Lockdown Effects on Air Quality in Megacities During the First and Second Waves of COVID-19 Pandemic
Lockdown Effects on Air Quality in Megacities During the First and Second Waves of COVID-19 Pandemic
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DOI：
10.1007/s40030-022-00702-9
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发表时间：
2022-11-24
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空气污染是世界范围内，特别是城市地区死亡率最高的因素之一。2020年春季，许多国家颁布了社交距离措施，以减缓正在进行的COVID-19大流行。一项特别严厉的措施是“封锁”，敦促人们在大流行的第一波（2020年）和第二波（2021年）期间呆在家里，从而防止新的COVID-19感染。反过来，它也减少了交通和工业活动。但这些封锁措施在多大程度上改善了大城市的空气质量？空气质量受到的影响有何不同？在这里，我们分析了两个特大城市的数据：以欧洲为例的伦敦和以亚洲为例的德里。我们考虑了第一波和第二波封锁期间的数据，并将其与2019年的数据进行了比较。总体而言，我们发现几乎所有的空气污染物都减少了，除了2021年的德里，两个城市之间存在着有趣的差异。在伦敦，尽管平均浓度较小，但我们仍然观察到2020年高污染状态和极端事件（封锁期间概率密度峰度较高）的趋势增加，2021年污染水平较低。对于德里，我们观察到污染浓度的下降幅度要大得多，包括2020年的高污染状态和2021年的更高污染水平。这些结果可能有助于制定政策，以改善特大城市的长期空气质量。在线版本包含补充资料，下载地址为10.1007/s40030-022-00702-9。
Air pollution is among the highest contributors to mortality worldwide, especially in urban areas. During spring 2020, many countries enacted social distancing measures in order to slow down the ongoing COVID-19 pandemic. A particularly drastic measure, the “lockdown”, urged people to stay at home and thereby prevent new COVID-19 infections during the first (2020) and second wave (2021) of the pandemic. In turn, it also reduced traffic and industrial activities. But how much did these lockdown measures improve air quality in large cities, and are there differences in how air quality was affected? Here, we analyse data from two megacities: London as an example for Europe and Delhi as an example for Asia. We consider data during first and second-wave lockdowns and compare them to 2019 values. Overall, we find a reduction in almost all air pollutants with intriguing differences between the two cities except Delhi in 2021. In London, despite smaller average concentrations, we still observe high-pollutant states and an increased tendency towards extreme events (a higher kurtosis of the probability density during lockdown) during 2020 and low pollution levels during 2021. For Delhi, we observe a much stronger decrease in pollution concentrations, including high pollution states during 2020 and higher pollution levels in 2021. These results could help to design policies to improve long-term air quality in megacities. The online version contains supplementary material available at 10.1007/s40030-022-00702-9.