Manish Soni1, Sunita Verma  2,3, Hiren Jethava4, Swagata Payra1, Lok Lamsal4, Priyanshu Gupta2, Janhavi Singh2 

1 Department of Physics, Birla Institute of Technology Mesra, Jaipur Campus, Rajasthan, India
2 Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi-221005, Uttar Pradesh, India
3 DST-Mahamana Centre of Excellence in Climate Change Research, Banaras Hindu University, Varanasi, India
4 Goddard Earth Sciences Technology and Research, Universities Space Research Association, Columbia, MD, USA


Received: June 16, 2020
Revised: November 6, 2020
Accepted: November 16, 2020

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.


Download Citation: ||https://doi.org/10.4209/aaqr.2020.06.0295  


Cite this article:

Soni, M., Verma, S., Jethava, H., Payra, S., Lamsal, L., Gupta, P., Singh, J. (2020). Impact of COVID-19 on the Air Quality over China and India Using Long-term (2009-2020) Multi-Satellite Data. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.2020.06.0295


HIGHLIGHTS

  • Long-term satellite data examined over SE-Asia to estimate AQ during COVID-19.
  • Over China, significant drop in NO2 (37%) and SO2 (76%) observed.
  • Over India, reduction of 16% and 20% in NO2 and SO2 observed.
  • Over IGP region, 25% increase in NO2 and SO2 due to large-scale urban settlement.
 

ABSTRACT


We have examined the air quality over China, India and demonstrated marked differences in levels of air pollution resulted from the COVID-19 restrictions during December-April, 2019-20 to that of 11 years mean of 2009-19. The criteria air quality indicators i.e. nitrogen dioxide (NO2), sulphur dioxide (SO2), Aerosol Index (AI) and aerosol optical depth (AOD) data are retrieved from the Ozone Monitoring Instrument (OMI), TROPOspheric Monitoring Instrument (TROPOMI), and MODerate Resolution Imaging Spectroradiometer (MODIS) sensor on the Terra and Aqua satellites, respectively. Over China, during COVID-19 lockdown a significant drop in columnar abundances of tropospheric NO2 (-37%), SO2 (-64%) and AOD (-8%) for 2020 in comparison to 11 years mean (2009-19) has been observed.  A noticeable difference in NO2 column burden is seen over SE (-35%), NE (-33%), NW (-13%) and SW (-5%) China. Over the SE and NE China, both NO2 and SO2 levels decreased dramatically in 2020 from that of 2009-19, by more than 40% and 65%, respectively, because of both stricter regulations of emissions and less traffic activity due to reduced social and industrial activities during COVID-19 restrictions. In contrast, the curve of monthly mean tropospheric columnar burden of NO2 and SO2 over India has shown moderate reduction of 16% and 20%, respectively because lockdown came into effect much later in March 2020. The mean NO2 and SO2 over IGP region is found to be 25% higher than whole India’s mean concentration due to large scale urban settlement and crop burning events. The statistical t-test analysis results confirm significant (p<0.05) improvements in AQ during lockdown. The COVID-19 pandemic provided an unprecedented opportunity to investigate such large-scale reduction in emissions of trace gases and aerosols. Therefore, it is important to further strengthen environmental policies to tackle air quality, human health, and climate change in this part of the world.


Keywords: OMI, MODIS, NO2, SO2, AOD, COVID-19, Air quality, Aerosol index, t-test.




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