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

Abhishek Dutta, Wanida Jinsart This email address is being protected from spambots. You need JavaScript enabled to view it.

Department of Environmental Science, Faculty of Science, Chulalongkorn University Pathumwan, Bangkok 10330, Thailand


Received: July 19, 2020
Revised: October 15, 2020
Accepted: October 27, 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.2020.07.0417  

Cite this article:

Dutta, A., Jinsart, W. (2021). Air Quality, Atmospheric Variables and Spread of COVID-19 in Delhi (India): An Analysis. Aerosol Air Qual. Res. 21, 200417. https://doi.org/10.4209/aaqr.2020.07.0417


  • COVID-19 control measures drastically reduced PM2.5, PM10, NO2 and CO.
  • COVID-19 control measures significantly increased air pollutants like O3 and SO2.
  • Low RH and the low-temperature situation supported COVID-19 virus diffusion.
  • Lower NO2 level maintained negative correlation with new COVID-19 cases.
  • O3 may positively correlate with COVID-19 infection at low RH and temperature.


Based on a time series analysis of the criteria pollutants, meteorological parameters, and COVID-19 positive cases, this paper explores the impact of epidemic prevention and control actions on air quality for five different periods of COVID-19 outbreak in Delhi, India. The study found that under the epidemic control measure during 11 May-19 June 2020, the average concentrations of atmospheric air pollutants PM2.5, PM10, NO2, and CO were reduced to 42.15 µg m-3, 128.68 µg m-3, 27.31 ppb, and 0.83 ppm respectively, and were 73.85%, 46.48%, 63.43%, and 50.18% lower than the pre-COVID-19 level of January 2020, respectively. The steep fall of PM2.5, NO2, and CO was due to a drastic reduction in vehicular emission, but PM10 did not fall below the National Ambient Air Quality Standard. Between January 2020 to 11 May -19 June 2020 period, the pollutants O3 and SO2 increased significantly by 217.33% and 57.58 % respectively. The rise of SO2 in Delhi was due to long-distance transfer, power plant emissions, and biomass burning. The sharp increase of O3 happened due to accumulation in the atmosphere. During the peak COVID-19 phase (9 April –10 May 2020) Delhi had unprecedented improved AQI classes of II and III only. However, the pivotal pollutants in terms of their cumulative contribution to the AQI classes were PM10 and O3. Low RH and low-temperature situations exhibited positive correlations with the new COVID-19 infection cases in Delhi. Comparatively lower NO2 level in the air demonstrated a significant negative correlation with new COVID-19 cases while average SO2 concentration in the air, when increased to 24.05 ppb, showed a negative correlation with new COVID-19 cases in Delhi. This study indicated a possibility of O3 exhibiting a positive correlation with new COVID-19 cases under the condition of comparatively low temperature and low humidity.

Keywords: COVID-19, Delhi, Air pollutants, Air Quality Index, Meteorological variables

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