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Fries J, Sardina G, Svensson G, Pumir A, Mehlig B. Lagrangian Supersaturation Fluctuations at the Cloud Edge. PHYSICAL REVIEW LETTERS 2023; 131:254201. [PMID: 38181342 DOI: 10.1103/physrevlett.131.254201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/06/2023] [Indexed: 01/07/2024]
Abstract
Evaporation of cloud droplets accelerates when turbulence mixes dry air into the cloud, affecting droplet-size distributions in atmospheric clouds, combustion sprays, and jets of exhaled droplets. The challenge is to model local correlations between droplet numbers, sizes, and supersaturation, which determine supersaturation fluctuations along droplet paths (Lagrangian fluctuations). We derived a statistical model that accounts for these correlations. Its predictions are in quantitative agreement with results of direct numerical simulations, and explain the key mechanisms at play.
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Affiliation(s)
- J Fries
- Department of Physics, Gothenburg University, SE-41296 Gothenburg, Sweden
| | - G Sardina
- Department of Mechanics and Maritime Sciences, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - G Svensson
- Department of Meteorology and Bolin Centre for Climate Research, Stockholm University, SE-106 91 Stockholm, Sweden
- Department of Engineering Mechanics, KTH Royal Institute of Technology, SE-114 28 Stockholm, Sweden
| | - A Pumir
- Université Lyon, ENS de Lyon, Université Claude Bernard, CNRS, Laboratoire de Physique, F-69342, Lyon, France
| | - B Mehlig
- Department of Physics, Gothenburg University, SE-41296 Gothenburg, Sweden
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2
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Chen TL, Lai CH, Chen YC, Ho YH, Chen AY, Hsiao TC. Source-oriented risk and lung-deposited surface area (LDSA) of ultrafine particles in a Southeast Asia urban area. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 870:161733. [PMID: 36682561 DOI: 10.1016/j.scitotenv.2023.161733] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/05/2023] [Accepted: 01/16/2023] [Indexed: 06/17/2023]
Abstract
Submicron and ultrafine particle (UFP) exposure may be epidemiologically and toxicologically linked to pulmonary, neurodegenerative, and cardiovascular diseases. This study explores UFP and fine particle sources using a positive matrix factorization (PMF) model based on PM2.5 chemical compositions and particle number size distributions (PNSDs). The particle chemical composition and size distribution contributions are simultaneously identified to evaluate lung deposition and excess cancer risks. High correlations between the PNSD and chemical composition apportionment results were observed. Fresh and aged traffic particles dominated the number concentrations, while heterogeneous, photochemical reactions and/or regional transport may have resulted in secondary aerosol formation. Fresh and aged road traffic particle sources mostly contributed to the lung deposition dosage in the pulmonary region (~53 %), followed by the tracheobronchial (~30.4 %) and head regions (~16.6 %). However, lung-deposited surface area (LDSA) concentrations were dominated by aged road traffic (~39.2 %) and secondary aerosol (~33.2 %) sources. The excess cancer risks caused by Cr6+, Ni, and As were also mainly contributed to by aged road traffic (~31.7 %) and secondary aerosols (~67 %). The source apportionments based on the physical and chemical properties of aerosol particles are complementary, offering a health impact benchmark of UFPs in a Southeast Asia urban city.
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Affiliation(s)
- Tse-Lun Chen
- Graduate Institute of Environmental Engineering, National Taiwan University, Taipei, Taiwan; Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland
| | - Chen-Hao Lai
- Graduate Institute of Environmental Engineering, National Taiwan University, Taipei, Taiwan
| | - Yu-Cheng Chen
- National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli, Taiwan
| | - Yu-Hsuan Ho
- Department of Civil Engineering, National Taiwan University, Taipei, Taiwan
| | - Albert Y Chen
- Department of Civil Engineering, National Taiwan University, Taipei, Taiwan
| | - Ta-Chih Hsiao
- Graduate Institute of Environmental Engineering, National Taiwan University, Taipei, Taiwan; Research Centre for Environmental Changes, Academia Sinica, Taipei, Taiwan.
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3
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Norvihoho LK, Yin J, Zhou ZF, Han J, Chen B, Fan LH, Lichtfouse E. Mechanisms controlling the transport and evaporation of human exhaled respiratory droplets containing the severe acute respiratory syndrome coronavirus: a review. ENVIRONMENTAL CHEMISTRY LETTERS 2023; 21:1701-1727. [PMID: 36846189 PMCID: PMC9944801 DOI: 10.1007/s10311-023-01579-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 02/13/2023] [Indexed: 05/24/2023]
Abstract
Transmission of the coronavirus disease 2019 is still ongoing despite mass vaccination, lockdowns, and other drastic measures to control the pandemic. This is due partly to our lack of understanding on the multiphase flow mechanics that control droplet transport and viral transmission dynamics. Various models of droplet evaporation have been reported, yet there is still limited knowledge about the influence of physicochemical parameters on the transport of respiratory droplets carrying the severe acute respiratory syndrome coronavirus 2. Here we review the effects of initial droplet size, environmental conditions, virus mutation, and non-volatile components on droplet evaporation and dispersion, and on virus stability. We present experimental and computational methods to analyze droplet transport, and factors controlling transport and evaporation. Methods include thermal manikins, flow techniques, aerosol-generating techniques, nucleic acid-based assays, antibody-based assays, polymerase chain reaction, loop-mediated isothermal amplification, field-effect transistor-based assay, and discrete and gas-phase modeling. Controlling factors include environmental conditions, turbulence, ventilation, ambient temperature, relative humidity, droplet size distribution, non-volatile components, evaporation and mutation. Current results show that medium-sized droplets, e.g., 50 µm, are sensitive to relative humidity. Medium-sized droplets experience delayed evaporation at high relative humidity, and increase airborne lifetime and travel distance. By contrast, at low relative humidity, medium-sized droplets quickly shrink to droplet nuclei and follow the cough jet. Virus inactivation within a few hours generally occurs at temperatures above 40 °C, and the presence of viral particles in aerosols impedes droplet evaporation.
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Affiliation(s)
- Leslie Kojo Norvihoho
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Jing Yin
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Zhi-Fu Zhou
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Jie Han
- School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Bin Chen
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Li-Hong Fan
- The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, 710061 Shaanxi People’s Republic of China
| | - Eric Lichtfouse
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
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4
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Mondal M, Chakrabarti S, Gao YQ, Bhattacharyya D, Chakrabarti J. Microscopic model on indoor propagation of respiratory droplets. Comput Biol Chem 2023; 102:107806. [PMID: 36608615 DOI: 10.1016/j.compbiolchem.2022.107806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 12/06/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022]
Abstract
Indoor propagation of airborne diseases is yet poorly understood. Here, we theoretically study a microscopic model based on the motions of virus particles in a respiratory microdroplet, responsible for airborne transmission of diseases, to understand their indoor propagation. The virus particles are driven by a driving force that mimics force due to gushing of air by devices like indoor air conditioning along with the gravity. A viral particle within the droplet experiences viscous drag due to the droplet medium, force due to interfacial tension at the droplet boundary, the thermal forces and mutual interaction forces with the other viral particles. We use Brownian Dynamics (BD) simulations and scaling arguments to study the motion of the droplet, given by that of the center of mass of the viral assembly. The BD simulations show that in presence of the gravity force alone, the time the droplet takes to reach the ground level, defined by the gravitational potential energy being zero, from a vertical height H,tf∼γ-0.1 dependence, where γ is the interfacial tension. In presence of the driving force of magnitude F0 and duration τ0, the horizontal propagation length, Ymax from the source increase linearly with τ0, where the slope is steeper for larger F0. Our scaling analysis explains qualitatively well the simulation observations and show long-distance transmission of airborne respiratory droplets in the indoor conditions due to F0 ∼ nano-dyne.
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Affiliation(s)
- Manas Mondal
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen 518107, China.
| | - Srabani Chakrabarti
- Department of Physics, Lady Brabourne College, P-1/2, Suhrawardy Avenue, Kolkata 700017, West Bengal, India.
| | - Yi Qin Gao
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen 518107, China; Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking University, Beijing 100871, China.
| | - Dhananjay Bhattacharyya
- Computational Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.
| | - Jaydeb Chakrabarti
- Department of Chemical, Biological and Macro-Molecular Sciences, Thematic unit of Excellence on Computational Materials Science and Technical Research Centre, S. N. Bose National Centre for Basic Sciences, Sector-III, Salt Lake, Kolkata 700098, India.
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5
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Vohra SB, Kumar CM. International survey of ophthalmic anaesthesia service provision, protection of anaesthesia providers and patients during COVID-19 pandemic: a wake-up call. Eye (Lond) 2023; 37:548-553. [PMID: 35220400 PMCID: PMC8881697 DOI: 10.1038/s41433-022-01979-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 01/25/2022] [Accepted: 02/08/2022] [Indexed: 11/09/2022] Open
Abstract
AIMS This international survey was conducted to study the impact of Covid-19 pandemic on the provision and practices of ophthalmic anaesthesia, evaluate the methods employed by parent ophthalmic units for safeguarding their anaesthesia providers and patients during lockdown, and to assess pandemic's effect on anaesthesia providers as individuals. The study was done with the hope that the results will help in protecting patients and safeguarding precious human resource by better management if this pandemic was to continue or there was to be another pandemic. METHODS An anonymous questionnaire survey was distributed electronically between December 2020-January 2021 to the practicing ophthalmic anaesthesia providers in different parts of the world. RESULTS The survey identified that apart from reducing elective operating services, the ophthalmic units were ill prepared for the pandemic and the overall management was lacklustre. There was a definite lack of effective peri-operative patient screening, and, streaming processes. Measures for personal protection of staff were not optimal especially during regional/local ophthalmic anaesthesia. Severity of the pandemic, sudden job plan changes, and redeployment to intensive care units/acute covid wards had an adverse psychological impact on the affected staff. CONCLUSION Ophthalmic anaesthesia services worldwide have had poor attentiveness to the life-threatening menace and reality of Covid-19 pandemic. A review of the institutional practices to address correctible deficiencies is urgently required. Robust, mandatory, elective, timely preventative strategies need to be implemented to protect patients, and, the precious ophthalmic workforce from potential adverse physical and psychological injuries.
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Affiliation(s)
- Shashi B. Vohra
- Department of Anaesthesia, Critical Care and Pain Management, Sandwell and West Birmingham Hospitals NHS Trust, Birmingham Midland Eye Centre, City Hospital, Dudley Road, Birmingham, B18 7QH UK
| | - Chandra M. Kumar
- Newcastle University, Gelang Patah, Johor Malaysia ,grid.415203.10000 0004 0451 6370Department of Anaesthesia, Khoo Teck Puat Hospital, Yishun Central 90, Singapore, 768828 Singapore
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Analysis of two choir outbreaks acting in concert to characterize long- range transmission risks through SARS-CoV-2, Berlin, Germany, 2020. PLoS One 2022; 17:e0277699. [PMID: 36395156 PMCID: PMC9671375 DOI: 10.1371/journal.pone.0277699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 11/02/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Superspreading events are important drivers of the SARS-CoV-2 pandemic and long-range (LR) transmission is believed to play a major role. We investigated two choir outbreaks with different attack rates (AR) to analyze the contribution of LR transmission and highlight important measures for prevention. METHODS We conducted two retrospective cohort studies and obtained demographic, clinical, laboratory and contact data, performed SARS-CoV-2 serology, whole genome sequencing (WGS), calculated LR transmission probabilities, measured particle emissions of selected choir members, and calculated particle air concentrations and inhalation doses. RESULTS We included 65 (84%) and 42 (100%) members of choirs 1 and 2, respectively, of whom 58 (89%) and 10 (24%) became cases. WGS confirmed strain identity in both choirs. Both primary cases transmitted presymptomatically. Particle emission rate when singing was 7 times higher compared to talking. In choir 1, the median concentration of primary cases' emitted particles in the room was estimated to be 8 times higher, exposure at least 30 minutes longer and room volume smaller than in choir 2, resulting in markedly different estimated probabilities for LR transmission (mode: 90% vs. 16%, 95% CI: 80-95% vs. 6-36%). According to a risk model, the first transmission in choir 1 occurred likely after 8 minutes of singing. CONCLUSIONS The attack rate of the two choirs differed significantly reflecting the differences in LR transmission risks. The pooled proportion of cases due to LR transmission was substantial (81%; 55/68 cases) and was facilitated by likely highly infectious primary cases, high particle emission rates, and indoor rehearsing for an extended time. Even in large rooms, singing of an infectious person may lead to secondary infections through LR exposure within minutes. In the context of indoor gatherings without mask-wearing and waning or insufficient immunity, these results highlight the ongoing importance of non-pharmaceutical interventions wherever aerosols can accumulate.
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Baek KH, Jang D, Kim T, Ryoo S, Yang JY, Park JS, Kim E, Lee S. Polyimide Surface Dielectric Barrier Discharge for Inactivation of SARS-CoV-2 Trapped in a Polypropylene Melt-Blown Filter. ACS APPLIED POLYMER MATERIALS 2022; 4:8127-8135. [PMID: 37552736 PMCID: PMC9612591 DOI: 10.1021/acsapm.2c01086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 10/12/2022] [Indexed: 08/10/2023]
Abstract
Surface dielectric barrier discharge (SDBD) was used to inactivate the infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) trapped in a polypropylene (PP) melt-blown filter. We used a dielectric barrier made of polyimide films with hexagonal holes through which air flowed. In a cylindrical wind tunnel, the SDBD device supplied reactive oxygen species such as ozone to the SARS-CoV-2 trapped in the PP filter. A plaque assay showed that SDBD at an ozone concentration of approximately 51.6 ppm and exposure time of 30 min induced more than 99.78% reduction for filter-adhered SARS-CoV-2. A carbon catalyst after SDBD effectively reduced ozone exhaust below 0.05 ppm. The combination of SDBD, PP filter, and catalyst could be a promising way to decrease the risk of secondary infection due to indoor air purifiers.
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Affiliation(s)
- Ki Ho Baek
- Department of Nano-Bio Convergence, Korea
Institute of Materials Science, Changwon51508,
Korea
| | - Donghwan Jang
- Clinical Research Centre, Masan National
Tuberculosis Hospital, Changwon51755, Korea
| | - Taeyoon Kim
- Clinical Research Centre, Masan National
Tuberculosis Hospital, Changwon51755, Korea
| | - Sungweon Ryoo
- Clinical Research Centre, Masan National
Tuberculosis Hospital, Changwon51755, Korea
| | - Jun-Yeong Yang
- Department of Nano-Bio Convergence, Korea
Institute of Materials Science, Changwon51508,
Korea
| | - Jun Soon Park
- VALS Innovation, 255
Horyeong-ro, Seocho-gu, Seoul06653, Korea
| | - Eunggon Kim
- VALS Innovation, 255
Horyeong-ro, Seocho-gu, Seoul06653, Korea
| | - Seunghun Lee
- Department of Nano-Bio Convergence, Korea
Institute of Materials Science, Changwon51508,
Korea
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8
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Avni O, Dagan Y. Dispersion of free-falling saliva droplets by two-dimensional vortical flows. THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS 2022; 36:993-1011. [PMID: 36373071 PMCID: PMC9638496 DOI: 10.1007/s00162-022-00633-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
ABSTRACT The dispersion of respiratory saliva droplets by indoor wake structures may enhance the transmission of various infectious diseases, as the wake spreads virus-laden droplets across the room. Thus, this study analyzes the interaction between vortical wake structures and exhaled multi-component saliva droplets. A self-propelling analytically described dipolar vortex is chosen as a model wake flow, passing through a cloud of micron-sized evaporating saliva droplets. The droplets' spatial location, velocity, diameter, and temperature are traced, coupled to their local flow field. For the first time, the wake structure decay is incorporated and analyzed, which is proved essential for accurately predicting the settling distances of the dispersed droplets. The model also considers the nonvolatile saliva components, adequately capturing the essence of droplet-aerosol transition and predicting the equilibrium diameter of the residual aerosols. Our analytic model reveals non-intuitive interactions between wake flows, droplet relaxation time, gravity, and transport phenomena. We reveal that given the right conditions, a virus-laden saliva droplet might translate to distances two orders of magnitude larger than the carrier-flow characteristic size. Moreover, accounting for the nonvolatile contents inside the droplet may lead to fundamentally different dispersion and settling behavior compared to non-evaporating particles or pure water droplets. Ergo, we suggest that the implementation of more complex evaporation models might be critical in high-fidelity simulations aspiring to assess the spread of airborne respiratory droplets.
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Affiliation(s)
- Orr Avni
- Faculty of Aerospace Engineering, Technion - Israel Institute of Technology, 320003 Haifa, Israel
| | - Yuval Dagan
- Faculty of Aerospace Engineering, Technion - Israel Institute of Technology, 320003 Haifa, Israel
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Foat TG, Higgins B, Abbs C, Maishman T, Coldrick S, Kelsey A, Ivings MJ, Parker ST, Noakes CJ. Modeling the effect of temperature and relative humidity on exposure to SARS-CoV-2 in a mechanically ventilated room. INDOOR AIR 2022; 32:e13146. [PMID: 36437673 PMCID: PMC10099484 DOI: 10.1111/ina.13146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 10/05/2022] [Accepted: 10/06/2022] [Indexed: 06/16/2023]
Abstract
Computational fluid dynamics models have been developed to predict airborne exposure to the SARS-CoV-2 virus from a coughing person in a mechanically ventilated room. The models were run with three typical indoor air temperatures and relative humidities (RH). Quantile regression was used to indicate whether these have a statistically significant effect on the airborne exposure. Results suggest that evaporation is an important effect. Evaporation leads to respiratory particles, particularly those with initial diameters between 20 and 100 μm, remaining airborne for longer, traveling extended distances and carrying more viruses than expected from their final diameter. In a mechanically ventilated room, with all of the associated complex air movement and turbulence, increasing the RH may result in reduced airborne exposure. However, this effect may be so small that other factors, such as a small change in proximity to the infected person, could rapidly counter the effect. The effect of temperature on the exposure was more complex, with both positive and negative correlations. Therefore, within the range of conditions studied here, there is no clear guidance on how the temperature should be controlled to reduce exposure. The results highlight the importance of ventilation, face coverings and maintaining social distancing for reducing exposure.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Catherine J. Noakes
- Leeds Institute for Fluid Dynamics, School of Civil EngineeringUniversity of LeedsLeedsUK
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Zeng G, Chen L, Yuan H, Yamamoto A, Chen H, Maruyama S. Analysis of airborne sputum droplets flow dynamic behaviors under different ambient conditions and aerosol size effects. CHEMOSPHERE 2022; 307:135708. [PMID: 35850221 PMCID: PMC9283082 DOI: 10.1016/j.chemosphere.2022.135708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 07/04/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
The coronavirus (COVID-19) is becoming more threatening with the emergence of new mutations. New virus transmission and infection processes remain challenging and re-examinations of proper protection methods are urgently needed. From fluid dynamic viewpoint, the transmission of virus-carrying droplets and aerosols is one key to understanding the virus-transmission mechanisms. This study shows virus transmission by incorporating flow-evaporation model into the Navier-Stokes equation to describe the group of airborne sputum droplets exhaled under Rosin-Rammler distribution. Solid components and humidity field evolution are incorporated in describing droplet and ambient conditions. The numerical model is solved by an inhouse code using advection-diffusion equation for the temperature field and the humidity field, discretized by applying the total-variation diminishing Runge-Kutta method. The results of this study are presented in detail to show the different trends under various ambient conditions and to reveal the major viral-transmission routes as a function of droplet size.
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Affiliation(s)
- Gang Zeng
- Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, China; School of Mathematics and Computational Science, Xiangtan University, Xiangtan, 411105, China
| | - Lin Chen
- Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Innovation Academy for Light-duty Gas Turbine, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Haizhuan Yuan
- School of Mathematics and Computational Science, Xiangtan University, Xiangtan, 411105, China
| | - Ayumi Yamamoto
- National Institute of Technology, Hachinohe College, Hachinohe, Aomori, 039-1192, Japan
| | - Haisheng Chen
- Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shigenao Maruyama
- National Institute of Technology, Hachinohe College, Hachinohe, Aomori, 039-1192, Japan
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Poydenot F, Abdourahamane I, Caplain E, Der S, Haiech J, Jallon A, Khoutami I, Loucif A, Marinov E, Andreotti B. Risk assessment for long- and short-range airborne transmission of SARS-CoV-2, indoors and outdoors. PNAS NEXUS 2022; 1:pgac223. [PMID: 36712338 PMCID: PMC9802175 DOI: 10.1093/pnasnexus/pgac223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 09/30/2022] [Indexed: 11/17/2022]
Abstract
Preventive measures to reduce infection are needed to combat the COVID-19 pandemic and prepare for a possible endemic phase. Current prophylactic vaccines are highly effective to prevent disease but lose their ability to reduce viral transmission as viral evolution leads to increasing immune escape. Long-term proactive public health policies must therefore complement vaccination with available nonpharmaceutical interventions aiming to reduce the viral transmission risk in public spaces. Here, we revisit the quantitative assessment of airborne transmission risk, considering asymptotic limits that considerably simplify its expression. We show that the aerosol transmission risk is the product of three factors: a biological factor that depends on the viral strain, a hydrodynamical factor defined as the ratio of concentration in viral particles between inhaled and exhaled air, and a face mask filtering factor. The short-range contribution to the risk, present both indoors and outdoors, is related to the turbulent dispersion of exhaled aerosols by air drafts and by convection (indoors), or by the wind (outdoors). We show experimentally that airborne droplets and CO2 molecules present the same dispersion. As a consequence, the dilution factor, and therefore the risk, can be measured quantitatively using the CO2 concentration, regardless of the room volume, the flow rate of fresh air, and the occupancy. We show that the dispersion cone leads to a concentration in viral particles, and therefore a short-range transmission risk, inversely proportional to the squared distance to an infected person and to the flow velocity. The aerosolization criterion derived as an intermediate result, which compares the Stokes relaxation time to the Lagrangian time-scale, may find application for a broad class of aerosol-borne pathogens and pollutants.
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Affiliation(s)
- Florian Poydenot
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Ismael Abdourahamane
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Elsa Caplain
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Samuel Der
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Jacques Haiech
- Cogitamus Laboratory and CNRS UMR 7242 BSC, 300 Bd Sébastien Brant, CS 10413, 67412 Illkirch Cedex, France
| | - Antoine Jallon
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Inés Khoutami
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Amir Loucif
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Emil Marinov
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
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12
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Sharma S, Jain S, Saha A, Basu S. Evaporation dynamics of a surrogate respiratory droplet in a vortical environment. J Colloid Interface Sci 2022; 623:541-551. [DOI: 10.1016/j.jcis.2022.05.061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 05/06/2022] [Accepted: 05/10/2022] [Indexed: 10/18/2022]
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13
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Morawska L, Buonanno G, Mikszewski A, Stabile L. The physics of respiratory particle generation, fate in the air, and inhalation. NATURE REVIEWS. PHYSICS 2022; 4:723-734. [PMID: 36065441 PMCID: PMC9430019 DOI: 10.1038/s42254-022-00506-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/03/2022] [Indexed: 05/31/2023]
Abstract
Given that breathing is one of the most fundamental physiological functions, there is an urgent need to broaden our understanding of the fluid dynamics that governs it. There would be many benefits from doing so, including a better assessment of respiratory health, a basis for more precise delivery of pharmaceutical drugs for treatment, and the understanding and potential minimization of respiratory infection transmission. We review the physics of particle generation in the respiratory tract, the fate of these particles in the air on exhalation and the physics of particle inhalation. The main focus is on evidence from experimental studies. We conclude that although there is qualitative understanding of the generation of particles in the respiratory tract, a basic quantitative knowledge of the characteristics of the particles emitted during respiratory activities and their fate after emission, and a theoretical understanding of particle deposition during inhalation, nevertheless the general understanding of the entire process is rudimentary, and many open questions remain.
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Affiliation(s)
- Lidia Morawska
- Queensland University of Technology, International Laboratory for Air Quality & Health (ILAQH), Brisbane, Queensland Australia
- Global Centre for Clean Air Research, Department of Civil and Environmental Engineering, University of Surrey, Guildford, UK
| | - Giorgio Buonanno
- Queensland University of Technology, International Laboratory for Air Quality & Health (ILAQH), Brisbane, Queensland Australia
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, Italy
| | - Alex Mikszewski
- Queensland University of Technology, International Laboratory for Air Quality & Health (ILAQH), Brisbane, Queensland Australia
| | - Luca Stabile
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, Italy
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14
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Prediction of respiratory droplets evolution for safer academic facilities planning amid COVID-19 and future pandemics: A numerical approach. JOURNAL OF BUILDING ENGINEERING 2022; 54:104593. [PMCID: PMC9107331 DOI: 10.1016/j.jobe.2022.104593] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Revised: 04/06/2022] [Accepted: 04/27/2022] [Indexed: 05/29/2023]
Abstract
Airborne dispersion of the novel SARS-CoV-2 through the droplets produced during expiratory activities is one of the main transmission mechanisms of this virus from one person to another. Understanding how these droplets spread when infected humans with COVID-19 or other airborne infectious diseases breathe, cough or sneeze is essential for improving prevention strategies in academic facilities. This work aims to assess the transport and fate of droplets in indoor environments using Computational Fluid Dynamics (CFD). This study employs unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations with the Euler-Lagrange approach to visualize the location of thousands of droplets released in a respiratory event and their size evolution. Furthermore, we assess the dispersion of coughing, sneezing, and breathing saliva droplets from an infected source in a classroom with air conditioning and multiple occupants. The results indicate that the suggested social distancing protocol is not enough to avoid the transmission of COVID-19 since small saliva droplets ( ≤ 12 μm) can travel in the streamwise direction up to 4 m when an infected person coughs and more than 7 m when sneezes. These droplets can reach those distances even when there is no airflow from the wind or ventilation systems. The number of airborne droplets in locations close to the respiratory system of a healthy person increases when the relative humidity of the indoor environment is low. This work sets an accurate, rapid, and validated numerical framework reproducible for various indoor environments integrating qualitative and quantitative data analysis of the droplet size evolution of respiratory events for a safer design of physical distancing standards and air cleaning technologies.
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15
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The effects of indoor temperature and humidity on local transmission of COVID-19 and how it relates to global trends. PLoS One 2022; 17:e0271760. [PMID: 35947557 PMCID: PMC9365153 DOI: 10.1371/journal.pone.0271760] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 07/07/2022] [Indexed: 11/30/2022] Open
Abstract
During the COVID-19 pandemic, analyses on global data have not reached unanimous consensus on whether warmer and humid weather curbs the spread of the SARS-CoV-2 virus. We conjectured that this lack of consensus is due to the discrepancy between global environmental data such as temperature and humidity being collected outdoors, while most infections have been reported to occur indoors, where conditions can be different. Thus, we have methodologically investigated the effect of temperature and relative humidity on the spread of expired respiratory droplets from the mouth, which are assumed to be the main cause of most short-range infections. Calculating the trajectory of individual droplets using an experimentally validated evaporation model, the final height and distance of the evaporated droplets is obtained, and then correlated with global COVID-19 spread. Increase in indoor humidity is associated with reduction in COVID-19 spread, while temperature has no statistically significant effect.
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16
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Assessing suspension and infectivity times of virus-loaded aerosols involved in airborne transmission. Proc Natl Acad Sci U S A 2022; 119:e2204593119. [PMID: 35930663 PMCID: PMC9371747 DOI: 10.1073/pnas.2204593119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Airborne transmission occurs through droplet-mediated transport of viruses following the expulsion of an aerosol by an infected host. Transmission efficiency results from the interplay between virus survival in the drying droplet and droplet suspension time in the air, controlled by the coupling between water evaporation and droplet sedimentation. Furthermore, droplets are made of a respiratory fluid and thus, display a complex composition consisting of water and nonvolatile solutes. Here, we quantify the impact of this complex composition on the different phenomena underlying transmission. Solutes lead to a nonideal thermodynamic behavior, which sets an equilibrium droplet size that is independent of relative humidity. In contrast, solutes do not significantly hinder transport due to their low initial concentration. Realistic suspension times are computed and increase with increasing relative humidity or decreasing temperature. By uncoupling drying and suspended stages, we observe that enveloped viruses may remain infectious for hours in dried droplets. However, their infectivity decreases with increasing relative humidity or temperature after dozens of minutes. Examining expelled droplet size distributions in the light of these results leads to distinguishing two aerosols. Most droplets measure between 0 and 40 µm and compose an aerosol that remains suspended for hours. Its transmission efficiency is controlled by infectivity, which decreases with increasing humidity and temperature. Larger droplets form an aerosol that only remains suspended for minutes but corresponds to a much larger volume and thus, viral load. Its transmission efficiency is controlled by droplet suspension time, which decreases with increasing humidity and decreasing temperature.
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17
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Ji B, Singh A, Feng J. Water-to-Air Transfer of Nano/Microsized Particulates: Enrichment Effect in Bubble Bursting Jet Drops. NANO LETTERS 2022; 22:5626-5634. [PMID: 35658445 DOI: 10.1021/acs.nanolett.2c01102] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Bubbles dispersed in liquids are widely present in many natural and industrial processes and play a key role in mediating mass transfer during their lifetime from formation to rising to bursting. In particular, nano/microsized particulates and organisms present in the bulk water can be highly enriched in the jet drops ejected during bubble bursting, impacting global climate and public health. However, the detailed mechanism of this enrichment remains obscure with the enrichment factor being difficult to predict. Here, we experimentally investigate the enrichment of nano/microsized particles in bubble bursting jet drops and highlight the underlying hydrodynamic mechanism, combining the effects of bubble scavenge and bursting on the transport of particles. Scaling laws for the enrichment factor are subsequently proposed that describe both our and prior experimental results reasonably well. Our study may provide new insights for water-to-air transfer of bulk particulates such as microbes related to bubble bursting.
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Affiliation(s)
- Bingqiang Ji
- Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Amrit Singh
- Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Jie Feng
- Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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18
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Zhu M, Zeng Q, Saputro BIL, Chew SP, Chew I, Frendy H, Tan JW, Li L. Tracking the molecular evolution and transmission patterns of SARS-CoV-2 lineage B.1.466.2 in Indonesia based on genomic surveillance data. Virol J 2022; 19:103. [PMID: 35710544 PMCID: PMC9202327 DOI: 10.1186/s12985-022-01830-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 06/02/2022] [Indexed: 12/22/2022] Open
Abstract
Background As a new epi-center of COVID-19 in Asia and a densely populated developing country, Indonesia is facing unprecedented challenges in public health. SARS-CoV-2 lineage B.1.466.2 was reported to be an indigenous dominant strain in Indonesia (once second only to the Delta variant). However, it remains unclear how this variant evolved and spread within such an archipelagic nation. Methods For statistical description, the spatiotemporal distributions of the B.1.466.2 variant were plotted using the publicly accessible metadata in GISAID. A total of 1302 complete genome sequences of Indonesian B.1.466.2 strains with high coverage were downloaded from the GISAID’s EpiCoV database on 28 August 2021. To determine the molecular evolutionary characteristics, we performed a time-scaled phylogenetic analysis using the maximum likelihood algorithm and called the single nucleotide variants taking the Wuhan-Hu-1 sequence as reference. To investigate the spatiotemporal transmission patterns, we estimated two dynamic parameters (effective population size and effective reproduction number) and reconstructed the phylogeography among different islands. Results As of the end of August 2021, nearly 85% of the global SARS-CoV-2 lineage B.1.466.2 sequences (including the first one) were obtained from Indonesia. This variant was estimated to account for over 50% of Indonesia’s daily infections during the period of March–May 2021. The time-scaled phylogeny suggested that SARS-CoV-2 lineage B.1.466.2 circulating in Indonesia might have originated from Java Island in mid-June 2020 and had evolved into two disproportional and distinct sub-lineages. High-frequency non-synonymous mutations were mostly found in the spike and NSP3; the S-D614G/N439K/P681R co-mutations were identified in its larger sub-lineage. The demographic history was inferred to have experienced four phases, with an exponential growth from October 2020 to February 2021. The effective reproduction number was estimated to have reached its peak (11.18) in late December 2020 and dropped to be less than one after early May 2021. The relevant phylogeography showed that Java and Sumatra might successively act as epi-centers and form a stable transmission loop. Additionally, several long-distance transmission links across seas were revealed. Conclusions SARS-CoV-2 variants circulating in the tropical archipelago may follow unique patterns of evolution and transmission. Continuous, extensive and targeted genomic surveillance is essential. Supplementary Information The online version contains supplementary material available at 10.1186/s12985-022-01830-1.
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Affiliation(s)
- Mingjian Zhu
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, National Medical Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Qianli Zeng
- Shanghai Institute of Biological Products, Shanghai, China
| | | | - Sien Ping Chew
- Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ian Chew
- Zhejiang University School of Medicine, Hangzhou, China
| | - Holie Frendy
- Faculty of Medicine and Health Sciences, Krida Wacana Christian University, Jakarta, Indonesia
| | - Joanna Weihui Tan
- Faculty of Arts and Social Sciences, National University of Singapore, Singapore, Singapore
| | - Lanjuan Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, National Medical Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
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19
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Firle C, Steinmetz A, Stier O, Stengel D, Ekkernkamp A. Aerosol emission from playing wind instruments and related COVID-19 infection risk during music performance. Sci Rep 2022; 12:8598. [PMID: 35597808 PMCID: PMC9124212 DOI: 10.1038/s41598-022-12529-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 04/29/2022] [Indexed: 12/29/2022] Open
Abstract
The pandemic of COVID-19 led to restrictions in all kinds of music activities. Airborne transmission of SARS-CoV-2 requires risk assessment of wind instrument playing in various situations. Previous studies focused on short-range transmission, whereas long-range transmission risk has not been assessed. The latter requires knowledge of aerosol emission rates from wind instrument playing. We measured aerosol concentrations in a hermetically closed chamber of 20 m3 in an operating theatre as resulting from 20 min standardized wind instrument playing (19 flute, 11 oboe, 1 clarinet, 1 trumpet players). We calculated aerosol emission rates showing uniform distribution for both instrument groups. Aerosol emission from wind instrument playing ranged from 11 ± 288 particles/second (P/s) up to 2535 ± 195 P/s, expectation value ± uncertainty standard deviation. The analysis of aerosol particle size distributions shows that 70–80% of emitted particles had a size of 0.25–0.8 µm and thus are alveolar. Masking the bell with a surgical mask did not reduce aerosol emission. Aerosol emission rates were higher from wind instrument playing than from speaking or breathing. Differences between instrumental groups could not be found but high interindividual variance, as expressed by uniform distribution of aerosol emission rates. Our findings indicate that aerosol emission depends on physiological factors and playing techniques rather than on the type of instrument, in contrast to some previous studies. Based on our results, we present transmission risk calculations for long-range transmission of COVID-19 for three typical woodwind playing situations.
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Affiliation(s)
- Carl Firle
- GP Practice, Dr. Claudia-Isabella Wildfeuer, 10715, Berlin, Germany.
| | - Anke Steinmetz
- Physical and Rehabilitation Medicine, Department of Trauma, Reconstructive Surgery and Rehabilitation Medicine, University Medicine Greifswald, Greifswald, Germany
| | | | - Dirk Stengel
- BG Kliniken-Klinikverbund Der Gesetzlichen Unfallversicherung gGmbH, Berlin, Germany.,BG Klinikum Unfallkrankenhaus Berlin gGmbH, Berlin, Germany
| | - Axel Ekkernkamp
- Physical and Rehabilitation Medicine, Department of Trauma, Reconstructive Surgery and Rehabilitation Medicine, University Medicine Greifswald, Greifswald, Germany.,Department of Trauma, Reconstructive Surgery, and Rehabilitation Medicine, University Medicine Greifswald, Greifswald, Germany.,BG Klinikum Unfallkrankenhaus Berlin gGmbH, Berlin, Germany
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20
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Lavrinenko A, Fabregat A, Pallares J. Comparison between fully resolved and time-averaged simulations of particle cloud dispersion produced by a violent expiratory event. ACTA MECHANICA SINICA = LI XUE XUE BAO 2022; 38:721489. [PMID: 35756946 PMCID: PMC9207831 DOI: 10.1007/s10409-022-09032-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 01/30/2022] [Indexed: 06/15/2023]
Abstract
In this work we compare the DNS results (Fabregat et al. 2021, Fabregat et al. 2021) for a mild cough already reported in the literarure with those obtained with a compressible URANS equations with a k-ϵ turbulence model. In both cases, the dispersed phase has been modelled as spherical Lagrangian particles using the one-way coupling assumption. Overall, the URANS model is capable of reproducing the observed tendency of light particles under 64 µm in diameter to rise due to the action of the drag exerted by the buoyant puff generated by the cough. Both DNS and URANS found that particles above 64 µm will tend to describe parabolic trajectories under the action of gravitational forces. Grid independence analysis allows to qualify the impact of increasing mesh resolution on the particle cloud statistics as flow evolves. Results suggest that the k-ϵ model overpredicts the horizontal displacement of the particles smaller than 64 µm while the opposite occurs for the particles larger than 64 µm.
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Affiliation(s)
- Akim Lavrinenko
- Departament d’Enginyeria Mecánica, Universitat Rovira i Virgili, Spain, Av. Països Catalans, Tarragona 26, 43007 Spain
| | - Alexandre Fabregat
- Departament d’Enginyeria Mecánica, Universitat Rovira i Virgili, Spain, Av. Països Catalans, Tarragona 26, 43007 Spain
| | - Jordi Pallares
- Departament d’Enginyeria Mecánica, Universitat Rovira i Virgili, Spain, Av. Països Catalans, Tarragona 26, 43007 Spain
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21
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Tellier R. COVID-19: the case for aerosol transmission. Interface Focus 2022; 12:20210072. [PMID: 35261731 PMCID: PMC8831082 DOI: 10.1098/rsfs.2021.0072] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 12/06/2021] [Indexed: 01/21/2023] Open
Abstract
The COVID-19 pandemic is the most severe pandemic caused by a respiratory virus since the 1918 influenza pandemic. As is the case with other respiratory viruses, three modes of transmission have been invoked: contact (direct and through fomites), large droplets and aerosols. This narrative review makes the case that aerosol transmission is an important mode for COVID-19, through reviewing studies about bioaerosol physiology, detection of infectious SARS-CoV-2 in exhaled bioaerosols, prolonged SARS-CoV-2 infectivity persistence in aerosols created in the laboratory, detection of SARS-CoV-2 in air samples, investigation of outbreaks with manifest involvement of aerosols, and animal model experiments. SARS-CoV-2 joins influenza A virus as a virus with proven pandemic capacity that can be spread by the aerosol route. This has profound implications for the control of the current pandemic and for future pandemic preparedness.
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Affiliation(s)
- Raymond Tellier
- Department of Medicine, McGill University, Montreal, Quebec, Canada
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22
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Mazzino A, Rosti ME. Puff turbulence in the limit of strong buoyancy. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2022; 380:20210093. [PMID: 35094562 PMCID: PMC8802035 DOI: 10.1098/rsta.2021.0093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 07/27/2021] [Indexed: 06/14/2023]
Abstract
We provide a numerical validation of a recently proposed phenomenological theory to characterize the space-time statistical properties of a turbulent puff, both in terms of bulk properties, such as the mean velocity, temperature and size, and scaling laws for velocity and temperature differences both in the viscous and in the inertial range of scales. In particular, apart from the more classical shear-dominated puff turbulence, our main focus is on the recently discovered new regime where turbulent fluctuations are dominated by buoyancy. The theory is based on an adiabaticity hypothesis which assumes that small-scale turbulent fluctuations rapidly relax to the slower large-scale dynamics, leading to a generalization of the classical Kolmogorov and Kolmogorov-Obukhov-Corrsin theories for a turbulent puff hosting a scalar field. We validate our theory by means of massive direct numerical simulations finding excellent agreement. This article is part of the theme issue 'Scaling the turbulence edifice (part 2)'.
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Affiliation(s)
- Andrea Mazzino
- Department of Civil, Chemical and Environmental Engineering (DICCA), University of Genova, Via Montallegro 1, Genova, Italy
- INFN, Genova Section, Via Montallegro 1, 16145 Genova, Italy
| | - Marco Edoardo Rosti
- Complex Fluids and Flows Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan
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23
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Li X, Lester D, Rosengarten G, Aboltins C, Patel M, Cole I. A spatiotemporally resolved infection risk model for airborne transmission of COVID-19 variants in indoor spaces. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 812:152592. [PMID: 34954184 PMCID: PMC8695516 DOI: 10.1016/j.scitotenv.2021.152592] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 12/15/2021] [Accepted: 12/17/2021] [Indexed: 05/08/2023]
Abstract
The classic Wells-Riley model is widely used for estimation of the transmission risk of airborne pathogens in indoor spaces. However, the predictive capability of this zero-dimensional model is limited as it does not resolve the highly heterogeneous spatiotemporal distribution of airborne pathogens, and the infection risk is poorly quantified for many pathogens. In this study we address these shortcomings by developing a novel spatiotemporally resolved Wells-Riley model for prediction of the transmission risk of different COVID-19 variants in indoor environments. This modelling framework properly accounts for airborne infection risk by incorporating the latest clinical data regarding viral shedding by COVID-19 patients and SARS-CoV-2 infecting human cells. The spatiotemporal distribution of airborne pathogens is determined via computational fluid dynamics (CFD) simulations of airflow and aerosol transport, leading to an integrated model of infection risk associated with the exposure to SARS-CoV-2, which can produce quantitative 3D infection risk map for a specific SARS-CoV-2 variant in a given indoor space. Application of this model to airborne COVID-19 transmission within a hospital ward demonstrates the impact of different virus variants and respiratory PPE upon transmission risk. With the emergence of highly contagious SARS-CoV-2 variants such as the Delta and Omicron strains, respiratory PPE alone may not provide effective protection. These findings suggest a combination of optimal ventilation and respiratory PPE must be developed to effectively control the transmission of COVID-19 in healthcare settings and indoor spaces in general. This generalised risk estimation framework has the flexibility to incorporate further clinical data as such becomes available, and can be readily applied to consider a wide range of factors that impact transmission risk, including location and movement of infectious persons, virus variant and stage of infection, level of PPE and vaccination of infectious and susceptible individuals, impacts of coughing, sneezing, talking and breathing, and natural and mechanised ventilation and filtration.
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Affiliation(s)
- Xiangdong Li
- School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
| | - Daniel Lester
- School of Engineering, RMIT University, Melbourne, VIC 3000, Australia.
| | - Gary Rosengarten
- School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
| | - Craig Aboltins
- Department of Infectious Diseases, Northern Health, Epping, VIC 3076, Australia
| | - Milan Patel
- School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
| | - Ivan Cole
- School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
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24
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Nath AVS, Roy A, Govindarajan R, Ravichandran S. Transport of condensing droplets in Taylor-Green vortex flow in the presence of thermal noise. Phys Rev E 2022; 105:035101. [PMID: 35428137 DOI: 10.1103/physreve.105.035101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
We study the role of phase change and thermal noise in particle transport in turbulent flows. We employ a toy model to extract the main physics: Condensing droplets are modelled as heavy particles which grow in size, the ambient flow is modelled as a two-dimensional Taylor-Green flow consisting of an array of vortices delineated by separatrices, and thermal noise are modelled as uncorrelated Gaussian white noise. In general, heavy inertial particles are centrifuged out of regions of high vorticity and into regions of high strain. In cellular flows, we find, in agreement with earlier results, that droplets with Stokes numbers smaller than a critical value, St<St_{cr}, remain trapped in the vortices in which they are initialized, while larger droplets move ballistically away from their initial positions by crossing separatrices. We independently vary the Péclet number Pe characterizing the amplitude of thermal noise and the condensation rate Π to study their effects on the critical Stokes number for droplet trapping, as well as on the final states of motion of the droplets. We find that the imposition of thermal noise, or of a finite condensation rate, allows droplets of St<St_{cr} to leave their initial vortices. We find that the effects of thermal noise become negligible for growing droplets and that growing droplets achieve ballistic motion when their Stokes numbers become O(1). We also find an intermediate regime prior to attaining the ballistic state, in which droplets move diffusively away from their initial vortices in the presence of thermal noise.
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Affiliation(s)
- Anu V S Nath
- Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai 600036, India
| | - Anubhab Roy
- Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai 600036, India
| | - Rama Govindarajan
- International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bengaluru 560089, India
| | - S Ravichandran
- Nordita, KTH Royal Institute of Technology and Stockholm University, SE-10691 Stockholm, Sweden
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25
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Tan S, Zhang Z, Maki K, Fidkowski KJ, Capecelatro J. Beyond well-mixed: A simple probabilistic model of airborne disease transmission in indoor spaces. INDOOR AIR 2022; 32:e13015. [PMID: 35347784 DOI: 10.1111/ina.13015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 02/21/2022] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
We develop a simple model for assessing risk of airborne disease transmission that accounts for non-uniform mixing in indoor spaces and is compatible with existing epidemiological models. A database containing 174 high-resolution simulations of airflow in classrooms, lecture halls, and buses is generated and used to quantify the spatial distribution of expiratory droplet nuclei for a wide range of ventilation rates, exposure times, and room configurations. Imperfect mixing due to obstructions, buoyancy, and turbulent dispersion results in concentration fields with significant variance. The spatial non-uniformity is found to be accurately described by a shifted lognormal distribution. A well-mixed mass balance model is used to predict the mean, and the standard deviation is parameterized based on ventilation rate and room geometry. When employed in a dose-response function risk model, infection probability can be estimated considering spatial heterogeneity that contributes to both short- and long-range transmission.
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Affiliation(s)
- Sijian Tan
- Department of Aerospace Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Zhihang Zhang
- Department of Naval Architecture and Marine Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Kevin Maki
- Department of Naval Architecture and Marine Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Krzysztof J Fidkowski
- Department of Aerospace Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Jesse Capecelatro
- Department of Aerospace Engineering, University of Michigan, Ann Arbor, Michigan, USA
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, USA
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26
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Eames I, Flór JB. Spread of infectious agents through the air in complex spaces. Interface Focus 2022; 12:20210080. [PMID: 35261735 PMCID: PMC8831084 DOI: 10.1098/rsfs.2021.0080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 01/18/2022] [Indexed: 12/12/2022] Open
Abstract
The fluid mechanical processes that govern the spread of infectious agents through the air in complex spaces are reviewed and the scientific gaps and challenges identified and discussed. Air, expelled from the nose and mouth, creates turbulent jets that form loosely coherent structures which quickly slow. For the transport and dispersion of aerosols, the suitability of the Eulerian as well as the Lagrangian approaches are brought into context. The effects of buoyancy and external turbulence are explored and shown to influence the horizontal extent of expulsion through distinct mechanisms which both inhibit penetration and enhance mixing. The general influence of inhomogeneous turbulence and stratification on the spread of infectious agents in enclosed complex spaces is discussed.
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Affiliation(s)
- Ian Eames
- Centre for Engineering in Extreme Environments, University College London, Gower Street, London WC1E 7JE, UK
| | - Jan-Bert Flór
- Laboratoire des Écoulements Géophysiques et Industriels (LEGI), CNRS, Université Grenoble Alpes, Grenoble INP, Grenoble 38000, France
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27
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Mathai V, Das A, Breuer K. Aerosol transmission in passenger car cabins: Effects of ventilation configuration and driving speed. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2022; 34:021904. [PMID: 35342278 PMCID: PMC8939464 DOI: 10.1063/5.0079555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 01/15/2022] [Indexed: 05/25/2023]
Abstract
Identifying the potential routes of airborne transmission during transportation is of critical importance to limit the spread of the SARS-CoV-2 virus. Here, we numerically solve the Reynolds-averaged Navier-Stokes equations along with the transport equation for a passive scalar in order to study aerosol transmission inside the passenger cabin of an automobile. Extending the previous work on this topic, we explore several driving scenarios including the effects of having the windows fully open, half-open, and one-quarter open, the effect of opening a moon roof, and the scaling of the aerosol transport as a function of vehicle speed. The flow in the passenger cabin is largely driven by the external surface pressure distribution on the vehicle, and the relative concentration of aerosols in the cabin scales inversely with vehicle speed. For the simplified geometry studied here, we find that the half-open windows configuration has almost the same ventilation effectively as the one with the windows fully open. The utility of the moonroof as an effective exit vent for removing the aerosols generated within the cabin space is discussed. Using our results, we propose a "speed-time" map, which gives guidance regarding the relative risk of transmission between driver and passenger as a function of trip duration and vehicle speed. A few strategies for the removal of airborne contaminants during low-speed driving, or in a situation where the vehicle is stuck in traffic, are suggested.
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Affiliation(s)
- Varghese Mathai
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Asimanshu Das
- Center for Fluid Mechanics, Brown University, Providence, Rhode Island 02912, USA
| | - Kenneth Breuer
- Center for Fluid Mechanics, Brown University, Providence, Rhode Island 02912, USA
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Fei L, Qin F, Wang G, Luo KH, Derome D, Carmeliet J. Droplet evaporation in finite-size systems: Theoretical analysis and mesoscopic modeling. Phys Rev E 2022; 105:025101. [PMID: 35291136 DOI: 10.1103/physreve.105.025101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 01/17/2022] [Indexed: 06/14/2023]
Abstract
The classical D^{2}-Law states that the square of the droplet diameter decreases linearly with time during its evaporation process, i.e., D^{2}(t)=D_{0}^{2}-Kt, where D_{0} is the droplet initial diameter and K is the evaporation constant. Though the law has been widely verified by experiments, considerable deviations are observed in many cases. In this work, a revised theoretical analysis of the single droplet evaporation in finite-size open systems is presented for both two-dimensional (2D) and 3D cases. Our analysis shows that the classical D^{2}-Law is only applicable for 3D large systems (L≫D_{0}, L is the system size), while significant deviations occur for small (L≤5D_{0}) and/or 2D systems. Theoretical solution for the temperature field is also derived. Moreover, we discuss in detail the proper numerical implementation of droplet evaporation in finite-size open systems by the mesoscopic lattice Boltzmann method (LBM). Taking into consideration shrinkage effects and an adaptive pressure boundary condition, droplet evaporation in finite-size 2D/3D systems with density ratio up to 328 within a wide parameter range (K=[0.003,0.18] in lattice units) is simulated, and remarkable agreement with the theoretical solution is achieved, in contrast to previous simulations. The present work provides insights into realistic droplet evaporation phenomena and their numerical modeling using diffuse-interface methods.
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Affiliation(s)
- Linlin Fei
- Chair of Building Physics, Department of Mechanical and Process Engineering, ETH Zürich (Swiss Federal Institute of Technology in Zürich), Zürich 8092, Switzerland
| | - Feifei Qin
- Chair of Building Physics, Department of Mechanical and Process Engineering, ETH Zürich (Swiss Federal Institute of Technology in Zürich), Zürich 8092, Switzerland
| | - Geng Wang
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, United Kingdom
| | - Kai H Luo
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, United Kingdom
| | - Dominique Derome
- Department of Civil and Building Engineering, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Jan Carmeliet
- Chair of Building Physics, Department of Mechanical and Process Engineering, ETH Zürich (Swiss Federal Institute of Technology in Zürich), Zürich 8092, Switzerland
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Investigation on the evaporation and dispersion of human respiratory droplets with COVID-19 virus. INTERNATIONAL JOURNAL OF MULTIPHASE FLOW 2022; 147. [PMCID: PMC8603237 DOI: 10.1016/j.ijmultiphaseflow.2021.103904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
On March 11, 2020, COVID-19 was declared as a pandemic by World Health Organization (WHO). Effective prevention is indispensable for defeating the ongoing COVID-19 pandemic. The evaporation and diffusion characteristics of the droplet in the air are the critical factors for the virus transmission by droplets. To better understand transmission routes of COVID-19 through respiratory droplets, a new evaporation and dispersion model for respiratory droplets is proposed to estimate droplet lifetime and the size of spreading zone in air. The importance of respiratory activities and environmental factors on the transmission of respiratory viruses are further discussed. The predictive results demonstrate initial particle size, ambient temperature and relative humidity all have significant effect on the survival time and infection distance of respiratory droplets. Decreasing droplet initial size always shortens the lifetime and the transmission distance of respiratory droplets. The 100 μm droplets expelled by talking or coughing can be carried more than 2 m away. Increasing ambient temperature and decreasing ambient humidity can effectively reduce the lifetime and propagation distance of respiratory droplets, thus reducing the risk of viral infection. These findings could contribute to developing effective prevention measures for controlling infectious disease transmission via droplets.
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Wang J, Dalla Barba F, Roccon A, Sardina G, Soldati A, Picano F. Modelling the direct virus exposure risk associated with respiratory events. J R Soc Interface 2022; 19:20210819. [PMID: 35016556 PMCID: PMC8753145 DOI: 10.1098/rsif.2021.0819] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 12/13/2021] [Indexed: 12/14/2022] Open
Abstract
The outbreak of the COVID-19 pandemic highlighted the importance of accurately modelling the pathogen transmission via droplets and aerosols emitted while speaking, coughing and sneezing. In this work, we present an effective model for assessing the direct contagion risk associated with these pathogen-laden droplets. In particular, using the most recent studies on multi-phase flow physics, we develop an effective yet simple framework capable of predicting the infection risk associated with different respiratory activities in different ambient conditions. We start by describing the mathematical framework and benchmarking the model predictions against well-assessed literature results. Then, we provide a systematic assessment of the effects of physical distancing and face coverings on the direct infection risk. The present results indicate that the risk of infection is vastly impacted by the ambient conditions and the type of respiratory activity, suggesting the non-existence of a universal safe distance. Meanwhile, wearing face masks provides excellent protection, effectively limiting the transmission of pathogens even at short physical distances, i.e. 1 m.
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Affiliation(s)
- Jietuo Wang
- Centro di Ateneo di Studi e Attività Spaziali - CISAS, University of Padova, Padova 35131, Italy
| | | | - Alessio Roccon
- Institute of Fluid Mechanics and Heat Transfer, TU Wien, Vienna 1060, Austria
- Polytechnic Department, University of Udine, 33100 Udine, Italy
| | - Gaetano Sardina
- Department of Mechanics and Maritime Sciences, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Alfredo Soldati
- Institute of Fluid Mechanics and Heat Transfer, TU Wien, Vienna 1060, Austria
- Polytechnic Department, University of Udine, 33100 Udine, Italy
| | - Francesco Picano
- Centro di Ateneo di Studi e Attività Spaziali - CISAS, University of Padova, Padova 35131, Italy
- Department of Industrial Engineering, University of Padova, Padova 35131, Italy
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31
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Biswas R, Pal A, Pal R, Sarkar S, Mukhopadhyay A. Risk assessment of COVID infection by respiratory droplets from cough for various ventilation scenarios inside an elevator: An OpenFOAM-based computational fluid dynamics analysis. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2022; 34:013318. [PMID: 35340680 PMCID: PMC8939552 DOI: 10.1063/5.0073694] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 12/30/2021] [Indexed: 05/15/2023]
Abstract
Respiratory droplets-which may contain disease spreading virus-exhaled during speaking, coughing, or sneezing are one of the significant causes for the spread of the ongoing COVID-19 pandemic. The droplet dispersion depends on the surrounding air velocity, ambient temperature, and relative humidity. In a confined space like an elevator, the risk of transmission becomes higher when there is an infected person inside the elevator with other individuals. In this work, a numerical investigation is carried out in a three-dimensional domain resembling an elevator using OpenFoam. Three different modes of air ventilation, viz., quiescent, axial exhaust draft, and exhaust fan, have been considered to investigate the effect of ventilation on droplet transmission for two different climatic conditions (30 °C , 50% relative humidity and 10 °C , 90% relative humidity). The risk assessment is quantified using a risk factor based on the time-averaged droplet count present near the passenger's hand to head region (risky height zone). The risk factor drops from 40% in a quiescent scenario to 0% in an exhaust fan ventilation condition in a hot dry environment. In general, cold humid conditions are safer than hot dry conditions as the droplets settle down quickly below the risky height zone owing to their larger masses maintained by negligible evaporation. However, an exhaust fan renders the domain in a hot dry ambience completely safe (risk factor, 0%) in 5.5 s whereas it takes 7.48 s for a cold humid ambience.
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Affiliation(s)
- Riddhideep Biswas
- Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, India
| | - Anish Pal
- Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, India
| | - Ritam Pal
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Sourav Sarkar
- Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, India
- Author to whom correspondence should be addressed:
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32
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Olivieri S, Cavaiola M, Mazzino A, Rosti ME. Transport and evaporation of virus-containing droplets exhaled by men and women in typical cough events. MECCANICA 2022; 57:567-575. [PMID: 35039689 PMCID: PMC8754081 DOI: 10.1007/s11012-021-01469-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 12/13/2021] [Indexed: 05/19/2023]
Abstract
The spreading of the virus-containing droplets exhaled during respiratory events, e.g., cough, is an issue of paramount importance for the prevention of many infections such as COVID-19. According to the scientific literature, remarkable differences can be ascribed to several parameters that govern such complex and multiphysical problem. Among these, a particular influence appears associated with the different airflows typical of male and female subjects. Focusing on a typical cough event, we investigate this aspect by means of highly-resolved direct numerical simulations of the turbulent airflow in combination with a comprehensive Lagrangian particle tracking model for the droplet motion and evaporation. We observe and quantify major differences between the case of male and female subjects, both in terms of the droplet final reach and evaporation time. Our results can be associated with the different characteristics in the released airflow and thus confirm the influence of the subject gender (or other physical properties providing different exhalation profiles) on both short-range and long-range airborne transmission.
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Affiliation(s)
- Stefano Olivieri
- Complex Fluids and Flows Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495 Japan
| | - Mattia Cavaiola
- INFN and Department of Civil, Chemical and Environmental Engineering (DICCA), University of Genova, Via Montallegro 1, 16145 Genova, Italy
| | - Andrea Mazzino
- INFN and Department of Civil, Chemical and Environmental Engineering (DICCA), University of Genova, Via Montallegro 1, 16145 Genova, Italy
| | - Marco E. Rosti
- Complex Fluids and Flows Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495 Japan
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33
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Xu C, Liu W, Luo X, Huang X, Nielsen PV. Prediction and control of aerosol transmission of SARS-CoV-2 in ventilated context: from source to receptor. SUSTAINABLE CITIES AND SOCIETY 2022; 76:103416. [PMID: 34611508 PMCID: PMC8484231 DOI: 10.1016/j.scs.2021.103416] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 05/24/2023]
Abstract
Global spread of COVID-19 has seriously threatened human life and health. The aerosol transmission route of SARS-CoV-2 is observed often associated with infection clusters under poorly ventilated environment. In the context of COVID-19 pandemic, significant transformation and optimization of traditional ventilation systems are needed. This paper is aimed to offer better understanding and insights into effective ventilation design to maximize its ability in airborne risk control, for particularly the COVID-19. Comprehensive reviews of each phase of aerosol transmission of SARS-CoV-2 from source to receptor are conducted, so as to provide a theoretical basis for risk prediction and control. Infection risk models and their key parameters for risk assessment of SARS-CoV-2 are analyzed. Special focus is given on the efficacy of different ventilation strategies in mitigating airborne transmission. Ventilation interventions are found mainly impacting on the dispersion and inhalation phases of aerosol transmission. The airflow patterns become a key factor in controlling the aerosol diffusion and distribution. Novel and personalized ventilation design, effective integration with other environmental control techniques and resilient HVAC system design to adapt both common and epidemic conditions are still remaining challenging, which need to be solved with the aid of multidisciplinary research and intelligent technologies.
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Affiliation(s)
- Chunwen Xu
- College of Pipeline and Civil Engineering, China University of Petroleum, Qingdao 266580, China
| | - Wenbing Liu
- College of Pipeline and Civil Engineering, China University of Petroleum, Qingdao 266580, China
| | - Xilian Luo
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Xingyu Huang
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Peter V Nielsen
- Division of Sustainability, Energy and Indoor Environment, Aalborg University, Aalborg 9000, Denmark
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34
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Bagheri G, Thiede B, Hejazi B, Schlenczek O, Bodenschatz E. An upper bound on one-to-one exposure to infectious human respiratory particles. Proc Natl Acad Sci U S A 2021; 118:e2110117118. [PMID: 34857639 PMCID: PMC8670465 DOI: 10.1073/pnas.2110117118] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2021] [Indexed: 01/31/2023] Open
Abstract
There is ample evidence that masking and social distancing are effective in reducing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. However, due to the complexity of airborne disease transmission, it is difficult to quantify their effectiveness, especially in the case of one-to-one exposure. Here, we introduce the concept of an upper bound for one-to-one exposure to infectious human respiratory particles and apply it to SARS-CoV-2. To calculate exposure and infection risk, we use a comprehensive database on respiratory particle size distribution; exhalation flow physics; leakage from face masks of various types and fits measured on human subjects; consideration of ambient particle shrinkage due to evaporation; and rehydration, inhalability, and deposition in the susceptible airways. We find, for a typical SARS-CoV-2 viral load and infectious dose, that social distancing alone, even at 3.0 m between two speaking individuals, leads to an upper bound of 90% for risk of infection after a few minutes. If only the susceptible wears a face mask with infectious speaking at a distance of 1.5 m, the upper bound drops very significantly; that is, with a surgical mask, the upper bound reaches 90% after 30 min, and, with an FFP2 mask, it remains at about 20% even after 1 h. When both wear a surgical mask, while the infectious is speaking, the very conservative upper bound remains below 30% after 1 h, but, when both wear a well-fitting FFP2 mask, it is 0.4%. We conclude that wearing appropriate masks in the community provides excellent protection for others and oneself, and makes social distancing less important.
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Affiliation(s)
- Gholamhossein Bagheri
- Laboratory for Fluid Physics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organization, Göttingen 37077, Germany;
| | - Birte Thiede
- Laboratory for Fluid Physics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organization, Göttingen 37077, Germany
| | - Bardia Hejazi
- Laboratory for Fluid Physics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organization, Göttingen 37077, Germany
| | - Oliver Schlenczek
- Laboratory for Fluid Physics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organization, Göttingen 37077, Germany
| | - Eberhard Bodenschatz
- Laboratory for Fluid Physics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organization, Göttingen 37077, Germany;
- Institute for Dynamics of Complex Systems, University of Göttingen, Göttingen 37077, Germany
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853
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35
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Jarvis MC. Drying of virus-containing particles: modelling effects of droplet origin and composition. JOURNAL OF ENVIRONMENTAL HEALTH SCIENCE & ENGINEERING 2021; 19:1987-1996. [PMID: 34754455 PMCID: PMC8569499 DOI: 10.1007/s40201-021-00750-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 10/17/2021] [Indexed: 05/13/2023]
Abstract
BACKGROUND AND PURPOSE Virus-containing aerosol droplets emitted by breathing, speech or coughing dry rapidly to equilibrium with ambient relative humidity (RH), increasing in solute concentration with effects on virus survival and decreasing in diameter with effects on sedimentation and respiratory uptake. The aim of this paper is to model the effect of ionic and macromolecular solutes on droplet drying and solute concentration. METHODS Deliquescence-efflorescence concepts and Kohler theory were used to simulate the evolution of solute concentrations and water activity in respiratory droplets, starting from efflorescence data on mixed NaCl/KCl aerosols and osmotic pressure data on respiratory macromolecules. RESULTS In NaCl/KCl solutions total salt concentrations were shown to reach 10-13 M at the efflorescence RH of 40-55%, depending on the K:Na ratio. Dependence on K:Na ratio implies that the evaporation curves differ between aerosols derived from saliva and from airway surfaces. The direct effect of liquid droplet size through the Kelvin term was shown to be smaller and restricted to the evolution of breath emissions. Modelling the effect of proteins and glycoproteins showed that salts determine drying equilibria down to the efflorescence RH, and macromolecules at lower RH. CONCLUSION Differences in solute composition between airway surfaces and saliva are predicted to lead to different drying behaviour of droplets emitted by breathing, speech and coughing. These differences may influence the inactivation of viruses.
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Affiliation(s)
- Michael C. Jarvis
- School of Chemistry, Glasgow University, Glasgow, Scotland G12 8QQ UK
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36
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Garcia W, Mendez S, Fray B, Nicolas A. Model-based assessment of the risks of viral transmission in non-confined crowds. SAFETY SCIENCE 2021; 144:105453. [PMID: 34511728 PMCID: PMC8418781 DOI: 10.1016/j.ssci.2021.105453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 07/10/2021] [Accepted: 08/16/2021] [Indexed: 05/06/2023]
Abstract
This work assesses the risks of Covid-19 spread in diverse daily-life situations involving crowds of maskless pedestrians, mostly outdoors. More concretely, we develop a method to infer the global number of new infections from patchy observations, by coupling ad hoc spatial models for disease transmission via respiratory droplets to detailed field-data about pedestrian trajectories and head orientations. This allows us to rank the investigated situations by the infection risks that they present; importantly, the obtained hierarchy of risks is very largely conserved across transmission models: Street cafés present the largest average rate of new infections caused by an attendant, followed by busy outdoor markets, and then metro and train stations, whereas the risks incurred while walking on fairly busy streets are comparatively quite low. While our models only approximate the actual transmission risks, their converging predictions lend credence to these findings. In situations with a moving crowd, density is the main factor influencing the estimated infection rate. Finally, our study explores the efficiency of street and venue redesigns in mitigating the viral spread: While the benefits of enforcing one-way foot traffic in (wide) walkways are unclear, changing the geometry of queues substantially affects disease transmission risks.
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Affiliation(s)
- Willy Garcia
- Institut Lumière Matière, CNRS & Université Claude Bernard Lyon 1, Villeurbanne, F-69622, France
| | - Simon Mendez
- Institut Montpelliérain Alexander Grothendieck, CNRS, University of Montpellier, Montpellier, F-34095, France
| | - Baptiste Fray
- Institut Lumière Matière, CNRS & Université Claude Bernard Lyon 1, Villeurbanne, F-69622, France
- École nationale des travaux publics de l'État (ENTPE), Université de Lyon, Vaulx-en-Velin, F-69518, France
| | - Alexandre Nicolas
- Institut Lumière Matière, CNRS & Université Claude Bernard Lyon 1, Villeurbanne, F-69622, France
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37
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Calmet H, Inthavong K, Both A, Surapaneni A, Mira D, Egukitza B, Houzeaux G. Large eddy simulation of cough jet dynamics, droplet transport, and inhalability over a ten minute exposure. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:125122. [PMID: 35002205 PMCID: PMC8728631 DOI: 10.1063/5.0072148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/28/2021] [Indexed: 06/14/2023]
Abstract
High fidelity simulations of expiratory events such as coughing provide the opportunity to predict the fate of the droplets from the turbulent jet cloud produced from a cough. It is well established that droplets carrying infectious pathogens with diameters of 1 - 5 μ m remain suspended in the air for several hours and transported by the air currents over considerable distances (e.g., in meters). This study used a highly resolved mesh to capture the multiphase turbulent buoyant cloud with suspended droplets produced by a cough. The cough droplets' dispersion was subjected to thermal gradients and evaporation and allowed to disperse between two humans standing 2 m apart. A nasal cavity anatomy was included inside the second human to determine the inhaled droplets. Three diameter ranges characterized the droplet cloud, < 5 μ m , which made up 93% of all droplets by number; 5 to 100 μm comprised 3%, and > 100 μ m comprising 4%. The results demonstrated the temporal evolution of the cough event, where a jet is first formed, followed by a thermally driven puff cloud with the latter primarily composed of droplets under 5 μm diameter, moving with a vortex string structure. After the initial cough, the data were interpolated onto a more coarse mesh to allow the simulation to cover ten minutes, equivalent to 150 breathing cycles. We observe that the critical diameter size susceptible to inhalation was 0.5 μ m , although most inhaled droplets after 10 min by the second human were approximately 0.8 μ m . These observations offer insight into the risk of airborne transmission and numerical metrics for modeling and risk assessment.
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Affiliation(s)
- Hadrien Calmet
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC-CNS), Barcelona, Spain
| | - Kiao Inthavong
- Mechanical & Automotive Engineering, School of Engineering, RMIT University, Melbourne, Australia
| | - Ambrus Both
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC-CNS), Barcelona, Spain
| | - Anurag Surapaneni
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC-CNS), Barcelona, Spain
| | - Daniel Mira
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC-CNS), Barcelona, Spain
| | - Beatriz Egukitza
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC-CNS), Barcelona, Spain
| | - Guillaume Houzeaux
- Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC-CNS), Barcelona, Spain
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38
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Bahl P, de Silva C, MacIntyre CR, Bhattacharjee S, Chughtai AA, Doolan C. Flow dynamics of droplets expelled during sneezing. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:111901. [PMID: 34803362 PMCID: PMC8597717 DOI: 10.1063/5.0067609] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/09/2021] [Indexed: 05/15/2023]
Abstract
Respiratory infections transmit through droplets and aerosols generated by the infected individual during respiratory emissions. It is essential to study the flow dynamics of these emissions to develop strategies for mitigating the risk of infection. In particular, the dynamics of droplets expelled during violent exhalations such as sneezing is crucial, but has received little attention to date. Here, for the first time, we present the results of droplet dynamics of 35 sneezes, obtained from four volunteers, using particle tracking velocimetry experiments. Our results reveal a mean droplet velocity of 2-5.4 m/s across the different subjects. These values are significantly lower than what is usually assumed in the studies simulating or replicating sneezes. Furthermore, the large variation in droplet speeds, flow direction, spread angle, and head movement is also quantified. These findings will enable the refinement of models and simulations of sneezes toward improving infection control guidelines.
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Affiliation(s)
- Prateek Bahl
- School of Mechanical and Manufacturing Engineering, UNSW Sydney, Kensington NSW 2052, Australia
| | - Charitha de Silva
- School of Mechanical and Manufacturing Engineering, UNSW Sydney, Kensington NSW 2052, Australia
| | - C. Raina MacIntyre
- Biosecurity Program, The Kirby Institute, UNSW Sydney, Kensington, NSW 2052, Australia
| | - Shovon Bhattacharjee
- Biosecurity Program, The Kirby Institute, UNSW Sydney, Kensington, NSW 2052, Australia
| | | | - Con Doolan
- School of Mechanical and Manufacturing Engineering, UNSW Sydney, Kensington NSW 2052, Australia
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39
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Li X, Mak CM, Wai Ma K, Wong HM. How the high-volume evacuation alters the flow-field and particle removal characteristics in the mock-up dental clinic. BUILDING AND ENVIRONMENT 2021; 205:108225. [PMID: 34376905 PMCID: PMC8343392 DOI: 10.1016/j.buildenv.2021.108225] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/17/2021] [Accepted: 08/02/2021] [Indexed: 05/09/2023]
Abstract
The exposure risk of droplets and aerosols emitted from the oral cavity to the dental professionals and patients has received more attention especially the ongoing outbreak of COVID-19. The aim of this study is to address the question about how the use of the high-volume evacuation (HVE) alters the risk profiles compared with the situation only personal protective equipment (PPE). The risk profiles of the different situations were analyzed in terms of droplet velocity, flow field characteristics, and particle removal efficiency. The ultrasonic scaling with suction was performed in the mock-up experimental dental clinic, and the instantaneous moment when the HVE acted on the droplets was visualized using a laser light scattering technique. From the results of the velocity profiles, the hypothesis about the moderate effect of the HVE on high-velocity small droplets near the mannequin's mouth had been firstly proven in this study. The suction can be characterized as low-threshold equipment to bring substantial benefits to reduce the area of the contaminated region. Once the cooperation of suction, the pair of vortexes that were in the face shield area of the dental professional would be eliminated, removing the high-level contaminated region near the breathing area of dental professionals. Compared with the low and medium volume evacuation, the particle removal efficiency of the HVE was more stable at 60%. The research will provide references to the HVE recommendation in the dentistry clinical practice guidelines.
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Affiliation(s)
- Xiujie Li
- Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Cheuk Ming Mak
- Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Kuen Wai Ma
- Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Hai Ming Wong
- Faculty of Dentistry, The University of Hong Kong, Pok Fu Lam, Hong Kong Island, Hong Kong
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40
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Trivedi S, Gkantonas S, Mesquita LCC, Iavarone S, de Oliveira PM, Mastorakos E. Estimates of the stochasticity of droplet dispersion by a cough. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:115130. [PMID: 35002201 PMCID: PMC8726635 DOI: 10.1063/5.0070528] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/24/2021] [Indexed: 06/01/2023]
Abstract
In this paper, the statistical distributions of the position and the size of the evaporating droplets after a cough are evaluated, thus characterizing the inherent stochasticity of respiratory releases due to turbulence. For that, ten independent realizations of a cough with realistic initial conditions and in a room at 20 °C and 40% relative humidity were performed with large eddy simulations and Lagrangian tracking of the liquid phase. It was found that although turbulence decreases far from the emitter, it results in large variations in the spatial distribution of the droplets. The total suspended liquid mass after 60 s from the cough is in good agreement with that estimated by a one-dimensional model accounting for settling and evaporation under quiescent conditions, while deposition times of droplets in the 10-100 μm range are found to vary significantly, reflected in the mass of liquid, and hence the virus content, potentially inhaled by a receptor. The high variability between events is due to the local fluctuations of temperature, humidity, and velocity on droplet evaporation and motion. The droplet distribution suggests that, in the absence of face coverings, an unprotected cough is not safe at 2 m away from the emitter even outdoors. The results indicate that mitigation measures, such as ventilation to address long-range transmission, can be based on the total suspended liquid content evaluated from reduced-order models. However, the large variability of viral content in the near field produces wide variations in estimates of risk; therefore, a stochastic approach is needed for evaluating short-range transmission risk.
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Affiliation(s)
- Shrey Trivedi
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
| | - Savvas Gkantonas
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
| | - Léo C. C. Mesquita
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
| | - Salvatore Iavarone
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
| | - Pedro M. de Oliveira
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
| | - Epaminondas Mastorakos
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
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Majee S, Saha A, Chaudhuri S, Chakravortty D, Basu S. Two-dimensional mathematical framework for evaporation dynamics of respiratory droplets. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:103302. [PMID: 34744412 PMCID: PMC8565799 DOI: 10.1063/5.0064635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Accepted: 09/10/2021] [Indexed: 05/06/2023]
Abstract
In majority of pandemics in human history, respiratory bio-aerosol is the most common route of transmission of diseases. These tiny droplets ejected through mouth and nose from an infected person during exhalation process like coughing, sneezing, speaking, and breathing consist of pathogens and a complex mixture of volatile and nonvolatile substances. A cloud of droplets ejected in such an event gets transmitted in the air, causing a series of coupled thermo-physical processes. Contemplating an individual airborne droplet in the cloud, boundary layers and wakes develop due to relative motion between the droplet and the ambient air. The complex phenomenon of the droplet's dynamics, such as shear-driven internal circulation of the liquid phase and Stefan flow due to vaporization or condensation, comes into effect. In this study, we present a mathematical description of the coupled subprocesses, including droplet aerodynamics, heat, and mass transfer, which were identified and subsequently solved. The presented two-dimensional model gives a complete analysis encompassing the gas phase coupled with the liquid phase responsible for the airborne droplet kinetics in the ambient environment. The transient inhomogeneity of temperature and concentration distribution in the liquid phase caused due to the convective and diffusive transports are captured in the 2D model. The evaporation time and distance traveled by droplets prior to nuclei or aerosol formation are computed for major geographical locations around the globe for nominal-windy conditions. The model presented can be used for determining the evaporation timescale of any viral or bacterial laden respiratory droplets across any geographical location.
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Affiliation(s)
- Sreeparna Majee
- Department of Mechanical Engineering, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Abhishek Saha
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093, USA
| | - Swetaprovo Chaudhuri
- Institute for Aerospace Studies, University of Toronto, Toronto, Ontario M3H 5T6, Canada
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Saptarshi Basu
- Department of Mechanical Engineering, Indian Institute of Science, Bengaluru, Karnataka 560012, India
- Author to whom correspondence should be addressed:
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42
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Short-range exposure to airborne virus transmission and current guidelines. Proc Natl Acad Sci U S A 2021; 118:2105279118. [PMID: 34465564 DOI: 10.1073/pnas.2105279118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
After the Spanish flu pandemic, it was apparent that airborne transmission was crucial to spreading virus contagion, and research responded by producing several fundamental works like the experiments of Duguid [J. P. Duguid, J. Hyg. 44, 6 (1946)] and the model of Wells [W. F. Wells, Am. J. Hyg. 20, 611-618 (1934)]. These seminal works have been pillars of past and current guidelines published by health organizations. However, in about one century, understanding of turbulent aerosol transport by jets and plumes has enormously progressed, and it is now time to use this body of developed knowledge. In this work, we use detailed experiments and accurate computationally intensive numerical simulations of droplet-laden turbulent puffs emitted during sneezes in a wide range of environmental conditions. We consider the same emission-number of drops, drop size distribution, and initial velocity-and we change environmental parameters such as temperature and humidity, and we observe strong variation in droplets' evaporation or condensation in accordance with their local temperature and humidity microenvironment. We assume that 3% of the initial droplet volume is made of nonvolatile matter. Our systematic analysis confirms that droplets' lifetime is always about one order of magnitude larger compared to previous predictions, in some cases up to 200 times. Finally, we have been able to produce original virus exposure maps, which can be a useful instrument for health scientists and practitioners to calibrate new guidelines to prevent short-range airborne disease transmission.
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43
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Mazzino A, Rosti ME. Unraveling the Secrets of Turbulence in a Fluid Puff. PHYSICAL REVIEW LETTERS 2021; 127:094501. [PMID: 34506163 DOI: 10.1103/physrevlett.127.094501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/13/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
Turbulent puffs are ubiquitous in everyday life phenomena. Understanding their dynamics is important in a variety of situations ranging from industrial processes to pure and applied science. In all these fields, a deep knowledge of the statistical structure of temperature and velocity space-time fluctuations is of paramount importance to construct models of chemical reaction (in chemistry) and of condensation of virus-containing droplets (in virology and/or biophysics) and optimal mixing strategies in industrial applications. As a matter of fact, results of turbulence in a puff are confined to bulk properties (i.e., average puff velocity and typical decay or growth time) and date back to the second half of the 20th century. There is, thus, a huge gap to fill to pass from bulk properties to two-point statistical observables. Here, we fill this gap by exploiting theory and numerics in concert to predict and validate the space-time scaling behaviors of both velocity and temperature structure functions including intermittency corrections. Excellent agreement between theory and simulations is found. Our results are expected to have a profound impact on developing evaporation models for virus-containing droplets carried by a turbulent puff, with benefits to the comprehension of the airborne route of virus contagion.
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Affiliation(s)
- Andrea Mazzino
- Department of Civil, Chemical and Environmental Engineering (DICCA), University of Genova, Via Montallegro 1, 16145 Genova, Italy; INFN, Genova Section, Via Montallegro 1, 16145 Genova, Italy
| | - Marco Edoardo Rosti
- Complex Fluids and Flows Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan
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44
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Abstract
The host-to-host transmission of respiratory infectious diseases is fundamentally enabled by the interaction of pathogens with a variety of fluids (gas or liquid) that shape pathogen encapsulation and emission, transport and persistence in the environment, and new host invasion and infection. Deciphering the mechanisms and fluid properties that govern and promote these steps of pathogen transmission will enable better risk assessment and infection control strategies, and may reveal previously underappreciated ways in which the pathogens might actually adapt to or manipulate the physical and chemical characteristics of these carrier fluids to benefit their own transmission. In this article, I review our current understanding of the mechanisms shaping the fluid dynamics of respiratory infectious diseases.
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Affiliation(s)
- Lydia Bourouiba
- The Fluid Dynamics of Disease Transmission Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
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Katre P, Banerjee S, Balusamy S, Sahu KC. Fluid dynamics of respiratory droplets in the context of COVID-19: Airborne and surfaceborne transmissions. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:081302. [PMID: 34471333 PMCID: PMC8404377 DOI: 10.1063/5.0063475] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 08/03/2021] [Indexed: 05/19/2023]
Abstract
The World Health Organization has declared COVID-19 a global pandemic. Several countries have experienced repeated periods of major spreading over the last two years. Many people have lost their lives, employment, and the socioeconomic situation has been severely impacted. Thus, it is considered to be one of the major health and economic disasters in modern history. Over the last two years, several researchers have contributed significantly to the study of droplet formation, transmission, and lifetime in the context of understanding the spread of such respiratory infections from a fluid dynamics perspective. The current review emphasizes the numerous ways in which fluid dynamics aids in the comprehension of these aspects. The biology of the virus, as well as other statistical studies to forecast the pandemic, is significant, but they are not included in this review.
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Affiliation(s)
- Pallavi Katre
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502285, Telangana, India
| | - Sayak Banerjee
- Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502285, Telangana, India
| | - Saravanan Balusamy
- Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502285, Telangana, India
| | - Kirti Chandra Sahu
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502285, Telangana, India
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Kudrolli A, Chang B, Consalvi J, Deti A, Frechette C, Scoville H, Sheinfeld GR, McGee WT. Mitigating exhalation puffs during oxygen therapy for respiratory disease. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:081903. [PMID: 34471335 PMCID: PMC8382086 DOI: 10.1063/5.0057227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
We investigate the dispersal of exhalations corresponding to a patient experiencing shortness of breath while being treated for a respiratory disease with oxygen therapy. Respiration through a nasal cannula and a simple O2 mask is studied using a supine manikin equipped with a controllable mechanical lung by measuring aerosol density and flow with direct imaging. Exhalation puffs are observed to travel 0.35 ± 0.02 m upward while wearing a nasal cannula, and 0.29 ± 0.02 m laterally through a simple O2 mask, posing a higher direct exposure risk to caregivers. The aerosol-laden air flows were found to concentrate in narrow conical regions through both devices at several times their concentration level compared with a uniform spreading at the same distance. We test a mitigation strategy by placing a surgical mask loosely over the tested devices. The mask is demonstrated to alleviate exposure by deflecting the exhalations from being launched directly above a supine patient. The surgical mask is found to essentially eliminate the concentrated aerosol regions above the patient over the entire oxygenation rates used in treatment in both devices.
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Affiliation(s)
- Arshad Kudrolli
- Department of Physics, Clark University, Worcester, Massachusetts 01610, USA
| | - Brian Chang
- Department of Physics, Clark University, Worcester, Massachusetts 01610, USA
| | - Jade Consalvi
- Department of Physics, Clark University, Worcester, Massachusetts 01610, USA
| | - Anton Deti
- Department of Physics, Clark University, Worcester, Massachusetts 01610, USA
| | - Christopher Frechette
- University of Massachusetts Medical School-Baystate, Springfield, Massachusetts 01107, USA
| | - Helen Scoville
- University of Massachusetts Medical School-Baystate, Springfield, Massachusetts 01107, USA
| | | | - William T. McGee
- University of Massachusetts Medical School-Baystate, Springfield, Massachusetts 01107, USA
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47
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Rowe BR, Canosa A, Drouffe JM, Mitchell JBA. Simple quantitative assessment of the outdoor versus indoor airborne transmission of viruses and COVID-19. ENVIRONMENTAL RESEARCH 2021; 198:111189. [PMID: 33872644 PMCID: PMC8051020 DOI: 10.1016/j.envres.2021.111189] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/06/2021] [Accepted: 04/12/2021] [Indexed: 05/15/2023]
Abstract
In this paper we develop a simple model of the inhaled flow rate of aerosol particles of respiratory origin i.e. that have been exhaled by other people. A connection is made between the exposure dose and the probability of developing an airborne disease. This allows a simple assessment of the outdoor versus indoor risk of contamination to be made in a variety of meteorological situations. It is shown quantitatively that for most cases, the outdoor risk is orders of magnitude less than the indoor risk and that it can become comparable only for extremely specific meteorological and topographical situations. It sheds light on various observations of COVID-19 spreading in mountain valleys with temperature inversions while at the same time other areas are much less impacted.
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Affiliation(s)
- B R Rowe
- Rowe Consulting, 22 Chemin des Moines, 22750, Saint Jacut de La Mer, France.
| | - A Canosa
- CNRS, IPR (Institut de Physique de Rennes)-UMR 6251, Université de Rennes, 35000, Rennes, France
| | - J M Drouffe
- 31B Chemin Du Couvent, 91190, Gif-sur-Yvette, France
| | - J B A Mitchell
- MERL-Consulting SAS, 21 Rue Sergent Guihard, 35000, Rennes, France
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Pokora R, Kutschbach S, Weigl M, Braun D, Epple A, Lorenz E, Grund S, Hecht J, Hollich H, Rietschel P, Schneider F, Sohmen R, Taylor K, Dienstbuehl I. Investigation of superspreading COVID-19 outbreak events in meat and poultry processing plants in Germany: A cross-sectional study. PLoS One 2021; 16:e0242456. [PMID: 34111143 PMCID: PMC8191887 DOI: 10.1371/journal.pone.0242456] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 05/24/2021] [Indexed: 12/22/2022] Open
Abstract
Since May 2020, several COVID-19 outbreaks have occurred in the German meat industry despite various protective measures, and temperature and ventilation conditions were considered as possible high-risk factors. This cross-sectional study examined meat and poultry plants to assess possible risk factors. Companies completed a self-administered questionnaire on the work environment and protective measures taken to prevent SARS-CoV-2 infection. Multivariable logistic regression analysis adjusted for the possibility to distance at least 1.5 meters, break rules, and employment status was performed to identify risk factors associated with COVID-19 cases. Twenty-two meat and poultry plants with 19,072 employees participated. The prevalence of COVID-19 in the seven plants with more than 10 cases was 12.1% and was highest in the deboning and meat cutting area with 16.1%. A subsample analysis where information on maximal ventilation rate per employee was available revealed an association with the ventilation rate (adjusted odds ratio (AOR) 0.996, 95% CI 0.993-0.999). When including temperature as an interaction term in the working area, the association with the ventilation rate did not change. When room temperatures increased, the chance of testing positive for COVID-19 (AOR 0.90 95% CI 0.82-0.99) decreased, and the chance for testing positive for COVID-19for the interaction term (AOR 1.001, 95% CI 1.000-1.003) increased. Employees who work where a minimum distance of less than 1.5 m between workers was the norm had a higher chance of testing positive (AOR 3.61; 95% CI 2.83-4.6). Our results further indicate that climate conditions and low outdoor air flow are factors that can promote the spread of SARS-CoV-2 aerosols. A possible requirement for pandemic mitigation strategies in industrial workplace settings is to increase the ventilation rate.
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Affiliation(s)
- Roman Pokora
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
- Institute of Medical Biostatistics, Epidemiology and Informatics, University hospital of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Susan Kutschbach
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
| | - Matthias Weigl
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
| | - Detlef Braun
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
| | - Annegret Epple
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
| | - Eva Lorenz
- Institute of Medical Biostatistics, Epidemiology and Informatics, University hospital of the Johannes Gutenberg-University Mainz, Mainz, Germany
- Infectious Disease Epidemiology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- German Center for Infection Research (DZIF), Hamburg-Borstel-Lübeck-Riems, Germany
| | - Stefan Grund
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
| | - Juergen Hecht
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
| | - Helmut Hollich
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
| | - Peter Rietschel
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
| | - Frank Schneider
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
| | - Roland Sohmen
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
| | - Katherine Taylor
- Institute of Medical Biostatistics, Epidemiology and Informatics, University hospital of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Isabel Dienstbuehl
- Division of Prevention, Berufsgenossenschaft Nahrungsmittel und Gastgewerbe (BGN), Germany
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Crawford C, Vanoli E, Decorde B, Lancelot M, Duprat C, Josserand C, Jilesen J, Bouadma L, Timsit JF. Modeling of aerosol transmission of airborne pathogens in ICU rooms of COVID-19 patients with acute respiratory failure. Sci Rep 2021; 11:11778. [PMID: 34083700 PMCID: PMC8175584 DOI: 10.1038/s41598-021-91265-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 05/11/2021] [Indexed: 01/06/2023] Open
Abstract
The COVID-19 pandemic has generated many concerns about cross-contamination risks, particularly in hospital settings and Intensive Care Units (ICU). Virus-laden aerosols produced by infected patients can propagate throughout ventilated rooms and put medical personnel entering them at risk. Experimental results found with a schlieren optical method have shown that the air flows generated by a cough and normal breathing were modified by the oxygenation technique used, especially when using High Flow Nasal Canulae, increasing the shedding of potentially infectious airborne particles. This study also uses a 3D Computational Fluid Dynamics model based on a Lattice Boltzmann Method to simulate the air flows as well as the movement of numerous airborne particles produced by a patient's cough within an ICU room under negative pressure. The effects of different mitigation scenarii on the amount of aerosols potentially containing SARS-CoV-2 that are extracted through the ventilation system are investigated. Numerical results indicate that adequate bed orientation and additional air treatment unit positioning can increase by 40% the number of particles extracted and decrease by 25% the amount of particles deposited on surfaces 45s after shedding. This approach could help lay the grounds for a more comprehensive way to tackle contamination risks in hospitals, as the model can be seen as a proof of concept and be adapted to any room configuration.
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Affiliation(s)
- Cyril Crawford
- Ecole Polytechnique, IP Paris, 91128, Palaiseau, France.
- Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, London, UK.
| | | | - Baptiste Decorde
- Laboratoire d'Hydrodynamique (LadHyX), UMR 7646 CNRS-Ecole Polytechnique, IP Paris, 91128, Palaiseau, France
| | | | - Camille Duprat
- Laboratoire d'Hydrodynamique (LadHyX), UMR 7646 CNRS-Ecole Polytechnique, IP Paris, 91128, Palaiseau, France
| | - Christophe Josserand
- Laboratoire d'Hydrodynamique (LadHyX), UMR 7646 CNRS-Ecole Polytechnique, IP Paris, 91128, Palaiseau, France
| | | | - Lila Bouadma
- AP-HP, Bichat Claude Bernard Hospital, Medical and Infectious Diseases ICU (MI2), 75018, Paris, France
- Université de Paris, IAME, INSERM, 75018, Paris, France
| | - Jean-François Timsit
- AP-HP, Bichat Claude Bernard Hospital, Medical and Infectious Diseases ICU (MI2), 75018, Paris, France
- Université de Paris, IAME, INSERM, 75018, Paris, France
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50
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Nasseri S, Yavarian J, Baghani AN, Azad TM, Nejati A, Nabizadeh R, Hadi M, Jandaghi NZS, Vakili B, Vaghefi SKA, Baghban M, Yousefi S, Nazmara S, Alimohammadi M. The presence of SARS-CoV-2 in raw and treated wastewater in 3 cities of Iran: Tehran, Qom and Anzali during coronavirus disease 2019 (COVID-19) outbreak. JOURNAL OF ENVIRONMENTAL HEALTH SCIENCE & ENGINEERING 2021; 19:573-584. [PMID: 33643658 PMCID: PMC7903026 DOI: 10.1007/s40201-021-00629-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/08/2021] [Indexed: 05/10/2023]
Abstract
This study aimed to identifying the presence of SARS-CoV-2 RNA in raw and treated wastewater during the COVID-19 outbreak in Tehran, Qom and Anzali cities (Iran). From three wastewater treatment plants (WWTPs), 28 treated and untreated wastewater composite samples were collected from April 4 to May 2, 2020. In this study, polyethylene glycol 6000 (PEG 6000) was used through one-step real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) for identification of RNA viruses. SARS-CoV-2 RNA was elicited from wastewater composite samples in all inlet samples taken from the three above mentioned cities. The results of outlet samples were as follows: 1) Results from Qom and East Anzali outlets showed no trace of SARS-CoV-2 RNA despite the difference in treatment disinfection method used (chlorine vs. ultraviolet (UV) disinfection). 2. In Tehran, SARS-CoV-2 RNA was not detected in any of the outlet samples taken from the modules disinfected by UV. Out of the four samples taken from the modules disinfected by chlorine, two were positive for the SARS-CoV-2 RNA which could have been caused by deficiencies in operation and maintenance. It can be concluded that meeting the standards of operation and maintenance (O&M) in WWTPs can considerably ensure that wastewater does not act as one of the roots of transmission for the disease.
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Affiliation(s)
- Simin Nasseri
- Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- Center for Water Quality Research (CWQR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran
| | - Jila Yavarian
- Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Abbas Norouzian Baghani
- Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Talat Mokhtari Azad
- Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Ahmad Nejati
- Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Ramin Nabizadeh
- Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahdi Hadi
- Center for Water Quality Research (CWQR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran
| | | | - Behnam Vakili
- Office of Improvement on Wastewater Operation Procedures, National Water and Wastewater Engineering Company, Tehran, Iran
| | | | - Mahtab Baghban
- Reference Laboratory of Water and Wastewater, Tehran Province of Water and Wastewater Company, Tehran, Iran
| | - Somayeh Yousefi
- Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Shahrokh Nazmara
- Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahmood Alimohammadi
- Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- Center for Water Quality Research (CWQR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran
- Health Equity Research Center (HERC), Tehran University of Medical Sciences, Tehran, Iran
- Department of Environmental Health Engineering, Health Faculty, Tehran University of Medical Sciences, Tehran, Iran
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