Assessing the recommended weight limit in manual carrying of loads in packaging lines of a factory in Qazvin

Background: Manual carrying of loads is one of the most important causes of occupational lumbago in workplaces. The reasons for application of recommended weight limit is due to injuries frequently occur in workers while pushing or conveying objects. Objective: The aim of this research was to assess the recommended weight limit in manual carrying of loads using NIOSH standard in Packaging lines of a factory within the industrial city of Qazvin. Methods: This was a descriptive cross-sectional study carried out in one of the factories of industrial city of Qazvin in 2008. Three palette workers who were selected randomly included in our study. On each palette, cartons were arranged in 4 rows each containing 16 cartons. From 16 points on each row, 8 points were selected for assessment. Later, through determination of the multipliers of load lifting, the RWL (resistible weight limit), which is the final product of this equation, was obtained and the LI (lifting index) of each worker calculated. Calculations (definition of variables and coefficients as well as calculation of RWL and LI) and drawing of diagrams were performed using Excel program. Findings: Considering the recommended RWL, the box weight used in this study (15 kg) was heavier than the recommended weight limit (9.55 kg for origin and 7.33 kg for destination) and the LI was excited in all cases. Conclusion: By correcting the coefficients associated with load lifting height, distance of load displacement, and turning angle of the body, the LI can decrease to a great extent.