Physiological Responses to Microclimate Cooling Used By the Air Soldier Dressed at MOPP 4 in an Extreme Desert Condition: Effects of Six Configurations.

摘要

This study supported the Technology Systems and Program Integration Directorate at the U.S. Army Natick Research, Development and Engineering Center as part of its effort to provide PM Air Warrior with the most effective MCCS for its personnel by evaluating the cooling potentials of two prototype MCCS. The two liquid vapor compression cooling units differed in size, weight, and cooling capacity. One system (LO) was 93 cubic inches, and weighed 3.2 kg, with a cooling capacity of 120 W. The other cooling unit (HI) was 201 cubic inches, and weighed 4.6 kg with a cooling capacity of 180 W. The purpose of this study was to support PM-Air Warrior's efforts to field lightweight portable MCCS for helicopter support crew working in hot environments who may be required to work up to 11 hours. During flight operations, Aircrew may have to wear complete CBRNE protective clothing and equipment, as well as body armor and helmets, while performing their duties. The insulation and low permeability of the garments impedes heat loss and the added weight of armor and equipment increases the metabolic rate. The net result is increased heat strain. This study determined how well two developmental MCCS reduced heat strain under these conditions, despite the additional load carriage (i.e. weight of the MCCS). The study also compared the effectiveness of the modified Army Combat Shirt (ACS) relative to the standard Air Warrior micro-climate cooling garment (MCG). After completing heat acclimation trials, eight male volunteers took part in 6 heat stress tests, with 6 clothing and equipment configurations all worn at MOPP 4. All tests were performed in a simulated extreme desert environment (51.7 C dry bulb (Tdb), 16.6 C dew point (Tdp) (14% rh), 1.3 m; sec- 1 wind speed). Each experimental trial consisted of three repeats of 35 minutes walking on a level treadmill at 3.2 km; h-1 (2.0 mph) followed by 25 minutes of rest, for a total heat exposure of 180 minutes. Time weighted mean metabolic rate during the experiments was 269 watts.