Identifying airborne transmission as the dominant route for the spread of COVID-19

Proceedings of the National Academy of Sciences, Journal Year: 2020, Volume and Issue: 117(26), P. 14857 - 14863

Published: June 11, 2020

Various mitigation measures have been implemented to fight the coronavirus disease 2019 (COVID-19) pandemic, including widely adopted social distancing and mandated face covering. However, assessing effectiveness of those intervention practices hinges on understanding virus transmission, which remains uncertain. Here we show that airborne transmission is highly virulent represents dominant route spread disease. By analyzing trend in Wuhan, China, Italy, New York City, from January 23 May 9, 2020, illustrate impacts are discernable trends pandemic. Our analysis reveals difference with without covering determinant shaping pandemic three epicenters. This protective measure alone significantly reduced number infections, is, by over 78,000 Italy April 6 9 66,000 City 17 9. Other measures, such as United States, insufficient themselves protecting public. We conclude wearing masks public corresponds most effective means prevent interhuman this inexpensive practice, conjunction simultaneous distancing, quarantine, contact tracing, likely fighting opportunity stop COVID-19 work also highlights fact sound science essential decision-making for current future health pandemics.

Language: Английский

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Unexpected air pollution with marked emission reductions during the COVID-19 outbreak in China

Science, Journal Year: 2020, Volume and Issue: 369(6504), P. 702 - 706

Published: June 17, 2020

Air pollution epidemic The lockdown enforced in most cities China response to the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) resulted virtual absence motor vehicle traffic and sharply reduced manufacturing activity for several weeks. Le et al. report some anticipated unanticipated effects that this had on air there, including unexpectedly high levels particulate matter abundances haze formation areas. This natural experiment will help assessment mitigation strategies. Science , issue p. 702

Language: Английский

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Contrasting trends of PM2.5 and surface-ozone concentrations in China from 2013 to 2017

National Science Review, Journal Year: 2020, Volume and Issue: 7(8), P. 1331 - 1339

Published: Feb. 27, 2020

Although much attention has been paid to investigating and controlling air pollution in China, the trends of air-pollutant concentrations on a national scale have remained unclear. Here, we quantitatively investigated variation pollutants China using long-term comprehensive data sets from 2013 2017, during which Chinese government made major efforts reduce anthropogenic emission polluted regions. Our results show significant decreasing trend PM2.5 concentration heavily regions eastern with an annual decrease ∼7% compared measurements 2013. The measured decreased SO2, NO2 CO (a proxy for volatile organic compounds) could explain large fraction different As consequence, days significantly corresponding Concentrations aerosol, nitrate, sulfate, ammonium chloride urban Beijing revealed remarkable reduction connecting decreases aerosol precursors chemical components closely. However, surface-ozone showed increasing most stations indicates stronger photochemical pollution. boundary-layer height capital cities no over Beijing-Tianjin-Hebei, Yangtze River Delta Pearl confirmed emissions. demonstrated that was successful particulate matter areas although ozone increased significantly, suggesting more complex mechanism improving quality future.

Language: Английский

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Ozone pollution in the North China Plain spreading into the late-winter haze season

Proceedings of the National Academy of Sciences, Journal Year: 2021, Volume and Issue: 118(10)

Published: March 1, 2021

Surface ozone is a severe air pollution problem in the North China Plain, which home to 300 million people. Ozone concentrations are highest summer, driven by fast photochemical production of hydrogen oxide radicals (HO

Language: Английский

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East Asian Study of Tropospheric Aerosols and their Impact on Regional Clouds, Precipitation, and Climate (EAST‐AIR_CPC)

Journal of Geophysical Research Atmospheres, Journal Year: 2019, Volume and Issue: 124(23), P. 13026 - 13054

Published: Oct. 23, 2019

Abstract Aerosols have significant and complex impacts on regional climate in East Asia. Cloud‐aerosol‐precipitation interactions (CAPI) remain most challenging studies. The quantitative understanding of CAPI requires good knowledge aerosols, ranging from their formation, composition, transport, radiative, hygroscopic, microphysical properties. A comprehensive review is presented here centered the based chiefly, but not limited to, publications special section named EAST‐AIRcpc concerning (1) observations aerosol loading properties, (2) relationships between aerosols meteorological variables affecting CAPI, (3) mechanisms behind (4) quantification impact climate. Heavy Asia has radiative effects by reducing surface radiation, increasing air temperature, lowering boundary layer height. key factor absorption, which particularly strong central China. This absorption can a wide range such as creating an imbalance forcing at top bottom atmosphere, leading to inconsistent retrievals cloud space‐borne ground‐based instruments. Aerosol delay or suppress initiation development convective clouds whose microphysics be further altered effect aerosols. For same thickness, likelihood precipitation influenced aerosols: suppressing light rain enhancing heavy rain, delaying intensifying thunderstorms, onset isolated showers parts Rainfall become more inhomogeneous extreme heavily polluted urban regions.

Language: Английский

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Changes of nitrogen deposition in China from 1980 to 2018

Environment International, Journal Year: 2020, Volume and Issue: 144, P. 106022 - 106022

Published: Aug. 11, 2020

China has experienced a dramatic change in atmospheric reactive nitrogen (Nr) emissions over the past four decades. However, it remains unclear how (N) deposition responded to increases and/or decreases Nr emissions. This study quantitatively assesses temporal and spatial variations measurements of bulk calculated dry N from 1980 2018. A long-term database (1980–2018) shows that peaked around 2000, had declined by 45% 2016–2018. Recent (based on monitoring 2011 2018) decreased 2018, with current average values 19.4 ± 0.8 20.6 0.4 kg ha−1 yr−1, respectively. Oxidized deposition, especially after 2010 due NOx emission controls. In contrast, reduced was approximately constant, reductions NH4+-N offset continuous increase NH3 deposition. Elevated concentrations were found at nationwide sites even urban sites, suggesting strong influence both agricultural non-agricultural sources. Current controls are reducing but further mitigation measures needed, NH3, built broader regional control strategies.

Language: Английский

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

Geophysical Research Letters, Journal Year: 2020, Volume and Issue: 47(12)

Published: June 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.

Language: Английский

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An unexpected catalyst dominates formation and radiative forcing of regional haze

Proceedings of the National Academy of Sciences, Journal Year: 2020, Volume and Issue: 117(8), P. 3960 - 3966

Published: Feb. 10, 2020

Significance Regional haze adversely affects human health and possibly counteracts global warming by greenhouse gases, but its formation radiative forcing remain unclear. Here we present field measurements to show reduced frequency not severity for heavy little-improved moderate haze, when SO 2 is significantly in China. Our laboratory experiments identify black carbon (BC)-catalyzed sulfate involving NO NH 3 . Radiative transfer calculations accounting this BC chemistry indicate small net climatic cooling/warming large surface cooling, atmospheric heating, air stagnation. work reveals that catalytic dominates the formation, trend, of regional suggesting necessity simultaneous reduction emissions , x air-quality improvement.

Language: Английский

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Multiphase Oxidation of Sulfur Dioxide in Aerosol Particles: Implications for Sulfate Formation in Polluted Environments

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 55(8), P. 4227 - 4242

Published: March 24, 2021

Atmospheric oxidation of sulfur dioxide (SO2) forms sulfate-containing aerosol particles that impact air quality, climate, and human ecosystem health. It is well-known in-cloud SO2 frequently dominates over gas-phase on regional global scales. Multiphase involving particles, fog, cloud droplets has been generally thought to scale with liquid water content (LWC) so multiphase would be negligible for due their low LWC. However, recent field evidence, particularly from East Asia, shows fast sulfate formation prevails in cloud-free environments are characterized by high loadings. By assuming the kinetics chemistry most atmospheric models do not capture this phenomenon. Therefore, blossomed past decade, many processes proposed bridge difference between modeled observed mass This review summarizes advances fundamental understanding SO2, a focus environmental conditions affect rate, experimental challenges, mechanisms results individual reaction pathways, future research directions. Compared dilute conditions, paper highlights differences arise at molecular level extremely solute strengths present particles.

Language: Английский

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Societal benefits of halving agricultural ammonia emissions in China far exceed the abatement costs

Nature Communications, Journal Year: 2020, Volume and Issue: 11(1)

Published: Aug. 31, 2020

Mitigating agricultural ammonia (NH3) emissions in China is urgently needed to avoid further damage human and ecosystem health. Effective feasible mitigation strategies hinge on integrated knowledge of the potential NH3 associated economic costs societal benefits. Here we present a comprehensive analysis marginal abatement benefits for China. The technical 38-67% (4.0-7.1 Tg N) with implementation estimated at US$ 6-11 billion. These are much lower than estimates overall 18-42 Avoiding unnecessary fertilizer use protein-rich animal feed could provide 30% this without additional or decreases productivity. Optimizing diets less animal-derived products offers reduction 12% by 2050.

Language: Английский

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