Wet-bulb globe temperature index: a predictor of physiological strain in hot environments

The readings of the natural wet-bulb (tnwb) and globe thermometer for computing Twbg index (indoors) were taken between 08.00 to 17.00 h at two-hour intervals in different work locations in the glass bangle and brassware industries. For assessing the physiological reliability of the Twbg index for heat stress, the radial pulse rate was monitored at two-hour intervals in 60 brassware workers and 77 glass bangle workers (mean ages: 25.3 +/- 8.8 and 28.1 +/- 5.7 years) belonging to various occupations exposed to thermal radiation for 9.3 +/- 8.5 and 11.2 +/- 4.8 years respectively. The mean values of Twbg index observed in the brassware and glass bangle industries were found to be almost of the same order (34.4 +/- 3.0 degrees C and 35.2 +/- 1.1 degrees C). The radiant heat seemed to make the most significant contribution to the environmental heat stress in these industries. The globe temperature near the main melting furnace was as high as 53.8 +/- 3.0 degrees C and 59.2 +/- 4.02 0C in the glass bangle and brassware industries respectively. It was, therefore, expected that the exposed workers would show pronounced physiological strain. Surprisingly the pulse rates of these workers did not indicate any significant physiological strain since the maximal pulse rates recorded did not exceed the safe limits of circulatory strain recommended by the WHO.(ABSTRACT TRUNCATED AT 250 WORDS)