Comparison of thermal responses between young children (1- to 3-year-old) and mothers during cold exposure.

To investigate thermal responses of children during cold exposure, children and their mothers were exposed to identical environmental conditions in climatic chambers. Subjects comprised 14 mothers (age, 29-40 years) and 15 children (age, 15 months-3 years; 9 boys, 6 girls). Each mother and child wore a t-shirt and short pants over underwear. Subjects were initially seated in a chamber at 25 degrees C for 60 min, then moved to a chamber at 15 degrees C where they were seated for 30 min. During the recovery period, they were returned to the 25 degrees C chamber and kept there for an additional 30 min. During exposure to 15 degrees C, declines in skin temperature (T (s)) of the hand and foot were significantly greater in children than in mothers. Rectal temperatures (T (re)) of children increased during cold exposure, whereas T (re) of mothers decreased. This variation in T (re) in children might be linked to homodynamic alterations accompanied by greater decreases in T (s) of the extremities due to a greater degree of vasoconstriction in distal regions during cold exposure. Increases in T (re) during cold exposure for children correlated with body surface area to mass (Ab/mass), mass and decreases in T (s) of the abdomen, thigh and leg. During the rewarming period, children exhibited a greater increase in T (s) of the arm, hand and foot than mothers, and this was attributed to greater relaxation of vasoconstriction in distal regions of children during exposure to the thermoneutral environment. T (re) in children and mothers decreased during the rewarming period. A gender difference was found only with regard to T (re) and heart rate (HR) responses in children during cold exposure, and neither physical characteristics nor any T (s) differed between genders. Furthermore, no significant differences were observed in resting HR of mothers and girls, whereas boys showed significantly lower heart rates at 15 degrees C than at 25 degrees C.

Environmental and behavioral conditions of bathing among elderly Japanese.

This study investigated the bathing conditions of elderly Japanese, and sought to find factors relating to regional differences in death rates from bathtub accidents. A questionnaire survey was carried out in 11 areas of Japan. Questionnaires including questions regarding the length of time since houses had been built, types of facilities, and subjects' indoor thermal sensations and behavior while bathing were distributed to detached houses in each area twice, once in summer and once in winter. Completed questionnaires were collected from approximately 160 elderly people over 65 years old. Information regarding thermal sensations of rooms in winter revealed that a prefabricated bath and insulating window glass eased the cold in the bathroom. Unexpectedly, more subjects in the southern region than in the northern region reported being cold or a little cold while bathing in winter. In the present study, thermal sensations and behaviors while bathing seemed to be more affected by facilities and the location of houses than by the sex and age of the subjects.

Influence of long-term exposure to an air-conditioned environment on the diurnal cortisol rhythm.

In the present study, the influence of the long-term use of air-conditioning in summer on the cortisol rhythm was examined by measuring the rhythm in subjects who had been exposed to air-conditioning for a short [S] or long [L] time. Investigations were conducted twice in July and September. Atmospheric temperature and relative humidity near the subjects were measured for three days in each season. Saliva samples for cortisol analysis were collected every 2 hours during the daytime beginning at 8:00 h with subsequent sampling times at 10:00, 12:00, 14:00, 16:00, 18:00, 20:00 and 22:00 h. A questionnaire on sleep and duration of air-conditioning use was also undertaken. Ambient mean temperature was higher in the S group (mean+/-SD; 30.8+/-1.2 degrees C in July, 28.0+/-0.8 degrees C in September) than in the L group (28.0+/-1.2 degrees C in July, 27.3+/-1.0 degrees C in September) (p<0.01), while mean relative humidity did not differ. There were no differences in bedtime, waking time and sleeping hours either between groups or months. Diurnal patterns of salivary cortisol rhythm in July and September were similar in the S group, but the L group had a delayed rise of morning cortisol secretion in September compared with July. These results suggest that long-term exposure to an air-conditioned environment might adversely affect the human cortisol rhythm.

Physiological and subjective responses in the elderly when using floor heating and air conditioning systems.

The purpose of this study was to investigate the effects of a floor heating and air conditioning system on thermal responses of the elderly. Eight elderly men and eight university students sat for 90 minutes in a chair under the following 3 conditions: air conditioning system (A), floor heating system (F) and no heating system (C). The air temperature of sitting head height for condition A was 25 degrees C, and the maximum difference in vertical air temperature was 4 degrees C. The air and floor temperature for condition F were 21 and 29 degrees C, respectively. The air temperature for condition C was 15 degrees C. There were no significant differences in rectal temperature and mean skin temperature between condition A and F. Systolic blood pressure of the elderly men in condition C significantly increased compared to those in condition A and F. No significant differences in systolic blood pressure between condition A and F were found. The percentage of subjects who felt comfortable under condition F was higher than that of those under condition A in both age groups, though the differences between condition F and A was not significant. Relationships between thermal comfort and peripheral (e.g., instep, calf, hand) skin temperature, and the relationship between thermal comfort and leg thermal sensation were significant for both age groups. However, the back and chest skin temperature and back thermal sensation for the elderly, in contrast to that for the young, was not significantly related to thermal comfort. These findings suggested that thermal responses and physiological strain using the floor heating system did not significantly differ from that using the air conditioning system, regardless of the subject age and despite the fact that the air temperature with the floor heating system was lower. An increase in BP for elderly was observed under the condition in which the air temperature was 15 degrees C, and it was suggested that it was necessary for the elderly people to heat the room somehow in winter. Moreover, it is particularly important for elderly people to avoid a decrease in peripheral skin temperature, and maintain awareness of the warmth of peripheral areas, such as the leg, in order to ensure thermal comfort.