Ahmad Mirzaei - Student Research Committee, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran.
Mostafa Shahmohammadi - Department of Occupational Engineering, Faculty of Health, Kermanshah University of Medical Sciences, Kermanshah, Iran.
Fazel Rajabi - Student Research Committee, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran.
Rasoul Mirzaei - Student Research Committee, School of Health, Hormozgan University of Medical Sciences, Hormozgan, Iran.
Abdolsattar Zare - Islam Abad E Garb Healthcare Network, Kermanshah University of Medical Sciences, Kermanshah, Iran.
Ehsan Bakhshi - Department of Ergonomics, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran.
Reza Kalantari - Department of Ergonomics, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran.

Background: Workload is defined as the amount of work assigned to employees. The imbalance of efforts and rewards may cause occupational stress. The present study aimed to assess the impact of workload-related factors on the effort-reward imbalance in various working groups at a gas refinery complex. Methods: This cross-sectional study was conducted on ۲۷۴ employees in five working groups in ۲۰۱۸. Data were collected using a demographic questionnaire, NASA TLX, need for recovery scale, and effort-reward imbalance (ERI) questionnaire. Data analysis was performed in SPSS version ۲۲. Results: In total, ۹۷ participants (۳۴.۳%) had the ERI score of more than one, and the imbalance was higher in the service workers. The ERI score was significantly correlated with the mental workload in the staff (P = ۰.۰۳۴) and engineering personnel (P = ۰.۰۴۵). A significant association was observed between the need for recovery and ERI score in the staff, engineering personnel, and middle managers (P < ۰.۰۵). Conclusion: The ERI score reduced with the reduction of workload-related factors through improving the workplace conditions, hiring sufficient employees, and proper rewards. Therefore, special attention must be paid to the needs of various working groups in order to enhance their working conditions.

Employees, Effort-reward imbalance, Need for recovery, Mental workload, Work characteristics.