Special Issue on COVID-19 Aerosol Drivers, Impacts and Mitigation (XI)

Satyendra K. Pandey  , V. Vinoj 

School of Earth, Ocean and Climate Science Indian Institute of Technology Bhubaneswar, Jatni – 752050, Odisha, India


Received: July 30, 2020
Revised: October 12, 2020
Accepted: November 11, 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.2020.07.0466  

Cite this article:

Pandey, S.K., Vinoj, V. (2021). Surprising Changes in Aerosol Loading over India amid COVID-19 Lockdown. Aerosol Air Qual. Res. 21, 200466. https://doi.org/10.4209/aaqr.2020.07.0466


  • A widespread decrease in aerosol loading was observed during the lockdown.
  • Aerosol optical depth over central India has increased up to 20% of the pre-lockdown values.
  • Atmospheric moisture and stagnant circulation appears to increase the aerosol loading.


Using ground-based and satellite observation along with aerosol reanalysis products, we show a widespread reduction in aerosol loading over the Indian subcontinent during the COVID-19 (COronaVIrus Disease 2019) lockdown. The pre-lockdown and lockdown period considered in the present study is 20th February–20th March 2020 and 24th March–22nd April 2020. In terms of aerosol optical depth (AOD), loading has reduced up to 40% over the most populated region of India. However, the central part of India shows an unexpected increase (~+20%) in AOD. A simultaneous increase (decrease) in mid-tropospheric relative humidity (wind speed (WS) at 850 hPa) by +85 ± 6.0% (–12 ± 3.9%) occurred during the lockdown. It is found that on a daily scale, the mean AOD is positively (negatively) correlated with mid-tropospheric RH (WS) with a statistically significant linear correlation coefficient of 0.53 (−0.43). An increase (decrease) in RH (WS) of 20% (1 m s1) was observed to increase AOD by 0.10 (0.04). Thus, we hypothesize that during the lockdown, the increased AOD over central India was due to increased atmospheric moisture coupled with stagnant circulation condition.

Keywords: COVID-19, Lockdown, Aerosols, Air pollution, Humidity.

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