Ambient fine particulate matter pollution over the megacity Delhi, India: an impact of COVID-19 lockdown

摘要

In this study, the authors investigate the impact of COVID-19 pandemic on PM_(2.5) levels in the national capital city Delhi, India. PM_(2.5) 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 PM_(2.5) from January to April 2020 and compared with that of preceding years (2018-19). The findings indicate that the PM_(2.5) level has reduced significantly during the lockdown period. About 40% of reduction in PM_(2.5) concentrations is observed when compared to the pre-lockdown phase. The significant role of meteorology in the dispersal of PM_(2.5) over Delhi is clear from the correlation analysis. A strong negative correlation (r=-0.546) between the temperature and PM_(2.5) indicates the better dispersion of air pollutants during high-temperature conditions. A higher reduction in PM_(2.5) 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.