Investigating Outdoor Heat Stress Using Environmental Parameters and Selected Thermal Indices in Northern India

Abstract

Heat stress is often an unacknowledged occupational health hazard especially in developing countries. Climatic zones like tropical and subtropical regions having higher air temperature, humidity and radiant temperature values may impose greater risks of heat-related illness and safety threats to users employed in developing countries having low and medium incomes. Present study aimed at assessing the environmental variables followed by evaluating the heat stress exposures levels at different time periods during the hot summer season utilizing widely used indices, i.e. wet bulb globe temperature (WBGT), discomfort index (DI), humidex (HD), heat index (HI), tropical summer index (TSI); so to have better insights of the stressful thermal climatic conditions experienced by the users engaged in outdoor work activities. Results revealed higher heat stress exposure levels attributable to noon and afternoon periods, indicating stressful climatic conditions, with respective indices exceeding the threshold limit values (TLVs). For WBGT, strong relationship was observed with TSI (R2-value = 0.918) and DI (R2-value = 0.891) indices, although least association with HI (R2-value = 0.644) and HD (R2-value = 0.566) indices. However, highest association was observed among HI and HD indices (r-value = 0.995; p-value < 0.01). From results, it may be concluded that noon and afternoon time periods could impose excessive heat strain on user’s work capabilities as compared to morning and evening periods, which could cause greater risks of heat-related morbidities and safety threats to workers/users employed, with consequent negative impacts on productivity and financial burden.KeywordsEnvironmental variablesNegative impactsHeat stress indicesExposure assessment