Quantifying heat stress using wet bulb globe temperature measurements during summer 2024 from field experiments in Pune

Abstract

Heat stress has emerged as a critical issue amid climate change, particularly in urbanizing areas like India. This study examines heat stress in Pune, focusing on the Wet Bulb Globe Temperature (WBGT) through field experiments conducted during the peak summer months of April and May 2024. The research aimed to understand how urban design, vegetation, and socio-economic factors influence heat stress levels. Three distinct locations in Pune: Indian Institute of Science Education and Research (IISER), Fergusson College (FC), and Agriculture College (AGR) were selected to represent varying degrees of urbanization. WBGT meters were installed uniformly at a height of 4 feet to ensure accurate readings, with hourly measurements taken from 9 AM to 6 PM. The highest WBGT index was recorded at FC, the most urbanized site, indicating increased heat stress. Analysis revealed that maximum heat stress typically occurred between 1 PM and 3 PM, with variations depending on the location. The study established WBGT threshold limits for Pune: 31.5 °C (90th percentile), 32 °C (95th percentile), and 33 °C (99th percentile), corresponding to low, moderate, and extreme heat stress levels. Further investigation into meteorological factors showed a strong positive correlation between WBGT and ambient temperature, while relative humidity and wind speed had a reverse correlation. Notably, southerly winds contributed most significantly to heat stress. The study highlights WBGT as a vital metric for assessing heat stress, integrating temperature, humidity, wind speed, and solar radiation. The findings provide essential insights for policymakers, urban planners, and environmentalists, guiding strategies to mitigate the challenges of climate change and enhance urban resilience against heat stress.