Evaluation of the environmental stress index (ESI) for hot/dry and hot/wet climates

Recently, a novel environmental stress index (ESI) which is composed from commonly used meteorological variables: ambient temperature (T(a)), relative humidity (RH), and solar radiation (SR) was suggested as follows: ESI = 0.63T(a)-0.03RH+0.002SR+0.0054(T(a) x RH)-0.073(0.1+SR)(-1); (degrees C) The purpose of the present study was to evaluate and validate the ESI for hot dry and hot wet climatic conditions. The ESI was applied to large meteorological databases from 2 different locations resembling hot/wet and hot/dry climates. Data analysis revealed high correlation between ESI and the wet bulb globe temperature (WBGT) index for each of the two databases: P < 0.05, R2 = 0.985 and 0.982, for the hot/dry and hot/wet conditions, respectively. Therefore, it is concluded that ESI, which is constructed from fast response and commonly used weather variables (T(a), RH, SR), and also found in a microsensor format is validated for hot/dry and hot/wet zones and as a potential index to serve as an alternative to the WBGT for heat category assessment.