- English
The study evaluates the impacts of India’s COVID-19 lockdown and unlocking periods on
the country’s ambient air quality. India experienced three strictly enforced lockdowns followed by
unlocking periods where economic and social restrictions were gradually lifted. We have examined
the in situ and satellite data of NO2 emissions for several Indian cities to assess the impacts of the
lockdowns in India. Additionally, we analyzed NO2 data acquired from the Sentinel-5P TROPOMI
sensor over a few districts of the Punjab state, as well as the National Capital Region. The comparisons
between the in situ and satellite NO2 emissions were performed for the years 2019, 2020 and
up to July 2021. Further analysis was conducted on the satellite data to map the NO2 emissions over
India during March to July for the years of 2019, 2020 and 2021. Based on the in situ and satellite
observations, we observed that the NO2 emissions significantly decreased by 45–55% in the first
wave and 30% in the second wave, especially over the Northern Indian cities during the lockdown
periods. The improved air quality over India is indicative of reduced pollution in the atmosphere
due to the lockdown process, which slowed down the industrial and commercial activities, including
the migration of humans from one place to another. Overall, the present study contributes to
the understanding of the trends of the ambient air quality over large geographical areas using the
Sentinel-5P satellite data and provides valuable information for regulatory bodies to design a better
decision support system to improve air quality.
- English
