A special thermal stress problem in ceramic industry.

While surveying the hygienic conditions in small to medium ceramic industries, it was noted that an acute thermal stress problem existed in kiln unloading operations being performed manually. A more detailed investigation of this problem in four typical ceramic factories confirmed that the thermal conditions imposed severe stress on the workers with WBGT values ranging between 43 and 54 degree C inside the kiln. However, the physiological strain experienced by even the workers who remain inside the kiln for unloading the saggers for 10 min or more at a tiem before coming out for a spell of rest was not excessive, except in a few cases. This suggests that the workers had fortuitously chosen, perhaps by experience, a work-rest schedule which did not prove too strenuous. It is considered that it would be desirable to regulate this operation in each factory on a systematic manner after necessary studies to rationalize the work-rest procedure.