EFFECTS OF EXTREMELY LOW HUMIDITY ON COMFORT AND FATIGUE OF JAPANESE OCCUPANTS

Subjective experiments were carried out in a climate chamber using Japanese subjects, in order toevaluate human comfort at very low humidity. Two levels of absolute humidity were set. Three airtemperature conditions for each absolute humidity level were examined. People were exposed in achamber for 90 minutes with sedentary activity.Subjective break up time got significantly shorter at extremely low absolute humidity. Air temperaturehad great impact on subjective general humidity sensation under the conditions set for this experiment.General dryness sensation at low absolute humidity was significantly greater than that at high absolutehumidity with same air temperature. Subjects felt their eyes were dryer at low air temperature at thesame moisture content in air. In case of the constant air temperature, low absolute humidity causedgreater eye dryness sensation. Subjective humidity discomfort of females was greater than male. Verylow humidity air dry up the human mucous membrane. Half of subjects perceived their palm of hand aswetted segment even at extremely low humidity. They could feel more tired at low humidity under thecool and thermally neutral condition, while they complained more at high humidity in hot environment. Itwas found that females tended to be more tired than males even under the same condition.