Caretti David M, Barker Daniel J
a U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground , Maryland.
J Occup Environ Hyg. 2014;11(5):269-81. doi: 10.1080/15459624.2013.858819.
This investigation assessed the thermophysiological and subjective impacts of different respirator ambient air cooling options while wearing chemical and biological personal protective equipment in a warm environment (32.7 ± 0.4°C, 49.6 ± 6.5% RH). Ten volunteers participated in 90-min heat exposure trials with and without respirator (Control) wear and performed computer-generated tasks while seated. Ambient air cooling was provided to respirators modified to blow air to the forehead (FHC) or to the forehead and the breathing zone (BZC) of a full-facepiece air-purifying respirator using a low-flow (45 L·min(-1)) mini-blower. An unmodified respirator (APR) trial was also completed. The highest body temperatures (TTY) and least favorable comfort ratings were observed for the APR condition. With ambient cooling over the last 60 min of heat exposure, TTY averaged 37.4 ± 0.6°C for Control, 38.0 ± 0.4°C for APR, 37.8 ± 0.5°C for FHC, and 37.6 ± 0.7°C for BZC conditions independent of time. Both the FHC and BZC ambient air cooling conditions reduced facial skin temperatures, reduced the rise in body temperatures, and led to more favorable subjective comfort and thermal sensation ratings over time compared to the APR condition; however statistical differences among conditions were inconsistent. Independent of exposure time, average breathing apparatus comfort scores with BZC (7.2 ± 2.5) were significantly different from both Control (8.9 ± 1.4) and APR (6.5 ± 2.2) conditions when ambient cooling was activated. These findings suggest that low-flow ambient air cooling of the face under low work rate conditions and mild hyperthermia may be a practical method to minimize the thermophysiological strain and reduce perceived respirator discomfort.
本研究评估了在温暖环境（32.7±0.4°C，相对湿度49.6±6.5%）中佩戴化学和生物个人防护装备时，不同呼吸器环境空气冷却选项对热生理和主观感受的影响。10名志愿者参与了90分钟的热暴露试验，试验中他们分别佩戴和不佩戴呼吸器（对照），并在就座时执行计算机生成的任务。使用低流量（45 L·min⁻¹）微型鼓风机，对全面罩空气净化呼吸器进行改装，使其向额头（FHC）或额头及呼吸区域（BZC）吹气，从而实现环境空气冷却。还完成了未改装呼吸器（APR）的试验。在APR条件下观察到最高体温（TTY）和最不利的舒适度评分。在热暴露的最后60分钟进行环境冷却时，无论时间如何，对照组的TTY平均为37.4±0.6°C，APR组为38.0±0.4°C，FHC组为37.8±0.5°C，BZC组为37.6±0.7°C。与APR条件相比，FHC和BZC环境空气冷却条件均降低了面部皮肤温度，减少了体温升高，并随着时间推移带来了更有利的主观舒适度和热感觉评分；然而，各条件之间的统计差异并不一致。在启动环境冷却时，与对照组（8.9±1.4）和APR组（6.5±2.2）相比，BZC组（7.2±2.5）的呼吸设备平均舒适度得分在暴露时间方面存在显著差异。这些结果表明，在低工作强度条件和轻度体温过高情况下，对面部进行低流量环境空气冷却可能是一种将热生理应激降至最低并减少呼吸器不适感的实用方法。
