Introduction: Noise exposure is known as a risk factor for hearing loss and one of its effects is noise-induced stress. Cortisol, as stress hormone- is used in noise-induced stress assessments studies. The aims of this study were:(1) measuring and comparing saliva cortisol concentrations in the morning and evening in normal work day and rest day between two groups, (2) assessing the relationship between industrial noise exposure and salivary cortisol concentrations between two groups.

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Material and Method: Two hundred male workers (100 industrial and 100 office employees) participated in this study. Morning and evening saliva samples were collected at 7 a.m and 4 p.m, respectively. Noise exposure levels were assessed by sound level meter and noise dosimeter. All measurements occurred in two days: one in rest day and other in working day. Descriptive statistics, paired and independent sample t-test and regression analysis were used as statistical tools with α=0.05.

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Result: On the rest day and work day, between morning salivary cortisol was no significant difference in two groups. Comparing evening cortisol concentrations in work day with rest day a significant difference was observed, in worker group, but it was not significant in the other group. The evening cortisol in the working day in was significantly higher among workers than officers.

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Conclusion: This study revealed that industrial noise exposure with levels higher than 80 dBA has a significant effect on salivary cortisol elevation.