Transformation of Air Quality over a Coastal Tropical Station Chennai during COVID-19 Lockdown in India

Jyotsna Singh; Bhishma Tyagi

doi:10.4209/aaqr.200490

Transformation of Air Quality over a Coastal Tropical Station Chennai during COVID-19 Lockdown in India

Jyotsna Singh¹, Bhishma Tyagi This email address is being protected from spambots. You need JavaScript enabled to view it.²

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¹ Shanti Raj Bhawan, Paramhans Nagar, Kandwa, Varanasi, India
²Department of Earth and Atmospheric Sciences, National Institute of Technology Rourkela, Rourkela, India

Received: July 31, 2020
Revised: November 12, 2020
Accepted: December 21, 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.200490

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Cite this article:

Singh, J., Tyagi, B. (2021). Transformation of Air Quality over a Coastal Tropical Station Chennai during COVID-19 Lockdown in India. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.200490

HIGHLIGHTS

The pollutants variation is not uniform during COVID-19 lockdown at different sites of Chennai.
SO₂ have increased at Teynampet and Velachery but reduced at Alandur and Manali.
NO_x, PM_2.5 and CO decreased at all sites during the lockdown period.
The weekly analysis shows non-uniformity in reduction with increased values at some weeks.
CWT analysis reveals different source regions pattern during the lockdown period.

ABSTRACT

To prevent the spread of COVID-19, Government of India imposed strict lockdown in the country from 24 March–31 May 2020, which allows the environment to revive with reduced emissions. The present work analyses the PM_2.5, NO₂, O₃, CO and SO₂ along with meteorological parameters (humidity, temperature and wind speed) at a tropical coastal station Chennai for March-May 2019 and 2020 at five locations: Alandur Bus depot, Velachery, Manali, Teynampet and U.S. Embassy Chennai. Chennai is a megacity of southern India and the state capital of Tamil Nadu, one of the worst affected states due to COVID-19. Though overall PM_2.5 values decreased for the lockdown (ranging from ~32 – 187%), weekly analysis shows the variation in reduction/increase. SO₂ and O₃ values were found increasing for two sites: Teynampet (~40% in SO₂ and ~48% in O₃) and Velachery (~42% in SO₂ and ~5% in O₃), but decreasing for Alandur (~30% in SO₂ and ~50% in O₃) and Manali (~247% in SO₂). NO_x and CO were reduced during the lockdown (~47–125%) for all the sites. The source regions examined by concentration weighted trajectory analysis were found to change for transporting pollution to the site. The analysis shows there are local scale variations in the air pollution for the city during COVID-19 lockdown.