Human Biophysical Evaluation of a Permeable Hood Attached to a Chemical Protective Overgarment

摘要

This report focuses on the physiological and biophysical evaluation of a prototype 70-mil permeable hood integrated into the standard 90-mil chemical protective overgarment and its potential in reducing heat strain during continuous exercise. Each of 14 CB-trained Marines (in two groups of seven) did treadmill exercise (heat production, M=470W) in six randomized environmental sequences: ambient air temperature (Ta)=32 deg C/80% rh/V=1 m/s and 5 m/s, 35 deg C/50% rh/V=1 m/s and 5 m/s, and 43 deg C/20% rh/V=1 m/s and 5 m/s. Each group used a similar uniform configuration each day until completion of the above environmental exposures, then altered the uniform configuration for additional runs. Uniform configurations were: permeable attached hood integrated to 90-mil standard overgarment (OG) in the closed configuration with underwear and MX-40 respiratory mask, (P-40); standard butyl rubber hood with OG and either the MX-40, (B-40) or the M17A respiratory mask (B-17). In general, use of a 70-mil permeable hood integrated hood integrated to a standard overgarment gave no significant advantages compared to a standard OG in reduction of: heat strain, improvement in vapor permeation to a given clo insulation and extension of endurance times. Although carbon-lined hoods offer optimal chemical protection for the head region, the use of a butyl hood with the M-40 mask suggests a preferable heat transfer option because of the reduced thickness of the hood (about 9 times less than the permeable hood) which offers an augmented im/clo with high wind speeds. (GC)