Iran Occupational Health

  Background and aims: Work-related musculoskeletal disorders (WMSDs) are the most prevalence problems of working populations in many developing countries and specifically in Iran. One of the most important disorders is Carpal Tunnel Syndrome (CTS) which has been reported in many industries, especially in workers of automotive companies. The aim of this study is the risk assessment of related factors of hand activity and combined effect of risk factors in occurring upper extremity musculoskeletal disorders (UEMSDs). In order to evaluate risk assessment the threshold of hand activity level technique (HAL_TLV) is used.

  Methods: The sectional descriptive-analytical method was used in this study. In this method 44 workman in the impulse and hydraulic press salons of automotive company was selected randomly, in addition sampling was carried out by censuses report. Data was collected through checklists of hand activity level (HAL) and normalized peak force (NPF) and also site observation. The results of combination of these variables were put in HAL_TLV graph, in order to evaluate the risk level of mentioned tasks. Data analyzing was done using SPSS18.

  Results: The Results shows that 31.25% (5 workman) was at risk level A (low risk) and 73.3% (11 workman) was at risk level B (moderate risk) in the impulse press salon and in the hydraulic press salon 3.57%(1 workman) and 96.4% (27 workman) of each group was at risk level A (low risk) and risk level C (high risk), respectively .The analysis of results indicates that there are reverse significant relationship between HAL and NPF in the salon of impulse press (p<0.014,r=0.881). Moreover the same result was obtained for two workman groups of the hydraulic press salon, as r=0.881, p<0.001 for group 1 and r=0.68, p<0.004 for group 2.

  Conclusion : The ergonomic risk assessment of hydraulic and impulse press salons shows hydraulic press compare to impulse press has the highest risk as level C (high risk) which may caused by excessive force with rapid and repetitive movements at this salon. Therefore it can be said, in occupations that workers must have set excessive force, the risk of upper extremity musculoskeletal disorders (UEMSDs) especially CTS may decrease via reducing the speed and repetition of movements. Finally the interaction between force, time and movement repetition may prevent musculoskeletal disorders.