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Burns, J.* ; Hoffmann, S.* ; Kurz, C.F. ; Laxy, M. ; Polus, S.* ; Rehfuess, E.*

COVID-19 mitigation measures and nitrogen dioxide - a quasi-experimental study of air quality in Munich, Germany.

Atmos. Environ. 246:118089 (2021)
Publ. Version/Full Text Research data DOI
Open Access Gold (Paid Option)
Creative Commons Lizenzvertrag
Background: In response to the COVID-19 pandemic, the Bavarian State government announced several COVID-19 mitigation measures beginning on March 16, 2020, which likely led to a reduction in traffic and a subsequent improvement in air quality. In this study, we evaluated the short-term effect of COVID-19 mitigation measures on NO2 concentrations in Munich, Germany. Methods: We applied two quasi-experimental approaches, a controlled interrupted time-series (c-ITS) approach and a synthetic control (SC) approach. Each approach compared changes occurring in 2020 to changes occurring in 2014-2019, and accounted for weather-related and other potential confounders. We hypothesized that the largest reductions in NO2 concentrations would be observed at traffic sites, with smaller reductions at urban background sites, and even small reductions, if any, at background sites. All hypotheses, as well as the main and additional analyses were defined a priori. We also conducted post-hoc analyses to ensure that observed effects were not due to factors other than the intervention. Results: Main analyses largely supported our hypotheses. Specifically, at the two traffic sites, using the c-ITS approach we observed reductions of 9.34 μg/m3 (95% confidence interval: -23.58; 4.90) and 10.02 μg/m3 (-19.25; -0.79). Using the SC approach we observed reductions of 15.65 μg/m3 (-27.58; -4.09) and 15.1 μg/m3 (-24.82; -9.83) at these same sites. We observed effects ranging from smaller in magnitude to no effect at urban background and background sites. Additional analyses showed that the effect was largest in the first two weeks following introduction of measures, and that a 3-day lagged intervention time also showed a larger effect. Post-hoc analyses suggested that at least some of the observed effects may have been attributable to changes in air quality occurring before the intervention, as well as unusually high concentrations in January 2020. Conclusion: We applied two quasi-experimental approaches in assessing the impact of the COVID-19 mitigation measures on NO2 concentrations in Munich. Taking the 2020 pre-intervention average concentrations as a reference, we observed reductions in NO2 concentrations of approximately 15-25% and 24-36% at traffic sites, suggesting that reducing traffic may be an effective measure to reduce NO2 concentrations in heavily trafficked areas by margins which could translate to public health benefits.
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Publication type Article: Journal article
Document type Scientific Article
Keywords Accountability ; Air Quality ; Covid-19 ; Nitrogen Dioxide ; Quasi-experimental Study
ISSN (print) / ISBN 1352-2310
e-ISSN 1873-2844
Quellenangaben Volume: 246, Issue: , Pages: , Article Number: 118089 Supplement: ,
Publisher Elsevier
Publishing Place The Boulevard, Langford Lane, Kidlington, Oxford Ox5 1gb, England
Reviewing status Peer reviewed