The study on heat pyrexia (heat stroke) in this issue of The Journal, p. 1175, is a derivative of human physiological research in hyperenvironments, conducted at the Aerospace Medical Laboratory, Wright-Patterson Air Force Base, Ohio. The Air Force has long been interested in the effects of extreme heat on crews of high-performance aircraft and of spacecraft to come. As a result, a comprehensive study was launched a few years ago in which it was hoped to learn the stepwise effect of quantitative loads of heat—to the point of clinical heat stroke—upon healthy, unanesthetized humans. That this could be done was principally due to two factors: the availability of human volunteers and the uniqueness of the environmental chambers at this laboratory. These chambers can simulate practically any combination of temperature, humidity, air motion, and even air pressure.
For the main part, thermal exposures were at a level of 130° F (54.4°