Effects of Exercise-Heat Stress While Wearing Five Toxic Agent Protective Systems

摘要

This study evaluated heat strain in four developmental toxic agent protective systems relative to the standard Toxic Agent Protective (TAP) suit during exercise-heat stress. Eight subjects (6M,2F) completed five experiments in a 38 deg C, 30% rh climate, wearing: (1) Self Contained Toxic Agent Protective Outfit (STEPO) with rebreather (STEPO-R); (2) STEPO with tether (STEPO-T); (3) Improved Toxicological Agent Protective (ITAP) suit with Self- Contained Breathing Apparatus (ITAP-SCBA); (4) ITAP with blower (ITAP-B); and (5) TAP. Experiments were treadmill walking at 0.89 m.sec-1, 0% grade, exercise/ rest cycles of 20/10 min, for 240 min in STEPO and 120 min in ITAP. Mean metabolic rates were: (1) STEPO-R, 298+/-26 W; (2) STEPO-T, 299+/-34 W; (3) ITAP-SCBA, 275+/-26 W; (4) ITAP-B, 255+/-27 W; and (5) TAP, 222+/-40 W. In STEPO, subjects received whole body cooling at; STEPO-R, 200+/-36 W; and STEPO- T, 186+/-59 W. In ITAP, subjects received shirt only cooling at: ITAP-SCBA 172+34 W; and ITAP-B, 178+/-41 W. TAP had no cooling. Comparisons were not made between STEPO and ITAP systems. Exposure time was longer (p<0.03) in STEPO-R (83+/-22 min) and STEPO-T (106+/-39 min) than in TAP (46+/-10 nun). Exposure time was longer (p<0.05) in ITAP-SCBA (85+/-20 min) and ITAP-B (87+/-25 min) than in TAP(46+/-10 min). Rate of heat storage (S) was less (p<0.05) in STEPO-R (37+/-8 W.m-2) and STEPO-T (38+/-12 W.m-2) than in TAP (77+/-15 W.m-2). S was less (p<0.05) in ITAP-SCBA (51+/-16 W.m-2) than in TAP (77+/-15 W.m-2). Microclimate cooling significantly reduced S in three of four systems and increased exposure time in all four systems relative to TAP.