The Multitask General Exposure Index (MultiGEI): An original model for analysing biomechanical risk factors in multitask jobs featuring weekly, monthly and annual macro-cycles

Abstract The assessment of exposure to biomechanical risk factors requires multiple different working risk factors to be considered and integrated in some way to determine overall exposure levels and risk. A particular challenge is posed when workers rotate between different tasks not only on a daily basis but over longer macro-cycles (which may be weekly, monthly, or even annual). There may be large numbers of rotated manual tasks, each with a different level of exposure and distribution pattern. This makes the multitask analysis more complex insofar as it must factor in multiple work activities over extended periods of time. This article presents a new general model specifically adapted to evaluating multiple tasks rotating over longer macro-cycles: the MultiGEI (Multitask General Exposure Index). The MultiGEI model uses similar criteria to current models to study daily rotations in tasks involving repetitive movements and exertions of the upper limbs (OCRA method) and manual lifting (the Revised NIOSH Lifting Equation or RNLE and Sequential Lifting Index). It can be applied to a variety of production and service sectors (agriculture, building construction, cleaning, retail, packaging, canteens, healthcare, etc.). It can also be applied to data obtained by other methods (other than OCRA and RNLE, here not presented) that specifically consider the relevant aspects of which tasks, their duration and their intrinsic risk score. The proposed approach is presented along with examples of applications, and advantages and limitations are discussed. A video showing examples of calculations carried out using free software, is also available.