Analyzing the impact of COVID-19 induced lockdown on thermal stress and comfort level of 17 major cities of India (2019–2020)

Abstract

The objective of the study is to evaluate the level of thermal stress/comfort experienced by 17 major cities of India during lockdown period (2020) and its comparison with the year 2019. The experiment incorporates daily air temperature and relative humidity data for a period of 6 months accessed from power.larc.nasa.gov. The thermal condition of the cities has been computed with thermo-hygrometric index (THI) and Relative Strain Index (RSI). Almost all cities portray decreasing air temperature with ascending relative humidity from the year 2019 to 2020. Changing air temperature with relative humidity modified the thermal condition of the cities. Most of the cities experienced increasing number of bio-climatic comfortable days in 2020 such as in Kolkata, Bangalore, Lucknow, Patna, Hyderabad, Delhi, Jodhpur, Bikaner, and Chandigarh. And on the contrary descending number of Torrid and Heat stroke risk days notably over Kolkata, Ahmadabad, Nagpur, Bhopal, Patna, and Lucknow. Overall, there is a sharp decline in the number of days with torrid climate in cities from 1386 to 1037 (based on THI) and risk of heat stroke from 200 to 103 (based on RSI) from the year 2019 to 2020. Further, the cities also experienced growing number of bio-climatic comfortable days (based on RSI) from 530 to 621. The decreasing trend of thermal stress over the cities has considerably reduced the vulnerable population to extreme urban climate.