Heat and moisture transport characteristics in hot environments while wearing clothing ensembles for live-line working. Hitomi USHIODA* and Takashi KISHIMOTO** *Hyogo University of Teacher Education ** Kinden Corporation

Live-line working is the maintenance of electrical equipment, often operation at high voltage. For the safety of live-line workers, they must wear thick rubber gloves and multiple- layer rubber jackets. Because rubber has no air permeability and no vapor permeability, those ensembles cause often higher core temperature of workers in hot environments.

The purpose of the present study was to investigate if the inner shirts of clothing ensembles for live-line working would cause different thermoregulatory responses and clothing comfort.

We prepared five kinds of inner shirts of clothing ensembles for the experiments, which had the characteristics shown in this table. Shirt A is the uniform of Kinden Corporation and many live-line workers wear their inner shirts, so we prepared the same undershirts shown in table. Shirt B is made of a mesh structure. Underwear of A, the shirts C, D, and E have the tags with the high water absorbency and the rapid dryness for sports wear.

For the experiments they wore their underwear and socks. They wore the same under shirts for ensembles A. Work pants, multiple-layer rubber jackets, rubber gloves, rubber boots and helmets were served as Kinden uniform.

Five healthy males of years old cooperated as subjects, experiments were repeated 2 times. We measured their skin humidity and temperature at the abdomen, inner shirts surface of abdomen area and inner shirts surface of chest area. Local skin wettedness (ω) on abdomen was calculated as ω=(P sk -P a )/(P ssk -P a ), where P sk is the vapor pressure at the skin surface obtained from the humidity sensors and P ssk is the saturated vapor pressure at the local T sk. 1 abdomen 2 inner shirts surface of abdomen 3 inner shirts surface of chest

The climatic chamber was controlled at 35ºC and 45%RH for every experiment. After all sensors were set for the subjects, they sat the chair for 5 minutes (rest). After 5 minutes, they started the dumbbell exercises (13 times/min) for 5 minutes (exercise 1). After the exercise 1 they sat the chair for 10 minutes (recovery 1). They repeated exercises 2 times (exercise 2, exercise 3) and recovery 1 time (recovery 2).

The mean value of skin temperature and mean humidity of the respective shirts averaged are shown in this table.

A T-test was conducted on the mean value of temperature and humidity. The significant-difference (p>0.05) was found that the A wearer had a highest abdomen temperature (A>B, C, D, E).

All shirts were shown in the same behavior that the inner clothing surface temperature of abdomen decreased from the start of experiments to the end of experiments though that of chest increased. The temperature and humidity of chest were higher than that of abdomen because of it.

The A and the B wearers had a higher abdomen humidity than the C, D and E (A, B>C, D, E) after the exercise.

Heat and moisture transport characteristics and the skin wettedness of shirts C, D, and E which had the high water absorbency and the rapid dryness were lower than that of shirts A and B in spite of impermeable microclimate.

Wet fabrics have the higher heat conductivity than the dry fabrics. In particular, polyester finished with the high water absorbency and the rapid dryness causes the capillary action in perspiration. And the textile in the shirts of D was composed by polyethylene vinyl alcohol which had a higher q max. We guess that the shirts D and E with the high water absorbency and the rapid dryness keep the skin dry in hot environment.

We measured the clo values by thermal manikin. The values are different tendency between the steady state and the walking state(ISO 15831). The clo values of steady state indicated A>C>D>B>E, but that of walking state indicated A>B>C,D>E. The clo value of the shirts B of walking state was bigger than that of the other shirts though the shirts B had a mesh structure.

Sensory evaluation of shirts was graded on a scale from -3 to +3, and they are shown in this figure. In this figure, positive axis indicates satisfaction, while negative one indicates dissatisfaction. A T-test was conducted on the mean value of appropriateness, comfortableness and favorite of shirts for live-line working in hot environment. The significant-difference was found that the shirts C had a lower appropriateness than the shirts D and E, the shirts D was a more comfortable than the shirts A, B and C, and the shirts B was evaluated a less favorite than the shirts A, D and E.

Conclusions The purpose of the present study was to investigate if the inner shirts of clothing ensembles for live-line working would cause different thermoregulatory responses and clothing comfort. The inner shirts of clothing ensembles for live-line working caused different thermoregulatory responses and clothing comfort. It was suggested that the shirts finished with the high water absorbency and the rapid dryness was keeping the skin dry and comfortable.