Modeling of moisture evaporation from the skin, eyes, and airway to evaluate sensations of dryness in low-humidity environments

Abstract

Occupants of low-humidity environments often complain of a sensation of dryness. According to the results of a questionnaire administered to 1000 Japanese office workers, 70% of that population experiences dryness during dry seasons. It is therefore important to clarify the environmental conditions that cause discomfort due to dryness and control the indoor environmental conditions to avoid such discomfort. For the purpose, this study aims at creating a numerical model to predict the sensation of dryness under certain environmental conditions. Since one of the causes of dryness would be the high evaporation rates from the body part where dryness is perceived, the modeling of moisture evaporation from the surface of skin, eyes, and airway was studied in this article, using the thermal model of human body. At the same time, the evaporation rates from the skin surface, eyes, and airway of a human were calculated for various air temperatures and humidity levels. It was shown quantitatively from the calculated results that the air temperature as well as the vapor pressure influences the evaporation rate because the air temperature thermally influences the temperature of the surface where evaporation occurs (skin, eyes, and throat).