Comparative Evaluation of Manual Material Handling Using of Snook Tables and NIOSH equation Methods in Stone cutting workshops

Activities and tasks of Manual Material Handling (includes lifting, carrying, lowering, pulling and pushing) are very common in work environments. The aim of this study was to determine the prevalence of musculoskeletal disorders and comparative evaluation of Manual Material Handling using of Snook Tables and NIOSH equation Methods in Stone cutting workshops. This cross-sectional study was carried out on 100 workers in stone cutting workshops in 2017. Snook Tables and NIOSH Equation methods and general Nordic questionnaire were used for the assessment of Manual Material Handling duties and the incidence of musculoskeletal disorders, respectively. Finally, these two methods were compared in terms of agreement on risk assessment. The results showed that the 48% of the workers had experienced pain at least once during the past year with highest frequency in the low back (48%), elbows (44%) and shoulders (36%). Loads of weight were more than the recommended weight limit (RWL) obtained from the NIOSH equation and the tables were Snook. The evaluation results of both methods showed that the risk level was high in the different workshops. Comparison of two methods showed that the accuracy of two methods for risk assessment are quite different. The results showed that prevalence of musculoskeletal disorders is high among workers and ergonomic measures is necessary to improve working conditions. It seems that NIOSH Equation has higher accuracy and stricter than Snook Tables in the risk and RWL estimation