Among the most important complaints of people exposed to noise are the feelings of resentment and annoyance, and the changes in mental conditions, which are among the main psychological consequences affecting the concentration and accuracy of workers. This study was designed to investigate the relationship between annoyance and cognitive performance of workers exposed to chronic noise. This is a descriptive-analytical study conducted on workers in an automotive company. Three hundred workers exposed to noise were entered into the study in two groups: administrative (150 people) and industrial (150 people). The Tower of London and the Stroop computerized psychological tests were used to determine the cognitive status of the workers, and a questionnaire with numbered questions (numbered 1 to 11) was used in order to determine their level of annoyance. There was a significant correlation between the workers' cognitive performance and annoyance levels (P value <0.001). Linear regression results showed that cognitive performance had a significant relationship with the received sound intensity, while the workers' annoyance had a significant relationship with cognitive performance only in the number of wrong answers, the number of unanswered questions, and the number of correct answers in the Stroop test (P value <0.001). The researchers concluded that exposure to chronic noise in work environments could bring about occupational annoyance, and consequently, cognitive disorders, which could increase the risk of errors. More studies are needed to further explore this relationship.

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Regarding the important role of occupational health in the continuous improvement of organizations, the aim of this study was to identify, select and prioritize key indicators for improvement of occupational health in an automotive company. This cross-sectional descriptive study was carried out in three stages. First, a semi-structured interview as well as an inspection and a review of the companyʼs documentation and studies were carried out, and a set of key indicators were identified and selected. Then, the validity of the indicators were determined by experts (N = 11). Following that, the indicators were prioritized based on SMART criteria. Following the study framework, we collected a set of indicators that included 45 health indicators and 17 educational ones. The results of examining their content validity showed that among the 45 primary health indicators and 17 educational ones, 12 and 9 indicators had acceptable validity, respectively, and a total of 21 indicators were suggested for the purpose of the study by the expert team. The results of prioritizing showed that the leading indicator such as the percentage of corrective and preventive health actions done with the weight of 0.146 was the first priority. A set of key indicators was proposed according to the results, based on the objective of the study, which can help managers and industrial hygiene experts to assess performance in the automotive industry.

Background: Chronic exposure to noise in workplaces is one of the most important physical agents that affects workers’ health and causes social and individual problems. The aim of this study was to investigate the relationship between noise annoyance and blood pressure (BP) of workers of an automotive industry. Methods: In this cross-sectional study, 250 workers were randomly selected. The subjects were classified in two groups based on the exposure to sound pressure levels lower and higher than 85 dB (106 and 144 workers, respectively). In this study, BP was measured using an ALPK2 mercury pressure gauge. To measure annoyance levels, an annoyance questionnaire containing a numerical question numbered 0–11 was used. Results: The mean age of the subjects was 36.19 (±3.75) years. The results showed that the systolic (SBP) and diastolic blood pressure (DBP) of the subjects exposed to the sound pressure levels higher than 85 dB were significantly higher than those exposed to a sound pressure level lower than 85 dB ( P < 0.01). Also, the results of the multivariate regression showed a significant relationship between the annoyance and DBP and SBP caused by chronic exposure to noise and sound pressure levels ( P < 0.01). Conclusion: The results of this study showed that the annoyance caused by exposure to chronic noise in the workplace causes stress in the workers and, in the long term, could increase the risk of high SBP and DBP.

Background: Noise is considered as one of the most significant and dangerous physical factors in work environments, and due to the advancement of industries, it has become a threat to physical and psychological health in the current era. In addition to its undesirable effects on the hearing system, noise can have harmful non-auditory effects that may cause physiological disorders and cognitive impairment. Objectives: This study aimed to investigate the relationship between hearing loss and workers’ cognitive performance in an industrial environment. Methods: A total of 300 individuals were enrolled in this study after their informed consent was obtained, and their compliance with the inclusion and exclusion criteria was confirmed. Based on the sound intensity level, the individuals were classified into two groups of exposure to > 85 dB (n = 196) and ≤ 85 dB (n = 104). To measure the individuals’ occupational exposure at an 8-hour equivalent level based on the ISO 9612: 2009 standard, the Testo device (Model CEL-815) was used with the precision of 0.5 dB. The most common weighting that is used in noise measurement is A-weighting. Like the human ear, this effectively cuts off the lower and higher frequencies that the average person cannot hear. The DANPLEX-AS54 device was also used to check audiometry. To investigate the workers’ hearing performance, two psychological tests, namely Stroop and TOL, were used as well. Results: Hearing loss was higher among workers exposed to a sound intensity level of > 85 dB than those exposed to a sound intensity level of ≤ 85 dB, and this difference was significant in all sound level frequencies (NIHL left ear: for ≤ 85 dB: 25.92 and for > 85 dB: 27.49) (NIHL right ear: for ≤ 85 dB: 27.62 and for > 85 dB: 29.50) (P value < 0.05). The results showed a significant positive relationship between cognitive indicators and hearing loss (P value < 0.05). Moreover, the study of cognitive indicators in the two groups revealed that the mean change of cognitive performance indicators was higher among subjects exposed to a higher sound intensity level (P value < 0.05). Conclusions: The results of this study showed that noise-induced hearing loss in work environments had a significant positive relationship with cognitive indicators. In other words, an increase in the hearing loss level would result in changes in cognitive indicators such as number of errors and response time.