Heat stress: a threat to health and safety.

This review offers a rational basis for the use of fundamental physiological controlling mechanisms in setting safe environmental limits for occupational situations where heat stress is encountered. There is no single index of heat stress that has been universally accepted. However, the use of wet bulb glove temperature (WBGT) has been adopted by various organizations on occupational health and safety in several industrial countries. Thermal limits suggested for everyday work continue to be subject to argument. The controversies arise from the fact that many factors such as individual variations, acclimatization, clothing, age, sex, physical fitness and work load lead to significant effects on tolerance of man to heat. Several measures for prevention of heat stress under industrial situations are summarized briefly. There is no agreement on a single measure to be used, rather a combination of these measures can be the most effective mean to alleviate or prevent severe heat stress. It is to be hoped that this review may help public health officials and medical doctors of various work occupations resolve some of the problems that arise in setting thermal limits and preventive measures, thus contributing to increase productivity and efficiency of work.