Effectiveness of an Air-Cooled Vest in Reducing Heat Stress of Soldiers in Chemical Protective Clothing

摘要

This study evaluated the effectiveness of an air-cooled vest in reducing physiological strain of soldiers in chemical protective clothing during exercise-heat stress. Four male soldiers attempted a 12-hour and a 3-hour heat exposure while wearing chemical protective clothing and an air-cooled vest (air supplied to vest = 16 C db, 3 C dp; 15 scfm to torso, 3 scfm to face). During these exposures, subjects performed repeated bouts of rest and treadmill walking: metabolic rate averaged 240 and 340 W for the 12- and 3-hour tests, respectively. Environmental conditions were 49 C db, 20 C dp; a radiant heat load of 70 W was added during the 3-hour test. All subjects were able to complete the 12- and 3-hour tests. Mathematical equations predicted tolerance times for the 12- and 3-hour tests with no auxiliary cooling to be about 110 and 80 min, respectively. During the 12-hour test, final rectal temperature (exercise) averaged 38.0 + or - 0.3 C and peak rectal temperature did not exceed 38.5 C for any subject. Final heart rate (exercise) averaged 140 + or - 19 b/min. Sweating rate averaged 275 + or - 19 g/sq m/hr. During the 3-hour test, final rectal temperature averaged 38.5 + or - 0.6 C and peak rectal temperature did not exceed 39.2 C for any subject. Final heart rate (exercise) was 150 + or - 15 b/min. Sweating rate averaged 566 + or - 50 g/sq m/h. The air-cooled vest was effective in reducing physiological strain, and increasing tolerance time, of soldiers during exercise-heat stress. In addition, soldiers rated the heat exposures with the vest as thermally comfortable.