Heat exchange during encapsulation in a chemical warfare agent protective patient wrap in four hot environments.
Tolerable encapsulation time in a Chemical Warfare Agent Protective Patient Wrap (dry insulative value = 1.44 clo; permeability index = 0.25) was determined in four hot environments including a simulated solar heat load (1152 W.m-2) for eight males. Mean body temperature (Tb), evaporative heat loss (EHL), dry heat gain (R + C), metabolic rate (M), and net heat flow (Msk) were measured or calculated from the heat balance equation. The ambient temperature (Ta) ranged from 54.7 degrees C (I) to 35.7 degrees C (IV) and the relative humidity ranged from 17% (I) to 63% (IV). EHL ranged from 173.5 W.m-2 (IV) to 277.8 W.m-2 (I) at min 30 of encapsulation. R + C ranged from -129 W.m-2 (IV) to -230 W.m-2 (I) at that time and Tb averaged 37.6(+/- 0.3) degrees C (IV) and 38.1(+/- 0.2) degrees C (I). The average time of encapsulation ranged from 61.8(+/- 0.2) degrees C (I). The average time of encapsulation ranged from 61.8(+/- 13.2) min (IV) to 38.4(+/- 5.0) min (I). A multiple linear regression equation to predict tolerable encapsulation was developed. These data show that tolerable encapsulation is severely limited in hot environments which have a marked solar heat load. A preliminary study (n = 2) indicated that encapsulation time in 54.7 degrees C/17%rh could be extended by some 23 min by covering the WRAP with wetted towels, thereby decreasing body heat storage by enhancing EHL from the surface of the WRAP.
Stephenson
L A
LA
U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760-5007.
Kolka
M A
MA
Allan
A E
AE
Santee
W R
WR
D001833:Body Temperature Regulation; D002619:Chemical Warfare Agents; D004781:Environmental Exposure; D006339:Heart Rate; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008889:Military Personnel; D011481:Protective Clothing; D013472:Sunlight / Q000009:adverse effects; D013484:Supination; D013546:Sweating; D013997:Time Factors
D002619:Chemical Warfare Agents