Abstract
An effective heat strain index (EHSI) using a hand calculator with memory is suggested for on-site evaluation of prevailing hot ambient conditions. The inputs to the programmed calculator include dry-bulb, wet-bulb and globe temperatures, and estimates of metabolism and air movements. The index is based on a program for calculation of the total heat balance and on the efficiency of sweating. The display of information on the ambient conditions includes: the total heat load; the ambient evaporative capacity; the skin wettedness and the applicable strain. The EHSI display is one of the following: no strain; low strain; high strain; or time limits of exposure.