THE RELATIVE INFLUENCE OF RADIATION AND CONVECTION UPON THE TEMPERATURE REGULATION OF THE CLOTHED BODY

Abstract

This study indicates that when a given operative temp. is produced by (a) air and walls of approximately the same temperature, and (b) cooler air and warmer walls, the physiological reactions of the clothed human body differ in the 2 cases, as follows: (a) Mean skin temps. are lower for the cold-air warm-wall situation, chiefly as a result of lower skin temperatures for upper and lower extremities, the head and trunk temperatures being less affected. (b) Conductance of the skin is very much lower for the cold-air warm-wall situation, particularly in the hot region. (c) As a result of higher skin temps., negative storage (heating of the body) is greater in the hot region, and positive storage (chilling of the body) is less in the cold region, for the cold-air warm-wall situation. (d) Wetted area is less for the cold-air hot-wall situation in the hot region. (e) As a result of the physiological reactions noted above, discomfort is less in the hot region and greater in the cold region for the cold-air warm-wall situation. Curves for conductance in the cold region level off at distinctly higher values for the equal wall and air situation than for the hot-wall cold-air conditions, and these differences in conductance must be related to equally significant differences in the depth of gradient. This seems to imply possible modification of the common assumptions with regard to vasoconstriction. It is ordinarily assumed that vasoconstric-tion is an "all or none" phenomenon, and that after constriction occurs, the body behaves like a purely physical mechanism. The results here presented strongly suggest that far down in the cold region there are still fundamental phvsiologieal regulative forces at work.