Iranian Journal of Ergonomics

Introduction: The progress of technology and modern technology has changed today’s workplaces and imposed more mental and cognitive demands to workers. Control room is an example of these workplaces. Currently, assessment of mental workload is a key point in the research and development of human-machine relationships in workplaces. This study aimed to validate an analytical approach in evaluating demanded mental workloads for control room operators in Pars combined cycle power plant.

Methods: This was a fundamental-practical and cross-sectional study. First of all, a task analysis was used to understand the operation steps of control room operators. Then, the Visual, Auditory, Cognitive, Psychomotor (VACP) technique was applied to determine the mental workload demanded for performing each step of the works. Finally, the assigned ratings of the VACP method were validated by the analysis of Pearson’s correlation with the answers of the NASA-Task Load Index (NASA-TLX) questionnaire, collected from the control room operators.

Results: Based on the results, the correlation between the assigned ratings of VACP technique and the answers of the NASA-TLX questionnaire was positive and significant.

Conclusions: Due to the high correlation between the assigned ratings of VACP technique and the answers of the NASA-TLX questionnaire, the proposed VACP technique, which can be carried out in the early stage of the design, was suitable as an analysis tool for predicting metal workloads of control room operators.

Background and Objectives: Musculoskeletal disorders cause about half of all work-related disease, and are the major cause of loss of time, increased costs, and labor injury. This study aims to evaluate the workload and its association with the prevalence of wrist disorders. It was carried out in the assembly workers of a manufacturing industry.
Methods: This cross-sectional study was conducted among 120 female workers employed. Theit mental workload, physical workload and prevalence of wrist MSDs were evaluated using the NASA-TLX, the OCRA method and the Nordic wrist and hand scan questionnaire respectively.
Results: The NASA-TLX showed that the physical demands and effort with mean scores of 78.79 and 78.37 were respectively the most important subjective mental workload (SMWL) scale. Also The results on the basis of the OCRA risk level showed that the highest right-hand risk was at risk level 3 and the highest left-hand risk was at risk level 1 .The Statistical analysis showed that OCRA risk levels and mean scale physical demands and efforts were significantly higher in those with wrist pain than those without pain (P<0.05).There was a direct correlation between the severity of the wrist pain with the OCRA risk index in both hands (P=0.001) and the total score of NASA (r=0.232, P<0.05).
Conclusion: It was revealed that mental load was high in assembly lines of the manufacturing industry and this result was also confirmed by physical evaluation. This study indicated that overall score of SMWL can affect the incidence of MSDs. That is why mental workload should be considered as a risk factor for MSDs.