Changes of Air Pollutants in Urban Cities during the COVID-19 Lockdown-Sri Lanka

Buddhi Pushpawela; Sherly Shelton; Gayathri Liyanage; Sanduni Jayasekara; Dimuthu Rajapaksha; Akila Jayasundara; Lesty Das Jayasuriya

doi:10.4209/aaqr.220223

Changes of Air Pollutants in Urban Cities during the COVID-19 Lockdown-Sri Lanka

Buddhi Pushpawela This email address is being protected from spambots. You need JavaScript enabled to view it.¹, Sherly Shelton², Gayathri Liyanage³, Sanduni Jayasekara³, Dimuthu Rajapaksha⁴, Akila Jayasundara⁵, Lesty Das Jayasuriya⁵

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¹ Department of Physics and Astronomy, The University of Alabama in Huntsville, Alabama, USA
²Department of Earth and Atmospheric Sciences, University of Nebraska Lincoln, Nebraska, USA
³ Industrial Technology Institute, Colombo, Sri Lanka
⁴ University of Moratuwa, Katubaddha, Sri lanka
⁵ Air Resource Management and Monitoring Unit, Central Environmental Authority, Battaramulla, Sri Lanka

Received: May 29, 2022
Revised: December 7, 2022
Accepted: January 9, 2023

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.

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Cite this article:

Pushpawela, B., Shelton, S., Liyanage, G., Jayasekara, S., Rajapaksha, D., Jayasundara, A., Jayasuriya, L.D. (2023). Changes of Air Pollutants in Urban Cities during the COVID-19 Lockdown-Sri Lanka. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.220223

HIGHLIGHTS

Analyses the impact of COVID-19 lockdown on CO, O₃, NO₂, SO₂, and PM concentrations.
The response of NO₂ to the lockdown was the most sensitive in the two cities.
PM₁₀ and PM_2.5concentrations declined by 40–55% during the lockdown.
Daytime O₃ concentration has increased by 7–28%, compensated for drops in NO₂.
Findings highlight air quality burden on the industrial and transportation sectors.

ABSTRACT

In response to the COVID-19 pandemic in early 2020, Sri Lanka underwent a nationwide lockdown that limited motor vehicle movement, industrial operations, and human activities. This study analyses the impact of COVID-19 lockdown on carbon monoxide (CO), ozone (O₃), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and particulate matter (PM₁₀, PM_2.5) concentrations in two urban cities (Colombo and Kandy) in Sri Lanka, by comparison of data from the lockdown period (March to May 2020) with its analogous period of 2019 and 2021. The results showed that the percentage change of daytime PM₁₀, PM_2.5, CO, and NO₂ concentration during the lockdown in Colombo (Kandy) is –42.3% (–39.5%), –46% (–54.2%), –14.7% (–8.8%) and –82.2% (–80.9%), respectively. In both cities, the response of NO₂ to the lockdown was the most sensitive. In contrast, daytime O₃ concentration in Colombo (Kandy) has increased by 6.7% (27.2%), suggesting that the increase in O₃ concentration was mainly due to a reduction in NO_x emissions leading to lower O₃ titration by NO. In addition, daytime SO₂ concentration in Colombo has increased by 22.9%, while daytime SO₂ concentration in Kandy has decreased by –40%. During the lockdown period, human activities were significantly reduced, causing significant reductions in industrial operations and transportation activities, further reducing emissions and improving air quality in two cities. The results of this study offer potential for local authorities to better understand the emission sources, assess the effectiveness of current air pollution control strategies, and form a basis for formulating better environmental policies to improve air quality and human health.