The relationship between environmental temperature and clothing insulation across a year.

People adapt to thermal environments, such as the changing seasons, predominantly by controlling the amount of clothing insulation, usually in the form of the clothing that they wear. The aim of this study was to determine the actual daily clothing insulation on sedentary human subjects across the seasons. Thirteen females and seven males participated in experiments from January to December in a thermal chamber. Adjacent months were grouped in pairs to give six environmental conditions: (1) January/February = 5°C; (2) March/April = 14°C; (3) May/June = 25°C; (4) July/August = 29°C; (5) September/October = 23°C; (6) November/December = 8°C. Humidity(45 ± 5%) and air velocity(0.14 ± 0.01 m/s) were constant across all six experimental conditions. Participants put on their own clothing that allowed them to achieve thermal comfort for each air temperature, and sat for 60 min (1Met). The clothing insulation (clo) required by these participants had a significant relationship with air temperature: insulation was reduced as air temperature increased. The range of clothing insulation for each condition was 1.87-3.14 clo at 5°C(Jan/Feb), 1.62-2.63 clo at 14°C(Mar/Apr), 0.87-1.59 clo at 25°C(May/Jun), 0.4-1.01 clo at 29°C(Jul/Aug), 0.92-1.81 clo at 23°C (Sept/Oct), and 2.12-3.09 clo at 8°C(Nov/Dec) for females, and 1.84-2.90 clo at 5°C, 1.52-1.98 clo at 14°C, 1.04-1.23 clo at 25°C, 0.51-1.30 clo at 29°C, 0.82-1.45 clo at 23°C and 1.96-3.53 clo at 8°C for males. The hypothesis was that thermal insulation of free living clothing worn by sedentary Korean people would vary across seasons. For Korean people, a comfortable air temperature with clothing insulation of 1 clo was approximately 27°C. This is greater than the typical comfort temperature for 1 clo. It was also found that women clearly increased their clothing insulation level of their clothing as winter approached but did not decrease it by the same amount when spring came.

Clothing insulation and temperature, layer and mass of clothing under comfortable environmental conditions.

This study was designed to investigate the relationship between the microclimate temperature and clothing insulation (Icl) under comfortable environmental conditions. In total, 20 subjects (13 women, 7 men) took part in this study. Four environmental temperatures were chosen: 14°C (to represent March/April), 25°C (May/June), 29°C (July/August), and 23°C (September/October). Wind speed (0.14ms-1) and humidity (45%) were held constant. Clothing microclimate temperatures were measured at the chest (Tchest) and on the interscapular region (Tscapular). Clothing temperature of the innermost layer (Tinnermost) was measured on this layer 30 mm above the centre of the left breast. Subjects were free to choose the clothing that offered them thermal comfort under each environmental condition. We found the following results. 1) All clothing factors except the number of lower clothing layers (Llower), showed differences between the different environmental conditions (P<0.05). The ranges of Tchest were 31.6 to 33.5°C and 32.2 to 33.4°C in Tscapular. The range of Tinnermost was 28.6 to 32.0°C. The range of the upper clothing layers (Lupper) and total clothing mass (Mtotal) was 1.1 to 3.2 layers and 473 to 1659 g respectively. The range of Icl was 0.78 to 2.10 clo. 2) Post hoc analyses showed that analysis of Tinnermost produced the same results as for that of Icl. Likewise, the analysis of Lupper produced the same result as the analysis of the number of total layers (Ltotal) within an outfit. 3) Air temperature (ta) had positive relationships with Tchest and Tscapular and with Tinnermost but had inverse correlations with Icl, Mtotal, Lupper and Ltotal. Tchest, Tscapular, and Tinnermost increased as ta rose. 4) Icl had inverse relationships with Tchest and Tinnermost, but positive relationships with Mtotal, Lupper and Ltotal. Icl could be estimated by Mtotal, Lupper, and Tscapular using a multivariate linear regression model. 5) Lupper had positive relationships with Icl and Mtotal, but Llower did not. Subjects hardly changed Llower under environmental comfort conditions between March and October. This indicates that each of the Tchest, Mtotal, and Lupper was a factor in predicting Icl. Tinnermost might also be a more influential factor than the clothing microclimate temperature.

Determination of body surface area and formulas to estimate body surface area using the alginate method.

The purpose of this study was to determine the body surface area (BSA) based on the alginate method, to derive formulae for estimating BSA, and to compare the error of the present formula to previous formulas obtained from other countries. We directly measured the entire body surface area of 34 males (20-60 years old, 158.5-187.5 cm in height, 48.5-103.1 kg in body weight) and 31 females (20-63 years old, 140.6-173.1 cm, 36.8-106.1 kg) using alginate. The measurements showed that the BSA had a mean of 18,339 cm(2) (15,416-22,753 cm(2)) for males, and 16,452 cm(2) (12,825-22,025 cm(2)) for females. Based on these measurements, a regression model to estimate BSA was derived: Estimated BSA (cm(2))=73.31 Height (cm)(0.725) x Weight (kg)(0.425) (r(2)=0.999). The mean error of the formula was -0.1%, and did not show any significant difference by gender or body shape. When applied to the datasets (n=506) composed of various races (Caucasians, Africans, and Asians), the mean error of the formula was 0.4% and was smaller than that of DuBois & DuBois's, Gehan & George's, and Mosteller's formulas when applied to the same datasets. The errors of the three previous formulas were also within 2%. Overall, formulas based on the DuBois exponent (Weight(0.425) Height (0.725)) did not show any tendency of overestimation or underestimation by body shape, but other BSA-formulae showed differences by body shape. The present BSA formula has shown good accuracy in Korean adults of all weight categories compared to traditional formulas.

Alleviation of heat strain by cooling different body areas during red pepper harvest work at WBGT 33 degrees C.

The purpose of the present study was to examine the effects of different types of personal cooling equipments (PCE) on the alleviation of heat strain during red pepper harvest simulated in a climatic chamber. The experiment consisted of eight conditions: 1) Control, 2) Neck cooling scarf A with a cooling area of 68 cm2, 3) Neck cooling scarf B (cooling area 154 cm2), 4) Brimmed hat with a frozen gel pack, 5) Cooling vest (cooling area 606 cm2), 6) Hat+Neck Scarf B, 7) Hat+Vest, and 8) Hat+Neck Scarf B+Vest. Twelve subjects worked a red pepper harvest simulated in a climatic chamber of WBGT 33 degrees C. The result showed that rectal temperature (T(re)) was effectively maintained under 38 degrees C by wearing PCE. Mean skin temperature (T(sk)) and heart rate (HR) became more stable through wearing PCE. When wearing the 'Hat+Scarf B+Vest', particularly, T(sk) and HR quickly decreased to the comfort level during the mid-rest stage. We confirmed that the vest with a cooling area of only 3.3% body surface area (BSA) was effective in alleviating heat strain in a simulated harvest work. Furthermore, the heat strain of farm workers can be considerably eliminated by the combination of the cooling vest, a scarf, and a brimmed hat, with the total cooling area of 4.2% BSA.

Does wearing thermal underwear in mild cold affect skin temperatures and perceived thermal sensation in the hands and feet of the elderly?

The present study was to investigate whether increasing thermal insulation affects thermal sensation in the hands and feet; and whether aging is an influential factor in the relationship between thermal responses and subjective thermal perceptions. Six young males (YM), 5 young females (YF), 6 elderly males (OM), and 6 elderly females (OF) volunteered as subjects. Subjects conducted two trials at a constant air temperature of 19 degrees C: One condition included thermal underwear (19CUW) while the other did not (19C). The results showed that (1) rectal temperature (T(re)) did not show any significant differences between conditions with and without thermal underwear. The T(re) of the OF was greater than that of the YF (p<0.05) for the 19C condition, while the young and elderly male groups showed similar values. (2) The hand and foot skin temperatures (T(hand), T(foot)) were greater in the OF than in the YF group for the 19C condition (p<0.001). (3) For overall thermal sensation, the OF group was less sensitive to differences between the 19CUW and 19C condition, when compared with the old male and young groups. (4) For thermal sensation in the hands and feet, the elderly groups were less sensitive than the YF. In particular, all elderly females felt the hands were thermally neutral, even in the 19C condition. (5) Hand thermal sensation for the OF group appeared to be irrelevant to T(hand). (6) Thermal preference of the elderly groups did not change significantly after adding thermal underwear compared to the young group. In conclusion, wearing thermal underwear in mild cold did not affect local skin temperatures and thermal sensation in the hands and feet for the elderly male and female groups. Adding thermal underwear in mild cold affected the hand skin temperature and thermal sensation of the young female group. In particular, elderly females had specific features concerning local skin temperatures and thermal sensations distinguished from elderly males and young groups.

Determination of hand surface area by sex and body shape using alginate.

Hand surface area (HSA) has been utilized for burned skin area estimation in burn therapy, heat exchange in thermal physiology, exposure assessment in occupational toxicology, and the development of manual equipment/ protective gloves in ergonomics. The purpose of this study was to determine the hand surface area to the total body surface area (BSA) and derive a formula for estimating HSA. Thirty-four Korean males (20-60 years old; 158.5-187.5 cm in height; 48.5-103.1 kg in body weight) and thirty-one Korean females (20-63 years old; 140.6-173.1 cm; 36.8-106.1 kg) participated as subjects. The HSA and BSA of 65 subjects were directly measured using alginate. The measurements showed 1) the surface area of the hand had a mean of 448 (371-540) cm(2) for males, and 392 (297-482) cm(2) for females. 2) The hand as a percentage of the total body surface area for males and females was 2.5% and 2.4% respectively, showing no significant difference. 3) The hand as a percentage of BSA by body shape was 2.5% for the lean group and 2.3% for overweight people (p=0.001). 4) When estimating the surface area of a hand, formulae based on hand length or hand circumference were more valid than formulae based on height and body weight. We obtained the following formula for estimating HSA: Estimated HSA(cm(2))=1.219 Hand length(cm) x Hand circumference(cm).

Validity and reliability of an alginate method to measure body surface area.

The purpose of this study was to evaluate the validity and reliability of coating methods (plaster bandage, inelastic tape, and the alginate method) and an indirect method using a three dimensional (3D) whole body scanner. The surface area of geometric solids was measured five times using the three coating methods, and analyzed through 2D scanning and a planimeter. Second, to examine the accuracy of the alginate method more closely, the surface areas of boards with different surface properties at various inclines were measured and compared. Lastly, the surface area of a human arm was measured using the three coating methods and a 3D scanning method. The results are as follows: 1) The three coating methods were statistically valid and reliable for measuring the surface area of geometric solids. 2) The planimeter was rejected because the mean error was bigger than in 2D scanning. 3) The method showing the least error was the inelastic tape method, but that method was not recommended because it was too tiresome and laborious. 4) The greater the curvature and smaller the size of a geometric solid, the greater the error. 5) In measuring surface area using the alginate method, the objects that were smoother and had steeper angles showed a greater surface area: however, the mean error was less than 1%. 6) In measuring a human arm, the surface area obtained by 3D scanning was less than any other surface area obtained in the three coating methods, because the 3D scanner could not discern the armpit and fingers. In conclusion, the method using alginate was statistically valid and reliable in the measuring of surface area both of geometric solids and real human skin.

Effects of thermal underwear on thermal and subjective responses in winter.

This study was conducted to obtain basic data in improving the health of Koreans, saving energy and protecting environments. This study investigated the effects of wearing thermal underwear for keeping warm in the office in winter where temperature is not as low as affecting work efficiency, on thermoregulatory responses and subjective sensations. In order to create an environment where every subject feels the same thermal sensation, two experimental conditions were selected through preliminary experiments: wearing thermal underwear in 18 degrees C air (18-condition) and not wearing thermal underwear in 23 degrees C air (23-condition). Six healthy male students participated in this study as experiment subjects. Measurement items included rectal temperature (T(re)), skin temperature (T(sk)), clothing microclimate temperature (T(cm)), thermal sensation and thermal comfort. The results are as follows: (1) T(re) of all subjects was maintained constant at 37.1 degrees C under both conditions, indicating no significant differences. (2) (T)(sk) under the 18-condition and the 23-condition were 32.9 degrees C and 33.7 degrees C, respectively, indicating a significant level of difference (p<0.05). (3) Among local skin temperature, trunk part (forehead and abdomen) did not show significant differences. After 90-min exposure, the skin temperature of hands and feet under the 18-condition was significantly lower than that under the 23-condition (p<0.001). (4) More than 80% of all the respondents felt comfortable under both conditions. It was found (T)(sk) decreased due to a drop in the skin temperature of hands and feet, and the subjects felt cooler wearing only one layer of normal thermal underwear at 18 degrees C. Yet, the thermal comfort level, T(re) and T(cm) of chest part under the 18-condition were the same as those under the 23-condition. These results show that the same level of comfort, T(re) and T(cm) can be maintained as that of an environment about 5 degrees C higher in the office in winter, by wearing one layer of thermal underwear. In this regard, this study suggests that lowering indoor temperature by wearing thermal underwear in winter can contribute to saving energy and improving health.