Abstract
In winter, dry indoor air is a common phenomenon which is considered to be the cause for dry skin. A field study was carried out to investigate the thermal and humidity environment and its effect on the oldest-old people (80+ years old) residents{\textquoteright} thermal and humidity comfort and skin condition in a Scottish care home in winter. Eleven oldest-old residents participated voluntarily in the research. The room temperature and humidity were measured together with two skin parameters: Transepidermal Water Loss (TEWL) and Stratum Corneum Hydration (SCH). The participants{\textquoteright} personal thermal and humidity comfort was studied by a questionnaire survey and short interviews.The monitoring results show that the average relative humidity (RH) in the bedrooms was lower than 40%, the minimum RH level in winter recommended by the CIBSE Guide A. The SCH appeared to be a good indicator for humidity comfort as it was significantly correlated with the room absolute humidity. The correlation makes it possible to predict the minimum humidity to prevent dry skin. The questionnaire results show the participants perceived a change in the room temperature but did not perceive the humidity changes. These research findings provide evidence-based data that could help to develop the indoor environment standard for these special occupants group of elderly people in care homes.