Heat and cold stress indices for people exposed to our changing climate

Abstract

The aim of the experiment presented in this paper was to evaluate and develop climate indices that are currently used to assess human health. Twenty people were exposed to a range of climatic conditions, outside near a weather station, in the UK. Measurements of the climate included air temperature, radiant temperature (including solar load), humidity and wind speed. Subjective responses were taken and physiological measurements included internal body temperature, heart rate and sweat loss. The responses of the participants over a one hour exposure were compared with those that would have been predicted using ISO Standards and in particular the Wet Bulb Globe Temperature (WBGT) index (ISO 7243), the Predicted Mean Vote (PMV, ISO 7730) and the Wind Chill Index (WCI, ISO 11079) as well as The PMVsolar index which is the PMV index created for the affects of direct solar radiation. The results show that all indices considered provided statistically significant (p<0.01) correlations between the index value and the thermal sensation of subjects. The highest correlations overall was with the WBGT index. This preliminary finding will be tested in more extensive trials involving more subjects and covering all seasons in the UK.