The relationship between noise annoyance and salivary cortisol

•The noise exposure causes the secretion of different stress hormones, including cortisol.•There was a direct and positive relationship between noise annoyance and cortisol secretion.•The salvia cortisol is an indication of noise annoyance. The noise exposure causes the secretion of different stress hormones, including cortisol. Since noise annoyance does not depend just on the level of noise, the main objective of this study was to examine the relationship between noise annoyance and salivary cortisol levels based on individual variables. 78 individuals from a car manufacturing company participated in this study which include two experimental groups (The first group was exposed to 75–85 dBA and the second to 85–95 dBA noise levels) and control group (the individuals in this group were exposed to 60–70 dBA noise levels). Saliva samples were taken once in the morning (6:30–7) and once in the afternoon (12–12:30) which were analyzed using IBL ELISA test kits. The degree of annoyance was measured using a noise annoyance questionnaire. The result shows that there was a significant relationship between cortisol level and work experience at the end of the work shift (P = 0.021). Also, there was a significant difference between the mean cortisol level at the beginning of the shift (15.50 µg per liter) and at the end of it (10.97 µg per liter) (P = 0.000). The study results showed that salivary cortisol levels were not significantly related to the annoyance level at the beginning of the shift (P = 0.942), but is significantly related to the level of noise annoyance at the end of the shift (P = 0.006). This study shows that there is a significant relationship between annoyance and cortisol secretion level after noise exposure.