An Evaluation of the Heat Stress of a Protective Face Mask

Abstract

This paper examines the physiological response of a group of four volunteers working for 120 min in a warm environment, DB/WB 34/25-5°C, whilst wearing each of two clothing assemblies, KD and OG, with and without the UK NBC S6 respirator. The men were given 10 days training and heat acclimation prior to commencing the tests.

The clothing assembly OG produced a significantly higher level of heat stress when compared to the KD assembly. The stress of both assemblies was significantly raised by the inclusion of the mask. This was demonstrated by an increased sweat rata (KD only), increased rectal temperature, increased epigastric skin temperature, and an increased heart rate. Some of the increase in heart rate due to wearing the mask could not be attributed solely to changes in body temperature.

It is concluded that the protective face mask imposes a significant additional heat stress which increases with the level of the prevailing stress and would indicate a possible source of error in those calculations of heat stress which add the same constant for a clothing condition at all levels of stress.