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

doi:10.5194/acp-2020-446

GSTDTAP > 地球科学

DOI	10.5194/acp-2020-446
	Meteorology-normalized impact of COVID-19 lockdown upon NO₂ pollution in Spain
	Hervé Petetin, Dene Bowdalo, Albert Soret, Marc Guevara, Oriol Jorba, Kim Serradell, and Carlos Pérez García-Pando
	2020-05-25
发表期刊	Atmospheric Chemistry and Physics
出版年	2020
英文摘要	The spread of the new coronavirus (COVID-19) forced the Spanish Government to implement extensive lockdown measures to reduce the number of hospital admissions, starting on March 14^th 2020. Over the following days and weeks, strong reductions of nitrogen dioxide (NO₂) pollution were reported in many regions of Spain. A substantial part of these reductions is obviously due to decreased local and regional anthropogenic emissions. Yet, the confounding effect of meteorological variability hinders a reliable quantification of the lockdown 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 business-as-usual with the actually 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. During the period of study, going from the enforcement of the state of alarm in Spain on March 14^th to April 23^rd, we found the lockdown measures to be responsible for a 50 % reduction of NO₂ levels on average over all provinces and islands. The lockdown in Spain has gone through several phases with different levels of severity in the mobility restrictions. As expected the meteorology-normalized change of NO₂ was found to be stronger during the phases II (the most stringent one) and III 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 to urban background ones. Our results are consistent with foreseen (although still uncertain) changes in anthropogenic emissions induced by the lockdown. We also show the importance of taking into account meteorological variability for accurately assessing the impact of the lockdown on NO₂ levels, in particular at fine spatial and temporal scales. Meteorology-normalized estimates such as the ones presented here are crucial to reliably quantify the health implications of the lockdown due to reduced air pollution.
领域	地球科学
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文献类型	期刊论文
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/271648
专题	地球科学
推荐引用方式 GB/T 7714	Hervé Petetin, Dene Bowdalo, Albert Soret, Marc Guevara, Oriol Jorba, Kim Serradell, and Carlos Pérez García-Pando. Meteorology-normalized impact of COVID-19 lockdown upon NO₂ pollution in Spain[J]. Atmospheric Chemistry and Physics,2020.
APA	Hervé Petetin, Dene Bowdalo, Albert Soret, Marc Guevara, Oriol Jorba, Kim Serradell, and Carlos Pérez García-Pando.(2020).Meteorology-normalized impact of COVID-19 lockdown upon NO₂ pollution in Spain.Atmospheric Chemistry and Physics.
MLA	Hervé Petetin, Dene Bowdalo, Albert Soret, Marc Guevara, Oriol Jorba, Kim Serradell, and Carlos Pérez García-Pando."Meteorology-normalized impact of COVID-19 lockdown upon NO₂ pollution in Spain".Atmospheric Chemistry and Physics (2020).