Physiological evaluation of liquid-barrier, vapor-permeable protective clothing ensembles for work in hot environments.

Work clothes using fabrics with vapor-transmitting characteristics are in limited use in various industrial applications, and there is a growing interest in their purported ability to help reduce heat stress. This study was performed to compare two vapor-transmitting ensembles with other clothing ensembles previously tested. The evaluation was based on an established experimental protocol that determines the critical values of air temperature and water-vapor pressure so that an individual maintains thermal balance, while controlling other factors that contribute to worker heat stress (e.g., air motion and metabolism). There were no differences between the two vapor-transmitting garments in their effects on worker heat stress. When compared to the results of other studies, the two vapor-transmitting garments had critical environmental characteristics similar to two layers of cotton coveralls and they performed better from a heat stress standpoint than a disposable vapor-barrier suit worn over cloth coveralls.