Ambient Fine Particulate Matter Pollution Over the Megacity Delhi, India: An Impact Of COVID-19 Lockdown

In this study, we investigate the impact of the COVID- 19 pandemic on PM2.5 levels in the national capital city Delhi, India. PM2.5 and meteorological data from 35 ground-based monitoring stations over Delhi city are utilized for the present study. Geographic Information System-based spatial interpolation method was employed to analyse the spatial pattern of PM2.5 from January to April 2020 and compared with that of preceding years (2018–19). The findings indicate that the PM2.5 level has reduced significantly during the lockdown period. About 40% of reduction in PM2.5 concentrations is observed when compared to the prelockdown phase. Exclusively between 25 March and 30 April, about 94.44% of days were within the NAAQS 24-h standard limit of 60 μg/m³. The significant role of meteorology in the dispersal of PM2.5 over Delhi is clear from the correlation analysis. A strong negative correlation (r = –0.546) between the Temp and PM2.5 indicates the better dispersion of air pollutants during high-temperature conditions. A higher reduction in PM2.5 has been observed in Central, Northern and Eastern parts of the megacity. The present study provides insights to policymakers to prepare and implement future policy measures for controlling air pollution levels in the megacity.