The physiological responses of human subjects have been investigated in the thermal environments ranging from 120 to 240 deg F while wearing the MA-2 ventilating garment, an MK-IV exposure suit, and other garments comprising 2.15 clo2 of thermal resistance. The ventilating garment was given air inputs ranging from 2 to 14 cfm in volume, and from 50 to 90 F in temperature. The thermal responses of the subjects are shown graphically in terms of heat storage, heart rates, sweat rates, and composite indexes of these variables. The results of these experiments have been prepared in terms of an equation which is presented graphically as a nomograph. This nomograph predicts the cooling power of the MA-2 ventilating garment and is to be used in conjunction with the tolerance chart. The tolerance data, which were determined on steady exposures in a preheated chamber, are used to predict human tolerance for conditions where the air and wall temperatures are not constant.

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