Implications of COVID-19 Restriction Measures in Urban Air Quality of Thessaloniki, Greece: A Machine Learning Approach

Department of Environment and Hydroeconomy, Directorate of Environment, Industry, Energy and Natural Resources, of the Region of Central Macedonia, 54642 Thessaloniki, Greece

Department of Environment of the Municipality of Thessaloniki, 54642 Thessaloniki, Greece

Author to whom correspondence should be addressed.

Academic Editors: Gunnar W. Schade, Nicole Mölders, Daniele Contini, Gabriele Curci, Francesca Costabile, Prashant Kumar and Chris G. Tzanis

Atmosphere 2021, 12(11), 1500; https://doi.org/10.3390/atmos12111500

Received: 14 September 2021 / Revised: 2 November 2021 / Accepted: 10 November 2021 / Published: 14 November 2021

(This article belongs to the Special Issue Coronavirus Pandemic Shutdown Effects on Urban Air Quality)

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Abstract

Following the rapid spread of COVID-19, a lockdown was imposed in Thessaloniki, Greece, resulting in an abrupt reduction of human activities. To unravel the impact of restrictions on the urban air quality of Thessaloniki, NO

_{2}

and O

_{3}

observations are compared against the business-as-usual (BAU) concentrations for the lockdown period. BAU conditions are modeled, applying the XGBoost (eXtreme Gradient Boosting) machine learning algorithm on air quality and meteorological surface measurements, and reanalysis data. A reduction in NO

_{2}

concentrations is found during the lockdown period due to the restriction policies at both AGSOFIA and EGNATIA stations of −24.9 [−26.6, −23.2]% and −18.4 [−19.6, −17.1]%, respectively. A reverse effect is revealed for O

_{3}

concentrations at AGSOFIA with an increase of 12.7 [10.8, 14.8]%, reflecting the reduced O

_{3}

titration by NO

_{x}

. The implications of COVID-19 lockdowns in the urban air quality of Thessaloniki are in line with the results of several recent studies for other urban areas around the world, highlighting the necessity of more sophisticated emission control strategies for urban air quality management. View Full-Text

Keywords: COVID-19; air quality; machine learning; NO₂; O₃; Thessaloniki; Greece

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Akritidis, D.; Zanis, P.; Georgoulias, A.K.; Papakosta, E.; Tzoumaka, P.; Kelessis, A. Implications of COVID-19 Restriction Measures in Urban Air Quality of Thessaloniki, Greece: A Machine Learning Approach. Atmosphere 2021, 12, 1500. https://doi.org/10.3390/atmos12111500

AMA Style

Akritidis D, Zanis P, Georgoulias AK, Papakosta E, Tzoumaka P, Kelessis A. Implications of COVID-19 Restriction Measures in Urban Air Quality of Thessaloniki, Greece: A Machine Learning Approach. Atmosphere. 2021; 12(11):1500. https://doi.org/10.3390/atmos12111500

Chicago/Turabian Style

Akritidis, Dimitris, Prodromos Zanis, Aristeidis K. Georgoulias, Eleni Papakosta, Paraskevi Tzoumaka, and Apostolos Kelessis. 2021. "Implications of COVID-19 Restriction Measures in Urban Air Quality of Thessaloniki, Greece: A Machine Learning Approach" Atmosphere 12, no. 11: 1500. https://doi.org/10.3390/atmos12111500

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Implications of COVID-19 Restriction Measures in Urban Air Quality of Thessaloniki, Greece: A Machine Learning Approach

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