Psychophysical Responses of Waste Workers in Lifting Tasks at Two Different Levels

Manual Material Handling (MMH) is one of the key problems related to musculoskeletal disorders at the occupational settings. It is essential to assess the risk related to these tasks. The psychophysical approach can be used to assess and redesign the MMH tasks. Following a psychophysical approach and bearing in mind the specific problem faced by waste workers in a Portuguese hospital, this work aimed to determine, the Maximum Acceptable Weight (MAW) for the tasks of BIOBOX’s lifting. Two different levels of BIOBOX’s were assessed based on workers’ usual tasks. The subjects were instructed to lift the box from the height of 110 cm and 174 cm (handling height) up to the height of 84 cm, the same height of the truck. Each set of experiments was conducted for 10 minutes. The heart rate was continuously monitored. At the end of each task, the MAW was achieved and subjects were requested to assess the Index of Perceived Exertion (IPE). The MAW determined at 110 cm and 174 cm was, respectively, 10.0 kg and 6.8 kg. The regions of the shoulders, arms and back were identified as presenting more pain during the tasks. The results show that workers are at risk of musculoskeletal disorders. Therefore, a strategy to reduce the risk related to these tasks is needed.