Evaluating the effectiveness of emissions reduction measures and ambient air quality variability through ground-based and Sentinel-5P observations under the auspices of COVID pandemic lockdown in Tamil Nadu, India

Abstract

ABSTRACT COVID-19 pandemic situation has highly restricted the human movements including public transport, commercial and industrial activities in India since the end of March 2020. With the necessity to demonstrate the effectiveness of local emissions, the study aims in analysing the relative variation of ambient air quality before and during COVID-19 with the aid of in situ measurement and Sentinel 5P space technologies. ESA Sentinel 5P Level 2 data \\sets including Carbon monoxide (CO), nitrogen dioxide (NO2), Sulphur dioxide (SO2), and Ozone (O3)were pre-processed in SNAP and QGIS platform for the extraction of air quality parameters. Results concluded that the concentration of air quality parameters CO, NO2, SO2, and O3reduced 50.52%, 85.81%, 71.61% and 313.4%, respectively, between March and June 2020. Accuracy of air quality parameters CO, NO2, SO2, and O3obtained from Sentinel 5P datasets are found to be 89.5%, 83.54%, 86% and 94%, respectively, when compared with the in situ measurements. As a favourable outcome of the COVID 19 lockdown, better air quality is recorded over the vulnerable locations due to the absence of significant activities and with the improvement in the air quality the study illustrates the importance of temporary pollution source control measures in a suitable time interval. Integration of in situ measurements and satellite datasets will remove the conventional barriers and provide spatially distributed observations that can assist the decision-makers in formulating the best air pollution control strategy.