Effects of Vertical Air Temperature Gradients on Physiological and Psychological Responses in the Elderly

The purpose of this study was to investigate the effects of thermal environments in which the air temperature close to the floor is lower than the temperature close to the ceiling on physiological and subjective responses in the elderly. The temperatures around the upper and lower parts of the body were controlled independently using a climatic box placed in a climatic chamber. Sixteen healthy male subjects (8 elderly and 8 young) were exposed to four conditions involving various temperature differences between the upper (25°C) and lower (16, 19, 22, or 25°C) parts of their body. Although there was no significant difference in mean lower body skin temperature between the two age groups, the skin temperatures of the hand and fingers decreased more in the elderly at temperatures of 22°C and below. Systolic blood pressure significantly increased in low air temperature conditions in the elderly, but not in the young. Age differences in thermal sensation of the whole body and lower body thermal comfort were detected, and the perception of the vertical air temperature gradient was reduced in the elderly. These findings suggest that the skin temperatures of the fingers and hand decrease and blood pressure increases in the elderly in unequal thermal environments in which the air temperature close to the floor is lower than that in the upper part of the room, although their perception of the temperature difference is reduced. It is necessary to avoid air temperature depression in the lower part of the room to maintain thermal comfort and stabilize blood pressure in the elderly.