Shiftwork in the hot environment.

The study examined the risks of heat induced workplace accidents (textile industry, N = 4125) and the heat tolerability of the rotating day (morning and afternoon, N = 16) and permanent night shift workers (N = 13) in hot-dry and hot-humid environment (34 to 49 degrees C, 50-80% RH; 31 to 42 degrees C ET, Basic). Accident prevalence was significantly high in the summer months (May-June) when the ambient temperature ranged between 42 and 48 degrees C (hot-dry). The influence of hot climate in accident causation was evident from the shift-wise variations in the occurrence of accidents. The longitudinal study showed that the night workers were more vulnerable and less tolerant to heat, the tolerance time being less by about 15% (31 degrees C ET) to 40% (39 degrees C ET), compared to the rotating day workers. The relationship of the segmental and compartmental temperatures (segmental triggering response) played a critical role in heat dissipation/accumulation mechanism, and reflected in the heat tolerability of the day and night workers.