RESPIRATORY AND THERMAL PHYSIOLOGY OF FACE MASKS

呼吸保护装置（面罩）必须 保护佩戴者免受周围空气中的颗粒和蒸汽的影响 当其他空气净化装置不可用时。 但许多 应该佩戴这些设备的工人没有佩戴，或者 在他们应该穿的时候把它们脱下来。 使用 人工空气供应到面具，设置在不同的组合， 温度和湿度，我们最近定义了热 舒适区，即面罩的温度条件 对于佩戴者来说是可接受的。 为编写本 应用，我们已经检查了多孔口罩，口罩与 过滤器和阀门，以了解它们如何干扰热量损失 从脸上。 似乎影响热效应的因素 这种面具的可接受性是：1）从辐射热损失 2）热传递通过所述表面， 面罩壁，3）面罩外表面的热损失 4）呼吸道与呼吸道之间的热传递 道，和吸入的空气和5）面罩空气之间的热传递， 面罩壁、呼出的空气和环境。 使用的设备 测量面罩的传热和温度梯度 包括热电偶、热敏电阻、热辐射计， 湿度传感器、传热盘和空气流量计。 这些 用于建立定量的热分布和热 口罩内外的传输率 恒定 温度室和自行车测力计用于设置 受试者的条件和工作量。 心理生理评定 使用量表来评估受试者的热舒适度。 面罩被修改以改变气流的模式， 热传递，重新评估舒适性和可接受性， 和客观的测量传热率和热 面具内外的渐变。 假设是 测试表明，面部的热不适是一个主要因素， 工人没有佩戴呼吸保护装置。

Respiratory protective devices (face masks) are required to protect to wearer from particles and vapors in the ambient air when other means of air purification are unavailable. But many workers who ought to wear these devices fail to put them on, or else take them off when they should be wearing them. Using an artificial air supply to the mask, set at different combinations of temperature and humidity, we recently defined the thermal comfort zone, i.e. the temperature conditions of the mask acceptable to the wearer. In preparation for the present application, we have examined porous masks, and masks with filters and valves, to find out how they interfere with heat loss from the face. Factors that appear to affect the thermal acceptability of such masks are: 1) Radiant heat loss from the face to the inner surface of the mask, 2) heat transfer through the wall of the mask, 3) heat loss from the outer surface of the mask to the environment, 4) heat transfer between the respiratory tract, and inspired air and 5) heat transfer between the mask air, mask wall, the expired air and environment. The equipment used to measure heat transfer and temperature gradients of face masks consists of thermocouples, thermistors, thermal radiometers, humidity sensors, heat transfer discs, and air flow meters. These are used to establish quantitative thermal profiles and heat transfer rates inside and outside the masks. A constant temperature room and cycle ergometer are used to set the conditions and work load for the subjects. Psychophsyical rating scales are used for assessment of thermal comfort of the subjects. The masks are modified to change the patterns of airflow and heat transfer, with reassessment of comfort and acceptability, and objective measurements of heat transfer rates and thermal gradients inside and outside the mask. The hypothesis to be tested is that thermal discomfort of the face is a major factor in workers not wearing respiratory protective devices.