Above which level of heat stress index it is not possible to work comfoably -: (A) 20 - 40, (B) 40 - 60, (C) 60 - 80, (D) 80 - 100
Answer is B. 0 No thermal stress 10-30 Moderate to mild heat strain 40-60 severe heat strain 70-90 very severe heat strain 100 upper limit of heat tolerance Park's Textbook of Preventive and Social Medicine, 25th edition, Page No. 807