An Environmental Stress Index (ESI) as a Substitute for the Wet Bulb Globe Temperature (WBGT)

This report summarizes the development of a new environmental stress index ESI to asses heat stress. Two independent studies containing four different databases were analyzed in order to evaluate ESI and a small light sensor that measures global radiation. The purpose of the first study was to develop a new environmental stress index ESI. Meteorological measurements were taken in three climatic zones hotwet, hotdry, and extremely hotdry for 60 days, and a new stress index with the following algorithm was developed ESI0.63Ta-0,03RH0,002SR0.0054 TaRH-0.0730.1SR-1 where Ta ambient temperature, RH relative humidity, and SR solar radiation. The correlation coefficients between ESI and WBGT were very high R20.981. Therefore, we concluded that ESI, based on fast response and accurate climatic microsensors Ta, RH, SR which can be combined in a portable device, has the potential to be a practical alternative to the WBGT. A second study evaluated a small 5mm light L sensor in order to measure global radiation GR for use in heat stress assessment and in the ESI. Data were collected from three instruments L, pyranometer P and black globe.