101
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Jimenez JL, Marr LC, Randall K, Ewing ET, Tufekci Z, Greenhalgh T, Tellier R, Tang JW, Li Y, Morawska L, Mesiano‐Crookston J, Fisman D, Hegarty O, Dancer SJ, Bluyssen PM, Buonanno G, Loomans MGLC, Bahnfleth WP, Yao M, Sekhar C, Wargocki P, Melikov AK, Prather KA. What were the historical reasons for the resistance to recognizing airborne transmission during the COVID-19 pandemic? INDOOR AIR 2022; 32:e13070. [PMID: 36040283 PMCID: PMC9538841 DOI: 10.1111/ina.13070] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 05/25/2022] [Accepted: 05/30/2022] [Indexed: 05/05/2023]
Abstract
The question of whether SARS-CoV-2 is mainly transmitted by droplets or aerosols has been highly controversial. We sought to explain this controversy through a historical analysis of transmission research in other diseases. For most of human history, the dominant paradigm was that many diseases were carried by the air, often over long distances and in a phantasmagorical way. This miasmatic paradigm was challenged in the mid to late 19th century with the rise of germ theory, and as diseases such as cholera, puerperal fever, and malaria were found to actually transmit in other ways. Motivated by his views on the importance of contact/droplet infection, and the resistance he encountered from the remaining influence of miasma theory, prominent public health official Charles Chapin in 1910 helped initiate a successful paradigm shift, deeming airborne transmission most unlikely. This new paradigm became dominant. However, the lack of understanding of aerosols led to systematic errors in the interpretation of research evidence on transmission pathways. For the next five decades, airborne transmission was considered of negligible or minor importance for all major respiratory diseases, until a demonstration of airborne transmission of tuberculosis (which had been mistakenly thought to be transmitted by droplets) in 1962. The contact/droplet paradigm remained dominant, and only a few diseases were widely accepted as airborne before COVID-19: those that were clearly transmitted to people not in the same room. The acceleration of interdisciplinary research inspired by the COVID-19 pandemic has shown that airborne transmission is a major mode of transmission for this disease, and is likely to be significant for many respiratory infectious diseases.
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Affiliation(s)
- Jose L. Jimenez
- Department of Chemistry and Cooperative Institute for Research in Environmental SciencesUniversity of ColoradoBoulderColoradoUSA
| | - Linsey C. Marr
- Department of Civil and Environmental EngineeringVirginia TechBlacksburgVirginiaUSA
| | | | | | - Zeynep Tufekci
- School of JournalismColumbia UniversityNew YorkNew YorkUSA
| | - Trish Greenhalgh
- Department of Primary Care Health SciencesMedical Sciences DivisionUniversity of OxfordOxfordUK
| | | | - Julian W. Tang
- Department of Respiratory SciencesUniversity of LeicesterLeicesterUK
| | - Yuguo Li
- Department of Mechanical EngineeringUniversity of Hong KongHong KongChina
| | - Lidia Morawska
- International Laboratory for Air Quality and HeathQueensland University of TechnologyBrisbaneQueenslandAustralia
| | | | - David Fisman
- Dalla Lana School of Public HealthUniversity of TorontoTorontoOntarioCanada
| | - Orla Hegarty
- School of Architecture, Planning & Environmental PolicyUniversity College DublinDublinIreland
| | - Stephanie J. Dancer
- Department of MicrobiologyHairmyres Hospital, Glasgow, and Edinburgh Napier UniversityGlasgowUK
| | - Philomena M. Bluyssen
- Faculty of Architecture and the Built EnvironmentDelft University of TechnologyDelftThe Netherlands
| | - Giorgio Buonanno
- Department of Civil and Mechanical EngineeringUniversity of Cassino and Southern LazioCassinoItaly
| | - Marcel G. L. C. Loomans
- Department of the Built EnvironmentEindhoven University of Technology (TU/e)EindhovenThe Netherlands
| | - William P. Bahnfleth
- Department of Architectural EngineeringThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
| | - Maosheng Yao
- College of Environmental Sciences and EngineeringPeking UniversityBeijingChina
| | - Chandra Sekhar
- Department of the Built EnvironmentNational University of SingaporeSingaporeSingapore
| | - Pawel Wargocki
- Department of Civil EngineeringTechnical University of DenmarkLyngbyDenmark
| | - Arsen K. Melikov
- Department of Civil EngineeringTechnical University of DenmarkLyngbyDenmark
| | - Kimberly A. Prather
- Scripps Institution of OceanographyUniversity of California San DiegoLa JollaCaliforniaUSA
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102
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Yan K, Lin J, Albaugh S, Yang M, Wang E, Cyberski T, Abasiyanik MF, Wroblewski KE, O'Connor M, Klock A, Tung A, Shahul S, Kurian D, Tay S, Pinto JM. Measuring SARS-CoV-2 aerosolization in rooms of hospitalized patients. Laryngoscope Investig Otolaryngol 2022; 7:1033-1041. [PMID: 35942422 PMCID: PMC9350181 DOI: 10.1002/lio2.802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 04/12/2022] [Indexed: 11/11/2022] Open
Abstract
Objective Airborne spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains a significant risk for healthcare workers. Understanding transmission of SARS-CoV-2 in the hospital could help minimize nosocomial infection. The objective of this pilot study was to measure aerosolization of SARS-CoV-2 in the hospital rooms of COVID-19 patients. Methods Two air samplers (Inspirotec) were placed 1 and 4 m away from adults with SARS-CoV-2 infection hospitalized at an urban, academic tertiary care center from June to October 2020. Airborne SARS-CoV-2 concentration was measured by quantitative reverse transcription polymerase chain reaction and analyzed by clinical parameters and patient demographics. Results Thirteen patients with COVID-19 (eight females [61.5%], median age: 57 years old, range 25-82) presented with shortness of breath (100%), cough (38.5%) and fever (15.4%). Respiratory therapy during air sampling varied: mechanical ventilation via endotracheal tube (n = 3), high flow nasal cannula (n = 4), nasal cannula (n = 4), respiratory helmet (n = 1), and room air (n = 1). SARS-CoV-2 RNA was identified in rooms of three out of three intubated patients compared with one out of 10 of the non-intubated patients (p = .014). Airborne SARS-CoV-2 tended to decrease with distance (1 vs. 4 m) in rooms of intubated patients. Conclusions Hospital rooms of intubated patients had higher levels of aerosolized SARS-CoV-2, consistent with increased aerosolization of virus in patients with severe disease or treatment with positive pressure ventilation through an endotracheal tube. While preliminary, these data have safety implications for health care workers and design of protective measures in the hospital. Level of Evidence 2.
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Affiliation(s)
- Kenneth Yan
- Department of Head and Neck SurgeryUniversity of California Los AngelesCaliforniaLos AngelesUSA
| | - Jing Lin
- Pritzker School of Molecular EngineeringThe University of ChicagoChicagoIllinoisUSA
- Institute for Genomics and Systems BiologyThe University of ChicagoChicagoIllinoisUSA
| | - Shaley Albaugh
- Pritzker School of MedicineThe University of ChicagoChicagoIllinoisUSA
| | - Meredith Yang
- Pritzker School of MedicineThe University of ChicagoChicagoIllinoisUSA
| | - Esther Wang
- Pritzker School of MedicineThe University of ChicagoChicagoIllinoisUSA
| | - Thomas Cyberski
- Pritzker School of MedicineThe University of ChicagoChicagoIllinoisUSA
| | - Mustafa Fatih Abasiyanik
- Pritzker School of Molecular EngineeringThe University of ChicagoChicagoIllinoisUSA
- Institute for Genomics and Systems BiologyThe University of ChicagoChicagoIllinoisUSA
| | | | - Michael O'Connor
- Department of Anesthesiology & Critical CareThe University of ChicagoChicagoIllinoisUSA
| | - Allan Klock
- Department of Anesthesiology & Critical CareThe University of ChicagoChicagoIllinoisUSA
| | - Avery Tung
- Department of Anesthesiology & Critical CareThe University of ChicagoChicagoIllinoisUSA
| | - Sajid Shahul
- Department of Anesthesiology & Critical CareThe University of ChicagoChicagoIllinoisUSA
| | - Dinesh Kurian
- Department of Anesthesiology & Critical CareThe University of ChicagoChicagoIllinoisUSA
| | - Savaş Tay
- Pritzker School of Molecular EngineeringThe University of ChicagoChicagoIllinoisUSA
- Institute for Genomics and Systems BiologyThe University of ChicagoChicagoIllinoisUSA
| | - Jayant M. Pinto
- Section of Otolaryngology‐Head and Neck Surgery, Department of SurgeryThe University of ChicagoChicagoIllinoisUSA
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103
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Silva PG, Branco PTBS, Soares RRG, Mesquita JR, Sousa SIV. SARS-CoV-2 air sampling: A systematic review on the methodologies for detection and infectivity. INDOOR AIR 2022; 32:e13083. [PMID: 36040285 PMCID: PMC9538005 DOI: 10.1111/ina.13083] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 07/06/2022] [Accepted: 07/08/2022] [Indexed: 06/15/2023]
Abstract
This systematic review aims to present an overview of the current aerosol sampling methods (and equipment) being used to investigate the presence of SARS-CoV-2 in the air, along with the main parameters reported in the studies that are essential to analyze the advantages and disadvantages of each method and perspectives for future research regarding this mode of transmission. A systematic literature review was performed on PubMed/MEDLINE, Web of Science, and Scopus to assess the current air sampling methodologies being applied to SARS-CoV-2. Most of the studies took place in indoor environments and healthcare settings and included air and environmental sampling. The collection mechanisms used were impinger, cyclone, impactor, filters, water-based condensation, and passive sampling. Most of the reviewed studies used RT-PCR to test the presence of SARS-CoV-2 RNA in the collected samples. SARS-CoV-2 RNA was detected with all collection mechanisms. From the studies detecting the presence of SARS-CoV-2 RNA, fourteen assessed infectivity. Five studies detected viable viruses using impactor, water-based condensation, and cyclone collection mechanisms. There is a need for a standardized protocol for sampling SARS-CoV-2 in air, which should also account for other influencing parameters, including air exchange ratio in the room sampled, relative humidity, temperature, and lighting conditions.
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Affiliation(s)
- Priscilla G Silva
- Laboratory for Integrative and Translational Research in Population Health (ITR), Porto, Portugal
- School of Medicine and Biomedical Sciences (ICBAS), University of Porto, Porto, Portugal
- LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Porto, Portugal
- ALiCE - Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal
- Epidemiology Research Unit (EPI Unit), Institute of Public Health, University of Porto, Porto, Portugal
| | - Pedro T B S Branco
- LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Porto, Portugal
- ALiCE - Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal
| | - Ruben R G Soares
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
- Division of Nanobiotechnology, Department of Protein Science, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
| | - João R Mesquita
- Laboratory for Integrative and Translational Research in Population Health (ITR), Porto, Portugal
- Epidemiology Research Unit (EPI Unit), Institute of Public Health, University of Porto, Porto, Portugal
| | - Sofia I V Sousa
- LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Porto, Portugal
- ALiCE - Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal
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104
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Prevention of SARS-CoV-2 and respiratory viral infections in healthcare settings: current and emerging concepts. Curr Opin Infect Dis 2022; 35:353-362. [PMID: 35849526 DOI: 10.1097/qco.0000000000000839] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
PURPOSE OF REVIEW COVID-19 has catalyzed a wealth of new data on the science of respiratory pathogen transmission and revealed opportunities to enhance infection prevention practices in healthcare settings. RECENT FINDINGS New data refute the traditional division between droplet vs airborne transmission and clarify the central role of aerosols in spreading all respiratory viruses, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), even in the absence of so-called 'aerosol-generating procedures' (AGPs). Indeed, most AGPs generate fewer aerosols than talking, labored breathing, or coughing. Risk factors for transmission include high viral loads, symptoms, proximity, prolonged exposure, lack of masking, and poor ventilation. Testing all patients on admission and thereafter can identify early occult infections and prevent hospital-based clusters. Additional prevention strategies include universal masking, encouraging universal vaccination, preferential use of N95 respirators when community rates are high, improving native ventilation, utilizing portable high-efficiency particulate air filters when ventilation is limited, and minimizing room sharing when possible. SUMMARY Multifaceted infection prevention programs that include universal testing, masking, vaccination, and enhanced ventilation can minimize nosocomial SARS-CoV-2 infections in patients and workplace infections in healthcare personnel. Extending these insights to other respiratory viruses may further increase the safety of healthcare and ready hospitals for novel respiratory viruses that may emerge in the future.
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105
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Gerami Seresht N. Enhancing resilience in construction against infectious diseases using stochastic multi-agent approach. AUTOMATION IN CONSTRUCTION 2022; 140:104315. [PMID: 35573273 PMCID: PMC9091540 DOI: 10.1016/j.autcon.2022.104315] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 04/18/2022] [Accepted: 04/29/2022] [Indexed: 06/15/2023]
Abstract
To recover from the adverse impacts of COVID-19 on construction and to avoid further losses to the industry in future pandemics, the resilience of construction industry needs to be enhanced against infectious diseases. Currently, there is a gap for modelling frameworks to simulate the spread of infectious diseases in construction projects at micro-level and to test interventions' effectiveness for data-informed decision-making. Here, this gap is addressed by developing a simulation framework using stochastic agent-based modelling, which enables construction researchers and practitioners to simulate and limit the spread of infectious diseases in construction projects. This is specifically important, since the results of a building project case-study reveals that, in comparison to the general population, infectious diseases may spread faster among construction workers and fatalities can be significantly higher. The proposed framework motivates future research on micro-level modelling of infectious diseases and efforts for intervening the spread of diseases in construction projects.
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Affiliation(s)
- Nima Gerami Seresht
- Department of Mechanical and Construction Engineering, Northumbria University, Newcastle Upon Tyne NE1 8ST, United Kingdom
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106
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Lunati I, Mucignat C. Infection risk in cable cars and other enclosed spaces. INDOOR AIR 2022; 32:e13094. [PMID: 36040286 PMCID: PMC9539082 DOI: 10.1111/ina.13094] [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: 01/09/2022] [Revised: 06/10/2022] [Accepted: 07/15/2022] [Indexed: 06/15/2023]
Abstract
As virus-laden aerosols can accumulate and remain suspended for hours in insufficiently ventilated enclosed spaces, indoor environments can heavily contribute to the spreading of airborne infections. In the COVID-19 pandemics, the role possibly played by cable cars has attracted media attention following several outbreaks in ski resort. To assess the real risk of infection, we experimentally characterize the natural ventilation in cable cars and develop a general stochastic model of infection in an arbitrary indoor space that accounts for the epidemiological situation, the virological parameters, and the indoor characteristics (ventilation rate and occupant number density). As a results of the high air exchange rate (we measured up to 180 air changes per hour) and the relatively short duration of the journey, the infection probability in cable cars traveling with open windows is remarkably lower than in other enclosed spaces such as aircraft cabins, train cars, offices, classrooms, and dining rooms. Accounting for the typical duration of the stay, the probability of infection during a cable-car ride is lower by two to three orders of magnitude than in the other examples considered (the highest risk being estimated in case of a private gathering in a poorly ventilated room). For most practical purposes, the infection probability can be approximated by the inhaled viral dose, which provides an upper bound and allows a simple comparison between different indoor situations once the air exchange rate and the occupant number density are known. Our approach and findings are applicable to any indoor space in which the viral transmission is predominately airborne and the air is well mixed.
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Affiliation(s)
- Ivan Lunati
- Laboratory of Multiscale Studies in Building Physics, EmpaDübendorfSwitzerland
| | - Claudio Mucignat
- Laboratory of Multiscale Studies in Building Physics, EmpaDübendorfSwitzerland
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107
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Greenhalgh T, Fisman D, Cane DJ, Oliver M, Macintyre CR. Adapt or die: how the pandemic made the shift from EBM to EBM+ more urgent. BMJ Evid Based Med 2022; 27:bmjebm-2022-111952. [PMID: 35853682 PMCID: PMC9510422 DOI: 10.1136/bmjebm-2022-111952] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/05/2022] [Indexed: 12/12/2022]
Abstract
Evidence-based medicine (EBM's) traditional methods, especially randomised controlled trials (RCTs) and meta-analyses, along with risk-of-bias tools and checklists, have contributed significantly to the science of COVID-19. But these methods and tools were designed primarily to answer simple, focused questions in a stable context where yesterday's research can be mapped more or less unproblematically onto today's clinical and policy questions. They have significant limitations when extended to complex questions about a novel pathogen causing chaos across multiple sectors in a fast-changing global context. Non-pharmaceutical interventions which combine material artefacts, human behaviour, organisational directives, occupational health and safety, and the built environment are a case in point: EBM's experimental, intervention-focused, checklist-driven, effect-size-oriented and deductive approach has sometimes confused rather than informed debate. While RCTs are important, exclusion of other study designs and evidence sources has been particularly problematic in a context where rapid decision making is needed in order to save lives and protect health. It is time to bring in a wider range of evidence and a more pluralist approach to defining what counts as 'high-quality' evidence. We introduce some conceptual tools and quality frameworks from various fields involving what is known as mechanistic research, including complexity science, engineering and the social sciences. We propose that the tools and frameworks of mechanistic evidence, sometimes known as 'EBM+' when combined with traditional EBM, might be used to develop and evaluate the interdisciplinary evidence base needed to take us out of this protracted pandemic. Further articles in this series will apply pluralistic methods to specific research questions.
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Affiliation(s)
- Trisha Greenhalgh
- Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
| | - David Fisman
- Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
| | - Danielle J Cane
- Coalition for Healthcare Acquired Infection Reduction, Cambridge, Ontario, Canada
| | - Matthew Oliver
- Association of Professional Engineers and Geoscientists, Edmonton, Alberta, Canada
| | - Chandini Raina Macintyre
- The Biosecurity Program, Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia
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108
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Aerosol emissions from wind instruments: effects of performer age, sex, sound pressure level, and bell covers. Sci Rep 2022; 12:11303. [PMID: 35788635 PMCID: PMC9252563 DOI: 10.1038/s41598-022-15530-x] [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: 03/16/2022] [Accepted: 06/24/2022] [Indexed: 12/30/2022] Open
Abstract
Aerosol emissions from wind instruments are a suspected route of transmission for airborne infectious diseases, such as SARS-CoV-2. We evaluated aerosol number emissions (from 0.25 to 35.15 μm) from 81 volunteer performers of both sexes and varied age (12 to 63 years) while playing wind instruments (bassoon, clarinet, flute, French horn, oboe, piccolo, saxophone, trombone, trumpet, and tuba) or singing. Measured emissions spanned more than two orders of magnitude, ranging in rate from < 8 to 1,815 particles s-1, with brass instruments, on average, producing 191% (95% CI 81-367%) more aerosol than woodwinds. Being male was associated with a 70% increase in emissions (vs. female; 95% CI 9-166%). Each 1 dBA increase in sound pressure level was associated with a 28% increase (95% CI 10-40%) in emissions from brass instruments; sound pressure level was not associated with woodwind emissions. Age was not a significant predictor of emissions. The use of bell covers reduced aerosol emissions from three brass instruments tested (trombone, tuba, and trumpet), with average reductions ranging from 53 to 73%, but not for the two woodwind instruments tested (oboe and clarinet). Results from this work can facilitate infectious disease risk management for the performing arts.
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109
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Jia W, Wei J, Cheng P, Wang Q, Li Y. Exposure and respiratory infection risk via the short-range airborne route. BUILDING AND ENVIRONMENT 2022; 219:109166. [PMID: 35574565 PMCID: PMC9085449 DOI: 10.1016/j.buildenv.2022.109166] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/16/2022] [Accepted: 05/02/2022] [Indexed: 05/09/2023]
Abstract
Leading health authorities have suggested short-range airborne transmission as a major route of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). However, there is no simple method to assess the short-range airborne infection risk or identify its governing parameters. We proposed a short-range airborne infection risk assessment model based on the continuum model and two-stage jet model. The effects of ventilation, physical distance and activity intensity on the short-range airborne exposure were studied systematically. The results suggested that increasing physical distance and ventilation reduced short-range airborne exposure and infection risk. However, a diminishing return phenomenon was observed when the ventilation rate or physical distance was beyond a certain threshold. When the infectious quantum concentration was less than 1 quantum/L at the mouth, our newly defined threshold distance and threshold ventilation rate were independent of quantum concentration. We estimated threshold distances of 0.59, 1.1, 1.7 and 2.6 m for sedentary/passive, light, moderate and intense activities, respectively. At these distances, the threshold ventilation was estimated to be 8, 20, 43, and 83 L/s per person, respectively. The findings show that both physical distancing and adequate ventilation are essential for minimising infection risk, especially in high-intensity activity or densely populated spaces.
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Affiliation(s)
- Wei Jia
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Jianjian Wei
- Institute of Refrigeration and Cryogenics/Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Pan Cheng
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Qun Wang
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
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110
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Blumberg S, Lu P, Kwan AT, Hoover CM, Lloyd-Smith JO, Sears D, Bertozzi SM, Worden L. Modeling scenarios for mitigating outbreaks in congregate settings. PLoS Comput Biol 2022; 18:e1010308. [PMID: 35857774 PMCID: PMC9342784 DOI: 10.1371/journal.pcbi.1010308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/01/2022] [Accepted: 06/16/2022] [Indexed: 11/18/2022] Open
Abstract
The explosive outbreaks of COVID-19 seen in congregate settings such as prisons and nursing homes, has highlighted a critical need for effective outbreak prevention and mitigation strategies for these settings. Here we consider how different types of control interventions impact the expected number of symptomatic infections due to outbreaks. Introduction of disease into the resident population from the community is modeled as a stochastic point process coupled to a branching process, while spread between residents is modeled via a deterministic compartmental model that accounts for depletion of susceptible individuals. Control is modeled as a proportional decrease in the number of susceptible residents, the reproduction number, and/or the proportion of symptomatic infections. This permits a range of assumptions about the density dependence of transmission and modes of protection by vaccination, depopulation and other types of control. We find that vaccination or depopulation can have a greater than linear effect on the expected number of cases. For example, assuming a reproduction number of 3.0 with density-dependent transmission, we find that preemptively reducing the size of the susceptible population by 20% reduced overall disease burden by 47%. In some circumstances, it may be possible to reduce the risk and burden of disease outbreaks by optimizing the way a group of residents are apportioned into distinct residential units. The optimal apportionment may be different depending on whether the goal is to reduce the probability of an outbreak occurring, or the expected number of cases from outbreak dynamics. In other circumstances there may be an opportunity to implement reactive disease control measures in which the number of susceptible individuals is rapidly reduced once an outbreak has been detected to occur. Reactive control is most effective when the reproduction number is not too high, and there is minimal delay in implementing control. We highlight the California state prison system as an example for how these findings provide a quantitative framework for understanding disease transmission in congregate settings. Our approach and accompanying interactive website (https://phoebelu.shinyapps.io/DepopulationModels/) provides a quantitative framework to evaluate the potential impact of policy decisions governing infection control in outbreak settings.
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Affiliation(s)
- Seth Blumberg
- University of California San Francisco, Francis I. Proctor Foundation, San Francisco, California, United States of America
- Modeling Infectious Diseases in Healthcare Network, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
- University of California San Francisco, Department of Medicine, San Francisco, California, United States of America
| | - Phoebe Lu
- University of California San Francisco, Francis I. Proctor Foundation, San Francisco, California, United States of America
- Modeling Infectious Diseases in Healthcare Network, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Ada T. Kwan
- University of California San Francisco, Department of Medicine, San Francisco, California, United States of America
| | - Christopher M. Hoover
- University of California San Francisco, Francis I. Proctor Foundation, San Francisco, California, United States of America
- Modeling Infectious Diseases in Healthcare Network, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - James O. Lloyd-Smith
- University of California Los Angeles, Department of Ecology and Evolutionary Biology, Los Angeles, California, United States of America
| | - David Sears
- University of California San Francisco, Department of Medicine, San Francisco, California, United States of America
| | - Stefano M. Bertozzi
- University of California Berkeley, School of Public Health, Berkeley, California, United States of America
- University of Washington, Department of Global Health, Seattle, Washington, United States of America
- National Institute of Public Health of Mexico, Cuernavaca, Mexico
| | - Lee Worden
- University of California San Francisco, Francis I. Proctor Foundation, San Francisco, California, United States of America
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111
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Nazaroff WW. 30+ years of knowledge creation: Indoor Air 1991-2021. INDOOR AIR 2022; 32:e13074. [PMID: 35904388 DOI: 10.1111/ina.13074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 06/20/2022] [Accepted: 06/24/2022] [Indexed: 06/15/2023]
Affiliation(s)
- William W Nazaroff
- Department of Civil and Environmental Engineering, University of California, Berkeley, California, USA
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112
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Li B, Cai W. A novel CO 2-based demand-controlled ventilation strategy to limit the spread of COVID-19 in the indoor environment. BUILDING AND ENVIRONMENT 2022; 219:109232. [PMID: 35637641 PMCID: PMC9132786 DOI: 10.1016/j.buildenv.2022.109232] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 05/03/2022] [Accepted: 05/23/2022] [Indexed: 05/09/2023]
Abstract
Ventilation is of critical importance to containing COVID-19 contagion in indoor environments. Keeping the ventilation rate at high level is recommended by many guidelines to dilute virus-laden respiratory particles and mitigate airborne transmission risk. However, high ventilation rate will cause high energy use. Demand-controlled ventilation is a promising technology option for controlling indoor air quality in an energy-efficient manner. This paper proposes a novel CO2-based demand-controlled ventilation strategy to limit the spread of COVID-19 in indoor environments. First, the quantitative relationship is established between COVID-19 infection risk and average CO2 level. Then, a sufficient condition is proposed to ensure COVID-19 event reproduction number is less than 1 under a conservative consideration of the number of infectors. Finally, a ventilation control scheme is designed to make sure the above condition can be satisfied. Case studies of different indoor environments have been conducted on a testbed of a real ventilation system to validate the effectiveness of the proposed strategy. Results show that the proposed strategy can efficiently maintain the reproduction number less than 1 to limit COVID-19 contagion while saving about 30%-50% of energy compared with the fixed ventilation scheme. The proposed strategy offers more practical values compared with existing studies: it is applicable to scenarios where there are multiple infectors, and the number of infectors varies with time; it only requires CO2 sensors and does not require occupancy detection sensors. Since CO2 sensors are very mature and low-cost, the proposed strategy is suitable for mass deployment in most existing ventilation systems.
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Affiliation(s)
- Bingxu Li
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
- Energy Research Institute @ NTU (ERI@N), Interdisciplinary Graduate Programme, Nanyang Technological University, Singapore
| | - Wenjian Cai
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
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Huang J, Hao T, Liu X, Jones P, Ou C, Liang W, Liu F. Airborne transmission of the Delta variant of SARS-CoV-2 in an auditorium. BUILDING AND ENVIRONMENT 2022; 219:109212. [PMID: 35645452 PMCID: PMC9128309 DOI: 10.1016/j.buildenv.2022.109212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/23/2022] [Accepted: 05/16/2022] [Indexed: 05/30/2023]
Abstract
The Delta variant of SARS-CoV-2 has inflicted heavy burdens on healthcare systems globally, although direct evidence on the quantity of exhaled viral shedding from Delta cases is lacking. The literature remains inconclusive on whether existing public health guidance, based on earlier evidence of COVID-19, should respond differently to more infectious viral strains. This paper describes a study on an outbreak of the Delta variant of COVID-19 in an auditorium, where one person contracted the virus from three asymptomatic index cases sitting in a different row. Field inspections were conducted on the configuration of seating, building and ventilation systems. Numerical simulation was conducted to retrospectively assess the exhaled viral emission, decay, airborne dispersion, with a modified Wells-Riley equation used to calculate the inhalation exposure and disease infection risks at the seat level. Results support the airborne disease transmission. The viral emission rate for Delta cases was estimated at 31 quanta per hour, 30 times higher than those of the original variant. The high quantity of viral plume exhaled by delta cases can create a high risk zone nearby, which, for a mixing ventilation system, cannot be easily mitigated by raising mixing rates or introducing fresh air supply. Such risks can be reduced by wearing an N95 respirator, less so for social distancing. A displacement ventilation system, through which the air is supplied at the floor and returned from the ceiling, can reduce risks compared with a mixing system. The study has implications for ventilation guidelines and hygiene practices in light of more infectious viral strains of COVID-19.
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Affiliation(s)
- Jianxiang Huang
- Department of Urban Planning and Design, The University of Hong Kong, Pokfulam Rd, Hong Kong SAR, China
- The University of Hong Kong Shenzhen Institute of Research and Innovation, 5/F, Key Laboratory Platform Building, Shenzhen Virtual University Park, No.6, Yuexing 2nd Rd, Nanshan, Shenzhen, 518057, China
- Sustainable High Density Cities Lab, HKUrban Lab, The University of Hong Kong, Pokfulam Rd, Hong Kong SAR, China
| | - Tongping Hao
- Department of Urban Planning and Design, The University of Hong Kong, Pokfulam Rd, Hong Kong SAR, China
- The University of Hong Kong Shenzhen Institute of Research and Innovation, 5/F, Key Laboratory Platform Building, Shenzhen Virtual University Park, No.6, Yuexing 2nd Rd, Nanshan, Shenzhen, 518057, China
- Sustainable High Density Cities Lab, HKUrban Lab, The University of Hong Kong, Pokfulam Rd, Hong Kong SAR, China
| | - Xiao Liu
- School of Architecture, South China University of Technology, Guangzhou, 510641, China
- Sustainable High Density Cities Lab, HKUrban Lab, The University of Hong Kong, Pokfulam Rd, Hong Kong SAR, China
| | - Phil Jones
- Welsh School of Architecture, Cardiff University, King Edward VII Avenue, Cardiff, United Kingdom
| | - Cuiyun Ou
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
| | - Weihui Liang
- School of Architecture and Urban Planning, Nanjing University, Nanjing, 210093, China
| | - Fuqiang Liu
- Office of Emergency Response to Public Health Emergencies, Hunan Provincial Center for Disease Control and Prevention, No. 450, Section 1, Furong Middle Road, Kaifu District, Changsha City, Hunan Province, China
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114
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Yan S, Wang LL, Birnkrant MJ, Zhai J, Miller SL. Evaluating SARS-CoV-2 airborne quanta transmission and exposure risk in a mechanically ventilated multizone office building. BUILDING AND ENVIRONMENT 2022; 219:109184. [PMID: 35602249 PMCID: PMC9102535 DOI: 10.1016/j.buildenv.2022.109184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/19/2022] [Accepted: 05/09/2022] [Indexed: 05/11/2023]
Abstract
The world has faced tremendous challenges during the COVID-19 pandemic since 2020, and effective clean air strategies that mitigate infectious risks indoors have become more essential. In this study, a novel approach based on the Wells-Riley model applied to a multizone building was proposed to simulate exposure to infectious doses in terms of "quanta". This modeling approach quantifies the relative benefits of different risk mitigation strategies so that their effectiveness could be compared. A case study for the US Department of Energy large office prototype building was conducted to illustrate the approach. The infectious risk propagation from the infection source throughout the building was evaluated. Different mitigation strategies were implemented, including increasing outdoor air ventilation rates and adding air-cleaning devices such as Minimum Efficiency Reporting Value (MERV) filters and portable air cleaners (PACs) with HEPA filters in-room/in-duct germicidal ultraviolet (GUV) lights, layering with wearing masks. Results showed that to keep the risk of the infection propagating low the best strategy without universal masking was the operation of in-room GUV or a large industrial-sized PAC; whereas with masking all strategies were acceptable. This study contributes to a better understanding of the airborne transmission risks in multizone, mechanically ventilated buildings and how to reduce infection risk from a public health perspective of different mitigation strategies.
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Affiliation(s)
- Shujie Yan
- Dept. of Building, Civil & Environmental Engineering, Concordia University, 1455 de Maisonneuve Blvd. West, Montreal, Quebec, H3G1M8, Canada
| | - Liangzhu Leon Wang
- Dept. of Building, Civil & Environmental Engineering, Concordia University, 1455 de Maisonneuve Blvd. West, Montreal, Quebec, H3G1M8, Canada
| | | | - John Zhai
- Department of Civil, Environmental and Architectural Engineering, University of Colorado, Boulder, USA
| | - Shelly L Miller
- Department of Mechanical Engineering, University of Colorado, Boulder, USA
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115
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Duval D, Palmer JC, Tudge I, Pearce-Smith N, O'Connell E, Bennett A, Clark R. Long distance airborne transmission of SARS-CoV-2: rapid systematic review. BMJ 2022; 377:e068743. [PMID: 35768139 PMCID: PMC9240778 DOI: 10.1136/bmj-2021-068743] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/04/2022] [Indexed: 12/22/2022]
Abstract
OBJECTIVES To evaluate the potential for long distance airborne transmission of SARS-CoV-2 in indoor community settings and to investigate factors that might influence transmission. DESIGN Rapid systematic review and narrative synthesis. DATA SOURCES Medline, Embase, medRxiv, Arxiv, and WHO COVID-19 Research Database for studies published from 27 July 2020 to 19 January 2022; existing relevant rapid systematic review for studies published from 1 January 2020 to 27 July 2020; and citation analysis in Web of Science and Cocites. ELIGIBILITY CRITERIA FOR STUDY SELECTION Observational studies reporting on transmission events in indoor community (non-healthcare) settings in which long distance airborne transmission of SARS-CoV-2 was the most likely route. Studies such as those of household transmission where the main transmission route was likely to be close contact or fomite transmission were excluded. DATA EXTRACTION AND SYNTHESIS Data extraction was done by one reviewer and independently checked by a second reviewer. Primary outcomes were SARS-CoV-2 infections through long distance airborne transmission (>2 m) and any modifying factors. Methodological quality of included studies was rated using the quality criteria checklist, and certainty of primary outcomes was determined using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework. Narrative synthesis was themed by setting. RESULTS 22 reports relating to 18 studies were identified (methodological quality was high in three, medium in five, and low in 10); all the studies were outbreak investigations. Long distance airborne transmission was likely to have occurred for some or all transmission events in 16 studies and was unclear in two studies (GRADE: very low certainty). In the 16 studies, one or more factors plausibly increased the likelihood of long distance airborne transmission, particularly insufficient air replacement (very low certainty), directional air flow (very low certainty), and activities associated with increased emission of aerosols, such as singing or speaking loudly (very low certainty). In 13 studies, the primary cases were reported as being asymptomatic, presymptomatic, or around symptom onset at the time of transmission. Although some of the included studies were well conducted outbreak investigations, they remain at risk of bias owing to study design and do not always provide the level of detail needed to fully assess transmission routes. CONCLUSION This rapid systematic review found evidence suggesting that long distance airborne transmission of SARS-CoV-2 might occur in indoor settings such as restaurants, workplaces, and venues for choirs, and identified factors such as insufficient air replacement that probably contributed to transmission. These results strengthen the need for mitigation measures in indoor settings, particularly the use of adequate ventilation. SYSTEMATIC REVIEW REGISTRATION PROSPERO CRD42021236762.
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Affiliation(s)
- Daphne Duval
- COVID-19 Rapid Evidence Service, UK Health Security Agency, London, UK
| | - Jennifer C Palmer
- COVID-19 Rapid Evidence Service, UK Health Security Agency, London, UK
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
- Population Health Science, Bristol Medical School, University of Bristol, Bristol, UK
| | - Isobel Tudge
- COVID-19 Rapid Evidence Service, UK Health Security Agency, London, UK
| | | | - Emer O'Connell
- COVID-19 Advice and Guidance, UK Health Security Agency, London, UK
| | - Allan Bennett
- Biosafety, Air, and Water Microbiology Group, Research and Evaluation, UK Health Security Agency, Porton, UK
| | - Rachel Clark
- COVID-19 Rapid Evidence Service, UK Health Security Agency, London, UK
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116
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Liu F, Qian H. Uncertainty analysis of facemasks in mitigating SARS-CoV-2 transmission. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 303:119167. [PMID: 35307493 PMCID: PMC8926848 DOI: 10.1016/j.envpol.2022.119167] [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: 12/22/2021] [Revised: 02/14/2022] [Accepted: 03/14/2022] [Indexed: 05/09/2023]
Abstract
In the context of global spread of coronavirus disease 2019 (COVID-19) caused by a novel coronavirus (SARS-CoV-2), there is a controversial issue on whether the use of facemasks is promising to control or mitigate the COVID-19 transmission. This study modeled the SARS-CoV-2 transmission process and analyzed the ability of surgical mask and N95 in reducing the infection risk with Sobol's analysis. Two documented outbreaks of COVID-19 with no involvers wearing face masks were reviewed in a restaurant in Guangzhou (China) and a choir rehearsal in Mount Vernon (USA), suggesting that the proposed model can be well validated when airborne transmission is assumed to dominate the virus transmission indoors. Subsequently, the uncertainty analysis of the protection efficiency of N95 and surgical mask were conducted with Monte Carlo simulations, with three main findings: (1) the uncertainty in infection risk is primarily apportioned by respiratory activities, virus dynamics, environment factors and individual exposures; (2) wearing masks can effectively reduce the SARS-CoV-2 infection risk to an acceptable level (< 10-3) by at least two orders of magnitude; (3) faceseal leakage can reduce protection efficiency by approximately 4% when the infector is speaking or coughing, and by approximately 28% when the infector is sneezing. This work indicates the effectiveness of non-pharmaceutical interventions during the pandemic, and implies the importance of the synergistic studies of medicine, environment, social policies and strategies, etc., on reducing hazards and risks of the pandemic.
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Affiliation(s)
- Fan Liu
- School of Energy and Environment, Southeast University, Nanjing, China; School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai, China
| | - Hua Qian
- School of Energy and Environment, Southeast University, Nanjing, China; Engineering Research Center for Building Energy Environments & Equipments, Ministry of Education, China.
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Cheng P, Chen W, Xiao S, Xue F, Wang Q, Chan PW, You R, Lin Z, Niu J, Li Y. Probable cross-corridor transmission of SARS-CoV-2 due to cross airflows and its control. BUILDING AND ENVIRONMENT 2022; 218:109137. [PMID: 35502296 PMCID: PMC9045881 DOI: 10.1016/j.buildenv.2022.109137] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 03/12/2022] [Accepted: 04/20/2022] [Indexed: 06/01/2023]
Abstract
A COVID-19 outbreak occurred in May 2020 in a public housing building in Hong Kong - Luk Chuen House, located in Lek Yuen Estate. The horizontal cluster linked to the index case' flat (flat 812) remains to be explained. Computational fluid dynamics simulations were conducted to obtain the wind-pressure coefficients of each external opening on the eighth floor of the building. The data were then used in a multi-zone airflow model to estimate the airflow rate and aerosol concentration in the flats and corridors on that floor. Apart from flat 812 and corridors, the virus-laden aerosol concentrations in flats 811, 813, 815, 817 and 819 (opposite to flat 812, across the corridor) were the highest on the eighth floor. When the doors of flats 813 and 817 were opened by 20%, the hourly-averaged aerosol concentrations in these two flats were at least four times as high as those in flats 811, 815 and 819 during the index case's home hours or the suspected exposure period of secondary cases. Thus, the flats across the corridor that were immediately downstream from flat 812 were at the highest exposure risk under a prevailing easterly wind, especially when their doors or windows that connected to the corridor were open. Given that the floorplan and dimension of Luk Chuen House are similar to those of many hotels, our findings provide a probable explanation for COVID-19 outbreaks in quarantine hotels. Positive pressure and sufficient ventilation in the corridor would help to minimise such cross-corridor infections.
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Affiliation(s)
- Pan Cheng
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Wenzhao Chen
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Shenglan Xiao
- School of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, China
| | - Fan Xue
- Department of Real Estate and Construction, The University of Hong Kong, Hong Kong SAR, China
| | - Qun Wang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Pak Wai Chan
- Hong Kong Observatory, Kowloon, Hong Kong SAR, China
| | - Ruoyu You
- Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Zhang Lin
- Division of Building Science and Technology, City University of Hong Kong, Hong Kong SAR, China
| | - Jianlei Niu
- Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
- School of Public Health, The University of Hong Kong, Hong Kong SAR, China
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118
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Prentiss M, Chu A, Berggren KK. Finding the infectious dose for COVID-19 by applying an airborne-transmission model to superspreader events. PLoS One 2022; 17:e0265816. [PMID: 35679278 PMCID: PMC9182663 DOI: 10.1371/journal.pone.0265816] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 03/08/2022] [Indexed: 12/19/2022] Open
Abstract
We probed the transmission of COVID-19 by applying an airborne transmission model to five well-documented case studies—a Washington state church choir, a Korean call center, a Korean exercise class, and two different Chinese bus trips. For all events the likely index patients were pre-symptomatic or mildly symptomatic, which is when infective patients are most likely to interact with large groups of people. Applying the model to those events yields results that suggest the following: (1) transmission was airborne; (2) superspreading events do not require an index patient with an unusually high viral load; (3) the viral loads for all of the index patients were of the same order of magnitude and consistent with experimentally measured values for patients at the onset of symptoms, even though viral loads across the population vary by a factor of >108. In particular we used a Wells-Riley exposure model to calculate q, the total average number of infectious quanta inhaled by a person at the event. Given the q value for each event, the simple airborne transmission model was used to determined Sq, the rate at which the index patient exhaled infectious quanta and N0, the characteristic number of COVID-19 virions needed to induce infection. Despite the uncertainties in the values of some parameters of the superspreading events, all five events yielded (N0∼300–2,000 virions), which is similar to published values for influenza. Finally, this work describes the conditions under which similar methods can provide actionable information on the transmission of other viruses.
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Affiliation(s)
- Mara Prentiss
- Department of Physics, Harvard University, Cambridge, MA, United States of America
- * E-mail:
| | - Arthur Chu
- QVT Family Office, New York, NY, United States of America
| | - Karl K. Berggren
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States of America
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119
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Lokhande T, Yang X, Xie Y, Cook K, Liang J, LaBelle S, Meyers C. GIS-based classroom management system to support COVID-19 social distance planning. COMPUTATIONAL URBAN SCIENCE 2022; 2:11. [PMID: 35669158 PMCID: PMC9143716 DOI: 10.1007/s43762-022-00040-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 04/27/2022] [Indexed: 11/30/2022]
Abstract
Schools across the United States and around the world canceled in-person classes beginning in March 2020 to contain the spread of the COVID-19 virus, a public health emergency. Many empirical pieces of research have demonstrated that educational institutions aid students’ overall growth and studies have stressed the importance of prioritizing in-person learning to cultivate social values through education. Two years into the COVID-19 pandemic, policymakers and school administrators have been making plans to reopen schools. However, few scientific studies had been done to support planning classroom seating while complying with the social distancing policy. To ensure a safe return to campus, we designed a ‘community-safe’ method for classroom management that incorporates social distancing and computes seating capacity. In this paper, we present custom GIS tools developed for two types of classroom settings – classrooms with fixed seating and classrooms with movable seating. The fixed model tool is based on an optimized backtracking algorithm. Our flexible model tool can consider various classroom dimensions, fixtures, and a safe social distance. The tool is built on a python script that can be executed to calculate revised seating capacity to maintain a safe social distance for any defined space. We present a real-world implementation of the system at Eastern Michigan University, United States, where it was used to support campus reopening planning in 2020. Our proposed GIS-based technique could be applicable for seating planning in other indoor and outdoor settings.
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Affiliation(s)
- Trupti Lokhande
- Department of Geography and Geology, Eastern Michigan University, Ypsilanti, MI 48197 USA
| | - Xining Yang
- Department of Geography and Geology, Eastern Michigan University, Ypsilanti, MI 48197 USA.,Institute of Geospatial Research and Education, Eastern Michigan University, Ypsilanti, MI 48197 USA
| | - Yichun Xie
- Department of Geography and Geology, Eastern Michigan University, Ypsilanti, MI 48197 USA.,Institute of Geospatial Research and Education, Eastern Michigan University, Ypsilanti, MI 48197 USA
| | - Katherine Cook
- Department of Geography and Geology, Eastern Michigan University, Ypsilanti, MI 48197 USA
| | - Jianyuan Liang
- Department of Geography and Geology, Eastern Michigan University, Ypsilanti, MI 48197 USA
| | - Shannon LaBelle
- Department of Geography and Geology, Eastern Michigan University, Ypsilanti, MI 48197 USA
| | - Cassidy Meyers
- Department of Geography and Geology, Eastern Michigan University, Ypsilanti, MI 48197 USA
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120
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Afrasiabian E, Douglas R, Geron M, Cunningham G. A numerical evaluation of a novel recovery fresh air heat pump concept for a generic electric bus. APPLIED THERMAL ENGINEERING 2022; 209:118181. [PMID: 35153534 PMCID: PMC8820066 DOI: 10.1016/j.applthermaleng.2022.118181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 12/22/2021] [Accepted: 02/03/2022] [Indexed: 06/14/2023]
Abstract
Since the outbreak of the worldwide COVID-19 pandemic, public transportation networks have faced unprecedented challenges and have looked for practical solutions to address the rising safety concerns. It is deemed that in confined spaces, operating heating units (and cooling) in non-re-circulation mode (i. e., all-fresh air mode) could reduce the airborne transmission of this infectious disease, by reducing the density of the pathogen and exposure time. However, this will expectedly increase the energy demand and reduce the driving range of electric buses. To tackle both the airborne transmission and energy efficiency issues, in this paper a novel recovery heat pump concept, operating in all-fresh air mode, was proposed. The novelty of this concept lies in its potential to be applied to already manufactured/in-service heat pump units as it does not require any additional components or need for redesigning the heating systems. In this concept, the cabin exhaust air is directed to pass through the evaporator of the heat pump system to recover part of the waste heat from the cabin and to improve the efficiency of the system. In this paper, a 0D/1D coupled model of a generic single-deck cabin and a heat pump system was developed in the Simulink environment of MATLAB (R2020b) software. The model was run in two different modes, namely the all-fresh air (as a baseline and a recovery heat pump concepts), and the air re-circulation mode (as a conventional heat pump concept with a 50% re-circulation ratio). The performance of these concepts was investigated to evaluate how an all-fresh air policy could affect the performance of the system, as well as the energy-saving potential of the proposed recovery concept. The performance of the system was studied under different ambient temperatures of -5 °C, 0 °C, and 5 °C, and for low and moderate occupancy levels. Results show that implementing the all-fresh air policy in the recovery and baseline concepts significantly improved the ventilation rate per person by at least 102% and at most 125%, compared to the air-re-circulating heat pump. Moreover, adopting the recovery concept reduced the power demand by at least 8% and at most 11%, compared to the baseline all-fresh air heat pump, for the selected fan and blower flow rates. The presented results in this paper along with the applicability of this concept to in-service mobile heat pumps could make it a feasible, practical, and quick trade-off solution to help the bus operators to protect people and improve the energy efficiency of their service.
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Affiliation(s)
- Ehsan Afrasiabian
- School of Mechanical & Aerospace Engineering, Queen's University Belfast, Belfast BT9 5AH, UK
| | - Roy Douglas
- School of Mechanical & Aerospace Engineering, Queen's University Belfast, Belfast BT9 5AH, UK
| | - Marco Geron
- School of Mechanical & Aerospace Engineering, Queen's University Belfast, Belfast BT9 5AH, UK
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Bauer K, Hardege R, Neumann S, Schwarze R, Fuchs M, Heinrich Pieper L. How Safe is Singing Under Pandemic Conditions? - CO 2-Measurements as Simple Method for Risk Estimation During Choir Rehearsals. J Voice 2022:S0892-1997(22)00136-9. [PMID: 35667988 DOI: 10.1016/j.jvoice.2022.05.003] [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: 03/16/2022] [Revised: 05/02/2022] [Accepted: 05/02/2022] [Indexed: 11/16/2022]
Abstract
OBJECTIVES The SARS-CoV-2 pandemic has forced choirs to pause or at least to restrict rehearsals and concerts. Nevertheless, an uncertainty about the risks of infection while singing remains, especially with regard to distances, duration of singing, number of singers and their positions in the room, size of the room as well as ventilation strategies. Based on the assumption that CO2 is a suitable indicator for the exhaled aerosols in a room, it is the aim of this study to deduce recommendations for a choir rehearsal with a minimum risk of infection. METHODS During two choir rehearsals in a typical, nonventilated classroom, we installed 30 CO2 sensors, which allow spatial and temporal evaluation of the CO2 dispersion during singing. Various singing and ventilation phases were applied and the rates of CO2 increase during singing as well as its decrease during ventilation phases were evaluated and compared for different scenarios. RESULTS The measurements reveal a linear relation between the duration of singing, size of the room and number of persons. For our size of the room of 200 m3 the average CO2 increase is 1.83 ppm/min per person. Masks or pure breathing without singing do - in contrast to aerosol dispersion - not influence the rate of CO2 increase. CO2 disperses fast and homogeneously on horizontal planes. However, a vertical layering with a maximum CO2 concentration is observed near the ceiling. Shock ventilation shows the largest CO2 decrease within the first 5 min, after 10 min of ventilation the outside base concentration of 400 ppm is reached again. CONCLUSION The evaluated relations allow to calculate safe singing times for a defined number of singers and size of the room until a critical threshold of 800 ppm is reached. Furthermore, in order to monitor the actual CO2 concentration during choir rehearsal, just one CO2 sensor is representative for the air quality and CO2 concentration of the whole room and thus considered sufficient. For an early warning, it should be installed near the ceiling. Direct singing into a sensor should be avoided. A ventilation time of just 5 min is recommended which represents a compromise between strong CO2 reduction and still sufficient room temperature during winter time.
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Affiliation(s)
- Katrin Bauer
- Institute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Freiberg 09599, Germany.
| | - Robert Hardege
- Institute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Freiberg 09599, Germany
| | - Sebastian Neumann
- Institute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Freiberg 09599, Germany
| | - Rüdiger Schwarze
- Institute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Freiberg 09599, Germany
| | - Michael Fuchs
- Division of Phoniatrics and Audiology, University of Leipzig, Liebigstrasse 10-14, Leipzig 04103, Germany; Institute for Musicians' Medicine, University of Leipzig, Liebigstrasse 10-14, Leipzig 04103, Germany
| | - Lennart Heinrich Pieper
- Division of Phoniatrics and Audiology, University of Leipzig, Liebigstrasse 10-14, Leipzig 04103, Germany; Institute for Musicians' Medicine, University of Leipzig, Liebigstrasse 10-14, Leipzig 04103, Germany
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122
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Zhao X, Liu S, Yin Y, Zhang T(T, Chen Q. Airborne transmission of COVID-19 virus in enclosed spaces: An overview of research methods. INDOOR AIR 2022; 32:e13056. [PMID: 35762235 PMCID: PMC9349854 DOI: 10.1111/ina.13056] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 04/28/2022] [Accepted: 05/06/2022] [Indexed: 05/22/2023]
Abstract
Since the outbreak of COVID-19 in December 2019, the severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) has spread worldwide. This study summarized the transmission mechanisms of COVID-19 and their main influencing factors, such as airflow patterns, air temperature, relative humidity, and social distancing. The transmission characteristics in existing cases are providing more and more evidence that SARS CoV-2 can be transmitted through the air. This investigation reviewed probabilistic and deterministic research methods, such as the Wells-Riley equation, the dose-response model, the Monte-Carlo model, computational fluid dynamics (CFD) with the Eulerian method, CFD with the Lagrangian method, and the experimental approach, that have been used for studying the airborne transmission mechanism. The Wells-Riley equation and dose-response model are typically used for the assessment of the average infection risk. Only in combination with the Eulerian method or the Lagrangian method can these two methods obtain the spatial distribution of airborne particles' concentration and infection risk. In contrast with the Eulerian and Lagrangian methods, the Monte-Carlo model is suitable for studying the infection risk when the behavior of individuals is highly random. Although researchers tend to use numerical methods to study the airborne transmission mechanism of COVID-19, an experimental approach could often provide stronger evidence to prove the possibility of airborne transmission than a simple numerical model. All in all, the reviewed methods are helpful in the study of the airborne transmission mechanism of COVID-19 and epidemic prevention and control.
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Affiliation(s)
- Xingwang Zhao
- School of Energy and EnvironmentSoutheast UniversityNanjingChina
| | - Sumei Liu
- Tianjin Key Laboratory of Indoor Air Environmental Quality ControlSchool of Environmental Science and EngineeringTianjin UniversityTianjinChina
| | - Yonggao Yin
- School of Energy and EnvironmentSoutheast UniversityNanjingChina
- Engineering Research Center of Building Equipment, Energy, and EnvironmentMinistry of EducationNanjingChina
| | - Tengfei (Tim) Zhang
- Tianjin Key Laboratory of Indoor Air Environmental Quality ControlSchool of Environmental Science and EngineeringTianjin UniversityTianjinChina
| | - Qingyan Chen
- Department of Building Environment and Energy EngineeringThe Hong Kong Polytechnic UniversityKowloonHong Kong SARChina
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Bi Y, Aganovic A, Mathisen HM, Cao G. Experimental study on the exposure level of surgical staff to SARS-CoV-2 in operating rooms with mixing ventilation under negative pressure. BUILDING AND ENVIRONMENT 2022; 217:109091. [PMID: 35469260 PMCID: PMC9021120 DOI: 10.1016/j.buildenv.2022.109091] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 03/06/2022] [Accepted: 04/10/2022] [Indexed: 06/09/2023]
Abstract
The purpose of this study was to reveal the exposure level of surgical staff to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from the patient's nose and wound during operations on COVID-19 patients. The tracer gas N2O is used to simulate SARS-CoV-2 from the patient's nose and wound. In this study, concentration levels of tracer gas were measured in the breathing zones of these surgical staff in the operating room under three pressure difference conditions: -5 pa-15 pa and -25 pa compared to the adjunction room. These influencing factors on exposure level are analyzed in terms of ventilation efficiency and the thermal plume distribution characteristics of the patient. The results show that the assistant surgeon faces 4 to 12 times higher levels of exposure to SARS-CoV-2 than other surgical staff. Increasing the pressure difference between the OR lab and adjunction room can reduce the level of exposure for the main surgeon and assistant surgeon. Turning on the cooling fan of the endoscope imager may result in a higher exposure level for the assistant surgeon. Surgical nurses outside of the surgical microenvironment are exposed to similar contaminant concentration levels in the breathing zone as in the exhaust. However, the ventilation efficiency is not constant near the surgical patient or in the rest of the room and will vary with a change in pressure difference. This may suggest that the air may not be fully mixed in the surgical microenvironment.
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Affiliation(s)
- Yang Bi
- Norwegian University of Science and Technology, Trondheim, Norway
| | | | | | - Guangyu Cao
- Norwegian University of Science and Technology, Trondheim, Norway
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de Kreij RJB, Davies Wykes MS, Woodward H, Linden PF. Modeling disease transmission in a train carriage using a simple 1D-model. INDOOR AIR 2022; 32:e13066. [PMID: 35762236 DOI: 10.1111/ina.13066] [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: 01/06/2022] [Revised: 05/15/2022] [Accepted: 05/19/2022] [Indexed: 06/15/2023]
Abstract
Understanding airborne infectious disease transmission on public transport is essential to reducing the risk of infection of passengers and crew members. We propose a new one-dimensional (1D) model that predicts the longitudinal dispersion of airborne contaminants and the risk of disease transmission inside a railway carriage. We compare the results of this 1D-model to the predictions of a model that assumes the carriage is fully mixed. The 1D-model is validated using measurements of controlled carbon-dioxide experiments conducted in a full-scale railway carriage. We use our results to provide novel insights into the impact of various strategies to reduce the risk of airborne transmission on public transport.
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Affiliation(s)
- Rick J B de Kreij
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Cambridge, UK
| | | | - Huw Woodward
- Centre for Environmental Policy, Imperial College London, London, UK
| | - Paul F Linden
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Cambridge, UK
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Abstract
This paper simulates the spread of COVID-19 at universities via airborne transmission in classroom settings. The transmission risk model used for these simulations accounts for student-specific class schedules, classroom sizes and occupancy, and ventilation rates, as well as vaccination rate and efficacy. We show the simulations reproduce trends observed in weekly infection rates at a large US university. We also evaluate the impact of campus operational policies. Model predictions show moving 90% of classes online can reduce new infections by as much as 18×, and universal mask usage can reduce new infections by up to 3.6×. For full-time in-person instruction, high vaccination rates are predicted to curb transmission even for more contagious variants of severe acute respiratory syndrome coronavirus 2. We study the airborne transmission risk associated with holding in-person classes on university campuses for the original strain and a more contagious variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We adopt a model for airborne transmission risk in an enclosed room that considers room properties, mask efficiency, and initial infection probability of the occupants. Additionally, we study the effect of vaccination on the spread of the virus. The presented model has been evaluated in simulations using fall 2019 (prepandemic) and fall 2020 (hybrid instruction) course registration data of a large US university, allowing for assessing the difference in transmission risk between in-person and hybrid programs and the impact of occupancy reduction, mask-wearing, and vaccination. The simulations indicate that without vaccination, moving 90% of the classes online leads to a 17 to 18× reduction in new cases, and universal mask usage results in an ∼2.7 to 3.6× reduction in new infections through classroom interactions. Furthermore, the results indicate that for the original variant and using vaccines with efficacy greater than 90%, at least 23% (64%) of students need to be vaccinated with (without) mask usage in order to operate the university at full occupancy while preventing an increase in cases due to classroom interactions. For the more contagious variant, even with universal mask usage, at least 93% of the students need to be vaccinated to ensure the same conditions. We show that the model is able to predict trends observed in weekly infection rates for fall 2021.
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126
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Coleman KK, Tay DJW, Tan KS, Ong SWX, Than TS, Koh MH, Chin YQ, Nasir H, Mak TM, Chu JJH, Milton DK, Chow VTK, Tambyah PA, Chen M, Tham KW. Viral Load of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Respiratory Aerosols Emitted by Patients With Coronavirus Disease 2019 (COVID-19) While Breathing, Talking, and Singing. Clin Infect Dis 2022; 74:1722-1728. [PMID: 34358292 DOI: 10.1101/2021.07.15.21260561] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Indexed: 05/24/2023] Open
Abstract
BACKGROUND Multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) superspreading events suggest that aerosols play an important role in driving the coronavirus disease 2019 (COVID-19) pandemic. To better understand how airborne SARS-CoV-2 transmission occurs, we sought to determine viral loads within coarse (>5 μm) and fine (≤5 μm) respiratory aerosols produced when breathing, talking, and singing. METHODS Using a G-II exhaled breath collector, we measured viral RNA in coarse and fine respiratory aerosols emitted by COVID-19 patients during 30 minutes of breathing, 15 minutes of talking, and 15 minutes of singing. RESULTS Thirteen participants (59%) emitted detectable levels of SARS-CoV-2 RNA in respiratory aerosols, including 3 asymptomatic and 1 presymptomatic patient. Viral loads ranged from 63-5821 N gene copies per expiratory activity per participant, with high person-to-person variation. Patients earlier in illness were more likely to emit detectable RNA. Two participants, sampled on day 3 of illness, accounted for 52% of total viral load. Overall, 94% of SARS-CoV-2 RNA copies were emitted by talking and singing. Interestingly, 7 participants emitted more virus from talking than singing. Overall, fine aerosols constituted 85% of the viral load detected in our study. Virus cultures were negative. CONCLUSIONS Fine aerosols produced by talking and singing contain more SARS-CoV-2 copies than coarse aerosols and may play a significant role in SARS-CoV-2 transmission. Exposure to fine aerosols, especially indoors, should be mitigated. Isolating viable SARS-CoV-2 from respiratory aerosol samples remains challenging; whether this can be more easily accomplished for emerging SARS-CoV-2 variants is an urgent enquiry necessitating larger-scale studies.
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Affiliation(s)
- Kristen K Coleman
- Program in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore
| | - Douglas Jie Wen Tay
- Department of the Built Environment, National University of Singapore, Singapore
| | - Kai Sen Tan
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
- Department of Otolaryngology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
- Infectious Diseases Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
- Biosafety Level 3 Core Facility, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
| | - Sean Wei Xiang Ong
- National Centre for Infectious Diseases, Singapore
- Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore
| | - The Son Than
- Program in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore
- Department of the Built Environment, National University of Singapore, Singapore
| | - Ming Hui Koh
- Department of the Built Environment, National University of Singapore, Singapore
| | - Yi Qing Chin
- National Centre for Infectious Diseases, Singapore
| | - Haziq Nasir
- Division of Infectious Diseases, Department of Medicine, National University Health System, National University of Singapore, Singapore
| | - Tze Minn Mak
- National Centre for Infectious Diseases, Singapore
| | - Justin Jang Hann Chu
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
- Infectious Diseases Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
- Biosafety Level 3 Core Facility, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Donald K Milton
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, Maryland, USA
| | - Vincent T K Chow
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
- Infectious Diseases Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
| | - Paul Anantharajah Tambyah
- Infectious Diseases Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
- Division of Infectious Diseases, Department of Medicine, National University Health System, National University of Singapore, Singapore
| | - Mark Chen
- National Centre for Infectious Diseases, Singapore
- Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore
| | - Kwok Wai Tham
- Department of the Built Environment, National University of Singapore, Singapore
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127
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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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128
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Wang X, Wu T, Oliveira LFS, Zhang D. Sheet, Surveillance, Strategy, Salvage and Shield in global biodefense system to protect the public health and tackle the incoming pandemics. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 822:153469. [PMID: 35093353 PMCID: PMC8799268 DOI: 10.1016/j.scitotenv.2022.153469] [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: 09/21/2021] [Revised: 01/23/2022] [Accepted: 01/23/2022] [Indexed: 06/14/2023]
Abstract
The pandemic of COVID-19 challenges the global health system and raises our concerns on the next waves of other emerging infectious diseases. Considering the lessons from the failure of world's pandemic warning system against COVID-19, many scientists and politicians have mentioned different strategies to improve global biodefense system, among which Sheet, Surveillance, Strategy, Salvage and Shield (5S) are frequently discussed. Nevertheless, the current focus is mainly on the optimization and management of individual strategy, and there are limited attempts to combine the five strategies as an integral global biodefense system. Sheet represents the biosafety datasheet for biohazards in natural environment and human society, which helps our deeper understanding on the geographical pattern, transmission routes and infection mechanism of pathogens. Online surveillance and prognostication network is an environmental Surveillance tool for monitoring the outbreak of pandemic diseases and alarming the risks to take emergency actions, targeting aerosols, waters, soils and animals. Strategy is policies and legislations for social distancing, lockdown and personal protective equipment to block the spread of infectious diseases in communities. Clinical measures are Salvage on patients by innovating appropriate medicines and therapies. The ultimate defensive Shield is vaccine development to protect healthy crowds from infection. Fighting against COVID-19 and other emerging infectious diseases is a long rocky journey, requiring the common endeavors of scientists and politicians from all countries around the world. 5S in global biodefense system bring a ray of light to the current darkest and future road from environmental and geographical perspectives.
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Affiliation(s)
- Xinzi Wang
- School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Tianyun Wu
- Research Institute for Environmental Innovation (Tsinghua-Suzhou), Suzhou 215163, PR China
| | - Luis F S Oliveira
- Departamento de Ingeniería Civil y Arquitectura, Universidad de Lima, Avenida Javier Prado Este 4600, Santiago de Surco 1503, Peru; Department of Civil and Environmental, Universidad de la Costa, Calle 58 #55-66, 080002 Barranquilla, Atlántico, Colombia
| | - Dayi Zhang
- College of New Energy and Environment, Jilin University, Changchun 130021, PR China.
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129
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Ferriot C, Durance C, Trutt L, Rozo C, Louvigné C, Bressollette-Bodin C, Birgand G. A COVID-19 Superspreading Event Involving Two Variants during Sociotherapy Activities in French Mental Health Centre. J Hosp Infect 2022; 127:34-38. [PMID: 35594982 PMCID: PMC9113770 DOI: 10.1016/j.jhin.2022.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 05/04/2022] [Accepted: 05/05/2022] [Indexed: 11/19/2022]
Abstract
A COVID-19 superspreading event during sociotherapy activities highlighted the risk of a choir for transmission in mental health centres and the community, and the need for close control of such activities. The simultaneous identification of delta and beta variants of SARS-CoV-2 illustrated their different spreading abilities.
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Affiliation(s)
- C Ferriot
- Centre d'appui pour la Prévention des Infections Associées aux Soins des Pays de la Loire, Nantes, Pays de la Loire, France.
| | - C Durance
- EPSYLAN, Blain, Pays la Loire, France
| | - L Trutt
- Agence Régionale de Santé des Pays de la Loire, Nantes, Pays de la Loire, France
| | - C Rozo
- EPSYLAN, Blain, Pays la Loire, France
| | - C Louvigné
- Centre d'appui pour la Prévention des Infections Associées aux Soins des Pays de la Loire, Nantes, Pays de la Loire, France
| | - C Bressollette-Bodin
- Service de virologie, Centre Hospitalier Universitaire de Nantes, Nantes, Pays de la Loire, France
| | - G Birgand
- Centre d'appui pour la Prévention des Infections Associées aux Soins des Pays de la Loire, Nantes, Pays de la Loire, France
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130
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Cheng VCC, Lung DC, Wong SC, Au AKW, Wang Q, Chen H, Xin L, Chu AWH, Ip JD, Chan WM, Tsoi HW, Tse H, Ng KHL, Kwan MYW, Chuang SK, To KKW, Li Y, Yuen KY. Outbreak investigation of airborne transmission of Omicron (B.1.1.529) - SARS-CoV-2 variant of concern in a restaurant: Implication for enhancement of indoor air dilution. JOURNAL OF HAZARDOUS MATERIALS 2022; 430:128504. [PMID: 35739650 PMCID: PMC8848576 DOI: 10.1016/j.jhazmat.2022.128504] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/06/2022] [Accepted: 02/13/2022] [Indexed: 05/06/2023]
Abstract
Airborne transmission of SARS-CoV-2 has been increasingly recognized in the outbreak of COVID-19, especially with the Omicron variant. We investigated an outbreak due to Omicron variant in a restaurant. Besides epidemiological and phylogenetic analyses, the secondary attack rates of customers of restaurant-related COVID-19 outbreak before (Outbreak R1) and after enhancement of indoor air dilution (Outbreak R2) were compared. On 27th December 2021, an index case stayed in restaurant R2 for 98 min. Except for 1 sitting in the same table, six other secondary cases sat in 3 corners at 3 different zones, which were served by different staff. The median exposure time was 34 min (range: 19-98 min). All 7 secondary cases were phylogenetically related to the index. Smoke test demonstrated that the airflow direction may explain the distribution of secondary cases. Compared with an earlier COVID-19 outbreak in another restaurant R1 (19th February 2021), which occurred prior to the mandatory enhancement of indoor air dilution, the secondary attack rate among customers in R2 was significantly lower than that in R1 (3.4%, 7/207 vs 28.9%, 22/76, p<0.001). Enhancement of indoor air dilution through ventilation and installation of air purifier could minimize the risk of SARS-CoV-2 transmission in the restaurants.
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Affiliation(s)
- Vincent Chi-Chung Cheng
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China; Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China
| | - David Christopher Lung
- Department of Pathology, Queen Elizabeth Hospital, Hong Kong Special Administrative Region, China
| | - Shuk-Ching Wong
- Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China
| | - Albert Ka-Wing Au
- Centre for Health Protection, Department of Health, Hong Kong Special Administrative Region, China
| | - Qun Wang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Hong Chen
- Centre for Health Protection, Department of Health, Hong Kong Special Administrative Region, China
| | - Li Xin
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Allen Wing-Ho Chu
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Jonathan Daniel Ip
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Wan-Mui Chan
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Hoi-Wah Tsoi
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Herman Tse
- Department of Pathology, Hong Kong Children's Hospital, Hong Kong Special Administrative Region, China
| | - Ken Ho-Leung Ng
- Centre for Health Protection, Department of Health, Hong Kong Special Administrative Region, China
| | - Mike Yat-Wah Kwan
- Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Hong Kong Special Administrative Region, China
| | - Shuk-Kwan Chuang
- Centre for Health Protection, Department of Health, Hong Kong Special Administrative Region, China
| | - Kelvin Kai-Wang To
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Kwok-Yung Yuen
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.
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131
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Oberlin TJ, DuBois CK, Sheppard M, Quam JD, Kramer AJ, Logan PW, Murphy MJ. COVID-19 aerosol transmission modeling in support of company HVAC guideline. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2022; 19:327-334. [PMID: 35349386 DOI: 10.1080/15459624.2022.2058701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A company COVID-19 Heating, Ventilation, and Air Conditioning Guideline was implemented globally, as part of a larger control measure toolset, to minimize the potential for SARS-CoV-2 aerosol transmission. The COVID-19 Heating, Ventilation, and Air Conditioning Guideline informed and provided the process to optimize existing ventilation systems, set occupancy duration limits, and set clearance periods for a given space. Aerosol transmission modeling was used extensively to determine space limitations to reduce the potential for aerosol transmission in various manufacturing, lab, warehouse, aircraft, and administrative workspaces. This paper focuses on the modeling completed for administrative spaces (e.g., offices, conference rooms, restrooms, elevators) due to their lower ventilation rates, higher occupant densities, and greater vocalization levels. A detailed description of how the Guideline was implemented, with examples showing the evaluation and determinations made for specific spaces, is provided. World-wide implementation of this Guideline, as one of the layers of protection, was a key component in the overall strategy to reduce aerosol transmission of the SARS-CoV-2 virus.
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Affiliation(s)
- Ty J Oberlin
- 3M Company Corporate Safety & Health, Saint Paul, Minnesota
| | | | - Mike Sheppard
- 3M Canada Co 3M Canada Corporate EHS, London, Ontario, Canada
| | - Jodi D Quam
- 3M Company Corporate Safety & Health, Saint Paul, Minnesota
| | | | - Perry W Logan
- 3M Company Corporate Safety & Health, Saint Paul, Minnesota
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132
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Gregson FKA, Shrimpton AJ, Hamilton F, Cook TM, Reid JP, Pickering AE, Pournaras DJ, Bzdek BR, Brown J. Identification of the source events for aerosol generation during oesophago-gastro-duodenoscopy. Gut 2022; 71:871-878. [PMID: 34187844 PMCID: PMC8245282 DOI: 10.1136/gutjnl-2021-324588] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/16/2021] [Indexed: 12/17/2022]
Abstract
OBJECTIVE To determine if oesophago-gastro-duodenoscopy (OGD) generates increased levels of aerosol in conscious patients and identify the source events. DESIGN A prospective, environmental aerosol monitoring study, undertaken in an ultraclean environment, on patients undergoing OGD. Sampling was performed 20 cm away from the patient's mouth using an optical particle sizer. Aerosol levels during OGD were compared with tidal breathing and voluntary coughs within subject. RESULTS Patients undergoing bariatric surgical assessment were recruited (mean body mass index 44 and mean age 40 years, n=15). A low background particle concentration in theatres (3 L-1) enabled detection of aerosol generation by tidal breathing (mean particle concentration 118 L-1). Aerosol recording during OGD showed an average particle number concentration of 595 L-1 with a wide range (3-4320 L-1). Bioaerosol-generating events, namely, coughing or burping, were common. Coughing was evoked in 60% of the endoscopies, with a greater peak concentration and a greater total number of sampled particles than the patient's reference voluntary coughs (11 710 vs 2320 L-1 and 780 vs 191 particles, n=9 and p=0.008). Endoscopies with coughs generated a higher level of aerosol than tidal breathing, whereas those without coughs were not different to the background. Burps also generated increased aerosol concentration, similar to those recorded during voluntary coughs. The insertion and removal of the endoscope were not aerosol generating unless a cough was triggered. CONCLUSION Coughing evoked during OGD is the main source of the increased aerosol levels, and therefore, OGD should be regarded as a procedure with high risk of producing respiratory aerosols. OGD should be conducted with airborne personal protective equipment and appropriate precautions in those patients who are at risk of having COVID-19 or other respiratory pathogens.
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Affiliation(s)
| | - Andrew J Shrimpton
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
- Department of Anaesthesia and Intensive Care Medicine, North Bristol NHS Trust, Bristol, UK
| | - Fergus Hamilton
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Tim M Cook
- Department of Anaesthesia and Intensive Care Medicine, Royal United Hospitals NHS Trust, Bath, and Bristol Medical School, University of Bristol, Bristol, UK
| | | | - Anthony E Pickering
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
- Bristol Anaesthesia, Pain and Critical Care Sciences, Translational Health Sciences, Bristol Medical School, Bristol, UK
| | - Dimitri J Pournaras
- Department of Upper Gastrointestinal and Bariatric/Metabolic Surgery, North Bristol NHS Trust, Bristol, UK
| | - Bryan R Bzdek
- School of Chemistry, University of Bristol, Bristol, UK
| | - Jules Brown
- Department of Anaesthesia and Intensive Care Medicine, North Bristol NHS Trust, Bristol, UK
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133
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Shang Y, Dong J, Tian L, He F, Tu J. An improved numerical model for epidemic transmission and infection risks assessment in indoor environment. JOURNAL OF AEROSOL SCIENCE 2022; 162:105943. [PMID: 35034977 PMCID: PMC8748225 DOI: 10.1016/j.jaerosci.2021.105943] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 11/24/2021] [Accepted: 12/23/2021] [Indexed: 05/08/2023]
Abstract
Social distance will remain the key measure to contain COVID-19 before the global widespread vaccination coverage expected in 2024. Containing the virus outbreak in the office is prioritised to relieve socio-economic burdens caused by COVID-19 and potential pandemics in the future. However, "what is the transmissible distance of SARS-CoV-2" and "what are the appropriate ventilation rates in the office" have been under debate. Without quantitative evaluation of the infection risk, some studies challenged the current social distance policies of 1-2 m adopted by most countries and suggested that longer social distance rule is required as the maximum transmission distance of cough ejected droplets could reach 3-10 m. With the emergence of virus variants such as the Delta variant, the applicability of previous social distance rules are also in doubt. To address the above problem, this study conducted transient Computational Fluid Dynamics (CFD) simulations to evaluate the infection risks under calm and wind scenarios. The calculated Social Distance Index (SDI) indicates that lower humidity leads to a higher infection risk due to weaker evaporation. The infection risk in office was found more sensitive to social distance than ventilation rate. In standard ventilation conditions, social distance of 1.7 m-1.8 m is sufficient distances to reach low probability of infection (PI) target in a calm scenario when coughing is the dominant transmission route. However in the wind scenario (0.25 m/s indoor wind), distance of 2.8 m is required to contain the wild virus type and 3 m is insufficient to contain the spread of the Delta variant. The numerical methods developed in this study provide a framework to evaluate the COVID-19 infection risk in indoor environment. The predicted PI will be beneficial for governments and regulators to make appropriate social-distance and ventilation rules in the office.
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Affiliation(s)
- Yidan Shang
- College of Air Transportation, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Jingliang Dong
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
| | - Lin Tian
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
| | - Fajiang He
- College of Air Transportation, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Jiyuan Tu
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
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134
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Albettar M, Leon Wang L, Katal A. A real-time web tool for monitoring and mitigating indoor airborne COVID-19 transmission risks at city scale. SUSTAINABLE CITIES AND SOCIETY 2022; 80:103810. [PMID: 35261876 PMCID: PMC8891144 DOI: 10.1016/j.scs.2022.103810] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 01/27/2022] [Accepted: 02/25/2022] [Indexed: 05/25/2023]
Abstract
Airborne transmission of aerosols contributes to a large portion of the SARS-CoV-2 spread indoors. This study develops a real-time interactive web-based platform for the public to compare various strategies to curb indoor airborne transmission of COVID-19 in different archetype buildings at a city scale. Although many countries have started vaccination and a gradual re-opening, because of emerging new variants of the virus and the possibility of future pandemics, a lively updated tool for monitoring and mitigation of infection risk is essential. As a demonstration, we evaluated the impacts of six mitigation measures on the infection risks in various building types in a city. It shows that the same strategy could perform quite differently, depending on building types and properties. All strategies are shown to reduce the infection risk but wearing a mask and reducing exposure time are the most effective strategies in many buildings, with around 60% reduction. Doubling the minimum required outdoor air ventilation rate is not as effective as other strategies to reduce the risk. It also causes considerable penalties on energy consumption. Therefore, new building ventilation standards, control actions, and design criteria should be considered to mitigate the infection risk and save energy.
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Affiliation(s)
- Maher Albettar
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal H3G 1M8, Canada
| | - Liangzhu Leon Wang
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal H3G 1M8, Canada
| | - Ali Katal
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal H3G 1M8, Canada
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135
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Liu C, Xiang H, Manyande A, Xu W, Fan L, Zhang Y, Xiang B. Epidemiologic characteristics and differential management strategies of seven case series with COVID-19 outbreaks caused by asymptomatic carriers from June 2020 to May 2021 in China. Am J Transl Res 2022; 14:2244-2255. [PMID: 35559380 PMCID: PMC9091077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 03/17/2022] [Indexed: 06/15/2023]
Abstract
With the COVID-19 epidemic quickly under control in China in the early stage of 2020, global cooperation/communications may pose great challenges to epidemic control and prevention in the country. Large-scale spread by asymptomatic carriers was a concern. We obtained data on new cluster outbreak regions with COVID-19 caused by asymptomatic carriers from June 2020 to May 2021 in China, and reported the epidemiological characteristics, the possible routes of viral transmission and infection, and different control strategies. These results show the importance of regular screening for high-risk populations and differential management strategies for epidemic control, which provide an objective basis for suppressing the spread of the SARS-CoV-2 virus. These experiences can be used as a reference to minimize the subsequent spread of virus mutants in various places.
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Affiliation(s)
- Cheng Liu
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and TechnologyWuhan 430030, Hubei, P. R. China
| | - Hongbing Xiang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and TechnologyWuhan 430030, Hubei, P. R. China
| | - Anne Manyande
- School of Human and Social Sciences, University of West LondonLondon, United Kingdom
| | - Weiguo Xu
- Department of Orthopedics, Tongji Hospital of Tongji Medical College, Huazhong University of Science and TechnologyWuhan 430030, P. R. China
| | - Li Fan
- Department of Orthopedics, Union Hospital of Tongji Medical College, Huazhong University of Science and TechnologyWuhan 430030, P. R. China
| | - Yunhua Zhang
- Hubei Provincial Hospital of Traditional Chinese MedicineWuhan 430061, P. R. China
- Clinical Medical College of Hubei University of Chinese MedicineWuhan 430061, P. R. China
- Hubei Province Academy of Traditional Chinese MedicineWuhan 430061, P. R. China
| | - Boqi Xiang
- School of Public Health, Rutgers UniversityNew Brunswick, New Jersey 08854, USA
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136
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Buonanno G, Robotto A, Brizio E, Morawska L, Civra A, Corino F, Lembo D, Ficco G, Stabile L. Link between SARS-CoV-2 emissions and airborne concentrations: Closing the gap in understanding. JOURNAL OF HAZARDOUS MATERIALS 2022; 428:128279. [PMID: 35063838 PMCID: PMC8760841 DOI: 10.1016/j.jhazmat.2022.128279] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/11/2022] [Accepted: 01/12/2022] [Indexed: 05/03/2023]
Abstract
The airborne transmission of SARS-CoV-2 remains surprisingly controversial; indeed, health and regulatory authorities still require direct proof of this mode of transmission. To close this gap, we measured the viral load of SARS-CoV-2 of an infected subject in a hospital room (through an oral and nasopharyngeal swab), as well as the airborne SARS-CoV-2 concentration in the room resulting from the person breathing and speaking. Moreover, we simulated the same scenarios to estimate the concentration of RNA copies in the air through a novel theoretical approach and conducted a comparative analysis between experimental and theoretical results. Results showed that for an infected subject's viral load ranging between 2.4 × 106 and 5.5 × 106 RNA copies mL-1, the corresponding airborne SARS-CoV-2 concentration was below the minimum detection threshold when the person was breathing, and 16.1 (expanded uncertainty of 32.8) RNA copies m-3 when speaking. The application of the predictive approach provided concentrations metrologically compatible with the available experimental data (i.e. for speaking activity). Thus, the study presented significant evidence to close the gap in understanding airborne transmission, given that the airborne SARS-CoV-2 concentration was shown to be directly related to the SARS-CoV-2 emitted. Moreover, the theoretical analysis was shown to be able to quantitatively link the airborne concentration to the emission.
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Affiliation(s)
- G Buonanno
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, FR, Italy; International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Qld, Australia; Infectious Diseases Unit, Department of Medical Sciences, Amedeo di Savoia Hospital, University of Turin, Torino, Italy
| | - A Robotto
- Environmental Protection Agency of Piedmont (ARPA Piemonte), Italy; Infectious Diseases Unit, Department of Medical Sciences, Amedeo di Savoia Hospital, University of Turin, Torino, Italy
| | - E Brizio
- Environmental Protection Agency of Piedmont (ARPA Piemonte), Italy; Infectious Diseases Unit, Department of Medical Sciences, Amedeo di Savoia Hospital, University of Turin, Torino, Italy
| | - L Morawska
- International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Qld, Australia; Infectious Diseases Unit, Department of Medical Sciences, Amedeo di Savoia Hospital, University of Turin, Torino, Italy
| | - A Civra
- Dept. of Clinical and Biological Science, Azienda Ospedaliero-Universitaria San Luigi Gonzaga, University of Turin, Italy; Infectious Diseases Unit, Department of Medical Sciences, Amedeo di Savoia Hospital, University of Turin, Torino, Italy
| | - F Corino
- Environmental Protection Agency of Piedmont (ARPA Piemonte), Italy; Infectious Diseases Unit, Department of Medical Sciences, Amedeo di Savoia Hospital, University of Turin, Torino, Italy
| | - D Lembo
- Dept. of Clinical and Biological Science, Azienda Ospedaliero-Universitaria San Luigi Gonzaga, University of Turin, Italy; Infectious Diseases Unit, Department of Medical Sciences, Amedeo di Savoia Hospital, University of Turin, Torino, Italy
| | - G Ficco
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, FR, Italy; Infectious Diseases Unit, Department of Medical Sciences, Amedeo di Savoia Hospital, University of Turin, Torino, Italy
| | - L Stabile
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, FR, Italy; Infectious Diseases Unit, Department of Medical Sciences, Amedeo di Savoia Hospital, University of Turin, Torino, Italy.
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137
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Jensen A, Brown N, Kosacki N, Spacek S, Bradley A, Katz D, Jimenez JL, de Gouw J. Teaching Instrumental Analysis during the Pandemic: Application of Handheld CO 2 Monitors to Explore COVID-19 Transmission Risks. JOURNAL OF CHEMICAL EDUCATION 2022; 99:1794-1801. [PMID: 35431325 PMCID: PMC9003892 DOI: 10.1021/acs.jchemed.1c01154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 02/09/2022] [Indexed: 06/14/2023]
Abstract
The COVID-19 pandemic has posed a challenge for maintaining an engaging learning environment while using remote laboratory formats. In this work, we describe a Student Choice Project (SCP) in an undergraduate instrumental analysis course that was adapted for remote learning without sacrificing research-based learning goals. We discuss the implementation and assessment of this SCP, selected student results, and student feedback. Students were provided handheld carbon dioxide monitors and charged with designing and implementing an investigation centered on COVID-19 airborne transmission. The real-time monitors provided experience with a new analytical tool that demanded considerations and analysis not common to other methods discussed in the course. Students were motivated by the ability to design their own projects and by the real-world implications of their findings. They performed well for all assessments, reported a positive experience, and recommended these monitors be added to the typical repertoire of instrumentation for the course.
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Affiliation(s)
- Andrew Jensen
- Department
of Chemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Niamh Brown
- Department
of Chemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139, United States
| | - Nathalie Kosacki
- Department
of Chemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Sara Spacek
- Department
of Chemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Alexander Bradley
- Department
of Chemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Daniel Katz
- Department
of Chemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Jose L. Jimenez
- Department
of Chemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Joost de Gouw
- Department
of Chemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
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138
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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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139
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Ding S, Lee JS, Mohamed MA, Ng BF. Infection risk of SARS-CoV-2 in a dining setting: Deposited droplets and aerosols. BUILDING AND ENVIRONMENT 2022; 213:108888. [PMID: 35169378 PMCID: PMC8828387 DOI: 10.1016/j.buildenv.2022.108888] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/01/2022] [Accepted: 02/08/2022] [Indexed: 05/06/2023]
Abstract
Considering that safe-distancing and mask-wearing measures are not strictly enforced in dining settings in the context of SARS-CoV-2, the infection risks of patrons in a dining outlet (e.g., a cafe) is assessed in this study. The size-resolved aerosol emission rate (AER) and droplets deposition rate (DDR) on dining plates from speaking were obtained through chamber measurements and droplet deposition visualization via fluorescent imaging technique (FIT), respectively. The AER from speaking was 24698 #/min in the size range of 0.3-5.5 μm, while the DDR was 365 #/min in the size range of 43-2847 μm. Furthermore, an infection risk model was adopted and revised to evaluate the infection risk of 120 diners for a "3-h event" in the cafe. In a four-person dining setting around a rectangular table, a diner seated diagonally across an infected person posed the least infection risk due to the deposited droplets on dining plates. The deposited droplets on a dining plate were dominant in possible viral transmission as compared to the long-range airborne route when a diner shared a table with the infected person. Yet, long-range airborne transmission had the potential to infect other diners in the cafe, even resulting in super-spreading events. A fresh air supply of 12.1-17.0 L/s per person is recommended for the cafe to serve 4-20 diners concurrently to minimize infection risks due to aerosols. Current ventilation standards (e.g., 8-10 L/s per person) for a cafe are not enough to avoid the airborne transmission of SARS-CoV-2.
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Affiliation(s)
- Shirun Ding
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Jia Shing Lee
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Mohamed Arif Mohamed
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Bing Feng Ng
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
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140
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Impact of natural ventilation on exposure to SARS-CoV 2 in indoor/semi-indoor terraces using CO 2 concentrations as a proxy. JOURNAL OF BUILDING ENGINEERING 2022; 46:103725. [PMCID: PMC8632854 DOI: 10.1016/j.jobe.2021.103725] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/20/2021] [Accepted: 11/19/2021] [Indexed: 06/16/2023]
Abstract
Nowadays, it is necessary a better airborne transmission understanding of respiratory diseases in shared indoor and semi-indoor environments with natural ventilation in order to adopt effective people's health protection measures. The aim of this work is to evaluate the relative exposure to SARS-CoV 2 in a set of virtual scenarios representing enclosed and semi-enclosed terraces under different outdoor meteorological conditions. For this purpose, indoor CO2 concentration is used as a proxy for the risk assessment. Airflow and people exhaled CO2 in different scenarios are simulated through Computational Fluid Dynamics (CFD) modelling with Unsteady Reynolds-Averaged Navier-Stokes (URANS) approach. Both spatial average concentrations and local concentrations are analyzed. In general, spatial average concentrations decrease as ventilation increases, however, depending on the people arrangement inside the terrace, spatial average concentrations and local concentrations can be very different. Therefore, for assessing the relative exposure to SARS-CoV 2 it is necessary to consider the indoor flow patterns between infectors and susceptibles. This research provides detailed information about CO2 dispersion in enclosed/semi-enclosed scenarios, which can be very useful for reducing the transmission risk through better natural ventilation designs and improving the classic risk models since it allows to check their hypotheses in real-world scenarios. Although CFD ventilation studies in indoor/semi-indoor environments have been already addressed in the literature, this research is focused on restaurant terraces, scenarios scarcely investigated. Likewise, one of the novelties of this study is to take into account the outdoor meteorological conditions to appropriately simulate natural ventilation.
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141
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Eadie E, Hiwar W, Fletcher L, Tidswell E, O'Mahoney P, Buonanno M, Welch D, Adamson CS, Brenner DJ, Noakes C, Wood K. Far-UVC (222 nm) efficiently inactivates an airborne pathogen in a room-sized chamber. Sci Rep 2022; 12:4373. [PMID: 35322064 PMCID: PMC8943125 DOI: 10.1038/s41598-022-08462-z] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 03/07/2022] [Indexed: 12/04/2022] Open
Abstract
Many infectious diseases, including COVID-19, are transmitted by airborne pathogens. There is a need for effective environmental control measures which, ideally, are not reliant on human behaviour. One potential solution is Krypton Chloride (KrCl) excimer lamps (often referred to as Far-UVC), which can efficiently inactivate pathogens, such as coronaviruses and influenza, in air. Research demonstrates that when KrCl lamps are filtered to remove longer-wavelength ultraviolet emissions they do not induce acute reactions in the skin or eyes, nor delayed effects such as skin cancer. While there is laboratory evidence for Far-UVC efficacy, there is limited evidence in full-sized rooms. For the first time, we show that Far-UVC deployed in a room-sized chamber effectively inactivates aerosolised Staphylococcus aureus. At a room ventilation rate of 3 air-changes-per-hour (ACH), with 5 filtered-sources the steady-state pathogen load was reduced by 98.4% providing an additional 184 equivalent air changes (eACH). This reduction was achieved using Far-UVC irradiances consistent with current American Conference of Governmental Industrial Hygienists threshold limit values for skin for a continuous 8-h exposure. Our data indicate that Far-UVC is likely to be more effective against common airborne viruses, including SARS-CoV-2, than bacteria and should thus be an effective and "hands-off" technology to reduce airborne disease transmission. The findings provide room-scale data to support the design and development of effective Far-UVC systems.
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Affiliation(s)
- Ewan Eadie
- NHS Tayside, Photobiology Unit, Ninewells Hospital and Medical School, Dundee, DD1 9SY, UK.
| | - Waseem Hiwar
- School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Louise Fletcher
- School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Emma Tidswell
- School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Paul O'Mahoney
- NHS Tayside, Photobiology Unit, Ninewells Hospital and Medical School, Dundee, DD1 9SY, UK
- School of Medicine Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK
| | - Manuela Buonanno
- Center for Radiological Research, Columbia University Medical Center, New York, NY, USA
| | - David Welch
- Center for Radiological Research, Columbia University Medical Center, New York, NY, USA
| | - Catherine S Adamson
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, KY16 9ST, UK
| | - David J Brenner
- Center for Radiological Research, Columbia University Medical Center, New York, NY, USA
| | - Catherine Noakes
- School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Kenneth Wood
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK
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142
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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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143
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Leonardi AJ, Mishra AK. A Sanitation Argument for Clean Indoor Air: Meeting a Requisite for Safe Public Spaces. Front Public Health 2022; 10:805780. [PMID: 35237550 PMCID: PMC8883285 DOI: 10.3389/fpubh.2022.805780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 01/06/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
| | - Asit Kumar Mishra
- MaREI Centre, Ryan Institute & School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland
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144
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Schimmoller BJ, Trovão NS, Isbell M, Goel C, Heck BF, Archer TC, Cardinal KD, Naik NB, Dutta S, Daniel AR, Beheshti A. Covid-19 Exposure Assessment Tool (CEAT): Easy-to-use tool to quantify exposure based on airflow, group behavior, and infection prevalence in the community.. [PMID: 35291295 PMCID: PMC8923112 DOI: 10.1101/2022.03.02.22271806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The COVID-19 Exposure Assessment Tool (CEAT) allows users to compare respiratory relative risk to SARS-CoV-2 for various scenarios, providing understanding of how combinations of protective measures affect exposure, dose, and risk. CEAT incorporates mechanistic, stochastic and epidemiological factors including the: 1) emission rate of virus, 2) viral aerosol degradation and removal, 3) duration of activity/exposure, 4) inhalation rates, 5) ventilation rates (indoors/outdoors), 6) volume of indoor space, 7) filtration, 8) mask use and effectiveness, 9) distance between people, 10) group size, 11) current infection rates by variant, 12) prevalence of infection and immunity in the community, 13) vaccination rates of the community, and 14) implementation of COVID-19 testing procedures. Demonstration of CEAT, from published studies of COVID-19 transmission events, shows the model accurately predicts transmission. We also show how health and safety professionals at NASA Ames Research Center used CEAT to manage potential risks posed by SARS-CoV-2 exposures. Given its accuracy and flexibility, the wide use of CEAT will have a long lasting beneficial impact in managing both the current COVID-19 pandemic as well as a variety of other scenarios.
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145
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Cheng P, Luo K, Xiao S, Yang H, Hang J, Ou C, Cowling BJ, Yen HL, Hui DS, Hu S, Li Y. Predominant airborne transmission and insignificant fomite transmission of SARS-CoV-2 in a two-bus COVID-19 outbreak originating from the same pre-symptomatic index case. JOURNAL OF HAZARDOUS MATERIALS 2022; 425:128051. [PMID: 34910996 PMCID: PMC8656245 DOI: 10.1016/j.jhazmat.2021.128051] [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: 10/21/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 05/22/2023]
Abstract
The number of people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to increase worldwide, but despite extensive research, there remains significant uncertainty about the predominant routes of SARS-CoV-2 transmission. We conducted a mechanistic modeling and calculated the exposure dose and infection risk of each passenger in a two-bus COVID-19 outbreak in Hunan province, China. This outbreak originated from a single pre-symptomatic index case. Some human behavioral data related to exposure including boarding and alighting time of some passengers and seating position and mask wearing of all passengers were obtained from the available closed-circuit television images/clips and/or questionnaire survey. Least-squares fitting was performed to explore the effect of effective viral load on transmission risk, and the most likely quanta generation rate was also estimated. This study reveals the leading role of airborne SARS-CoV-2 transmission and negligible role of fomite transmission in a poorly ventilated indoor environment, highlighting the need for more targeted interventions in such environments. The quanta generation rate of the index case differed by a factor of 1.8 on the two buses and transmission occurred in the afternoon of the same day, indicating a time-varying effective viral load within a short period of five hours.
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Affiliation(s)
- Pan Cheng
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China
| | - Kaiwei Luo
- Hunan Provincial Center for Disease Control and Prevention, Changsha, China
| | - Shenglan Xiao
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China; School of Public Health, Sun Yat-sen University, Guangzhou, China
| | - Hongyu Yang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
| | - Jian Hang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
| | - Cuiyun Ou
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
| | | | - Hui-Ling Yen
- School of Public Health, The University of Hong Kong, Hong Kong, China
| | - David Sc Hui
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China
| | - Shixiong Hu
- Hunan Provincial Center for Disease Control and Prevention, Changsha, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China; School of Public Health, The University of Hong Kong, Hong Kong, China.
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146
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Wang Z, Galea ER, Grandison A, Ewer J, Jia F. A coupled Computational Fluid Dynamics and Wells-Riley model to predict COVID-19 infection probability for passengers on long-distance trains. SAFETY SCIENCE 2022; 147:105572. [PMID: 34803226 PMCID: PMC8590932 DOI: 10.1016/j.ssci.2021.105572] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 10/02/2021] [Accepted: 11/01/2021] [Indexed: 05/15/2023]
Abstract
Coupled Wells-Riley (WR) and Computational Fluid Dynamics (CFD) modelling (WR-CFD) facilitates a detailed analysis of COVID-19 infection probability (IP). This approach overcomes issues associated with the WR 'well-mixed' assumption. The WR-CFD model, which makes uses of a scalar approach to simulate quanta dispersal, is applied to Chinese long-distance trains (G-train). Predicted IPs, at multiple locations, are validated using statistically derived (SD) IPs from reported infections on G-trains. This is the first known attempt to validate a coupled WR-CFD approach using reported COVID-19 infections derived from the rail environment. There is reasonable agreement between trends in predicted and SD IPs, with the maximum SD IP being 10.3% while maximum predicted IP was 14.8%. Additionally, predicted locations of highest and lowest IP, agree with those identified in the statistical analysis. Furthermore, the study demonstrates that the distribution of infectious aerosols is non-uniform and dependent on the nature of the ventilation. This suggests that modelling techniques neglecting these differences are inappropriate for assessing mitigation measures such as physical distancing. A range of mitigation strategies were analysed; the most effective being the majority (90%) of passengers correctly wearing high efficiency masks (e.g. N95). Compared to the base case (40% of passengers wearing low efficiency masks) there was a 95% reduction in average IP. Surprisingly, HEPA filtration was only effective for passengers distant from an index patient, having almost no effect for those in close proximity. Finally, as the approach is based on CFD it can be applied to a range of other indoor environments.
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Affiliation(s)
- Zhaozhi Wang
- Fire Safety Engineering Group, University of Greenwich, Old Royal Naval College, 30 Park Row, Greenwich, London SE10 9LS, UK
| | - Edwin R Galea
- Fire Safety Engineering Group, University of Greenwich, Old Royal Naval College, 30 Park Row, Greenwich, London SE10 9LS, UK
| | - Angus Grandison
- Fire Safety Engineering Group, University of Greenwich, Old Royal Naval College, 30 Park Row, Greenwich, London SE10 9LS, UK
| | - John Ewer
- Fire Safety Engineering Group, University of Greenwich, Old Royal Naval College, 30 Park Row, Greenwich, London SE10 9LS, UK
| | - Fuchen Jia
- Fire Safety Engineering Group, University of Greenwich, Old Royal Naval College, 30 Park Row, Greenwich, London SE10 9LS, UK
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147
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Winck J, Almeida S, Correia G, Gabriel M, Marques G, Silva M. A call for a national strategy for indoor air quality. Pulmonology 2022; 28:245-251. [PMID: 35351401 PMCID: PMC8957366 DOI: 10.1016/j.pulmoe.2022.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 02/13/2022] [Accepted: 02/14/2022] [Indexed: 12/04/2022] Open
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148
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Tang L, Liu M, Ren B, Chen J, Liu X, Wu X, Huang W, Tian J. Transmission in home environment associated with the second wave of COVID-19 pandemic in India. ENVIRONMENTAL RESEARCH 2022; 204:111910. [PMID: 34464619 PMCID: PMC8401083 DOI: 10.1016/j.envres.2021.111910] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/05/2021] [Accepted: 08/17/2021] [Indexed: 05/02/2023]
Abstract
India has suffered from the second wave of COVID-19 pandemic since March 2021. This wave of the outbreak has been more serious than the first wave pandemic in 2020, which suggests that some new transmission characteristics may exist. COVID-19 is transmitted through droplets, aerosols, and contact with infected surfaces. Air pollutants are also considered to be associated with COVID-19 transmission. However, the roles of indoor transmission in the COVID-19 pandemic and the effects of these factors in indoor environments are still poorly understood. Our study focused on reveal the role of indoor transmission in the second wave of COVID-19 pandemic in India. Our results indicated that human mobility in the home environment had the highest relative influence on COVID-19 daily growth rate in the country. The COVID-19 daily growth rate was significantly positively correlated with the residential percent rate in most state-level areas in India. A significant positive nonlinear relationship was found when the residential percent ratio ranged from 100 to 120%. Further, epidemic dynamics modelling indicated that a higher proportion of indoor transmission in the home environment was able to intensify the severity of the second wave of COVID-19 pandemic in India. Our findings suggested that more attention should be paid to the indoor transmission in home environment. The public health strategies to reduce indoor transmission such as ventilation and centralized isolation will be beneficial to the prevention and control of COVID-19.
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Affiliation(s)
- Liwei Tang
- Shenzhen Key Laboratory of Marine Biotechnology and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China
| | - Min Liu
- Shenzhen Key Laboratory of Marine Biotechnology and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China; Shenzhen Bay Laboratory, Shenzhen, 518055, Guangdong, China; International Cancer Center, Health Science Center, Shenzhen University, Shenzhen, 518060, China
| | - Bingyu Ren
- Shenzhen Key Laboratory of Marine Biotechnology and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, Guangdong, 518055, China
| | - Jinghong Chen
- Shenzhen Key Laboratory of Marine Biotechnology and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China
| | - Xinwei Liu
- Shenzhen Key Laboratory of Marine Biotechnology and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China
| | - Xilin Wu
- Department of Neurology, Fujian Medical University Union Hospital Fujian Key Laboratory of Molecular Neurology, Fuzhou, Fu Jian, 350001, China
| | - Weiren Huang
- International Cancer Center, Health Science Center, Shenzhen University, Shenzhen, 518060, China; Department of Urology, Shenzhen Institute of Translational Medicine, the First Affiliated Hospital of Shenzhen University, Shenzhen Second People's Hospital, Shenzhen, Guangdong, 518035, China; Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, 518055, China
| | - Jing Tian
- Shenzhen Key Laboratory of Marine Biotechnology and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China.
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149
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Lau Z, Griffiths IM, English A, Kaouri K. Predicting the spatio-temporal infection risk in indoor spaces using an efficient airborne transmission model. Proc Math Phys Eng Sci 2022; 478:20210383. [PMID: 35310953 PMCID: PMC8924953 DOI: 10.1098/rspa.2021.0383] [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: 05/11/2021] [Accepted: 02/14/2022] [Indexed: 12/19/2022] Open
Abstract
We develop a spatially dependent generalization to the Wells–Riley model, which determines the infection risk due to airborne transmission of viruses. We assume that the infectious aerosol concentration is governed by an advection–diffusion–reaction equation with the aerosols advected by airflow, diffused due to turbulence, emitted by infected people, and removed due to ventilation, inactivation of the virus and gravitational settling. We consider one asymptomatic or presymptomatic infectious person breathing or talking, with or without a mask, and model a quasi-three-dimensional set-up that incorporates a recirculating air-conditioning flow. We derive a semi-analytic solution that enables fast simulations and compare our predictions to three real-life case studies—a courtroom, a restaurant, and a hospital ward—demonstrating good agreement. We then generate predictions for the concentration and the infection risk in a classroom, for four different ventilation settings. We quantify the significant reduction in the concentration and the infection risk as ventilation improves, and derive appropriate power laws. The model can be easily updated for different parameter values and can be used to make predictions on the expected time taken to become infected, for any location, emission rate, and ventilation level. The results have direct applicability in mitigating the spread of the COVID-19 pandemic.
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Affiliation(s)
- Zechariah Lau
- School of Mathematics, Cardiff University, CF24 4AG Cardiff, UK.,Mathematical Institute, University of Oxford, OX1 6GG Oxford, UK
| | - Ian M Griffiths
- Mathematical Institute, University of Oxford, OX1 6GG Oxford, UK
| | - Aaron English
- School of Mathematics, Cardiff University, CF24 4AG Cardiff, UK.,Department of Mechanical, Aerospace and Civil Engineering, University of Manchester, M13 9PL Manchester, UK
| | - Katerina Kaouri
- School of Mathematics, Cardiff University, CF24 4AG Cardiff, UK
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150
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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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