Design of job rotation schedules managing the exposure to age-related risk factors

Repetitive work involving manual handling of low loads at high frequency frequently leads to deteriorated posture and movement co-ordination, causing occupational diseases as the most common work-related musculoskeletal disorders (WMSD). Older workers are more predisposed to develop WMSD than younger workers because of their decreased functional capacity. The susceptibility for developing WMSD or injury is related to the difference between the demands of work and the worker's ability to perform a demanded activity. Current law requires the adoption of risk control measures to eliminate or reduce the exposure of workers to health and safety risk factors. When repetitive handling is unavoidable, job rotation is an effective risk control method to minimize the exposure of workers to the risks of repetitive movements and awkward postures. This paper presents a mathematical model for the design of activity schedules for aged workers exposed to the risk of repetitive work. The aim is to define the scheduling of the work activities for each worker from a bi-objective perspective. The first objective is to reduce the ergonomic risk of repetitive work by varying the required movements and their intensity during the work shift. The second objective charges the workers with the activities that better fit their skills and abilities. Finally, the proposed model includes the ergonomic risk assessment of each scheduling solution, ensuring an acceptable exposure of the workers to the risk of repetitive work.