Study on the lower limit of indoor humidity subject experiments on psychological responses

As a basis for determining the lower limit of acceptable humidity in an indoor environment, experiments were conducted for 25 subjects to assess the maximum expected sensations of dryness, discomfort based on humidity, and intolerance based on humidity, under conditions of 26°C and 10% RH. As results, distinct negative evaluations (dry, uncomfortable, or intolerable) were not obtained as the majority response; however, a small number of subjects declared distinct negative responses. In addition to the whole-body evaluation, the sensations for individual body parts were collected and found to be more intense for the eyes, nose, throat, and lips than for the other body parts. Significant differences between the genders were not found. For 8 of the subjects, similar experiments under a condition of 30% RH were conducted, and the difference between two humidity conditions was clearer for discomfort and intolerance than for dryness. The results suggest that the evaluation of the specific individuals who respond intensely, the consideration of intense responses for a specific part of the body, and the careful selection of an evaluation word for a psychological response might be effective to link this study to the determination of the lower limit of indoor humidity.