Meteorology-normalized variations of air quality during the COVID-19 lockdown in three Chinese megacities

Lv, Yaping; Tian, Hongyu; Luo, Lining; Liu, Shuhan; Bai, Xiaoxuan; Zhao, Hongyan; Lin, Shu‐Min; Zhao, Shuang; Guo, Zhihui; Xiao, Yifei; Yang, Junqi

doi:10.1016/j.apr.2022.101452

Cited by 17 publications

(3 citation statements)

References 45 publications

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“…Satellite images of the massive reduction in NO2 was directly observed by National Aeronautics and Space Administration (NASA) over China resulting from the economic slow-down and reduction in human activities (NASA, 2020). O3 increased in urban areas during the same COVID period that NOx and VOCs emissions sharply reduced (23,(27)(28)(29)(30)(31)(32). Sudden decreases in deweathered NO2 concentrations and increases in O3 in 11 cities globally were demonstrated via a deweathering machine learning technique (33).…”

Section: Introductionmentioning

confidence: 98%

Ground ozone rise caused by the larger emission reduction of nitrogen oxides than volatile organic components

Wang¹,

Li²,

Zhong³

et al. 2023

Preprint

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Ground-level ozone (O3) pollution has shifted from being a scientific topic to a governmental imperative in China. We analyze the mechanism for the O3 rise observed in Shanghai during the lockdown in the spread of COVID-19 in 2022 by combining utilizing ground-level observed data, an observation-based model, and a chemical transport model. We find that the increase in O3 can be mainly attributable to the larger emission reduction of nitrogen oxides (NOx) than volatile organic components (VOCs), of which the effect is amplified by the adverse meteorological conditions. The chemical transport modeling results suggest that a higher ratio of emission reduction of NOx to VOCs increases the daily maximum 8-hour moving average O3 concentration considerably relative to a counterfactual scenario assuming the same ratio of emission reduction of NOx to VOCs. This indicates that the concentration of O3 would depends not only on the strength of emission reduction but also the ratio of emission reduction between species. Our results highlight the importance of well-designed strategies with appropriate control of the VOCs to NOx ratio to mitigate O3 pollution in cities.

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Section: Introductionmentioning

confidence: 98%

Ground ozone rise caused by the larger emission reduction of nitrogen oxides than volatile organic components

Wang¹,

Li²,

Zhong³

et al. 2023

Preprint

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“…On this point, pandemic restrictions, which provide a significant natural testing environment, would help us meet the air pollution challenges. With this purpose, the early studies show that air pollution has generally improved due to COVID-19 lockdowns in many countries worldwide, such as in Argentina [ 19 ], Australia [ 20 ], Austria [ 21 ], Brazil [ 22 ], China [ 23 , 24 , 25 ], France [ 26 ], Greece [ 27 ], India [ 28 , 29 , 30 , 31 ], Indonesia [ 32 ], Iraq [ 33 ], Israel [ 34 ], Italy [ 35 , 36 ], Nepal [ 10 ], Poland [ 37 ], South Korea [ 38 ], Spain [ 11 , 39 , 40 , 41 ], Turkey [ 42 , 43 , 44 ], the United Kingdom [ 45 , 46 ], and the US [ 47 , 48 , 49 , 50 ]. These studies were usually based on statistical comparisons of pollutants considered before, during, and after pandemic lockdowns with either a shorter time frame or few in situ observations.…”

Section: Introductionmentioning

confidence: 99%

The Long-Term Impact of COVID-19 Lockdowns in Istanbul

Tan

2022

IJERPH

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The World Health Organization (WHO) have set sustainability development goals to reduce diseases, deaths, and the environmental impact of cities due to air pollution. In Istanbul, although average pollutant concentrations have been on a downward trend in recent years, extreme values and their annual exceedance numbers are high based on the air quality standards of WHO and the EU. Due to COVID-19 lockdowns, statistically significant reductions in emissions were observed for short periods. However, how long the effect of the lockdowns will last is unknown. For this reason, this study aims to investigate the impact of long-term lockdowns on Istanbul’s air quality. The restriction period is approximated to the same periods of the previous years to eliminate seasonal effects. A series of paired t-tests (p-value < 0.05) were applied to hourly data from 12 March 2016, until 1 July 2021, when quarantines were completed at 36 air quality monitoring stations in Istanbul. The findings reveal that the average air quality of Istanbul was approximately 17% improved during the long-term lockdowns. Therefore, the restriction-related changes in emission distributions continued in the long-term period of 476 days. However, it is unknown how long this effect will continue, which will be the subject of future studies. Moreover, it was observed that the emission probability density functions changed considerably during the lockdowns compared to the years before. Accordingly, notable decreases were detected in air quality limit exceedances in terms of both excessive pollutant concentrations and frequency of occurrence, respectively, for PM10 (−13% and −13%), PM2.5 (−16% and −30%), and NO2 (−3% and −8%), but not for O3 (+200% and +540%) and SO2 (−10% and +2.5%).

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“…The COVID-19 pandemic has led the governments of world countries to take strict measures, which are unparalleled in recent history, to limit the spread of this disease, such as stay-at-home orders via application of complete or partial lockdown. This led to a decrease in the transportation sector and industrial activities, and the consequent sudden decrease in the emission of air pollutants to the atmosphere ( Forster et al, 2020 ; Venter et al, 2020 ; He et al, 2021a , He et al, 2021b ; Naqvi et al, 2021 ; Lv et al, 2022 ). Although the complete and partial lockdown set up to limit the spread of the COVID-19 pandemic led to an unpredicted and fast reduction in economic and social movements, they give a unique scientific chance to understand the effects of anthropogenic emissions, from regional to global, on the earth's atmosphere ( Forster et al, 2020 ; He et al, 2020 ; Kroll et al, 2020 ; Le Que're´ et al, 2020 ; Liu et al, 2020b ) as well as on the climate and earth system ( Diffenbaugh et al, 2020 ; Phillips et al, 2020 ; Raymond et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

Effect of restricted emissions during COVID-19 on atmospheric aerosol chemistry in a Greater Cairo suburb: Characterization and enhancement of secondary inorganic aerosol production

Hassan

Alghamdi

Khoder

2022

Atmospheric Pollution Research

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Meteorology-normalized variations of air quality during the COVID-19 lockdown in three Chinese megacities

Cited by 17 publications

References 45 publications

Ground ozone rise caused by the larger emission reduction of nitrogen oxides than volatile organic components

Ground ozone rise caused by the larger emission reduction of nitrogen oxides than volatile organic components

The Long-Term Impact of COVID-19 Lockdowns in Istanbul

Effect of restricted emissions during COVID-19 on atmospheric aerosol chemistry in a Greater Cairo suburb: Characterization and enhancement of secondary inorganic aerosol production

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