Heat Stress When Wearing Body Armor
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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This study evaluated the heat strain induced by six configurations of a new modular body armor MBA design. Tests were conducted in two environments differing only by wind speed. The environments were 40 deg C 104 deg F, 20 rh, wind speeds 1.0 msec-1 2.2 mph and 2.5 msec-1 5.6 mph. The environments were chosen to maximize evaporative capacity. Six male subjects completed 12 experiments. The armor was worn at three wear levels open in front F, open at the sides S and fully closed C and at two protection levels partial armor P and total armor T. The six configurations were 1 MBA open in front, no shoulder or collar armor FP 2 MBA open at the sides, no shoulder or collar armor SP 3 MBA fully closed, no shoulder or collar armor CP 4 MBA open in front, all armor in place FT 5 MBA open at the sides, all armor in place ST and 6 MBA fully closed, all armor in place CT. Each day, subjects stood for a 5-minute rest, and walked for 100 minutes on a treadmill at approximately 425 watts moderate exercise. There were no significant differences in final core temperatures, final heart rates, rates of heat storage, sweating rates, and evaporative heat loss among the armor configurations in either environment. These results indicate that design changes allowing the armor to be worn at either open wear level and allowing for the removal of shoulder and collar armor do not effect heat loss under the conditions tested. These findings cannot be applied to high humidity environments or high work intensities.
- Stress Physiology