Resurfacing heat stress phenomena in Indian cities during the post-COVID-19 lockdown period

Abstract

This study investigates heat stress in 17 Indian cities during the post-COVID-19 lockdown period. The study compares thermal comfort experienced during the COVID-19 lockdown against that experienced during post-lockdown, which has not been previously studied. The analysis utilizes daily and monthly climate data from 1991 to 2022 obtained from the Langley Research Centre's official website. The net effective temperature (NET) and thermo-hygrometric index (THI) were employed to assess heat stress in cities. The findings indicate a sudden increase in heat stress levels during the post-lockdown period, particularly in cities like Lucknow, Chandigarh, Patna, Kolkata, Ahmadabad, Jodhpur, Guwahati, and Delhi. Moreover, there is a noticeable decline in the number of comfortable days for both THI and NET in certain cities, such as Delhi, Chandigarh, Bhopal, Ahmadabad, and Jodhpur, in 2021 and 2022. This analysis also reveals an overall rise in the number of torrid and very hot days, with significant increases recorded in 2022 compared to 2020. With a few exceptions, most cities show rising trends in THI and NET, causing Indian cities to experience more torrid and very hot months. This study clarifies the effect of the COVID-19 lockdown on bioclimatic comfort and offers important guidance for future studies in this field.