Air Quality and Its Relationship with COVID-19 Mortality in Hotspot Places of India: A Post-lockdown Analysis

The COVID-19 pandemic spread over the world like the wind with more than 400,000 documented cases as of March 24 th , 2020. In this regard, strict lockdown measures were imposed in India on the same date to stop the virus spread. Thereafter, various lockdown impacts were observed and one of the immediate effects was a reduction in air pollution levels across the world. In this study, we have selected 14 major hotspot places where the COVID-19 cases were >1000 (as of 1 st June 2020) that represents more than 70% mortalities of India. We assessed the impact of lockdown on different air quality indicators including ground (PM 2.5 , PM 10 , NO 2 , SO 2 , O 3 , and AQI) and tropospheric nitric oxide (NO 2 ) concentrations through ground monitoring stations and Sentinel-5 satellite data respectively. We have found highest reduction in NO 2 (-48.68%), PM 2.5 (-34.84%) and PM 10 (-33.89%) air pollutant (unit in µg/m 3 ) levels post-lockdown. Moreover, tropospheric NO 2 (mol/m 2 ) concentrations were also improved over Delhi, Mumbai, Kolkata, Thane, and Ahmedabad metro cities. Interestingly, air pollutant indicators have been correlated with different periods (as of 1 st and 15 th June 2020) of COVID-19 mortalities data to assess the bounding between these variables. Accordingly, we have found a strong positive correlation of mortalities data with ground PM 10 (R 2 =0.145; r =0.38) and AQI (R 2 =0.17; r =0.412) indicators and this relationship has been improved significantly on second time point. The correlation finding suggests that the long-term bad air quality may aggravate the clinical symptoms of the disease.