harmful agents can be used in setting the action limit values.