Comparative Assessment of the Impact of COVID-19 Lockdown on Air Quality: A Multinational Study of SARS-CoV-2 Hotspots

Abstract

Abstract In response to the global COVID-19 pandemic, nations implemented lockdown measures to contain the virus. This study assessed air pollution levels during and after lockdowns, focusing on heavily affected locations: Oulu and Helsinki in Finland, Paris in France, Madrid in Spain, Milan in Italy, and Wuhan in China. Air Quality Index (AQI) data from these areas over two years were analyzed to understand lockdown effects. COVID-19 lockdowns in six cities were compared with SARS-CoV-2 measures using statistical methods. Pollutant Outdoor variations were evaluated via tests, showing significant differences. Parametric analyses and regression studied lockdown impacts on pollution and relationships. The study comprehensively analyzed COVID-19 lockdowns' effects on air quality, identifying differences, quantifying changes, and exploring patterns in Oulu and Helsinki. Pollutant correlations varied among cities during lockdowns. Regression analysis highlighted independent variables' impact on pollutants. Decreases in NO2 were seen in Helsinki, Madrid, Oulu, Paris, and Milan, reflecting reduced traffic and industry. PM2.5 and PM10 reductions occurred in these cities and also Wuhan, except for O3 levels which increased. Reduced human activities improved air quality, especially for NO2 and PM10. Regional variations necessitate tailored interventions. We observed that during the COVID-19 lockdowns, there was a substantial decrease in both PM2.5 and NO2 levels, indicating a direct correlation between reduced human activities, such as transportation and industrial operations, and improved air quality. This underscores the potential impact of environmental measures and suggests the need for sustainable practices to mitigate urban pollution.