Ergonomic Investigations of Asymmetrical Manual Lifting Tasks on Indian Male Workers

Abstract

In India, manual material handling tasks are very common in manufacturing industry and construction sites. Manual lifting activities involve moving construction materials at sites loading and unloading of jobs on machines or lifting and moving materials from one location to another with varying frequency and sometimes with asymmetrical postures. The incidence, severity and potential disability of musculoskeletal injury are in many cases directly related to the kind of manual material handling jobs entrusted to the workmen in the workplace. There is thus a need for a scientific study to investigate into the effect of performance of such jobs on human health. The present research work was undertaken to carry out experimentation on healthy workmen using different task parameters during manual material handling and determine the safe limits and a parametric combination of lifting tasks. The work was completed in two phases. In the first phase, an experimental study was conducted to evaluate the effect of lifting task parameters and their interactions in different ambient temperature conditions on the heart rate and oxygen uptake of workers involved in manual lifting tasks. Workers were involved in lifting a loaded container from different levels asymmetrically and placing these at target locations at different levels as per the designed experimental conditions. Experiments were conducted in two different ambient temperature conditions. The climate of north western region of India has extreme variation of temperature over the year. The temperature in summer varies between 30 and 45° C while in winters, the minimum temperature goes even below 50 C on some days. Further, high humidity levels cause very harsh work conditions for workers involved in manual material handling tasks. Therefore effect of environmental conditions (heat and cold) should be considered as an integral component of the lifting process.