Ergonomics evaluation of working posture adopted by women engaged in small scale industries

In India a good number of women workers, engaged in small scale industries, perform various tasks in a squatting-on-the-floor posture. Sometimes they use a patla (wooden plank) for sitting. Most of them suffer from severe cervical and lumbar joint problems along with knee and hip joint pains, as evident from their medical reports. To understand whether the continuous sitting-on-floor posture is the culprit for this kind of problem, and whether it can be rectified, a study was conducted with an aim for better designing of work stations for small scale industry. The study examined the work posture of 75 women workers (experimental group) engaged in a small scale industry performing the task of sorting, inverting and packing socks. The worker women had to maintain a constant seated position (squatting cross-legged) on the floor. Along with the worker group, an equal number of housewives belonging to the same socioeconomic status were also studied as a control group, these women never acquired such kinds of postures for prolonged periods. To ascertain the effect of work posture both qualitative and quantitative assessment procedures were followed for both the groups. The qualitative evaluation, which consisted of a questionnaire and direct observation, revealed that long term seated work had a cumulative load on the musculoskeletal structures, including the vertebral column which was reflected in the form of high prevalence of discomfort and pain in different body parts. The quantitative methods were grouped under the following headings, namely: anthropometric, biomechanical, physiological and psychophysiological issues. The methods were used both in the field and in laboratory studies. With the help of a simulated laboratory setup, using a forward-downward sloping patla with an adjustable top surface, it became evident that an angle around 12° of forward-downward slope was the most comfortable angle from the viewpoint of the electromyographic responses of the postural muscles and the worker´s comfort. A significant shift in the centre of gravity location towards the body was observed with the increment of the seat angle, which may be the reason of reduced postural muscular activity resulting in better comfort