1
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Kakeshpour T, Fennelly KP, Bax A. Snoring-generated fluid droplets as a potential mechanistic link between sleep-disordered breathing and pneumonia. Respir Res 2024; 25:224. [PMID: 38811937 PMCID: PMC11137920 DOI: 10.1186/s12931-024-02856-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Accepted: 05/18/2024] [Indexed: 05/31/2024] Open
Abstract
The soft palate and back of the throat represent vulnerable early infection sites for SARS-CoV-2, influenza, streptococci, and many other pathogens. We demonstrate that snoring causes aerosolization of pharyngeal fluid that covers these surfaces, which previously has escaped detection because the inspired airstream carries the micron-sized droplets into the lung, inaccessible to traditional aerosol detectors. While many of these droplets will settle in the lower respiratory tract, a fraction of the respirable smallest droplets remains airborne and can be detected in exhaled breath. We distinguished these exhaled droplets from those generated by the underlying breathing activity by using a chemical tracer, thereby proving their existence. The direct transfer of pharyngeal fluids and their pathogens into the deep lung by snoring represents a plausible mechanistic link between the previously recognized association between sleep-disordered breathing and pneumonia incidence.
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Affiliation(s)
- Tayeb Kakeshpour
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Kevin P Fennelly
- Pulmonary Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Adriaan Bax
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
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2
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Sinclair P, Zhao L, Beggs CB, Illingworth CJR. The airborne transmission of viruses causes tight transmission bottlenecks. Nat Commun 2024; 15:3540. [PMID: 38670957 PMCID: PMC11053022 DOI: 10.1038/s41467-024-47923-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
The transmission bottleneck describes the number of viral particles that initiate an infection in a new host. Previous studies have used genome sequence data to suggest that transmission bottlenecks for influenza and SARS-CoV-2 involve few viral particles, but the general principles of virus transmission are not fully understood. Here we show that, across a broad range of circumstances, tight transmission bottlenecks are a simple consequence of the physical process of airborne viral transmission. We use mathematical modelling to describe the physical process of the emission and inhalation of infectious particles, deriving the result that that the great majority of transmission bottlenecks involve few viral particles. While exceptions to this rule exist, the circumstances needed to create these exceptions are likely very rare. We thus provide a physical explanation for previous inferences of bottleneck size, while predicting that tight transmission bottlenecks prevail more generally in respiratory virus transmission.
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Affiliation(s)
- Patrick Sinclair
- MRC University of Glasgow Centre for Virus Research, Glasgow, UK
| | - Lei Zhao
- Section for GeoGenetics, Globe Institute, University of Copenhagen, Copenhagen, Denmark
| | - Clive B Beggs
- Carnegie School of Sport, Leeds Beckett University, Leeds, UK
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3
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Haddrell A, Oswin H, Otero-Fernandez M, Robinson JF, Cogan T, Alexander R, Mann JFS, Hill D, Finn A, Davidson AD, Reid JP. Ambient carbon dioxide concentration correlates with SARS-CoV-2 aerostability and infection risk. Nat Commun 2024; 15:3487. [PMID: 38664424 PMCID: PMC11045827 DOI: 10.1038/s41467-024-47777-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 04/11/2024] [Indexed: 04/28/2024] Open
Abstract
An improved understanding of the underlying physicochemical properties of respiratory aerosol that influence viral infectivity may open new avenues to mitigate the transmission of respiratory diseases such as COVID-19. Previous studies have shown that an increase in the pH of respiratory aerosols following generation due to changes in the gas-particle partitioning of pH buffering bicarbonate ions and carbon dioxide is a significant factor in reducing SARS-CoV-2 infectivity. We show here that a significant increase in SARS-CoV-2 aerostability results from a moderate increase in the atmospheric carbon dioxide concentration (e.g. 800 ppm), an effect that is more marked than that observed for changes in relative humidity. We model the likelihood of COVID-19 transmission on the ambient concentration of CO2, concluding that even this moderate increase in CO2 concentration results in a significant increase in overall risk. These observations confirm the critical importance of ventilation and maintaining low CO2 concentrations in indoor environments for mitigating disease transmission. Moreover, the correlation of increased CO2 concentration with viral aerostability need to be better understood when considering the consequences of increases in ambient CO2 levels in our atmosphere.
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Affiliation(s)
- Allen Haddrell
- School of Chemistry, Cantock's Close, University of Bristol, Bristol, UK.
| | - Henry Oswin
- School of Chemistry, Cantock's Close, University of Bristol, Bristol, UK
| | | | - Joshua F Robinson
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Tristan Cogan
- Bristol Veterinary School, University of Bristol, Langford House, Langford, Bristol, UK
| | - Robert Alexander
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - Jamie F S Mann
- Bristol Veterinary School, University of Bristol, Langford House, Langford, Bristol, UK
| | - Darryl Hill
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - Adam Finn
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
- School of Population Health Sciences, University of Bristol, Bristol, UK
| | - Andrew D Davidson
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK.
| | - Jonathan P Reid
- School of Chemistry, Cantock's Close, University of Bristol, Bristol, UK.
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4
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Myung H, Joung YS. Contribution of Particulates to Airborne Disease Transmission and Severity: A Review. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6846-6867. [PMID: 38568611 DOI: 10.1021/acs.est.3c08835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/24/2024]
Abstract
The emergence of coronavirus disease 2019 (COVID-19) has catalyzed great interest in the spread of airborne pathogens. Airborne infectious diseases are classified into viral, bacterial, and fungal infections. Environmental factors can elevate their transmission and lethality. Air pollution has been reported as the leading environmental cause of disease and premature death worldwide. Notably, ambient particulates of various components and sizes are harmful pollutants. There are two prominent health effects of particles in the atmosphere: (1) particulate matter (PM) penetrates the respiratory tract and adversely affects health, such as heart and respiratory diseases; and (2) bioaerosols of particles act as a medium for the spread of pathogens in the air. Particulates contribute to the occurrence of infectious diseases by increasing vulnerability to infection through inhalation and spreading disease through interactions with airborne pathogens. Here, we focus on the synergistic effects of airborne particulates on infectious disease. We outline the concepts and characteristics of bioaerosols, from their generation to transformation and circulation on Earth. Considering that microorganisms coexist with other particulates as bioaerosols, we investigate studies examining respiratory infections associated with airborne PM. Furthermore, we discuss four factors (meteorological, biological, physical, and chemical) that may impact the influence of PM on the survival of contagious pathogens in the atmosphere. Our review highlights the significant role of particulates in supporting the transmission of infectious aerosols and emphasizes the need for further research in this area.
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Affiliation(s)
- Hyunji Myung
- Department of Mechanical Systems Engineering, Sookmyung Women's University, 100, Cheongpa-ro 47-gil, Yongsan-gu, Seoul 04310, Republic of Korea
| | - Young Soo Joung
- Department of Mechanical Systems Engineering, Sookmyung Women's University, 100, Cheongpa-ro 47-gil, Yongsan-gu, Seoul 04310, Republic of Korea
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5
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Gibbons AM, Ohno PE. Relative Humidity-Dependent Phase Transitions in Submicron Respiratory Aerosols. J Phys Chem A 2024; 128:3015-3023. [PMID: 38593044 DOI: 10.1021/acs.jpca.4c00691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Respiratory viruses, such as influenza and severe acute respiratory syndrome coronavirus 2, represent a substantial public health burden and are largely transmitted through respiratory droplets and aerosols. Environmental factors such as relative humidity (RH) and temperature impact virus transmission rates, and a precise mechanistic understanding of the connection between these environmental factors and virus transmission would improve efforts to mitigate respiratory disease transmission. Previous studies on supermicrometer particles observed RH-dependent phase transitions and linked particle phase state to virus viability. Phase transitions in atmospheric aerosols are dependent on size in the submicrometer range, and actual respiratory particles are expelled over a large size range, including submicrometer aerosols that can transmit diseases over long distances. Here, we directly investigated the phase transitions of submicrometer model respiratory aerosols. A probe molecule, Nile red, was added to particle systems including multiple mucin/salt mixtures, a growth medium, and simulated lung fluid. For each system, the polarity-dependent fluorescence emission was measured following RH conditioning. Notably, the fluorescence measurements of mucin/NaCl and Dulbecco's modified Eagle's medium particles indicated that liquid-liquid phase separation (LLPS) also occurs in submicron particles, suggesting that LLPS can also impact the viability of viruses in submicron particles and thus affect aerosol virus transmission. Furthermore, the utility of fluorescence-based measurements to study submicrometer respiratory particle physicochemical properties in situ is demonstrated.
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Affiliation(s)
- Angel M Gibbons
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Paul E Ohno
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
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6
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Charness ME, Gupta K, Linsenmeyer K, Strymish J, Madjarov R, Stack G. Evidence from whole genome sequencing of aerosol transmission of SARS-CoV-2 almost 5 hours after hospital room turnover. Am J Infect Control 2024:S0196-6553(24)00162-7. [PMID: 38583778 DOI: 10.1016/j.ajic.2024.04.003] [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: 01/17/2024] [Revised: 04/02/2024] [Accepted: 04/03/2024] [Indexed: 04/09/2024]
Abstract
Experimental evidence suggests that Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) remains viable within aerosols with a half-life of approximately 3 hours; however, it remains unclear how long airborne SARS-CoV-2 can transmit infection. Whole genome sequencing during an outbreak suggested in-room transmission of SARS-CoV-2 to two patients admitted nearly 2 and 5 hours, respectively, after discharge of an asymptomatic infected patient. These findings suggest that airborne SARS-CoV-2 may transmit infection for over 4 hours, even in a hospital setting.
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Affiliation(s)
- Michael E Charness
- VA Boston Healthcare System, West Roxbury, MA; Department of Neurology, Harvard Medical School, Boston, MA; Department of Neurology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA.
| | - Kalpana Gupta
- VA Boston Healthcare System, West Roxbury, MA; Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston, MA
| | - Katherine Linsenmeyer
- VA Boston Healthcare System, West Roxbury, MA; Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston, MA
| | - Judith Strymish
- VA Boston Healthcare System, West Roxbury, MA; Department of Medicine, Harvard Medical School, Boston, MA
| | | | - Gary Stack
- VA Connecticut Healthcare System, West Haven, CT; Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT
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7
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Banholzer N, Jent P, Bittel P, Zürcher K, Furrer L, Bertschinger S, Weingartner E, Ramette A, Egger M, Hascher T, Fenner L. Air Cleaners and Respiratory Infections in Schools: A Modeling Study Based on Epidemiologic, Environmental, and Molecular Data. Open Forum Infect Dis 2024; 11:ofae169. [PMID: 38665173 PMCID: PMC11045022 DOI: 10.1093/ofid/ofae169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 03/19/2024] [Indexed: 04/28/2024] Open
Abstract
Background Using a multiple-measurement approach, we examined the real-world effectiveness of portable HEPA air filtration devices (air cleaners) in a school setting. Methods We collected data over 7 weeks during winter 2022/2023 in 2 Swiss secondary school classes: environmental (CO2, particle concentrations), epidemiologic (absences related to respiratory infections), audio (coughing), and molecular (bioaerosol and saliva samples). Using a crossover design, we compared particle concentrations, coughing, and risk of infection with and without air cleaners. Results All 38 students participated (age, 13-15 years). With air cleaners, mean particle concentration decreased by 77% (95% credible interval, 63%-86%). There were no differences in CO2 levels. Absences related to respiratory infections were 22 without air cleaners vs 13 with them. Bayesian modeling suggested a reduced risk of infection, with a posterior probability of 91% and a relative risk of 0.73 (95% credible interval, 0.44-1.18). Coughing also tended to be less frequent (posterior probability, 93%), indicating that fewer symptomatic students were in class. Molecular analysis detected mainly non-SARS-CoV-2 viruses in saliva (50/448 positive) but not in bioaerosols (2/105) or on the HEPA filters of the air cleaners (4/160). The molecular detection rate in saliva was similar with and without air cleaners. Spatiotemporal analysis of positive saliva samples identified several likely transmissions. Conclusions Air cleaners improved air quality and showed potential benefits in reducing respiratory infections. Airborne detection of non-SARS-CoV-2 viruses was rare, suggesting that these viruses may be more difficult to detect in the air. Future studies should examine the importance of close contact and long-range transmission and the cost-effectiveness of using air cleaners.
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Affiliation(s)
- Nicolas Banholzer
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Philipp Jent
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
- Department of Infectious Diseases, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Pascal Bittel
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Kathrin Zürcher
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Lavinia Furrer
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Simon Bertschinger
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
| | - Ernest Weingartner
- Institute for Sensors and Electronics, University of Applied Sciences and Arts Northwestern Switzerland, Windisch, Switzerland
| | - Alban Ramette
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Matthias Egger
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
- Population Health Sciences, University of Bristol, Bristol, UK
- Centre for Infectious Disease Epidemiology and Research, University of Cape Town, Cape Town, South Africa
| | - Tina Hascher
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
- Institute of Educational Science, University of Bern, Bern, Switzerland
| | - Lukas Fenner
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
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8
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Atamer Balkan B, Chang Y, Sparnaaij M, Wouda B, Boschma D, Liu Y, Yuan Y, Daamen W, de Jong MCM, Teberg C, Schachtschneider K, Sikkema RS, van Veen L, Duives D, ten Bosch QA. The multi-dimensional challenges of controlling respiratory virus transmission in indoor spaces: Insights from the linkage of a microscopic pedestrian simulation and SARS-CoV-2 transmission model. PLoS Comput Biol 2024; 20:e1011956. [PMID: 38547311 PMCID: PMC11003685 DOI: 10.1371/journal.pcbi.1011956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 04/09/2024] [Accepted: 02/29/2024] [Indexed: 04/11/2024] Open
Abstract
SARS-CoV-2 transmission in indoor spaces, where most infection events occur, depends on the types and duration of human interactions, among others. Understanding how these human behaviours interface with virus characteristics to drive pathogen transmission and dictate the outcomes of non-pharmaceutical interventions is important for the informed and safe use of indoor spaces. To better understand these complex interactions, we developed the Pedestrian Dynamics-Virus Spread model (PeDViS), an individual-based model that combines pedestrian behaviour models with virus spread models incorporating direct and indirect transmission routes. We explored the relationships between virus exposure and the duration, distance, respiratory behaviour, and environment in which interactions between infected and uninfected individuals took place and compared this to benchmark 'at risk' interactions (1.5 metres for 15 minutes). When considering aerosol transmission, individuals adhering to distancing measures may be at risk due to the buildup of airborne virus in the environment when infected individuals spend prolonged time indoors. In our restaurant case, guests seated at tables near infected individuals were at limited risk of infection but could, particularly in poorly ventilated places, experience risks that surpass that of benchmark interactions. Combining interventions that target different transmission routes can aid in accumulating impact, for instance by combining ventilation with face masks. The impact of such combined interventions depends on the relative importance of transmission routes, which is hard to disentangle and highly context dependent. This uncertainty should be considered when assessing transmission risks upon different types of human interactions in indoor spaces. We illustrated the multi-dimensionality of indoor SARS-CoV-2 transmission that emerges from the interplay of human behaviour and the spread of respiratory viruses. A modelling strategy that incorporates this in risk assessments can help inform policy makers and citizens on the safe use of indoor spaces with varying inter-human interactions.
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Affiliation(s)
- Büsra Atamer Balkan
- Quantitative Veterinary Epidemiology, Wageningen University & Research, Wageningen, The Netherlands
| | - You Chang
- Quantitative Veterinary Epidemiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Martijn Sparnaaij
- Department of Transport & Planning, Delft University of Technology, Delft, The Netherlands
| | - Berend Wouda
- Gamelab, Delft University of Technology, Delft, The Netherlands
| | - Doris Boschma
- Gamelab, Delft University of Technology, Delft, The Netherlands
| | - Yangfan Liu
- Quantitative Veterinary Epidemiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Yufei Yuan
- Department of Transport & Planning, Delft University of Technology, Delft, The Netherlands
| | - Winnie Daamen
- Department of Transport & Planning, Delft University of Technology, Delft, The Netherlands
| | - Mart C. M. de Jong
- Quantitative Veterinary Epidemiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Colin Teberg
- Steady State Scientific Computing, Chicago, Illinois, United States of America
| | | | | | - Linda van Veen
- Gamelab, Delft University of Technology, Delft, The Netherlands
| | - Dorine Duives
- Department of Transport & Planning, Delft University of Technology, Delft, The Netherlands
| | - Quirine A. ten Bosch
- Quantitative Veterinary Epidemiology, Wageningen University & Research, Wageningen, The Netherlands
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9
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Wolkoff P. Indoor air humidity revisited: Impact on acute symptoms, work productivity, and risk of influenza and COVID-19 infection. Int J Hyg Environ Health 2024; 256:114313. [PMID: 38154254 DOI: 10.1016/j.ijheh.2023.114313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 10/30/2023] [Accepted: 12/18/2023] [Indexed: 12/30/2023]
Abstract
Recent epidemiological and experimental findings reconfirm that low indoor air humidity (dry air) increases the prevalence of acute eye and airway symptoms in offices, result in lower mucociliary clearance in the airways, less efficient immune defense, and deteriorate the work productivity. New epidemiological and experimental research also support that the environmental conditions for the risk of infection of influenza and COVID-19 virus is lowest in the Goldilocks zone of 40-60% relative humidity (RH) by decrease of the airways' susceptibility, which can be elevated by particle exposure. Furthermore, low RH increases the generation of infectious virus laden aerosols exhaled from infected people. In general, elevation of the indoor air humidity from dry air increases the health of the airways concomitantly with lower viability of infectious virus. Thus, the negative effects of ventilation with dry outdoor air (low absolute air humidity) should be assessed according to 1) weakened health and functionality of the airways, 2) increased viability and possible increased transmissibility of infectious virus, and 3) evaporation of virus containing droplets to dry out to droplet nuclei (also possible at high room temperature), which increases their floating time in the indoor air. The removal of acid-containing ambient aerosols from the indoor air by filtration increases pH, viability of infectious viruses, and the risk of infection, which synergistically may further increase by particle exposure. Thus, the dilution of indoor air pollutants and virus aerosols by dry outdoor air ventilation should be assessed and compared with the beneficial health effects by control of the center zone of 40-60% RH, an essential factor for optimal functionality of the airways, and with the additional positive impact on acute symptoms, work productivity, and reduced risk of infection.
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Affiliation(s)
- Peder Wolkoff
- National Research Centre for the Working Environment, Denmark.
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10
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Groth R, Niazi S, Oswin HP, Haddrell AE, Spann K, Morawska L, Ristovski Z. Toward Standardized Aerovirology: A Critical Review of Existing Results and Methodologies. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:3595-3608. [PMID: 38355395 DOI: 10.1021/acs.est.3c07275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2024]
Abstract
Understanding the airborne survival of viruses is important for public health and epidemiological modeling and potentially to develop mitigation strategies to minimize the transmission of airborne pathogens. Laboratory experiments typically involve investigating the effects of environmental parameters on the viability or infectivity of a target airborne virus. However, conflicting results among studies are common. Herein, the results of 34 aerovirology studies were compared to identify links between environmental and compositional effects on the viability of airborne viruses. While the specific experimental apparatus was not a factor in variability between reported results, it was determined that the experimental procedure was a major factor that contributed to discrepancies in results. The most significant contributor to variability between studies was poorly defined initial viable virus concentration in the aerosol phase, causing many studies to not measure the rapid inactivation, which occurs quickly after particle generation, leading to conflicting results. Consistently, studies that measured their reference airborne viability minutes after aerosolization reported higher viability at subsequent times, which indicates that there is an initial loss of viability which is not captured in these studies. The composition of the particles which carry the viruses was also found to be important in the viability of airborne viruses; however, the mechanisms for this effect are unknown. Temperature was found to be important for aerosol-phase viability, but there is a lack of experiments that directly compare the effects of temperature in the aerosol phase and the bulk phase. There is a need for repeated measurements between different research groups under identical conditions both to assess the degree of variability between studies and also to attempt to better understand already published data. Lack of experimental standardization has hindered the ability to quantify the differences between studies, for which we provide recommendations for future studies. These recommendations are as follows: measuring the reference airborne viability using the "direct method"; use equipment which maximizes time resolution; quantify all losses appropriately; perform, at least, a 5- and 10-min sample, if possible; report clearly the composition of the virus suspension; measure the composition of the gas throughout the experiment. Implementing these recommendations will address the most significant oversights in the existing literature and produce data which can more easily be quantitatively compared.
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Affiliation(s)
- Robert Groth
- School of Earth and Atmospheric Sciences, International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Queensland 4000, Australia
| | - Sadegh Niazi
- School of Earth and Atmospheric Sciences, International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Queensland 4000, Australia
| | - Henry P Oswin
- School of Earth and Atmospheric Sciences, International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Queensland 4000, Australia
| | - Allen E Haddrell
- School of Chemistry, Cantock's Close, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Kirsten Spann
- School of Biomedical Sciences, Centre for Immunology and Infection Control, Queensland University of Technology, Brisbane, Queensland 4000, Australia
| | - Lidia Morawska
- School of Earth and Atmospheric Sciences, International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Queensland 4000, Australia
| | - Zoran Ristovski
- School of Earth and Atmospheric Sciences, International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Queensland 4000, Australia
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11
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Rockey NC, Le Sage V, Marr LC, Lakdawala SS. Seasonal influenza viruses decay more rapidly at intermediate humidity in droplets containing saliva compared to respiratory mucus. Appl Environ Microbiol 2024; 90:e0201023. [PMID: 38193683 PMCID: PMC10880610 DOI: 10.1128/aem.02010-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 11/27/2023] [Indexed: 01/10/2024] Open
Abstract
Expulsions of virus-laden aerosols or droplets from the oral and nasal cavities of an infected host are an important source of onward respiratory virus transmission. However, the presence of infectious influenza virus in the oral cavity during infection has not been widely considered, and thus, little work has explored the environmental persistence of influenza virus in oral cavity expulsions. Using the ferret model, we detected infectious virus in the nasal and oral cavities, suggesting that the virus can be expelled into the environment from both anatomical sites. We also assessed the stability of two influenza A viruses (H1N1 and H3N2) in droplets of human saliva or respiratory mucus over a range of relative humidities. We observed that influenza virus infectivity decays rapidly in saliva droplets at intermediate relative humidity, while viruses in airway surface liquid droplets retain infectivity. Virus inactivation was not associated with bulk protein content, salt content, or droplet drying time. Instead, we found that saliva droplets exhibited distinct inactivation kinetics during the wet and dry phases at intermediate relative humidity, and droplet residue morphology may lead to the elevated first-order inactivation rate observed during the dry phase. Additionally, distinct differences in crystalline structure and nanobead localization were observed between saliva and airway surface liquid droplets. Together, our work demonstrates that different respiratory fluids exhibit unique virus persistence profiles and suggests that influenza viruses expelled from the oral cavity may contribute to virus transmission in low- and high-humidity environments.IMPORTANCEDetermining how long viruses persist in the environment is important for mitigating transmission risk. Expelled infectious droplets and aerosols are composed of respiratory fluids, including saliva and complex mucus mixtures, but how well influenza viruses survive in such fluids is largely unknown. Here, we find that infectious influenza virus is present in the oral cavity of infected ferrets, suggesting that saliva-containing expulsions can play a role in onward transmission. Additionally, influenza virus in droplets composed of saliva degrades more rapidly than virus within respiratory mucus. Droplet composition impacts the crystalline structure and virus localization in dried droplets. These results suggest that viruses from distinct sites in the respiratory tract could have variable persistence in the environment, which will impact viral transmission fitness.
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Affiliation(s)
- Nicole C. Rockey
- Department of Microbiology and Molecular Genetics, The University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Civil and Environmental Engineering, Duke University, Durham, North Carolina, USA
| | - Valerie Le Sage
- Department of Microbiology and Molecular Genetics, The University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Linsey C. Marr
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia, USA
| | - Seema S. Lakdawala
- Department of Microbiology and Molecular Genetics, The University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
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12
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Oswin HP, Blake E, Haddrell AE, Finn A, Sriskandan S, Reid JP, Halliday A, Goenka A. An assessment of the airborne longevity of group A Streptococcus. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001421. [PMID: 38180461 PMCID: PMC10866022 DOI: 10.1099/mic.0.001421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 12/08/2023] [Indexed: 01/06/2024]
Abstract
Group A streptococcus (GAS) infections result in more than 500 000 deaths annually. Despite mounting evidence for airborne transmission of GAS, little is known about its stability in aerosol. Measurements of GAS airborne stability were carried out using the Controlled Electrodynamic Levitation and Extraction of Bioaerosols onto a Substrate (CELEBS) instrument. CELEBS measurements with two different isolates of GAS suggest that it is aerostable, with approximately 70 % of bacteria remaining viable after 20 min of levitation at 50 % relative humidity (RH), with lower survival as RH was reduced. GAS airborne viability loss was driven primarily by desiccation and efflorescence (i.e. salt crystallization), with high pH also potentially playing a role, given reduced survival in bicarbonate containing droplet compositions. At low enough RH for efflorescence to occur, a greater proportion of organic components in the droplet appeared to protect the bacteria from efflorescence. These first insights into the aerosol stability of GAS indicate that airborne transmission of these respiratory tract bacteria may occur, and that both the composition of the droplet containing the bacteria, and the RH of the air affect the duration of bacterial survival in this environment. Future studies will explore a broader range of droplet and air compositions and include a larger selection of GAS strains.
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Affiliation(s)
- Henry P. Oswin
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol, UK
| | - Evie Blake
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - Allen E. Haddrell
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol, UK
| | - Adam Finn
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
- Paediatric Immunology and Infectious Diseases, Bristol Royal Hospital for Children, Bristol, UK
| | - Shiranee Sriskandan
- NIHR Health Protection Research Unit in Healthcare-associated Infection and Antimicrobial Resistance, Imperial College London, London, UK
- Centre for Bacterial Resistance Biology, Imperial College London, London, UK
| | - Jonathan P. Reid
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol, UK
| | - Alice Halliday
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - Anu Goenka
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
- Paediatric Immunology and Infectious Diseases, Bristol Royal Hospital for Children, Bristol, UK
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13
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Banholzer N, Jent P, Bittel P, Zürcher K, Furrer L, Bertschinger S, Weingartner E, Ramette A, Egger M, Hascher T, Fenner L. Air cleaners and respiratory infections in schools: A modeling study using epidemiological, environmental, and molecular data. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.12.29.23300635. [PMID: 38234723 PMCID: PMC10793541 DOI: 10.1101/2023.12.29.23300635] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Background Using a multiple-measurement approach, we examined the real-world effectiveness of portable HEPA-air filtration devices (air cleaners) in a school setting. Methods We collected environmental (CO2, particle concentrations), epidemiological (absences related to respiratory infections), audio (coughing), and molecular data (bioaerosol and saliva samples) over seven weeks during winter 2022/2023 in two Swiss secondary school classes. Using a cross-over study design, we compared particle concentrations, coughing, and the risk of infection with vs without air cleaners. Results All 38 students (age 13-15 years) participated. With air cleaners, mean particle concentration decreased by 77% (95% credible interval 63%-86%). There were no differences in CO2 levels. Absences related to respiratory infections were 22 without vs 13 with air cleaners. Bayesian modeling suggested a reduced risk of infection, with a posterior probability of 91% and a relative risk of 0.73 (95% credible interval 0.44-1.18). Coughing also tended to be less frequent (posterior probability 93%). Molecular analysis detected mainly non-SARS-CoV-2 viruses in saliva (50/448 positive), but not in bioaerosols (2/105 positive) or HEPA-filters (4/160). The detection rate was similar with vs without air cleaners. Spatiotemporal analysis of positive saliva samples identified several likely transmissions. Conclusions Air cleaners improved air quality, showed a potential benefit in reducing respiratory infections, and were associated with less coughing. Airborne detection of non-SARS-CoV-2 viruses was rare, suggesting that these viruses may be more difficult to detect in the air. Future studies should examine the importance of close contact and long-range transmission, and the cost-effectiveness of using air cleaners.
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Affiliation(s)
- Nicolas Banholzer
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Philipp Jent
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
- Department of Infectious Diseases, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Pascal Bittel
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Kathrin Zürcher
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
| | - Lavinia Furrer
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Simon Bertschinger
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
| | - Ernest Weingartner
- Institute for Sensors and Electronics, University of Applied Sciences and Arts Northwestern Switzerland, Windisch, Switzerland
| | - Alban Ramette
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Matthias Egger
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
- Population Health Sciences, University of Bristol, Bristol, UK
- Centre for Infectious Disease Epidemiology and Research, University of Cape Town, Cape Town, South Africa
| | - Tina Hascher
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
- Institute of Educational Science, University of Bern, Bern, Switzerland
| | - Lukas Fenner
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
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14
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Niazi S, Groth R, Morawska L, Spann K, Ristovski Z. Dynamics and Viability of Airborne Respiratory Syncytial Virus under Various Indoor Air Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:21558-21569. [PMID: 38084588 DOI: 10.1021/acs.est.3c03455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
The factors governing the viability of airborne viruses embedded within respiratory particles are not well understood. This study aimed to investigate the relative humidity (RH)-dependent viability of airborne respiratory syncytial virus (RSV) in simulated respiratory particles suspended in various indoor air conditions. We tested airborne RSV viability in three static indoor air conditions, including sub-hysteresis (RH < 39%), hysteresis (39% < RH < 65%), and super-hysteresis (RH > 65%) air as well as in three dynamic indoor air conditions, including the transitions between the static conditions. The dynamic conditions were hysteresis → super-hysteresis → hysteresis, sub-hysteresis → hysteresis, and super-hysteresis → hysteresis. We found that after 45 min of particle aging in static conditions, the viability of RSV in sub-hysteresis, hysteresis, and super-hysteresis air was 0.72% ± 0.06%, 0.03% ± 0.006%, and 0.27% ± 0.008%, respectively. After 45 min of aging in dynamic conditions, the RSV viability decreased for particles that remained in a liquid (deliquesced) state during aging when compared with particles in a solid (effloresced) state. The decreased viability of airborne RSV for deliquesced particles is consistent with prolonged exposure to elevated aqueous solutes. These results represent the first measurements of the survival of airborne RSV over particle aging time, with equal viability in low, intermediate, and high RHs at 5 and 15 min and a V-shaped curve after 45 min.
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Affiliation(s)
- Sadegh Niazi
- International Laboratory for Air Quality and Health (ILAQH), School of Earth and Atmospheric Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia
| | - Robert Groth
- International Laboratory for Air Quality and Health (ILAQH), School of Earth and Atmospheric Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia
| | - Lidia Morawska
- International Laboratory for Air Quality and Health (ILAQH), School of Earth and Atmospheric Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia
| | - Kirsten Spann
- Centre for Immunology and Infection Control (CIIC), School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD 4006, Australia
| | - Zoran Ristovski
- International Laboratory for Air Quality and Health (ILAQH), School of Earth and Atmospheric Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia
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15
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Reissner J, Siller P, Bartel A, Roesler U, Friese A. Stability of Feline Coronavirus in aerosols and dried in organic matrices on surfaces at various environmental conditions. Sci Rep 2023; 13:22012. [PMID: 38086913 PMCID: PMC10716419 DOI: 10.1038/s41598-023-49361-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 12/07/2023] [Indexed: 12/18/2023] Open
Abstract
Enveloped respiratory viruses, including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), can be transmitted through aerosols and contact with contaminated surfaces. The stability of these viruses outside the host significantly impacts their transmission dynamics and the spread of diseases. In this study, we investigated the tenacity of Feline Coronavirus (FCoV) in aerosols and on surfaces under varying environmental conditions. We found that airborne FCoV showed different stability depending on relative humidity (RH), with higher stability observed at low and high RH. Medium RH conditions (50-60%) were associated with increased loss of infectivity. Furthermore, FCoV remained infectious in the airborne state over 7 h. On stainless-steel surfaces, FCoV remained infectious for several months, with stability influenced by organic material and temperature. The presence of yeast extract and a temperature of 4 °C resulted in the longest maintenance of infectivity, with a 5 log10 reduction of the initial concentration after 167 days. At 20 °C, this reduction was achieved after 19 days. These findings highlight the potential risk of aerosol and contact transmission of respiratory viruses, especially in enclosed environments, over extended periods. Studying surrogate viruses like FCoV provides important insights into the behavior of zoonotic viruses like SARS-CoV-2 in the environment.
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Affiliation(s)
- Janina Reissner
- Institute of Animal Hygiene and Environmental Health, Veterinary Centre for Resistance Research-TZR, School of Veterinary Medicine, Freie Universität Berlin, 14163, Berlin, Germany.
| | - Paul Siller
- Institute of Animal Hygiene and Environmental Health, Veterinary Centre for Resistance Research-TZR, School of Veterinary Medicine, Freie Universität Berlin, 14163, Berlin, Germany
- Federal Office of Consumer Protection and Food Safety, Department Veterinary Drugs, Mittelstraße 51-54, 10117, Berlin, Germany
| | - Alexander Bartel
- Institute of Veterinary Epidemiology and Biostatistics, School of Veterinary Medicine, Freie Universität Berlin, 14163, Berlin, Germany
| | - Uwe Roesler
- Institute of Animal Hygiene and Environmental Health, Veterinary Centre for Resistance Research-TZR, School of Veterinary Medicine, Freie Universität Berlin, 14163, Berlin, Germany
| | - Anika Friese
- Institute of Animal Hygiene and Environmental Health, Veterinary Centre for Resistance Research-TZR, School of Veterinary Medicine, Freie Universität Berlin, 14163, Berlin, Germany
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16
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Qiu G, Zhang X, deMello AJ, Yao M, Cao J, Wang J. On-site airborne pathogen detection for infection risk mitigation. Chem Soc Rev 2023; 52:8531-8579. [PMID: 37882143 PMCID: PMC10712221 DOI: 10.1039/d3cs00417a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Indexed: 10/27/2023]
Abstract
Human-infecting pathogens that transmit through the air pose a significant threat to public health. As a prominent instance, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that caused the COVID-19 pandemic has affected the world in an unprecedented manner over the past few years. Despite the dissipating pandemic gloom, the lessons we have learned in dealing with pathogen-laden aerosols should be thoroughly reviewed because the airborne transmission risk may have been grossly underestimated. From a bioanalytical chemistry perspective, on-site airborne pathogen detection can be an effective non-pharmaceutic intervention (NPI) strategy, with on-site airborne pathogen detection and early-stage infection risk evaluation reducing the spread of disease and enabling life-saving decisions to be made. In light of this, we summarize the recent advances in highly efficient pathogen-laden aerosol sampling approaches, bioanalytical sensing technologies, and the prospects for airborne pathogen exposure measurement and evidence-based transmission interventions. We also discuss open challenges facing general bioaerosols detection, such as handling complex aerosol samples, improving sensitivity for airborne pathogen quantification, and establishing a risk assessment system with high spatiotemporal resolution for mitigating airborne transmission risks. This review provides a multidisciplinary outlook for future opportunities to improve the on-site airborne pathogen detection techniques, thereby enhancing the preparedness for more on-site bioaerosols measurement scenarios, such as monitoring high-risk pathogens on airplanes, weaponized pathogen aerosols, influenza variants at the workplace, and pollutant correlated with sick building syndromes.
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Affiliation(s)
- Guangyu Qiu
- Institute of Medical Robotics, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
- Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland
- Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Xiaole Zhang
- Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland
- Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Andrew J deMello
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg1, Zürich, Switzerland
| | - Maosheng Yao
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, China
| | - Junji Cao
- Institute of Atmospheric Physics, Chinese Academy of Science, China
| | - Jing Wang
- Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland
- Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
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17
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Glas I, David SC. A new chapter of healthy indoor air: antiviral air treatments. EMBO Mol Med 2023; 15:e18710. [PMID: 37969101 DOI: 10.15252/emmm.202318710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 11/17/2023] Open
Abstract
Aerosol transmission remains a major challenge for the control of respiratory viruses. To date, prevention strategies include masks, vaccinations, physical distancing, travel restrictions, and lockdowns. Such measures are effective but come with heavy societal burdens and rely on public compliance. Additionally, most are simply not suitable as long-term measures. Other strategies evolve around the concept of improved indoor air quality and involve ventilation, relative humidity (RH) control, and air filtration. Unfortunately, natural ventilation increases exposure to airborne pollutants and vector-borne diseases, and incurs substantial energy losses in colder months. Mechanical ventilation concepts, including regular air changes and filtration, are effective but costly, and often require expensive engineering solutions and widespread renovations. Alternative options to reduce the spread of emerging and seasonal infections are sorely needed. In this issue of EMBO Molecular Medicine, Styles et al (2023) describe the use of propylene glycol (PG) to inactivate infectious bioaerosols and virus-containing droplets deposited on surfaces.
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Affiliation(s)
- Irina Glas
- Institute of Medical Virology, University of Zurich, Zürich, Switzerland
| | - Shannon C David
- Environmental Chemistry Laboratory, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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18
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Horne J, Dunne N, Singh N, Safiuddin M, Esmaeili N, Erenler M, Ho I, Luk E. Building parameters linked with indoor transmission of SARS-CoV-2. ENVIRONMENTAL RESEARCH 2023; 238:117156. [PMID: 37717799 DOI: 10.1016/j.envres.2023.117156] [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: 03/04/2023] [Revised: 07/27/2023] [Accepted: 09/14/2023] [Indexed: 09/19/2023]
Abstract
The rapid spread of Coronavirus Disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has emphasized the importance of understanding and adapting to the indoor remediation of transmissible diseases to decrease the risk for future pandemic threats. While there were many precautions in place to hinder the spread of COVID-19, there has also been a substantial increase of new research on SARS-CoV-2 that can be utilized to further mitigate the transmission risk of this novel virus. This review paper aims to identify the building parameters of indoor spaces that could have considerable influence on the transmission of SARS-CoV-2. The following building parameters have been identified and analyzed, emphasizing their link with the indoor transmission of SARS-CoV-2: temperature and relative humidity, temperature differences between rooms, ventilation rate and access to natural ventilation, occupant density, surface type and finish, airflow direction and speed, air stability, indoor air pollution, central air conditioning systems, capacity of air handling system and HVAC filter efficiency, edge sealing of air filters, room layout and interior design, and compartmentalization of interior space. This paper also explains the interactions of SARS-CoV-2 with indoor environments and its persistence. Furthermore, the modifications of the key building parameters have been discussed for controlling the transmission of SARS-CoV-2 in indoor spaces. Understanding the information provided in this paper is crucial to develop effective health and safety measures that will aid in infection prevention.
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Affiliation(s)
- Jacqueline Horne
- Centre for Construction and Engineering Technologies, George Brown College, Casa Loma Campus, 160 Kendal Avenue, Toronto, ON M5R 1M3, Canada
| | - Nicholas Dunne
- Centre for Construction and Engineering Technologies, George Brown College, Casa Loma Campus, 160 Kendal Avenue, Toronto, ON M5R 1M3, Canada
| | - Nirmala Singh
- Centre for Construction and Engineering Technologies, George Brown College, Casa Loma Campus, 160 Kendal Avenue, Toronto, ON M5R 1M3, Canada
| | - Md Safiuddin
- Centre for Construction and Engineering Technologies, George Brown College, Casa Loma Campus, 160 Kendal Avenue, Toronto, ON M5R 1M3, Canada.
| | - Navid Esmaeili
- Centre for Construction and Engineering Technologies, George Brown College, Casa Loma Campus, 160 Kendal Avenue, Toronto, ON M5R 1M3, Canada
| | - Merve Erenler
- Centre for Construction and Engineering Technologies, George Brown College, Casa Loma Campus, 160 Kendal Avenue, Toronto, ON M5R 1M3, Canada
| | - Ian Ho
- Sysconverge Inc., 7030 Woodbine Avenue, Suite 500, Markham, ON L3R 6G2, Canada
| | - Edwin Luk
- Sysconverge Inc., 7030 Woodbine Avenue, Suite 500, Markham, ON L3R 6G2, Canada
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19
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Alsved M, Nyström K, Thuresson S, Nygren D, Patzi-Churqui M, Hussein T, Fraenkel CJ, Medstrand P, Löndahl J. Infectivity of exhaled SARS-CoV-2 aerosols is sufficient to transmit covid-19 within minutes. Sci Rep 2023; 13:21245. [PMID: 38040798 PMCID: PMC10692216 DOI: 10.1038/s41598-023-47829-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 11/18/2023] [Indexed: 12/03/2023] Open
Abstract
Exhaled SARS-CoV-2-containing aerosols contributed significantly to the rapid and vast spread of covid-19. However, quantitative experimental data on the infectivity of such aerosols is missing. Here, we quantified emission rates of infectious viruses in exhaled aerosol from individuals within their first days after symptom onset from covid-19. Six aerosol samples from three individuals were culturable, of which five were successfully quantified using TCID50. The source strength of the three individuals was highest during singing, when they exhaled 4, 36, or 127 TCID50/s, respectively. Calculations with an indoor air transmission model showed that if an infected individual with this emission rate entered a room, a susceptible person would inhale an infectious dose within 6 to 37 min in a room with normal ventilation. Thus, our data show that exhaled aerosols from a single person can transmit covid-19 to others within minutes at normal indoor conditions.
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Affiliation(s)
- Malin Alsved
- Division of Ergonomics and Aerosol Technology, Department of Design Sciences, Lund University, Box 118, 22100, Lund, Sweden.
| | - Kristina Nyström
- Department of Clinical Microbiology, Sahlgrenska University Hospital, Region Västra Götaland, 41346, Gothenburg, Sweden
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 41346, Gothenburg, Sweden
| | - Sara Thuresson
- Division of Ergonomics and Aerosol Technology, Department of Design Sciences, Lund University, Box 118, 22100, Lund, Sweden
| | - David Nygren
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, 22100, Lund, Sweden
| | - Marianela Patzi-Churqui
- Department of Clinical Microbiology, Sahlgrenska University Hospital, Region Västra Götaland, 41346, Gothenburg, Sweden
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 41346, Gothenburg, Sweden
| | - Tareq Hussein
- Environmental and Atmospheric Research Laboratory (EARL), Department of Physics, School of Science, The University of Jordan, Amman, 11942, Jordan
- Institute for Atmospheric and Earth System Research (INAR/Physics), University of Helsinki, 00014, Helsinki, Finland
| | - Carl-Johan Fraenkel
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, 22100, Lund, Sweden
- Department of Clinical Microbiology and Infection Control, Region Skåne, 22185, Lund, Sweden
| | - Patrik Medstrand
- Department of Translational Medicine, Clinical Virology, Lund University, 22100, Lund, Sweden
- SciLifeLab, Lund University, 22100, Lund, Sweden
| | - Jakob Löndahl
- Division of Ergonomics and Aerosol Technology, Department of Design Sciences, Lund University, Box 118, 22100, Lund, Sweden.
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20
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Ozler G, Grosshans H. Airborne virus transmission: Increased spreading due to formation of hollow particles. ENVIRONMENTAL RESEARCH 2023; 237:116953. [PMID: 37648186 DOI: 10.1016/j.envres.2023.116953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/30/2023] [Accepted: 08/21/2023] [Indexed: 09/01/2023]
Abstract
The globally supported social distancing rules to prevent airborne transmission of COVID-19 assume small saliva droplets evaporate fast and large ones, which contain most viral copies, fall fast to the ground. However, during evaporation, solutes distribute non-uniformly within the droplets. We developed a numerical model to predict saliva droplet drying in different environments. We represent saliva droplets as a solution of NaCl mixed with water. In a hot and dry ambiance, the solutes form a shell on the droplets' surface, producing light, hollow particles. These hollow particles have a larger cross-sectional area compared to their solid counterparts and can float longer and travel farther in the air. We introduced the "hollowness factor," which serves as a measure of the ratio of the volume of a hollow particle and the volume of a solid residue formed during droplet drying. Through our investigations, we determined that under specific conditions, namely an ambient humidity level of 10% and a temperature of 40°C, the highest hollowness factor observed was 1.610. This finding indicates that in the case of hollow particle formation, the droplet nucleus expands by a factor of 1.610 compared to its original size.
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Affiliation(s)
- Gizem Ozler
- Physikalisch- Technische Bundesanstalt (PTB), Braunschweig 38116, Germany; Otto von Guericke University of Magdeburg, Institute of Aparatus and Environmental Technology, Magdeburg 39106, Germany.
| | - Holger Grosshans
- Physikalisch- Technische Bundesanstalt (PTB), Braunschweig 38116, Germany; Otto von Guericke University of Magdeburg, Institute of Aparatus and Environmental Technology, Magdeburg 39106, Germany.
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21
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Marschall J, Snyders RE, Sax H, Newland JG, Guimarães T, Kwon JH. Perspectives on research needs in healthcare epidemiology and antimicrobial stewardship: what's on the horizon - Part I. ANTIMICROBIAL STEWARDSHIP & HEALTHCARE EPIDEMIOLOGY : ASHE 2023; 3:e199. [PMID: 38028931 PMCID: PMC10654935 DOI: 10.1017/ash.2023.473] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 12/01/2023]
Abstract
In this overview, we articulate research needs and opportunities in the field of infection prevention that have been identified from insights gained during operative infection prevention work, our own research in healthcare epidemiology, and from reviewing the literature. The 10 areas of research need are: 1) transmissions and interruptions, 2) personal protective equipment and other safety issues in occupational health, 3) climate change and other crises, 4) device, diagnostic, and antimicrobial stewardship, 5) implementation and de-implementation, 6) health care outside the acute care hospital, 7) low- and middle-income countries, 8) networking with the "neighbors", 9) novel research methodologies, and 10) the future state of surveillance. An introduction and chapters 1-5 are presented in part I of the article, and chapters 6-10 and the discussion in part II. There are many barriers to advancing the field, such as finding and motivating the future IP workforce including professionals interested in conducting research, a constant confrontation with challenges and crises, the difficulty of performing studies in a complex environment, the relative lack of adequate incentives and funding streams, and how to disseminate and validate the often very local quality improvement projects. Addressing research gaps now (i.e., in the postpandemic phase) will make healthcare systems more resilient when facing future crises.
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Affiliation(s)
- Jonas Marschall
- Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO, USA
- BJC Healthcare, St. Louis, MO, USA
| | | | - Hugo Sax
- Bern University Hospital, University of Bern, Bern, Switzerland
| | - Jason G. Newland
- Division of Infectious Diseases, Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Thais Guimarães
- Infection Control Department, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Jennie H. Kwon
- Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO, USA
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22
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David SC, Vadas O, Glas I, Schaub A, Luo B, D'angelo G, Montoya JP, Bluvshtein N, Hugentobler W, Klein LK, Motos G, Pohl M, Violaki K, Nenes A, Krieger UK, Stertz S, Peter T, Kohn T. Inactivation mechanisms of influenza A virus under pH conditions encountered in aerosol particles as revealed by whole-virus HDX-MS. mSphere 2023; 8:e0022623. [PMID: 37594288 PMCID: PMC10597348 DOI: 10.1128/msphere.00226-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 06/23/2023] [Indexed: 08/19/2023] Open
Abstract
Multiple respiratory viruses, including influenza A virus (IAV), can be transmitted via expiratory aerosol particles, and aerosol pH was recently identified as a major factor influencing airborne virus infectivity. Indoors, small exhaled aerosols undergo rapid acidification to pH ~4. IAV is known to be sensitive to mildly acidic conditions encountered within host endosomes; however, it is unknown whether the same mechanisms could mediate viral inactivation within the more acidic aerosol micro-environment. Here, we identified that transient exposure to pH 4 caused IAV inactivation by a two-stage process, with an initial sharp decline in infectious titers mainly attributed to premature attainment of the post-fusion conformation of viral protein haemagglutinin (HA). Protein changes were observed by hydrogen-deuterium exchange coupled to mass spectrometry (HDX-MS) as early as 10 s post-exposure to acidic conditions. Our HDX-MS data are in agreement with other more labor-intensive structural analysis techniques, such as X-ray crystallography, highlighting the ease and usefulness of whole-virus HDX-MS for multiplexed protein analyses, even within enveloped viruses such as IAV. Additionally, virion integrity was partially but irreversibly affected by acidic conditions, with a progressive unfolding of the internal matrix protein 1 (M1) that aligned with a more gradual decline in viral infectivity with time. In contrast, no acid-mediated changes to the genome or lipid envelope were detected. Improved understanding of respiratory virus fate within exhaled aerosols constitutes a global public health priority, and information gained here could aid the development of novel strategies to control the airborne persistence of seasonal and/or pandemic influenza in the future. IMPORTANCE It is well established that COVID-19, influenza, and many other respiratory diseases can be transmitted by the inhalation of aerosolized viruses. Many studies have shown that the survival time of these airborne viruses is limited, but it remains an open question as to what drives their infectivity loss. Here, we address this question for influenza A virus by investigating structural protein changes incurred by the virus under conditions relevant to respiratory aerosol particles. From prior work, we know that expelled aerosols can become highly acidic due to equilibration with indoor room air, and our results indicate that two viral proteins are affected by these acidic conditions at multiple sites, leading to virus inactivation. Our findings suggest that the development of air treatments to quicken the speed of aerosol acidification would be a major strategy to control infectious bioburdens in the air.
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Affiliation(s)
- Shannon C. David
- Environmental Chemistry Laboratory, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Oscar Vadas
- Protein Platform, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Irina Glas
- Institute of Medical Virology, University of Zurich, Zürich, Switzerland
| | - Aline Schaub
- Environmental Chemistry Laboratory, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Beiping Luo
- Institute for Atmospheric and Climate Science, ETH Zurich, Zürich, Switzerland
| | - Giovanni D'angelo
- Laboratory of Lipid Cell Biology, School of Life Sciences, Interschool Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Jonathan Paz Montoya
- Laboratory of Lipid Cell Biology, School of Life Sciences, Interschool Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Nir Bluvshtein
- Institute for Atmospheric and Climate Science, ETH Zurich, Zürich, Switzerland
| | - Walter Hugentobler
- Laboratory of Atmospheric Processes and their Impacts, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Liviana K. Klein
- Institute for Atmospheric and Climate Science, ETH Zurich, Zürich, Switzerland
| | - Ghislain Motos
- Laboratory of Atmospheric Processes and their Impacts, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Marie Pohl
- Institute of Medical Virology, University of Zurich, Zürich, Switzerland
| | - Kalliopi Violaki
- Laboratory of Atmospheric Processes and their Impacts, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Athanasios Nenes
- Laboratory of Atmospheric Processes and their Impacts, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Chemical Engineering Sciences, Foundation for Research and Technology Hellas, Patras, Greece
| | - Ulrich K. Krieger
- Institute for Atmospheric and Climate Science, ETH Zurich, Zürich, Switzerland
| | - Silke Stertz
- Institute of Medical Virology, University of Zurich, Zürich, Switzerland
| | - Thomas Peter
- Institute for Atmospheric and Climate Science, ETH Zurich, Zürich, Switzerland
| | - Tamar Kohn
- Environmental Chemistry Laboratory, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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23
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Tanner K, Good KM, Goble D, Good N, Keisling A, Keller KP, L’Orange C, Morton E, Phillips R, Volckens J. Large Particle Emissions from Human Vocalization and Playing of Wind Instruments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:15392-15400. [PMID: 37796739 PMCID: PMC10586367 DOI: 10.1021/acs.est.3c03588] [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: 05/11/2023] [Revised: 09/14/2023] [Accepted: 09/15/2023] [Indexed: 10/07/2023]
Abstract
Humans emit large salivary particles when talking, singing, and playing musical instruments, which have implications for respiratory disease transmission. Yet little work has been done to characterize the emission rates and size distributions of such particles. This work characterized large particle (dp > 35 μm in aerodynamic diameter) emissions from 70 volunteers of varying age and sex while vocalizing and playing wind instruments. Mitigation efficacies for face masks (while singing) and bell covers (while playing instruments) were also examined. Geometric mean particle count emission rates varied from 3.8 min-1 (geometric standard deviation [GSD] = 3.1) for brass instruments playing to 95.1 min-1 (GSD = 3.8) for talking. On average, talking produced the highest emission rates for large particles, in terms of both number and mass, followed by singing and then instrument playing. Neither age, sex, CO2 emissions, nor loudness (average dBA) were significant predictors of large particle emissions, contrary to previous findings for smaller particle sizes (i.e., for dp < 35 μm). Size distributions were similar between talking and singing (count median diameter = 53.0 μm, GSD = 1.69). Bell covers did not affect large particle emissions from most wind instruments, but face masks reduced large particle count emissions for singing by 92.5% (95% CI: 97.9%, 73.7%).
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Affiliation(s)
- Ky Tanner
- Department
of Mechanical Engineering, Colorado State
University, Fort Collins, Colorado 80523, United States
| | - Kristen M. Good
- Department
of Environmental and Radiological Health Sciences, Colorado State University, Fort
Collins, Colorado 80523, United States
- Colorado
Department of Public Health and Environment, Denver, Colorado 80246, United States
| | - Dan Goble
- School
of Music, Theatre, and Dance, Colorado State
University, Fort Collins, Colorado 80523, United States
| | - Nicholas Good
- Department
of Civil and Environmental Engineering, Colorado State University, Fort
Collins, Colorado 80523, United States
| | - Amy Keisling
- Department
of Mechanical Engineering, Colorado State
University, Fort Collins, Colorado 80523, United States
- School
of Music, Theatre, and Dance, Colorado State
University, Fort Collins, Colorado 80523, United States
| | - Kayleigh P. Keller
- Department
of Statistics, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Christian L’Orange
- Department
of Mechanical Engineering, Colorado State
University, Fort Collins, Colorado 80523, United States
| | - Emily Morton
- School
of Music, Theatre, and Dance, Colorado State
University, Fort Collins, Colorado 80523, United States
| | - Rebecca Phillips
- School
of Music, Theatre, and Dance, Colorado State
University, Fort Collins, Colorado 80523, United States
| | - John Volckens
- Department
of Mechanical Engineering, Colorado State
University, Fort Collins, Colorado 80523, United States
- Department
of Environmental and Radiological Health Sciences, Colorado State University, Fort
Collins, Colorado 80523, United States
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24
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Madhusudanan A, Iddon C, Cevik M, Naismith JH, Fitzgerald S. Non-pharmaceutical interventions for COVID-19: a systematic review on environmental control measures. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20230130. [PMID: 37611631 PMCID: PMC10446906 DOI: 10.1098/rsta.2023.0130] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 06/06/2023] [Indexed: 08/25/2023]
Abstract
The purpose of this review was to identify the effectiveness of environmental control (EC) non-pharmaceutical interventions (NPIs) in reducing transmission of SARS-CoV-2 through conducting a systematic review. EC NPIs considered in this review are room ventilation, air filtration/cleaning, room occupancy, surface disinfection, barrier devices, [Formula: see text] monitoring and one-way-systems. Systematic searches of databases from Web of Science, Medline, EMBASE, preprint servers MedRxiv and BioRxiv were conducted in order to identify studies reported between 1 January 2020 and 1 December 2022. All articles reporting on the effectiveness of ventilation, air filtration/cleaning, room occupancy, surface disinfection, barrier devices, [Formula: see text] monitoring and one-way systems in reducing transmission of SARS-CoV-2 were retrieved and screened. In total, 13 971 articles were identified for screening. The initial title and abstract screening identified 1328 articles for full text review. Overall, 19 references provided evidence for the effectiveness of NPIs: 12 reported on ventilation, 4 on air cleaning devices, 5 on surface disinfection, 6 on room occupancy and 1 on screens/barriers. No studies were found that considered the effectiveness of [Formula: see text] monitoring or the implementation of one-way systems. Many of these studies were assessed to have critical risk of bias in at least one domain, largely due to confounding factors that could have affected the measured outcomes. As a result, there is low confidence in the findings. Evidence suggests that EC NPIs of ventilation, air cleaning devices and reduction in room-occupancy may have a role in reducing transmission in certain settings. However, the evidence was usually of low or very low quality and certainty, and hence the level of confidence ascribed to this conclusion is low. Based on the evidence found, it was not possible to draw any specific conclusions regarding the effectiveness of surface disinfection and the use of barrier devices. From these results, we further conclude that community agreed standards for well-designed epidemiological studies with low risk of bias are needed. Implementation of such standards would enable more confident assessment in the future of the effectiveness of EC NPIs in reducing transmission of SARS-CoV-2 and other pathogens in real-world settings. This article is part of the theme issue 'The effectiveness of non-pharmaceutical interventions on the COVID-19 pandemic: the evidence'.
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Affiliation(s)
| | - Christopher Iddon
- Department of Civil, Environmental and Geomatic Engineering, University College London, WC1E 6BT, London, UK
| | - Muge Cevik
- Department of Infection and Global Health, School of Medicine, University of St Andrews, KY16 9TF, St Andrews, UK
| | | | - Shaun Fitzgerald
- Department of Engineering, University of Cambridge, CB2 1PZ, Cambridge, UK
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25
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Lee B, Lau D, Mogk JPM, Lee M, Bibliowicz J, Goldstein R, Tessier A. Generative design for COVID-19 and future pathogens using stochastic multi-agent simulation. SUSTAINABLE CITIES AND SOCIETY 2023; 97:104661. [PMID: 37332845 PMCID: PMC10234365 DOI: 10.1016/j.scs.2023.104661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 05/17/2023] [Accepted: 05/17/2023] [Indexed: 06/20/2023]
Abstract
We propose a generative design workflow that integrates a stochastic multi-agent simulation with the intent of helping building designers reduce the risk posed by COVID-19 and future pathogens. Our custom simulation randomly generates activities and movements of individual occupants, tracking the amount of virus transmitted through air and surfaces from contagious to susceptible agents. The stochastic nature of the simulation requires that many repetitions be performed to achieve statistically reliable results. Accordingly, a series of initial experiments identified parameter values that balanced the trade-off between computational cost and accuracy. Applying generative design to a case study based on an existing office space reduced the predicted transmission by around 10% to 20% compared with a baseline set of layouts. Additionally, a qualitative examination of the generated layouts revealed design patterns that may reduce transmission. Stochastic multi-agent simulation is a computationally expensive yet plausible way to generate safer building designs.
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Affiliation(s)
- Bokyung Lee
- Autodesk Research, 661 University Ave, West Tower, Ste. 200, Toronto, M5G 1MA, ON, Canada
| | - Damon Lau
- Autodesk Research, 19 Morris Ave, Brooklyn Navy Yard, Building 128, Brooklyn, 11205, NY, USA
| | - Jeremy P M Mogk
- Autodesk Research, 661 University Ave, West Tower, Ste. 200, Toronto, M5G 1MA, ON, Canada
| | - Michael Lee
- Autodesk Research, 661 University Ave, West Tower, Ste. 200, Toronto, M5G 1MA, ON, Canada
| | - Jacobo Bibliowicz
- Autodesk Research, 661 University Ave, West Tower, Ste. 200, Toronto, M5G 1MA, ON, Canada
| | - Rhys Goldstein
- Autodesk Research, 661 University Ave, West Tower, Ste. 200, Toronto, M5G 1MA, ON, Canada
| | - Alexander Tessier
- Autodesk Research, 661 University Ave, West Tower, Ste. 200, Toronto, M5G 1MA, ON, Canada
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26
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Chen Y, Beattie H, Simpson A, Nicholls G, Sandys V, Keen C, Curran AD. A COVID-19 Outbreak in a Large Meat-Processing Plant in England: Transmission Risk Factors and Controls. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:6806. [PMID: 37835076 PMCID: PMC10572747 DOI: 10.3390/ijerph20196806] [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: 06/21/2023] [Revised: 08/11/2023] [Accepted: 09/19/2023] [Indexed: 10/15/2023]
Abstract
The meat-processing industry had frequent COVID-19 outbreaks reported worldwide. In May 2021, a large meat-processing plant in the UK had an outbreak affecting 4.1% (63/1541) of workers. A rapid on-site investigation was conducted to understand the virus transmission risk factors and control measures. This included observational assessments of work activities, control measures, real-time environmental measurements and surface microbial sampling. The production night-shift attack rate (11.6%, 44/380) was nearly five times higher than the production day-shift (2.4%, 9/380). Shared work transport was provided to 150 staff per dayshift and 104 per nightshift. Production areas were noisy (≥80 dB(A)) and physical distancing was difficult to maintain. Face visors were mandatory, additional face coverings were required for some activities but not always worn. The refrigeration system continuously recirculated chilled air. In some areas, the mean temperature was as low as 4.5 °C and mean relative humidity (RH) was as high as 96%. The adequacy of ventilation in the production areas could not be assessed reliably using CO2, due to the use of CO2 in the packaging process. While there were challenges in the production areas, the observed COVID-19 control measures were generally implemented well in the non-production areas. Sixty surface samples from all areas were tested for SARS-CoV-2 RNA and 11.7% were positive. Multi-layered measures, informed by a workplace specific risk assessment, are required to prevent and control workplace outbreaks of COVID-19 or other similar respiratory infectious diseases.
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Affiliation(s)
- Yiqun Chen
- Science Division, Health and Safety Executive, Buxton SK17 9JN, UK
| | - Helen Beattie
- Science Division, Health and Safety Executive, Buxton SK17 9JN, UK
| | - Andrew Simpson
- Science Division, Health and Safety Executive, Buxton SK17 9JN, UK
| | - Gillian Nicholls
- Science Division, Health and Safety Executive, Buxton SK17 9JN, UK
| | - Vince Sandys
- Science Division, Health and Safety Executive, Buxton SK17 9JN, UK
| | - Chris Keen
- Science Division, Health and Safety Executive, Buxton SK17 9JN, UK
| | - Andrew D Curran
- Science Division, Health and Safety Executive, Buxton SK17 9JN, UK
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27
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Sung JCC, Wu PL, So EYM, Wu KC, Chan SMN, Kwong KWY, Sze ETP. Assessment of novel antiviral filter using pseudo-type SARS-CoV-2 virus in fast air velocity vertical-type wind tunnel. Sci Rep 2023; 13:13947. [PMID: 37626166 PMCID: PMC10457382 DOI: 10.1038/s41598-023-41245-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 08/23/2023] [Indexed: 08/27/2023] Open
Abstract
Current evidence suggests that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can remain suspended spread in aerosols for longer period of time under poorly ventilated indoor setting. To minimize spreading, application of antiviral filter to capture infectious aerosols and to inactivate SARS-CoV-2 can be a promising solution. This study aimed to develop a method to assess simultaneously the filtration and removal efficiency of aerosolized pseudo-type SARS-CoV-2 using a vertical-type wind tunnel with relatively high face velocity (1.3 m/s). Comparing with the untreated spunlace non-woven filter, the C-POLAR™ treated filter increased the filtration efficiency from 74.2 ± 11.5% to 97.2 ± 1.7%, with the removal efficiency of 99.4 ± 0.051%. The results provided not only solid evidence to support the effectiveness of the cationic polymeric coated filter in fighting against the SARS-CoV-2 pandemic, but also a method to test viral filtration and removal efficiency under relative fast air velocity and with a safer environment to the operators.
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Affiliation(s)
| | - Pak-Long Wu
- School of Science and Technology, Hong Kong Metropolitan University, Hong Kong, China
| | - Ellis Yung-Mau So
- School of Science and Technology, Hong Kong Metropolitan University, Hong Kong, China
| | - Kam-Chau Wu
- Research Department, DreamTec Cytokines Limited, Hong Kong, China
| | - Sidney Man-Ngai Chan
- School of Science and Technology, Hong Kong Metropolitan University, Hong Kong, China
| | | | - Eric Tung-Po Sze
- School of Science and Technology, Hong Kong Metropolitan University, Hong Kong, China.
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28
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Morris JN, Esseili MA. The Effect of Water Hardness and pH on the Efficacy of Peracetic Acid and Sodium Hypochlorite against SARS-CoV-2 on Food-Contact Surfaces. Foods 2023; 12:2981. [PMID: 37627980 PMCID: PMC10453873 DOI: 10.3390/foods12162981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/29/2023] [Accepted: 08/06/2023] [Indexed: 08/27/2023] Open
Abstract
Sodium hypochlorite (NaOCl) and peracetic acid (PAA) are commonly used disinfectants with a maximum recommended concentration of 200 ppm for food-contact surfaces. The objectives of this study were to assess the effect of pH and water hardness on NaOCl and PAA efficacy against SARS-CoV-2 on stainless steel (SS). The two disinfectants were prepared at 200 ppm in water of hardness 150 or 300 ppm with the final pH adjusted to 5, 6, 7, or 8. Disinfectants were applied to virus-contaminated SS for one minute at room temperature following the ASTM E2197 standard assay. SARS-CoV-2 infectivity was quantified using TCID50 assay on Vero-E6 cells. In general, increasingly hard water decreased the efficacy of NaOCl while increasing the efficacy of PAA. Hard water at 300 ppm significantly increased virus log reduction with PAA at pH 8 by ~1.5 log. The maximum virus log reductions were observed at pH 5 for both NaOCl (~1.2 log) and PAA (~2 log) at 150 and 300 ppm hard water, respectively. In conclusion, PAA performed significantly better than NaOCl with harder water. However, both disinfectants at 200 ppm and one minute were not effective (≤3 log) against SARS-CoV-2 on contaminated food-contact surfaces, which may facilitate the role of these surfaces in virus transmission.
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Affiliation(s)
| | - Malak A. Esseili
- Center for Food Safety, Department of Food Science and Technology, University of Georgia, Griffin, GA 30223, USA;
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29
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Pan J, Gmati S, Roper BA, Prussin AJ, Hawks SA, Whittington AR, Duggal NK, Marr LC. Stability of Aerosolized SARS-CoV-2 on Masks and Transfer to Skin. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023. [PMID: 37399494 DOI: 10.1021/acs.est.3c01581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
The potential for masks to act as fomites in the transmission of SARS-CoV-2 has been suggested but not demonstrated experimentally or observationally. In this study, we aerosolized a suspension of SARS-CoV-2 in saliva and used a vacuum pump to pull the aerosol through six different types of masks. After 1 h at 28 °C and 80% RH, SARS-CoV-2 infectivity was not detectable on an N95 and surgical mask, was reduced by 0.7 log10 on a nylon/spandex mask, and was unchanged on a polyester mask and two different cotton masks when recovered by elution in a buffer. SARS-CoV-2 RNA remained stable for 1 h on all masks. We pressed artificial skin against the contaminated masks and detected the transfer of viral RNA but no infectious virus to the skin. The potential for masks contaminated with SARS-CoV-2 in aerosols to act as fomites appears to be less than indicated by studies involving SARS-CoV-2 in very large droplets.
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Affiliation(s)
- Jin Pan
- Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Selma Gmati
- Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Bryce A Roper
- Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Aaron J Prussin
- Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Seth A Hawks
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia 24061, United States
| | - Abby R Whittington
- Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
- Departments of Chemical Engineering and Macromolecular Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Nisha K Duggal
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia 24061, United States
| | - Linsey C Marr
- Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
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30
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Rahaman H, Barik D. Investigation of airborne spread of COVID-19 using a hybrid agent-based model: a case study of the UK. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230377. [PMID: 37501658 PMCID: PMC10369033 DOI: 10.1098/rsos.230377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 07/04/2023] [Indexed: 07/29/2023]
Abstract
Agent-based models have been proven to be quite useful in understanding and predicting the SARS-CoV-2 virus-originated COVID-19 infection. Person-to-person contact was considered as the main mechanism of viral transmission in these models. However, recent understanding has confirmed that airborne transmission is the main route to infection spread of COVID-19. We have developed a computationally efficient agent-based hybrid model to study the aerial propagation of the virus and subsequent spread of infection. We considered virus, a continuous variable, spreads diffusively in air and members of populations as discrete agents possessing one of the eight different states at a particular time. The transition from one state to another is probabilistic and age linked. Recognizing that population movement is a key aspect of infection spread, the model allows unbiased movement of agents. We benchmarked the model to recapture the temporal stochastic infection count data of the UK. The model investigates various key factors such as movement, infection susceptibility, new variants, recovery rate and duration, incubation period and vaccination on the infection propagation over time. Furthermore, the model was applied to capture the infection spread in Italy and France.
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Affiliation(s)
- Hafijur Rahaman
- School of Chemistry, University of Hyderabad, Central University PO, Hyderabad 500046, Telangana, India
| | - Debashis Barik
- School of Chemistry, University of Hyderabad, Central University PO, Hyderabad 500046, Telangana, India
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31
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Bray C, Vanberkel PT. A framework for comparing N95 and elastomeric facepiece respirators on cost and function for healthcare use during a pandemic- A literature review. Health Policy 2023; 134:104857. [PMID: 37336164 DOI: 10.1016/j.healthpol.2023.104857] [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: 06/29/2021] [Revised: 05/16/2023] [Accepted: 06/05/2023] [Indexed: 06/21/2023]
Abstract
SARS-CoV-2 has posed implications for personal protective equipment supply. In this literature review we examine if elastomeric facepiece respirators (EFRs) are effective substitutes for N95 respirators through comparing their functionality and cost. We reviewed 30 articles which researched the advantages and disadvantages of each respirator. We compiled the reported results and found, among other things, that users favour N95 respirators for comfort but prefer EFRs for protection. EFRs are more cost effective when N95s are used as designed (single use) but mixed strategies minimize costs when N95s are reused (as practiced during shortages). Future research is needed on multicriteria analyses and to incorporate SARS-CoV-2 specific data to support future pandemic planning.
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Affiliation(s)
- Ceilidh Bray
- Dalhousie University, Industrial Engineering, PO BOX 15000, Halifax, NS B3H 4R2, Canada
| | - Peter T Vanberkel
- Dalhousie University, Industrial Engineering, PO BOX 15000, Halifax, NS B3H 4R2, Canada.
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32
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Sanchez‐Vargas A, Mendez‐Astudillo J, López‐Vidal Y, López‐Carr D, Estrada F. Assessing the Effect of the U.S. Vaccination Program on the Coronavirus Positivity Rate With a Multivariate Framework. GEOHEALTH 2023; 7:e2022GH000771. [PMID: 37287700 PMCID: PMC10243209 DOI: 10.1029/2022gh000771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 05/08/2023] [Accepted: 05/18/2023] [Indexed: 06/09/2023]
Abstract
The factors influencing the incidence of COVID-19, including the impact of the vaccination programs, have been studied in the literature. Most studies focus on one or two factors, without considering their interactions, which is not enough to assess a vaccination program in a statistically robust manner. We examine the impact of the U.S. vaccination program on the SARS-CoV-2 positivity rate while simultaneously considering a large number of factors involved in the spread of the virus and the feedbacks among them. We consider the effects of the following sets of factors: socioeconomic factors, public policy factors, environmental factors, and non-observable factors. A time series Error Correction Model (ECM) was used to estimate the impact of the vaccination program at the national level on the positivity rate. Additionally, state-level ECMs with panel data were combined with machine learning techniques to assess the impact of the program and identify relevant factors to build the best-fitting models. We find that the vaccination program reduced the virus positivity rate. However, the program was partially undermined by a feedback loop in which increased vaccination led to increased mobility. Although some external factors reduced the positivity rate, the emergence of new variants increased the positivity rate. The positivity rate was associated with several forces acting simultaneously in opposite directions such as the number of vaccine doses administered and mobility. The existence of complex interactions, between the factors studied, implies that there is a need to combine different public policies to strengthen the impact of the vaccination program.
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Affiliation(s)
- A. Sanchez‐Vargas
- Institute of Economic ResearchNational Autonomous University of MexicoMexico CityMexico
| | - J. Mendez‐Astudillo
- Institute of Economic ResearchNational Autonomous University of MexicoMexico CityMexico
| | - Y. López‐Vidal
- Programa de Inmunología Molecular MicrobianaDepartamento de Microbiología y ParasitologíaFaculty of MedicineNational Autonomous University of MexicoMexico CityMexico
| | - D. López‐Carr
- Department of GeographyUniversity of California, Santa BarbaraSanta BarbaraCAUSA
| | - F. Estrada
- Instituto de Ciencias de la Atmósfera y Cambio ClimáticoNational Autonomous University of MexicoMexico CityMexico
- Institute for Environmental StudiesVrije Universiteit AmsterdamAmsterdamThe Netherlands
- Programa de Investigación en Cambio ClimáticoNational Autonomous University of MexicoMexico CityMexico
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Abubakar-Waziri H, Kalaiarasan G, Wawman R, Hobbs F, Adcock I, Dilliway C, Fang F, Pain C, Porter A, Bhavsar PK, Ransome E, Savolainen V, Kumar P, Chung KF. SARS-CoV2 in public spaces in West London, UK during COVID-19 pandemic. BMJ Open Respir Res 2023; 10:10/1/e001574. [PMID: 37202121 DOI: 10.1136/bmjresp-2022-001574] [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: 12/02/2022] [Accepted: 04/28/2023] [Indexed: 05/20/2023] Open
Abstract
BACKGROUND Spread of SARS-CoV2 by aerosol is considered an important mode of transmission over distances >2 m, particularly indoors. OBJECTIVES We determined whether SARS-CoV2 could be detected in the air of enclosed/semi-enclosed public spaces. METHODS AND ANALYSIS Between March 2021 and December 2021 during the easing of COVID-19 pandemic restrictions after a period of lockdown, we used total suspended and size-segregated particulate matter (PM) samplers for the detection of SARS-CoV2 in hospitals wards and waiting areas, on public transport, in a university campus and in a primary school in West London. RESULTS We collected 207 samples, of which 20 (9.7%) were positive for SARS-CoV2 using quantitative PCR. Positive samples were collected from hospital patient waiting areas, from hospital wards treating patients with COVID-19 using stationary samplers and from train carriages in London underground using personal samplers. Mean virus concentrations varied between 429 500 copies/m3 in the hospital emergency waiting area and the more frequent 164 000 copies/m3 found in other areas. There were more frequent positive samples from PM samplers in the PM2.5 fractions compared with PM10 and PM1. Culture on Vero cells of all collected samples gave negative results. CONCLUSION During a period of partial opening during the COVID-19 pandemic in London, we detected SARS-CoV2 RNA in the air of hospital waiting areas and wards and of London Underground train carriage. More research is needed to determine the transmission potential of SARS-CoV2 detected in the air.
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Affiliation(s)
| | - Gopinath Kalaiarasan
- Department of Civil and Environmental Engineering, Global Centre for Clean Air Research, Surrey, UK
| | - Rebecca Wawman
- Airway Disease, National Heart & Lung Institute, Imperial College London, London, UK
| | - Faye Hobbs
- Airway Disease, National Heart & Lung Institute, Imperial College London, London, UK
| | - Ian Adcock
- Airway Disease, National Heart & Lung Institute, Imperial College London, London, UK
| | - Claire Dilliway
- Airway Disease, National Heart & Lung Institute, Imperial College London, London, UK
| | - Fangxin Fang
- Airway Disease, National Heart & Lung Institute, Imperial College London, London, UK
| | - Christopher Pain
- Airway Disease, National Heart & Lung Institute, Imperial College London, London, UK
| | - Alexandra Porter
- Airway Disease, National Heart & Lung Institute, Imperial College London, London, UK
| | - Pankaj K Bhavsar
- Airway Disease, National Heart & Lung Institute, Imperial College London, London, UK
| | - Emma Ransome
- Airway Disease, National Heart & Lung Institute, Imperial College London, London, UK
| | - Vincent Savolainen
- Airway Disease, National Heart & Lung Institute, Imperial College London, London, UK
| | - Prashant Kumar
- Department of Civil and Environmental Engineering, Global Centre for Clean Air Research, Surrey, UK
| | - Kian Fan Chung
- Airway Disease, National Heart & Lung Institute, Imperial College London, London, UK
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Markov PV, Ghafari M, Beer M, Lythgoe K, Simmonds P, Stilianakis NI, Katzourakis A. The evolution of SARS-CoV-2. Nat Rev Microbiol 2023; 21:361-379. [PMID: 37020110 DOI: 10.1038/s41579-023-00878-2] [Citation(s) in RCA: 214] [Impact Index Per Article: 214.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2023] [Indexed: 04/07/2023]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused millions of deaths and substantial morbidity worldwide. Intense scientific effort to understand the biology of SARS-CoV-2 has resulted in daunting numbers of genomic sequences. We witnessed evolutionary events that could mostly be inferred indirectly before, such as the emergence of variants with distinct phenotypes, for example transmissibility, severity and immune evasion. This Review explores the mechanisms that generate genetic variation in SARS-CoV-2, underlying the within-host and population-level processes that underpin these events. We examine the selective forces that likely drove the evolution of higher transmissibility and, in some cases, higher severity during the first year of the pandemic and the role of antigenic evolution during the second and third years, together with the implications of immune escape and reinfections, and the increasing evidence for and potential relevance of recombination. In order to understand how major lineages, such as variants of concern (VOCs), are generated, we contrast the evidence for the chronic infection model underlying the emergence of VOCs with the possibility of an animal reservoir playing a role in SARS-CoV-2 evolution, and conclude that the former is more likely. We evaluate uncertainties and outline scenarios for the possible future evolutionary trajectories of SARS-CoV-2.
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Affiliation(s)
- Peter V Markov
- European Commission, Joint Research Centre (JRC), Ispra, Italy.
- London School of Hygiene & Tropical Medicine, University of London, London, UK.
| | - Mahan Ghafari
- Big Data Institute, University of Oxford, Oxford, UK
| | - Martin Beer
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Insel Riems, Germany
| | | | - Peter Simmonds
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Nikolaos I Stilianakis
- European Commission, Joint Research Centre (JRC), Ispra, Italy
- Department of Biometry and Epidemiology, University of Erlangen-Nuremberg, Erlangen, Germany
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Tuck AF. Natural Selection and Scale Invariance. Life (Basel) 2023; 13:life13040917. [PMID: 37109446 PMCID: PMC10144207 DOI: 10.3390/life13040917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 03/03/2023] [Accepted: 03/15/2023] [Indexed: 04/03/2023] Open
Abstract
This review points out that three of the essential features of natural selection—competition for a finite resource, variation, and transmission of memory—occur in an extremely simple, thermalized molecular population, one of colliding “billiard balls” subject to an anisotropy, a directional flux of energetic molecules. The emergence of scaling behavior, scale invariance, in such systems is considered in the context of the emergence of complexity driven by Gibbs free energy, the origins of life, and known chemistries in planetary and astrophysical conditions. It is suggested that the thermodynamic formalism of statistical multifractality offers a parallel between the microscopic and macroscopic views of non-equilibrium systems and their evolution, different from, empirically determinable, and therefore complementing traditional definitions of entropy and its production in living systems. Further, the approach supports the existence of a bridge between microscopic and macroscopic scales, the missing mesoscopic scale. It is argued that natural selection consequently operates on all scales—whether or not life results will depend on both the initial and the evolving boundary conditions. That life alters the boundary conditions ensures nonlinearity and scale invariance. Evolution by natural selection will have taken place in Earth’s fluid envelope; both air and water display scale invariance and are far from chemical equilibrium, a complex condition driven by the Gibbs free energy arising from the entropy difference between the incoming solar beam and the outgoing infrared radiation to the cold sink of space acting on the initial conditions within evolving boundary conditions. Symmetry breaking’s role in the atmospheric state is discussed, particularly in regard to aerosol fission in the context of airborne bacteria and viruses in both current and prebiotic times. Over 4.4 billion years, the factors operating to support natural selection will have evolved along with the entire system from relative simplicity to the current complexity.
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Li Y, Mao N, Guo L, Guo L, Chen L, Zhao L, Wang Q, Long E. Review of animal transmission experiments of respiratory viruses: Implications for transmission risk of SARS-COV-2 in humans via different routes. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2023. [PMID: 36973964 DOI: 10.1111/risa.14129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 02/22/2023] [Accepted: 02/23/2023] [Indexed: 06/18/2023]
Abstract
Exploring transmission risk of different routes has major implications for epidemic control. However, disciplinary boundaries have impeded the dissemination of epidemic information, have caused public panic about "air transmission," "air-conditioning transmission," and "environment-to-human transmission," and have triggered "hygiene theater." Animal experiments provide experimental evidence for virus transmission, but more attention is paid to whether transmission is driven by droplets or aerosols and using the dichotomy to describe most transmission events. Here, according to characteristics of experiment setups, combined with patterns of human social interactions, we reviewed and grouped animal transmission experiments into four categories-close contact, short-range, fomite, and aerosol exposure experiments-and provided enlightenment, with experimental evidence, on the transmission risk of severe acute respiratory syndrome coronavirus (SARS-COV-2) in humans via different routes. When referring to "air transmission," context should be showed in elaboration results, rather than whether close contact, short or long range is uniformly described as "air transmission." Close contact and short range are the major routes. When face-to-face, unprotected, horizontally directional airflow does promote transmission, due to virus decay and dilution in air, the probability of "air conditioning transmission" is low; the risk of "environment-to-human transmission" highly relies on surface contamination and human behavior based on indirect path of "fomite-hand-mucosa or conjunctiva" and virus decay on surfaces. Thus, when discussing the transmission risk of SARS-CoV-2, we should comprehensively consider the biological basis of virus transmission, environmental conditions, and virus decay. Otherwise, risk of certain transmission routes, such as long-range and fomite transmission, will be overrated, causing public excessive panic, triggering ineffective actions, and wasting epidemic prevention resources.
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Affiliation(s)
- Ying Li
- MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Ning Mao
- MOE Key Laboratory of Deep Earth Science and Engineering, Institute for Disaster Management and Reconstruction, Sichuan University, Chengdu, China
| | - Lei Guo
- MOE Key Laboratory of Deep Earth Science and Engineering, Institute for Disaster Management and Reconstruction, Sichuan University, Chengdu, China
| | - Luyao Guo
- MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Linlin Chen
- MOE Key Laboratory of Deep Earth Science and Engineering, Institute for Disaster Management and Reconstruction, Sichuan University, Chengdu, China
| | - Li Zhao
- China Academy of Building Research, Beijing, China
| | - Qingqin Wang
- China Academy of Building Research, Beijing, China
| | - Enshen Long
- MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu, China
- MOE Key Laboratory of Deep Earth Science and Engineering, Institute for Disaster Management and Reconstruction, Sichuan University, Chengdu, China
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Oswin HP, Haddrell AE, Hughes C, Otero-Fernandez M, Thomas RJ, Reid JP. Oxidative Stress Contributes to Bacterial Airborne Loss of Viability. Microbiol Spectr 2023; 11:e0334722. [PMID: 36912675 PMCID: PMC10101003 DOI: 10.1128/spectrum.03347-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 01/18/2023] [Indexed: 03/14/2023] Open
Abstract
While the airborne decay of bacterial viability has been observed for decades, an understanding of the mechanisms driving the decay has remained elusive. The airborne transport of bacteria is often a key step in their life cycle and as such, characterizing the mechanisms driving the airborne decay of bacteria is an essential step toward a more complete understanding of microbial ecology. Using the Controlled Electrodynamic Levitation and Extraction of Bioaerosols onto a Substrate (CELEBS), it was possible to systematically evaluate the impact of different physicochemical and environmental parameters on the survival of Escherichia coli in airborne droplets of Luria Bertani broth. Rather than osmotic stress driving the viability loss, as was initially considered, oxidative stress was found to play a key role. As the droplets evaporate and equilibrate with the surrounding environment, the surface-to-volume ratio increases, which in turn increased the formation of reactive oxygen species in the droplet. These reactive oxygen species appear to play a key role in driving the airborne loss of viability of E. coli. IMPORTANCE The airborne transport of bacteria has a wide range of impacts, from disease transmission to cloud formation. By understanding the factors that influence the airborne stability of bacteria, we can better understand these processes. However, while we have known for several decades that airborne bacteria undergo a gradual loss of viability, we have not previously identified the mechanisms driving this process. In this work, we discovered that oxygen surrounding an airborne droplet facilitates the formation of reactive oxygen species within the droplet, which then gradually damage and kill bacteria within the droplet. This discovery indicates that adaptations to help bacteria deal with oxidative stress may also aid their airborne survival and be essential adaptations for bacterial airborne pathogens. Understanding the adaptations bacteria need to survive in airborne droplets could eventually lead to the development of novel antimicrobials designed to inhibit their airborne survival, helping to prevent the transmission of disease.
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Affiliation(s)
- Henry P. Oswin
- School of Chemistry, Cantock’s Close, University of Bristol, Bristol, United Kingdom
| | - Allen E. Haddrell
- School of Chemistry, Cantock’s Close, University of Bristol, Bristol, United Kingdom
| | - Cordelia Hughes
- School of Chemistry, Cantock’s Close, University of Bristol, Bristol, United Kingdom
| | - Mara Otero-Fernandez
- School of Chemistry, Cantock’s Close, University of Bristol, Bristol, United Kingdom
| | - Richard J. Thomas
- Defence Science Technology Laboratory (DSTL), Porton Down, Salisbury, United Kingdom
| | - Jonathan P. Reid
- School of Chemistry, Cantock’s Close, University of Bristol, Bristol, United Kingdom
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Vossen JMBMVD, Kreikamp AP, Hatt V, Ouwens AMT, Brasem D, Heerikhuisen M, Montijn RC. Establishment and application of test methodology demonstrating the functionality of air purification systems in reducing virus loaded aerosol in indoor air. J Hosp Infect 2023; 135:74-80. [PMID: 36918067 PMCID: PMC10008183 DOI: 10.1016/j.jhin.2023.03.004] [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: 01/05/2023] [Revised: 02/20/2023] [Accepted: 03/03/2023] [Indexed: 03/13/2023]
Abstract
BACKGROUND The global COVID-19 pandemic has resulted in a greater interest in improving the ventilation of indoor environments in order to remove aerosolized virus and thus reduce transmission. Air purification systems have been proposed as a solution to improve aerosol removal. AIM The aim is to determine the efficacy of air purification systems in reducing the viral load in environmental air of a room. METHODS A containment room equipped with HEPA filter on air intake and exhaust was constructed. It was connected via an inlet with the BSL-2 facility. From the BSL-2, Feline Corona virus (FCoV) loaded aerosols were released into the containment room. After nebulization, air sampling was performed to determine the viral load in air prior to assessing the clean air delivery rate of the air purification systems. The infectivity of the captured viruses was also examined. FINDINGS The air purification systems realized a 97 to 99% reduction in viral load in air in one hour. Captured infectious FCoV was reduced by 99.9% to 99.99% by use of an ESP technology. CONCLUSIONS The air purification systems, using ESP technology or HEPA filter, reduce the viral load in air. The ESP purifiers inactivate captured FCoV viruses. Therefore, air purification systems can be used as an adjunctive infection control measure.
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Affiliation(s)
- Jos M B M van der Vossen
- The Netherlands Organisation for Applied Scientific Research TNO, department of Microbiology and Systems Biology, Sylviusweg 71, 2333 BE LEIDEN, the Netherlands.
| | - Angelique P Kreikamp
- The Netherlands Organisation for Applied Scientific Research TNO, department of Microbiology and Systems Biology, Sylviusweg 71, 2333 BE LEIDEN, the Netherlands
| | - Volmar Hatt
- The Netherlands Organisation for Applied Scientific Research TNO, department of Microbiology and Systems Biology, Sylviusweg 71, 2333 BE LEIDEN, the Netherlands
| | - Anita M T Ouwens
- The Netherlands Organisation for Applied Scientific Research TNO, department of Microbiology and Systems Biology, Sylviusweg 71, 2333 BE LEIDEN, the Netherlands
| | - Dena Brasem
- The Netherlands Organisation for Applied Scientific Research TNO, department of Microbiology and Systems Biology, Sylviusweg 71, 2333 BE LEIDEN, the Netherlands
| | - Margreet Heerikhuisen
- The Netherlands Organisation for Applied Scientific Research TNO, department of Microbiology and Systems Biology, Sylviusweg 71, 2333 BE LEIDEN, the Netherlands
| | - Roy C Montijn
- The Netherlands Organisation for Applied Scientific Research TNO, department of Microbiology and Systems Biology, Sylviusweg 71, 2333 BE LEIDEN, the Netherlands
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UVC-Based Air Disinfection Systems for Rapid Inactivation of SARS-CoV-2 Present in the Air. Pathogens 2023; 12:pathogens12030419. [PMID: 36986341 PMCID: PMC10053150 DOI: 10.3390/pathogens12030419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/24/2022] [Accepted: 12/28/2022] [Indexed: 03/09/2023] Open
Abstract
The World Health Organization (WHO) declared in May 2021 that SARS-CoV-2 is transmitted not only by close contact with infectious respiratory fluids from infected people or contaminated materials but also indirectly through air. Airborne transmission has serious implications for the control measures we can deploy, given the emergence of more transmissible variants. This emphasizes the need to deploy a mechanism to reduce the viral load in the air, especially in closed and crowded places such as hospitals, public transport buses, etc. In this study, we explored ultraviolet C (UVC) radiation for its ability to inactivate the SARS-CoV-2 particles present in aerosols and designed an air disinfection system to eliminate infectious viruses. We studied the virus inactivation kinetics to identify the UVC dosage required to achieve maximum virus inactivation. Based on the experimental data, UVC-based devices were designed for the sanitization of air through HVAC systems in closed spaces. Further, a risk assessment model to estimate the risk reduction was applied which showed that the use of UVC radiation could result in the reduction of the risk of infection in occupied spaces by up to 90%.
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40
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Groth R, Niazi S, Spann K, Johnson GR, Ristovski Z. Physicochemical characterization of porcine respiratory aerosol and considerations for future aerovirology. PNAS NEXUS 2023; 2:pgad087. [PMID: 37007717 PMCID: PMC10063220 DOI: 10.1093/pnasnexus/pgad087] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/08/2023] [Indexed: 06/19/2023]
Abstract
Understanding the mechanisms which inactivate airborne viruses is a current challenge. The composition of human respiratory aerosol is poorly understood and needs to be adequately investigated for use in aerovirology studies. Here, the physicochemical properties of porcine respiratory fluid (PRF) from the trachea and lungs were investigated both in bulk solutions and in aerosols. The mass ratio of Na:K in PRF compared with cell culture media (Dulbecco's Modified Eagle Medium, DMEM), which is frequently used in aerovirology studies, was significantly lower (∼2:1 vs ∼16:1). PRF contained significantly more potassium and protein than DMEM. PRF aerosols of all samples were similarly hygroscopic to human respiratory aerosol. PRF particles could nucleate with spatially separated crystals, indicating that the protein matrix was sufficiently viscous to prevent the complete coalescence of aqueous salts prior to efflorescence. The effects of these differences in compositions on the viability of viruses are currently not well understood. The virus suspensions in aerovirology studies need to be reconsidered to adequately reflect a real-world expiration scenario.
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Affiliation(s)
- Robert Groth
- School of Earth and Atmospheric Sciences, International Laboratory for Air Quality and Health, Faculty of Science, Queensland University of Technology, Brisbane, QLD 4000, Australia
| | - Sadegh Niazi
- School of Earth and Atmospheric Sciences, International Laboratory for Air Quality and Health, Faculty of Science, Queensland University of Technology, Brisbane, QLD 4000, Australia
| | - Kirsten Spann
- School of Biomedical Sciences, Centre for Immunology and Infection Control, Faculty of Health, Queensland University of Technology, Brisbane, QLD 4000, Australia
| | - Graham R Johnson
- School of Earth and Atmospheric Sciences, International Laboratory for Air Quality and Health, Faculty of Science, Queensland University of Technology, Brisbane, QLD 4000, Australia
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Yang YF, Lin YJ, You SH, Lu TH, Chen CY, Wang WM, Liao CM. Control measure implications of COVID-19 infection in healthcare facilities reconsidered from human physiological and engineering aspects. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:36228-36243. [PMID: 36547825 PMCID: PMC9772602 DOI: 10.1007/s11356-022-24815-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
The Wells-Riley model invokes human physiological and engineering parameters to successfully treat airborne transmission of infectious diseases. Applications of this model would have high potentiality on evaluating policy actions and interventions intended to improve public safety efforts on preventing the spread of COVID-19 in an enclosed space. Here, we constructed the interaction relationships among basic reproduction number (R0) - exposure time - indoor population number by using the Wells-Riley model to provide a robust means to assist in planning containment efforts. We quantified SARS-CoV-2 changes in a case study of two Wuhan (Fangcang and Renmin) hospitals. We conducted similar approach to develop control measures in various hospital functional units by taking all accountable factors. We showed that inhalation rates of individuals proved crucial for influencing the transmissibility of SARS-CoV-2, followed by air supply rate and exposure time. We suggest a minimum air change per hour (ACH) of 7 h-1 would be at least appropriate with current room volume requirements in healthcare buildings when indoor population number is < 10 and exposure time is < 1 h with one infector and low activity levels being considered. However, higher ACH (> 16 h-1) with optimal arranged-exposure time/people and high-efficiency air filters would be suggested if more infectors or higher activity levels are presented. Our models lay out a practical metric for evaluating the efficacy of control measures on COVID-19 infection in built environments. Our case studies further indicate that the Wells-Riley model provides a predictive and mechanistic basis for empirical COVID-19 impact reduction planning and gives a framework to treat highly transmissible but mechanically heterogeneous airborne SARS-CoV-2.
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Affiliation(s)
- Ying-Fei Yang
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan
| | - Yi-Jun Lin
- Institute of Food Safety and Health Risk Assessment, National Yang Ming Chia Tung University, Taipei, 11221, Taiwan
| | - Shu-Han You
- Institute of Food Safety and Risk Management, National Taiwan Ocean University, Keelung City, 20224, Taiwan
| | - Tien-Hsuan Lu
- Department of Environmental Engineering, Da-Yeh University, Changhua, 515006, Taiwan
| | - Chi-Yun Chen
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan
| | - Wei-Min Wang
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan
| | - Chung-Min Liao
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan.
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Viral Preservation with Protein-Supplemented Nebulizing Media in Aerosols. Appl Environ Microbiol 2023; 89:e0154522. [PMID: 36856430 PMCID: PMC10057872 DOI: 10.1128/aem.01545-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023] Open
Abstract
The outbreak of SARS-CoV-2 has emphasized the need for a deeper understanding of infectivity, spread, and treatment of airborne viruses. Bacteriophages (phages) serve as ideal surrogates for respiratory pathogenic viruses thanks to their high tractability and the structural similarities tailless phages bear to viral pathogens. However, the aerosolization of enveloped SARS-CoV-2 surrogate phi6 usually results in a >3-log10 reduction in viability, limiting its usefulness as a surrogate for aerosolized coronavirus in "real world" contexts, such as a sneeze or cough. Recent work has shown that saliva or artificial saliva greatly improves the stability of viruses in aerosols and microdroplets relative to standard dilution/storage buffers like suspension medium (SM) buffer. These findings led us to investigate whether we could formulate media that preserves the viability of phi6 and other phages in artificially derived aerosols. Results indicate that SM buffer supplemented with bovine serum albumin (BSA) significantly improves the recovery of airborne phi6, MS2, and 80α and outperforms commercially formulated artificial saliva. Particle sizing and acoustic particle trapping data indicate that BSA supplementation dose-dependently improves viral survivability by reducing the extent of particle evaporation. These data suggest that our viral preservation medium may facilitate a lower-cost alternative to artificial saliva for future applied aerobiology studies. IMPORTANCE We have identified common and inexpensive lab reagents that confer increased aerosol survivability on phi6 and other phages. Our results suggest that soluble protein is a key protective component in nebulizing medium. Protein supplementation likely reduces exposure of the phage to the air-water interface by reducing the extent of particle evaporation. These findings will be useful for applications in which researchers wish to improve the survivability of these (and likely other) aerosolized viruses to better approximate highly transmissible airborne viruses like SARS-CoV-2.
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Norvihoho LK, Yin J, Zhou ZF, Han J, Chen B, Fan LH, Lichtfouse E. Mechanisms controlling the transport and evaporation of human exhaled respiratory droplets containing the severe acute respiratory syndrome coronavirus: a review. ENVIRONMENTAL CHEMISTRY LETTERS 2023; 21:1701-1727. [PMID: 36846189 PMCID: PMC9944801 DOI: 10.1007/s10311-023-01579-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 02/13/2023] [Indexed: 05/24/2023]
Abstract
Transmission of the coronavirus disease 2019 is still ongoing despite mass vaccination, lockdowns, and other drastic measures to control the pandemic. This is due partly to our lack of understanding on the multiphase flow mechanics that control droplet transport and viral transmission dynamics. Various models of droplet evaporation have been reported, yet there is still limited knowledge about the influence of physicochemical parameters on the transport of respiratory droplets carrying the severe acute respiratory syndrome coronavirus 2. Here we review the effects of initial droplet size, environmental conditions, virus mutation, and non-volatile components on droplet evaporation and dispersion, and on virus stability. We present experimental and computational methods to analyze droplet transport, and factors controlling transport and evaporation. Methods include thermal manikins, flow techniques, aerosol-generating techniques, nucleic acid-based assays, antibody-based assays, polymerase chain reaction, loop-mediated isothermal amplification, field-effect transistor-based assay, and discrete and gas-phase modeling. Controlling factors include environmental conditions, turbulence, ventilation, ambient temperature, relative humidity, droplet size distribution, non-volatile components, evaporation and mutation. Current results show that medium-sized droplets, e.g., 50 µm, are sensitive to relative humidity. Medium-sized droplets experience delayed evaporation at high relative humidity, and increase airborne lifetime and travel distance. By contrast, at low relative humidity, medium-sized droplets quickly shrink to droplet nuclei and follow the cough jet. Virus inactivation within a few hours generally occurs at temperatures above 40 °C, and the presence of viral particles in aerosols impedes droplet evaporation.
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Affiliation(s)
- Leslie Kojo Norvihoho
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Jing Yin
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Zhi-Fu Zhou
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Jie Han
- School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Bin Chen
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Li-Hong Fan
- The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, 710061 Shaanxi People’s Republic of China
| | - Eric Lichtfouse
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
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Luo B, Schaub A, Glas I, Klein LK, David SC, Bluvshtein N, Violaki K, Motos G, Pohl MO, Hugentobler W, Nenes A, Krieger UK, Stertz S, Peter T, Kohn T. Expiratory Aerosol pH: The Overlooked Driver of Airborne Virus Inactivation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:486-497. [PMID: 36537693 PMCID: PMC9835828 DOI: 10.1021/acs.est.2c05777] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 12/06/2022] [Accepted: 12/07/2022] [Indexed: 06/01/2023]
Abstract
Respiratory viruses, including influenza virus and SARS-CoV-2, are transmitted by the airborne route. Air filtration and ventilation mechanically reduce the concentration of airborne viruses and are necessary tools for disease mitigation. However, they ignore the potential impact of the chemical environment surrounding aerosolized viruses, which determines the aerosol pH. Atmospheric aerosol gravitates toward acidic pH, and enveloped viruses are prone to inactivation at strong acidity levels. Yet, the acidity of expiratory aerosol particles and its effect on airborne virus persistence have not been examined. Here, we combine pH-dependent inactivation rates of influenza A virus (IAV) and SARS-CoV-2 with microphysical properties of respiratory fluids using a biophysical aerosol model. We find that particles exhaled into indoor air (with relative humidity ≥ 50%) become mildly acidic (pH ∼ 4), rapidly inactivating IAV within minutes, whereas SARS-CoV-2 requires days. If indoor air is enriched with nonhazardous levels of nitric acid, aerosol pH drops by up to 2 units, decreasing 99%-inactivation times for both viruses in small aerosol particles to below 30 s. Conversely, unintentional removal of volatile acids from indoor air may elevate pH and prolong airborne virus persistence. The overlooked role of aerosol acidity has profound implications for virus transmission and mitigation strategies.
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Affiliation(s)
- Beiping Luo
- Institute
for Atmospheric and Climate Science, ETH
Zurich, CH-8092Zurich, Switzerland
| | - Aline Schaub
- Environmental
Chemistry Laboratory, School of Architecture, Civil and Environmental
Engineering, Ecole Polytechnique Fédérale
de Lausanne (EPFL), CH-1015Lausanne, Switzerland
| | - Irina Glas
- Institute
of Medical Virology, University of Zurich, CH-8057Zurich, Switzerland
| | - Liviana K. Klein
- Institute
for Atmospheric and Climate Science, ETH
Zurich, CH-8092Zurich, Switzerland
| | - Shannon C. David
- Environmental
Chemistry Laboratory, School of Architecture, Civil and Environmental
Engineering, Ecole Polytechnique Fédérale
de Lausanne (EPFL), CH-1015Lausanne, Switzerland
| | - Nir Bluvshtein
- Institute
for Atmospheric and Climate Science, ETH
Zurich, CH-8092Zurich, Switzerland
| | - Kalliopi Violaki
- Laboratory
of Atmospheric Processes and Their Impacts, School of Architecture,
Civil and Environmental Engineering, Ecole
Polytechnique Fédérale de Lausanne (EPFL), CH-1015Lausanne, Switzerland
| | - Ghislain Motos
- Laboratory
of Atmospheric Processes and Their Impacts, School of Architecture,
Civil and Environmental Engineering, Ecole
Polytechnique Fédérale de Lausanne (EPFL), CH-1015Lausanne, Switzerland
| | - Marie O. Pohl
- Institute
of Medical Virology, University of Zurich, CH-8057Zurich, Switzerland
| | - Walter Hugentobler
- Laboratory
of Atmospheric Processes and Their Impacts, School of Architecture,
Civil and Environmental Engineering, Ecole
Polytechnique Fédérale de Lausanne (EPFL), CH-1015Lausanne, Switzerland
| | - Athanasios Nenes
- Laboratory
of Atmospheric Processes and Their Impacts, School of Architecture,
Civil and Environmental Engineering, Ecole
Polytechnique Fédérale de Lausanne (EPFL), CH-1015Lausanne, Switzerland
- Institute
of Chemical Engineering Sciences, Foundation
for Research and Technology Hellas, GR-26504Patras, Greece
| | - Ulrich K. Krieger
- Institute
for Atmospheric and Climate Science, ETH
Zurich, CH-8092Zurich, Switzerland
| | - Silke Stertz
- Institute
of Medical Virology, University of Zurich, CH-8057Zurich, Switzerland
| | - Thomas Peter
- Institute
for Atmospheric and Climate Science, ETH
Zurich, CH-8092Zurich, Switzerland
| | - Tamar Kohn
- Environmental
Chemistry Laboratory, School of Architecture, Civil and Environmental
Engineering, Ecole Polytechnique Fédérale
de Lausanne (EPFL), CH-1015Lausanne, Switzerland
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The Skagit County choir COVID-19 outbreak - have we got it wrong? Public Health 2023; 214:85-90. [PMID: 36525760 PMCID: PMC9659549 DOI: 10.1016/j.puhe.2022.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 10/26/2022] [Accepted: 11/04/2022] [Indexed: 11/16/2022]
Abstract
OBJECTIVES Over time, papers or reports may come to be taken for granted as evidence for some phenomenon. Researchers cite them without critically re-examining findings in the light of subsequent work. This can give rise to misleading or erroneous results and conclusions. We explore whether this has occurred in the widely reported outbreak of SARS-CoV-2 at a rehearsal of the Skagit Valley Chorale in March 2020, where it was assumed, and subsequently asserted uncritically, that the outbreak was due to a single infected person. STUDY DESIGN Review of original report and subsequent modelling and interpretations. METHODS We reviewed and analysed original outbreak data in relation to published data on incubation period, subsequent modelling drawing on the data, and interpretations of transmission characteristics of this incident. RESULTS We show it is vanishingly unlikely that this was a single point source outbreak as has been widely claimed and on which modelling has been based. CONCLUSION An unexamined assumption has led to erroneous policy conclusions about the risks of singing, and indoor spaces more generally, and the benefits of increased levels of ventilation. Although never publicly identified, one individual bears the moral burden of knowing what health outcomes have been attributed to their actions. We call for these claims to be re-examined and for greater ethical responsibility in the assumption of a point source in outbreak investigations.
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Qiu G, Spillmann M, Tang J, Zhao Y, Tao Y, Zhang X, Geschwindner H, Saleh L, Zingg W, Wang J. On-Site Quantification and Infection Risk Assessment of Airborne SARS-CoV-2 Virus Via a Nanoplasmonic Bioaerosol Sensing System in Healthcare Settings. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2204774. [PMID: 36310114 PMCID: PMC9762303 DOI: 10.1002/advs.202204774] [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] [Received: 08/19/2022] [Revised: 10/06/2022] [Indexed: 05/31/2023]
Abstract
On-site quantification and early-stage infection risk assessment of airborne severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with high spatiotemporal resolution is a promising approach for mitigating the spread of coronavirus disease 2019 (COVID-19) pandemic and informing life-saving decisions. Here, a condensation (hygroscopic growth)-assisted bioaerosol collection and plasmonic photothermal sensing (CAPS) system for on-site quantitative risk analysis of SARS-CoV-2 virus-laden aerosols is presented. The CAPS system provided rapid thermoplasmonic biosensing results after an aerosol-to-hydrosol sampling process in COVID-19-related environments including a hospital and a nursing home. The detection limit reached 0.25 copies/µL in the complex aerosol background without further purification. More importantly, the CAPS system enabled direct measurement of the SARS-CoV-2 virus exposures with high spatiotemporal resolution. Measurement and feedback of the results to healthcare workers and patients via a QR-code are completed within two hours. Based on a dose-responseµ model, it is used the plasmonic biosensing signal to calculate probabilities of SARS-CoV-2 infection risk and estimate maximum exposure durations to an acceptable risk threshold in different environmental settings.
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Affiliation(s)
- Guangyu Qiu
- Institute of Environmental EngineeringETH ZürichZürich8093Switzerland
- Laboratory for Advanced Analytical TechnologiesEmpaSwiss Federal Laboratories for Materials Science and TechnologyDübendorf8600Switzerland
- Institute of Medical RoboticsShanghai Jiao Tong UniversityShanghaiP. R. China
| | - Martin Spillmann
- Institute of Environmental EngineeringETH ZürichZürich8093Switzerland
| | - Jiukai Tang
- Institute of Environmental EngineeringETH ZürichZürich8093Switzerland
- Laboratory for Advanced Analytical TechnologiesEmpaSwiss Federal Laboratories for Materials Science and TechnologyDübendorf8600Switzerland
| | - Yi‐Bo Zhao
- Institute of Environmental EngineeringETH ZürichZürich8093Switzerland
- Laboratory for Advanced Analytical TechnologiesEmpaSwiss Federal Laboratories for Materials Science and TechnologyDübendorf8600Switzerland
| | - Yile Tao
- Institute of Environmental EngineeringETH ZürichZürich8093Switzerland
| | - Xiaole Zhang
- Institute of Environmental EngineeringETH ZürichZürich8093Switzerland
| | - Heike Geschwindner
- Nursing Research and ScienceSenior Health Centres of the City of ZurichZurichSwitzerland
| | - Lanja Saleh
- Institute of Clinical ChemistryUniversity Hospital ZurichUniversity of ZurichZurich8091Switzerland
| | - Walter Zingg
- Clinic for Infectious Diseases and Hospital HygieneUniversity Hospital of ZurichZurich8091Switzerland
| | - Jing Wang
- Institute of Environmental EngineeringETH ZürichZürich8093Switzerland
- Laboratory for Advanced Analytical TechnologiesEmpaSwiss Federal Laboratories for Materials Science and TechnologyDübendorf8600Switzerland
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Bushmaker T, Yinda CK, Morris DH, Holbrook MG, Gamble A, Adney D, Bushmaker C, van Doremalen N, Fischer RJ, Plowright RK, Lloyd-Smith JO, Munster VJ. Comparative aerosol and surface stability of SARS-CoV-2 Variants of Concern. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2022:2022.11.21.517352. [PMID: 36451892 PMCID: PMC9709801 DOI: 10.1101/2022.11.21.517352] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
SARS-CoV-2 is transmitted principally via air; contact and fomite transmission may also occur. Variants-of-concern (VOCs) are more transmissible than ancestral SARS-CoV-2. We find that early VOCs show greater aerosol and surface stability than the early WA1 strain, but Delta and Omicron do not. Stability changes do not explain increased transmissibility.
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Snoring may transmit infectious aerosols from the upper to the lower respiratory tract. Med Hypotheses 2022; 168:110966. [PMID: 36317052 PMCID: PMC9605781 DOI: 10.1016/j.mehy.2022.110966] [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: 08/29/2022] [Revised: 10/17/2022] [Accepted: 10/20/2022] [Indexed: 11/25/2022]
Abstract
Migration to the lungs of an initial upper airway infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or other respiratory pathogens can lead to pneumonia, associated with progression from mild to severe symptoms. Chemical pneumonitis or bacterial pneumonia may be caused by the ‘macroaspiration’ of large volumes of oropharyngeal or gastroesophageal secretions into the lower respiratory tract. ‘Microaspiration’, i.e., a similar mechanism but involving much smaller amounts of oropharyngeal secretions, is considered the pathogenetic mechanism for most pneumonias, including that associated with COVID-19. Here, we hypothesize an alternative mechanism: Rather than by microaspiration, these fluids enter the lungs as microdroplets that are generated by snoring and then carried by the inspired airstream. Laboratory measurements indicate that snoring generates (a) comparable numbers and sizes of oral fluid droplets as loud speaking and (b) total fluid quantities that are similar to those reported for microaspiration. Snoring propensity is strongly correlated to known risk factors for severe COVID-19, including male gender, age, obesity, diabetes, obstructive sleep apnea, and pregnancy. Therefore, more research is urgently needed to determine if various methods that decrease snoring can prevent progression to pneumonia after initial infection of the upper airways.
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49
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Poydenot F, Abdourahamane I, Caplain E, Der S, Haiech J, Jallon A, Khoutami I, Loucif A, Marinov E, Andreotti B. Risk assessment for long- and short-range airborne transmission of SARS-CoV-2, indoors and outdoors. PNAS NEXUS 2022; 1:pgac223. [PMID: 36712338 PMCID: PMC9802175 DOI: 10.1093/pnasnexus/pgac223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 09/30/2022] [Indexed: 11/17/2022]
Abstract
Preventive measures to reduce infection are needed to combat the COVID-19 pandemic and prepare for a possible endemic phase. Current prophylactic vaccines are highly effective to prevent disease but lose their ability to reduce viral transmission as viral evolution leads to increasing immune escape. Long-term proactive public health policies must therefore complement vaccination with available nonpharmaceutical interventions aiming to reduce the viral transmission risk in public spaces. Here, we revisit the quantitative assessment of airborne transmission risk, considering asymptotic limits that considerably simplify its expression. We show that the aerosol transmission risk is the product of three factors: a biological factor that depends on the viral strain, a hydrodynamical factor defined as the ratio of concentration in viral particles between inhaled and exhaled air, and a face mask filtering factor. The short-range contribution to the risk, present both indoors and outdoors, is related to the turbulent dispersion of exhaled aerosols by air drafts and by convection (indoors), or by the wind (outdoors). We show experimentally that airborne droplets and CO2 molecules present the same dispersion. As a consequence, the dilution factor, and therefore the risk, can be measured quantitatively using the CO2 concentration, regardless of the room volume, the flow rate of fresh air, and the occupancy. We show that the dispersion cone leads to a concentration in viral particles, and therefore a short-range transmission risk, inversely proportional to the squared distance to an infected person and to the flow velocity. The aerosolization criterion derived as an intermediate result, which compares the Stokes relaxation time to the Lagrangian time-scale, may find application for a broad class of aerosol-borne pathogens and pollutants.
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Affiliation(s)
- Florian Poydenot
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Ismael Abdourahamane
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Elsa Caplain
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Samuel Der
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Jacques Haiech
- Cogitamus Laboratory and CNRS UMR 7242 BSC, 300 Bd Sébastien Brant, CS 10413, 67412 Illkirch Cedex, France
| | - Antoine Jallon
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Inés Khoutami
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Amir Loucif
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
| | - Emil Marinov
- Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS), CNRS UMR 8023, Ecole Normale Supérieure, Université PSL, Sorbonne Université, and Université Paris Cité, 24 rue Lhomond, 75005 Paris, France
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50
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Expiratory aerosol pH is determined by indoor room trace gases and particle size. Proc Natl Acad Sci U S A 2022; 119:e2212140119. [PMID: 36037391 PMCID: PMC9522367 DOI: 10.1073/pnas.2212140119] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
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