Abrupt but smaller than expected changes in surface air quality attributable to COVID-19 lockdowns

Science Advances, Год журнала: 2021, Номер 7(3)

Опубликована: Янв. 13, 2021

True air quality improvements during the COVID-19 lockdowns in global cities are more limited than we thought.

Язык: Английский

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Puzzling Haze Events in China During the Coronavirus (COVID‐19) Shutdown

Geophysical Research Letters, Год журнала: 2020, Номер 47(12)

Опубликована: Июнь 10, 2020

It is a puzzle as to why more severe haze formed during the New Year Holiday in 2020 (NYH-20), when China was an unprecedented state of shutdown contain coronavirus (COVID-19) outbreak, than 2019 (NYH-19). We performed comprehensive measurement and modeling analysis aerosol chemistry physics at multiple sites (mainly Shanghai) before, during, after NYH-19 NYH-20. Much higher secondary fraction PM2.5 were observed NYH-20 (73%) (59%). During NYH-20, levels correlated significantly with oxidation ratio nitrogen (r2 = 0.77, p < 0.01), aged particles from northern found impede atmospheric new particle formation growth Shanghai. A markedly enhanced efficiency nitrate along transport pathways despite overall low NO2 levels.

Язык: Английский

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The global impacts of COVID-19 lockdowns on urban air pollution

Elementa Science of the Anthropocene, Год журнала: 2021, Номер 9(1)

Опубликована: Янв. 1, 2021

The coronavirus-19 (COVID-19) pandemic led to government interventions limit the spread of disease which are unprecedented in recent history; for example, stay at home orders sudden decreases atmospheric emissions from transportation sector. In this review article, current understanding influence emission reductions on pollutant concentrations and air quality is summarized nitrogen dioxide (NO2), particulate matter (PM2.5), ozone (O3), ammonia, sulfur dioxide, black carbon, volatile organic compounds, carbon monoxide (CO). first 7 months following onset pandemic, more than 200 papers were accepted by peer-reviewed journals utilizing observations ground-based satellite instruments. Only about one-third literature incorporates a specific method meteorological correction or normalization comparing data lockdown period with prior reference despite importance doing so interpretation results. We use stringency index (SI) as an indicator severity measures show how key pollutants change SI increases. observed decrease NO2 increasing general agreement inventories that account lockdown. Other compounds such O3, PM2.5, CO also broadly covered. Due chemistry O3 PM2.5 concentrations, their responses may not be linear respect primary pollutants. At most sites, we found increased, whereas decreased slightly, SI. Changes other understudied. highlight future research needs emerging sets preview state atmosphere world targeted permanent emissions. Finally, emphasize need effects meteorology, trends, when determining concentrations.

Язык: Английский

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A chemical cocktail during the COVID-19 outbreak in Beijing, China: Insights from six-year aerosol particle composition measurements during the Chinese New Year holiday

The Science of The Total Environment, Год журнала: 2020, Номер 742, С. 140739 - 140739

Опубликована: Июль 4, 2020

Язык: Английский

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Revealing Drivers of Haze Pollution by Explainable Machine Learning

Environmental Science & Technology Letters, Год журнала: 2022, Номер 9(2), С. 112 - 119

Опубликована: Янв. 4, 2022

Many places on earth still suffer from a high level of atmospheric fine particulate matter (PM2.5) pollution. Formation pollution event or haze episode (HE) involves many factors, including meteorology, emissions, and chemistry. Understanding the direct causes key drivers behind HE is thus essential. Traditionally, this done via chemical transport models. However, substantial uncertainties are introduced into model estimation when there significant changes in emissions inventory due to interventions (e.g., COVID-19 lockdown). Here we applied Random Forest coupled with Shapley additive explanation algorithm, post hoc technique, investigate roles major meteorological primary chemistry five severe HEs that occurred before during lockdown China. We discovered that, addition PM2.5 these episodes was largely driven by effects (with average contributions 30–65 μg m–3 for HEs), followed (∼15–30 m–3). Photochemistry likely pathway formation nitrate, while air humidity predominant factor forming sulfate. Our results highlight machine learning data has potential be complementary tool predicting interpreting

Язык: Английский

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Driving Forces of Changes in Air Quality during the COVID-19 Lockdown Period in the Yangtze River Delta Region, China

Environmental Science & Technology Letters, Год журнала: 2020, Номер 7(11), С. 779 - 786

Опубликована: Сен. 14, 2020

During the COVID-19 lockdown period (from January 23 to February 29, 2020), ambient PM2.5 concentrations in Yangtze River Delta (YRD) region were observed be much lower, while maximum daily 8 h average (MDA8) O3 became higher compared those before 1 22, 2020). Here, we show that emission reduction is major driving force for change, contributing a decrease by 37% 55% four YRD cities (i.e., Shanghai, Hangzhou, Nanjing, and Hefei), but MDA8 increase driven both (29%-52%) variation meteorological conditions (17%- 49%). Among all pollutants, emissions mainly of primary PM contributes 28% 46%, NOx 7% 10%. Although dominates (38%-59%), volatile organic compounds (VOCs) lead 5% 9% decrease. Increased promotes secondary aerosol formation partially offsets caused reductions. The results demonstrate more coordinated air pollution control strategies are needed YRD.

Язык: Английский

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Air quality changes in cities during the COVID-19 lockdown: A critical review

Atmospheric Research, Год журнала: 2021, Номер 264, С. 105823 - 105823

Опубликована: Авг. 25, 2021

Язык: Английский

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Opportunistic experiments to constrain aerosol effective radiative forcing

Atmospheric chemistry and physics, Год журнала: 2022, Номер 22(1), С. 641 - 674

Опубликована: Янв. 17, 2022

Aerosol-cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due human activities. The nonlinearity cloud-state changes aerosol perturbations make it challenging attribute causality in observed relationships forcing. Using correlations infer can when meteorological variability also drives both and cloud independently. Natural anthropogenic from well-defined sources provide "opportunistic experiments" (also known as natural experiments) investigate ACI cases where may more confidently inferred. These cover a wide range locations spatiotemporal scales, including point such volcanic eruptions or industrial sources, plumes biomass burning forest fires, tracks individual ships shipping corridors. We review different experimental conditions conduct synthesis available satellite datasets field campaigns place these opportunistic experiments on common footing, facilitating new insights clearer understanding key uncertainties Cloud albedo strongly sensitive background conditions. Strong liquid water path increases largely ruled out by averaging across experiments. Opportunistic have significantly improved process-level ACI, but remains unclear how reliably found scaled global level, thus demonstrating need for deeper investigation order improve assessments climate change.

Язык: Английский

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Long-term characterization of aerosol chemistry in cold season from 2013 to 2020 in Beijing, China

Environmental Pollution, Год журнала: 2020, Номер 268, С. 115952 - 115952

Опубликована: Ноя. 3, 2020

Язык: Английский

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Air pollution episodes during the COVID-19 outbreak in the Beijing–Tianjin–Hebei region of China: An insight into the transport pathways and source distribution

Environmental Pollution, Год журнала: 2020, Номер 267, С. 115617 - 115617

Опубликована: Сен. 8, 2020

Язык: Английский

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