Impact of lockdown measures to combat Covid-19 on air quality over western Europe

Menut, Laurent; Bessagnet, Bertrand; Siour, Guillaume; Mailler, Sylvain; Pennel, Romain; Cholakian, Arineh

doi:10.1016/j.scitotenv.2020.140426

Cited by 327 publications

(337 citation statements)

References 41 publications

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“…In particular, we found daily mean NO 2 levels reduced by 35–41%, depending on the measuring site, during the first phase of the lockdown in Graz. We can compare our findings to the results of Ordóñez et al (2020) on Menut et al (2020) on NO 2 levels in Europe. Although the methods and time spans under analysis vary considerably, their results indicate reductions of 34.4% and 37.1%, respectively, in Austrian urban areas.…”

Section: Summary and Discussionsupporting

confidence: 74%

“…They found that under lockdown, the levels of NO 2 , PM 10 , and CO were reduced by 25%, 14%, and 5%, respectively. Using the CHIMERE multi-scale model, Menut et al (2020) carried out simulations for the month of March 2020. A reference scenario with emissions as usual was compared to a scenario that took into account the reduction of pollutant emissions due to lockdown measures.…”

Section: Introductionmentioning

confidence: 99%

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Separating the impact of gradual lockdown measures on air pollutants from seasonal variability

Hörmann

Jammoul

Kuenzer

et al. 2021

Atmospheric Pollution Research

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Analysis of near-surface measurements at several measuring points in Graz, Austria, reveals the impact of restrictive measures during the COVID-19 pandemic on the emission of atmospheric pollutants. We quantify the effects at traffic hotspots, industrial and residential areas. Using historical data collected over several years, we are able to account for meteorological and seasonal confounders. Our analysis is based on daily means as well as intraday pollution level curves. Nitrogen dioxide (NO 2 ) has decreased drastically while the levels of particulate matter PM 10 and carbon monoxide (CO) mostly exhibit little change. Traffic data shows that the decrease in traffic frequency is parallel to the decline in the levels of NO 2 and NO.

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Section: Summary and Discussionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Separating the impact of gradual lockdown measures on air pollutants from seasonal variability

Hörmann

Jammoul

Kuenzer

et al. 2021

Atmospheric Pollution Research

View full text Add to dashboard Cite

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“…The machine-learning modeling in this study is performed using the "scikit-learn" Python package (Pedregosa et al, 2011). The GBM model comprises a number of hyperparameters to be tuned.…”

Section: Choice Of Features and Modeling Strategymentioning

confidence: 99%

Meteorology-normalized impact of the COVID-19 lockdown upon NO<sub>2</sub> pollution in Spain

et al. 2020

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Abstract. The spread of the new coronavirus SARS-CoV-2 that causes COVID-19 forced the Spanish Government to implement extensive lockdown measures to reduce the number of hospital admissions, starting on 14 March 2020. Over the following days and weeks, strong reductions in nitrogen dioxide (NO2) pollution were reported in many regions of Spain. A substantial part of these reductions was obviously due to decreased local and regional anthropogenic emissions. Yet, the confounding effect of meteorological variability hinders a reliable quantification of the lockdown's impact upon the observed pollution levels. Our study uses machine-learning (ML) models fed by meteorological data along with other time features to estimate the “business-as-usual” NO2 mixing ratios that would have been observed in the absence of the lockdown. We then quantify the so-called meteorology-normalized NO2 reductions induced by the lockdown measures by comparing the estimated business-as-usual values with the observed NO2 mixing ratios. We applied this analysis for a selection of urban background and traffic stations covering the more than 50 Spanish provinces and islands. The ML predictive models were found to perform remarkably well in most locations, with an overall bias, root mean square error and correlation of +4 %, 29 % and 0.86, respectively. During the period of study, from the enforcement of the state of alarm in Spain on 14 March to 23 April, we found the lockdown measures to be responsible for a 50 % reduction in NO2 levels on average over all provinces and islands. The lockdown in Spain has gone through several phases with different levels of severity with respect to mobility restrictions. As expected, the meteorology-normalized change in NO2 was found to be stronger during phase II (the most stringent phase) and phase III of the lockdown than during phase I. In the largest agglomerations, where both urban background and traffic stations were available, a stronger meteorology-normalized NO2 change is highlighted at traffic stations compared with urban background sites. Our results are consistent with foreseen (although still uncertain) changes in anthropogenic emissions induced by the lockdown. We also show the importance of taking the meteorological variability into account for accurately assessing the impact of the lockdown on NO2 levels, in particular at fine spatial and temporal scales. Meteorology-normalized estimates such as those presented here are crucial to reliably quantify the health implications of the lockdown due to reduced air pollution.

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“…Chinese cities not having official lockdown but having other disease control measures like social distancing or stay at the home practice also experienced a decline (7%) in PM2.5 level (He et al, 2020). Menut et al (2020) reported a 5% to 15% reduction of ambient PM2.5 in Western…”

Section: Accepted Manuscriptmentioning

confidence: 99%

How are the Two Most Polluted Metro-cities of India Combating Air Pollution? Way Forward after Lifting of COVID-19 Lockdown

Majumdar

2021

Aerosol Air Qual. Res.

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The national capital region of Delhi and Kolkata are the two metro cities in India worst affected by poor air quality. Multiple policies have been declared and implemented by the city authority in the recent past with the hope of improving the air quality of the cities and to attain the national ambient air quality standard. This study assesses that these present policies can help to reduce air pollution in these cities as much as 20% in the optimistic assessment, which may not be sufficient to attain the clean-air goal soon. During April and May 2020, the nationwide lockdown to control the pandemic of COVID-19 has unintentionally resulted in improved air quality due to force reduction at pollution emission sources. Significant pollution emitting sectors in NCR-Delhi are still not covered in current policy measures adequately. The substantial contribution of secondary aerosol formation from its precursor gases is still not addressed in any city-specific policies. The present study attempts to assess these gaps in current air pollution control policies. A way forward is indicated to empower these two polluted metro cities to attain clean air after lifting of the lockdown for the safety of the city inhabitants.

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Impact of lockdown measures to combat Covid-19 on air quality over western Europe

Cited by 327 publications

References 41 publications

Separating the impact of gradual lockdown measures on air pollutants from seasonal variability

Separating the impact of gradual lockdown measures on air pollutants from seasonal variability

Meteorology-normalized impact of the COVID-19 lockdown upon NO<sub>2</sub> pollution in Spain

How are the Two Most Polluted Metro-cities of India Combating Air Pollution? Way Forward after Lifting of COVID-19 Lockdown

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Impact of lockdown measures to combat Covid-19 on air quality over western Europe

Cited by 327 publications

References 41 publications

Separating the impact of gradual lockdown measures on air pollutants from seasonal variability

Separating the impact of gradual lockdown measures on air pollutants from seasonal variability

Meteorology-normalized impact of the COVID-19 lockdown upon NO&lt;sub&gt;2&lt;/sub&gt; pollution in Spain

How are the Two Most Polluted Metro-cities of India Combating Air Pollution? Way Forward after Lifting of COVID-19 Lockdown

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Meteorology-normalized impact of the COVID-19 lockdown upon NO<sub>2</sub> pollution in Spain