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Greentree DH, Wilson BM, Donskey CJ. Carbon Dioxide Monitoring Demonstrates Variations in the Quality of Ventilation on Public Transportation Buses and University Student Shuttle Vans and Identifies Effective Interventions. Pathog Immun 2023; 8:148-160. [PMID: 38035133 PMCID: PMC10686372 DOI: 10.20411/pai.v8i1.619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 10/13/2023] [Indexed: 12/02/2023] Open
Abstract
Background There is a risk for transmission of severe acute respiratory syndrome 2 (SARS-CoV-2) and other respiratory viruses in motor vehicles, particularly if ventilation is inadequate. Methods We used carbon dioxide monitoring to examine the quality of ventilation in several public transportation buses and in university student shuttle vans in the Cleveland metro area during peak and non-peak travel times. Carbon dioxide levels above 800 parts per million (ppm) were considered an indicator of suboptimal ventilation for the number of people present. In the shuttle vans, we evaluated the impact of an intervention to improve ventilation. Results In large articulated buses with 2 ventilation systems, carbon dioxide concentrations never exceeded 800 ppm, whereas in standard buses with 1 ventilation system concentrations rose above 800 ppm during peak travel times and on some trips during non-peak travel times. In shuttle vans, the ventilation system was not turned on during routine operation, and carbon dioxide levels rose above 800 ppm on all trips during peak and non-peak travel times. In the shuttle vans, an intervention involving operation of the existing ventilation system resulted in a significant reduction in carbon dioxide levels (mean concentration, 1,042 no intervention versus 785 with intervention; P < 0.001). Conclusions Our findings demonstrate substantial variability in the quality of ventilation in public transportation buses and university shuttle vans. There is a need for efforts to assess and optimize ventilation in motor vehicles used for public transportation to reduce the risk for aerosol-mediated transmission of respiratory viruses. Carbon dioxide monitoring may provide a useful tool to assess and improve ventilation.
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Affiliation(s)
- David Henry Greentree
- Department of Biology, College of Arts and Sciences, Case Western Reserve University, Cleveland, Ohio
- College of Medicine, The Ohio State University, Columbus, Ohio
| | - Brigid M. Wilson
- Geriatric Research, Education and Clinical Center, Louis Stokes Veterans Affairs Medical Center, Cleveland, Ohio
- School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Curtis J. Donskey
- Geriatric Research, Education and Clinical Center, Louis Stokes Veterans Affairs Medical Center, Cleveland, Ohio
- School of Medicine, Case Western Reserve University, Cleveland, Ohio
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Donskey CJ. High technology and low technology measures to reduce risk of SARS-CoV-2 transmission. Am J Infect Control 2023; 51:A126-A133. [PMID: 37890942 DOI: 10.1016/j.ajic.2023.03.007] [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: 03/07/2023] [Accepted: 03/09/2023] [Indexed: 10/29/2023]
Abstract
During the coronavirus disease 2019 (COVID-19) pandemic, a variety of low technology and high technology measures have been proposed to reduce the risk for transmission. Identifying those measures likely to be useful in reducing viral transmission without undue expense or potential for adverse effects has been a challenge for infection control programs. The challenge has been compounded by the lack of tools that can be used to assess the risk for viral transmission in different settings. This review discusses practical tools that can be used to assess ventilation and airflow and evaluates some of the low technology and high technology measures that have been proposed as control measures for COVID-19. Some typical questions posed to infection control programs during the pandemic are presented to illustrate real-world application of the concepts being discussed.
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Affiliation(s)
- Curtis J Donskey
- Geriatric Research, Education and Clinical Center, Louis Stokes Cleveland VA Medical Center, Cleveland, OH; Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH.
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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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Ha W, Stiefel MA, Gries JR, Cadnum JL, Torres-Teran MM, Wilson BM, Donskey CJ. Evaluation of Interventions to Improve Ventilation in Households to Reduce Risk for Transmission of Severe Acute Respiratory Syndrome Coronavirus 2. Pathog Immun 2022; 7:120-130. [PMID: 36655199 PMCID: PMC9836208 DOI: 10.20411/pai.v7i2.553] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 11/19/2022] [Indexed: 12/14/2022] Open
Abstract
Background Inadequate ventilation may contribute to the high risk for household transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods We evaluated the effectiveness of several interventions recommended to improve ventilation in households. In 7 residential homes, carbon dioxide monitoring was conducted to assess ventilation in occupied open areas such as family rooms and in bedrooms and/or offices. Carbon dioxide levels above 800 parts per million (ppm) were considered an indicator of suboptimal ventilation for the number of people present. In 1 of the 7 homes, various interventions to improve ventilation or to filter air were assessed in a kitchen area by measuring clearance of aerosol particles produced using an aerosol-based spray system and carbon dioxide generated by cooking with a gas stove. Results Carbon dioxide levels rose above 800 ppm in bedrooms and offices with 2 occupants when windows and doors were closed and in open areas during gatherings of 5 to 10 people; carbon dioxide levels decreased when windows or doors were opened. Clearance of carbon dioxide and aerosol particles significantly increased with interventions including running fans, operating portable air cleaners, and opening windows, particularly when there was a noticeable breeze or when a window fan was used to blow contaminated air outside. Conclusion In households, several measures to improve ventilation or air filtration were effective in reducing carbon dioxide accumulation or enhancing clearance of carbon dioxide and aerosol particles. Studies are needed to determine if interventions to improve ventilation can reduce the risk for airborne transmission of SARS-CoV-2 in households.
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Affiliation(s)
- Wilson Ha
- John Carroll University, University Heights, Ohio
| | | | | | - Jennifer L. Cadnum
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
| | | | - Brigid M. Wilson
- Geriatric Research, Education, and Clinical Center, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
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Safranek CW, Scheinker D. A computer modeling method to analyze rideshare data for the surveillance of novel strains of SARS-CoV-2. Ann Epidemiol 2022; 76:136-142. [PMID: 36087658 PMCID: PMC9452418 DOI: 10.1016/j.annepidem.2022.08.051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 07/15/2022] [Accepted: 08/29/2022] [Indexed: 12/14/2022]
Abstract
PURPOSE No method is available to systematically study SARS-CoV-2 transmission dynamics using the data that rideshare companies share with government agencies. We developed a proof-of-concept method for the analysis of SARS-CoV-2 transmissions between rideshare passengers and drivers. METHOD To assess whether this method could enable hypothesis testing about SARS-CoV-2, we repeated ten 200-day agent-based simulations of SARS-CoV-2 propagation within the Los Angeles County rideshare network. Assuming data access for 25% of infections, we estimated an epidemiologist's ability to analyze the observable infection patterns to correctly identify a baseline viral variant A, as opposed to viral variant A with mask use (50% reduction in viral particle exchange), or a more infectious viral variant B (300% higher cumulative viral load). RESULTS Simulations had an average of 190,387 potentially infectious rideshare interactions, resulting in 409 average diagnosed infections. Comparison of the number of observed and expected passenger-to-driver infections under each hypothesis demonstrated our method's ability to consistently discern large infectivity differences (viral variant A vs. viral variant B) given partial data from one large city, and to discern smaller infectivity differences (viral variant A vs. viral variant A with masks) given partial data aggregated across multiple cities. CONCLUSIONS This novel statistical method suggests that, for the present and subsequent pandemics, government-facilitated analysis of rideshare data combined with diagnosis records may augment efforts to better understand viral transmission dynamics and to measure changes in infectivity associated with nonpharmaceutical interventions and emergent viral strains.
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Affiliation(s)
- Conrad W. Safranek
- Department of Biology, Computational Biology, Stanford University, CA,Department of Management Science and Engineering, Stanford University School of Engineering, CA
| | - David Scheinker
- Department of Management Science and Engineering, Stanford University School of Engineering, CA; Department of Pediatrics, Stanford University School of Medicine, CA; Clinical Excellence Research Center, Stanford University School of Medicine, CA.
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Frequent detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA on hands and skin of patients with coronavirus disease 2019 (COVID-19). Infect Control Hosp Epidemiol 2022; 43:1976-1977. [PMID: 34486504 PMCID: PMC8446585 DOI: 10.1017/ice.2021.403] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Cadnum JL, Jencson AL, Memic S, Osborne AO, Torres-Teran MM, Wilson BM, Deshpande A, Donskey CJ. Real-World Evidence on the Effectiveness of Plexiglass Barriers in Reducing Aerosol Exposure. Pathog Immun 2022; 7:66-77. [PMID: 36381131 PMCID: PMC9651177 DOI: 10.20411/pai.v7i2.533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 10/13/2022] [Indexed: 08/17/2023] Open
Abstract
UNLABELLED Reprinted with permission, Cleveland Clinic Foundation ©2022. All Rights Reserved. BACKGROUND Barriers are commonly installed in workplace situations where physical distancing cannot be maintained to reduce the risk for transmission of respiratory viruses. Although some types of barriers have been shown to reduce exposure to aerosols in laboratory-based testing, limited information is available on the efficacy of barriers in real-world settings. METHODS In an acute care hospital, we tested the effectiveness of in-use plexiglass barriers in reducing exposure of staff to aerosolized particles. A nebulizer was used to release 5% NaCl aerosol 1 meter from staff members with and without the barrier positioned between the point of aerosol release and the hospital staff. Particle counts on the staff side of the barrier were measured using a 6-channel particle counter. A condensed moisture (fog) generating device was used to visualize the airflow patterns. RESULTS Of 13 in-use barriers tested, 6 (46%) significantly reduced aerosol particle counts detected behind the barrier, 6 (46%) reduced particle counts to a modest, non-significant degree, and 1 (8%) significantly increased particle counts behind the barrier. Condensed moisture fog accumulated in the area where staff were seated behind the barrier that increased particle exposure, but not behind the other barriers. After repositioning the ineffective barrier, the condensed moisture fog no longer accumulated behind the barrier and aerosol exposure was reduced. CONCLUSION In real-world settings, plexiglass barriers vary widely in effectiveness in reducing staff exposure to aerosols, and some barriers may increase risk for exposure if not positioned correctly. Devices that visualize airflow patterns may be useful as simple tools to assess barriers.
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Affiliation(s)
- Jennifer L. Cadnum
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
| | - Annette L. Jencson
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
| | - Samir Memic
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
| | | | | | - Brigid M. Wilson
- Case Western Reserve University School of Medicine, Cleveland, Ohio
- Geriatric Research, Education, and Clinical Center, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
| | - Abhishek Deshpande
- Center for Value-Based Care Research, Cleveland Clinic Lerner College of Medicine, Cleveland, Ohio
| | - Curtis J. Donskey
- Case Western Reserve University School of Medicine, Cleveland, Ohio
- Geriatric Research, Education, and Clinical Center, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
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A pilot randomized trial to evaluate the efficacy of oral and nasal povidone iodine in reducing the burden of severe acute respiratory syndrome coronavirus 2 RNA in patients with coronavirus disease 2019. Infect Control Hosp Epidemiol 2022; 44:679-681. [PMID: 36268600 DOI: 10.1017/ice.2022.257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Chan ER, Jones LD, Linger M, Kovach JD, Torres-Teran MM, Wertz A, Donskey CJ, Zimmerman PA. COVID-19 infection and transmission includes complex sequence diversity. PLoS Genet 2022; 18:e1010200. [PMID: 36074769 PMCID: PMC9455841 DOI: 10.1371/journal.pgen.1010200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 07/27/2022] [Indexed: 12/16/2022] Open
Abstract
SARS-CoV-2 whole genome sequencing has played an important role in documenting the emergence of polymorphisms in the viral genome and its continuing evolution during the COVID-19 pandemic. Here we present data from over 360 patients to characterize the complex sequence diversity of individual infections identified during multiple variant surges (e.g., Alpha and Delta). Across our survey, we observed significantly increasing SARS-CoV-2 sequence diversity during the pandemic and frequent occurrence of multiple biallelic sequence polymorphisms in all infections. This sequence polymorphism shows that SARS-CoV-2 infections are heterogeneous mixtures. Convention for reporting microbial pathogens guides investigators to report a majority consensus sequence. In our study, we found that this approach would under-report sequence variation in all samples tested. As we find that this sequence heterogeneity is efficiently transmitted from donors to recipients, our findings illustrate that infection complexity must be monitored and reported more completely to understand SARS-CoV-2 infection and transmission dynamics. Many of the nucleotide changes that would not be reported in a majority consensus sequence have now been observed as lineage defining SNPs in Omicron BA.1 and/or BA.2 variants. This suggests that minority alleles in earlier SARS-CoV-2 infections may play an important role in the continuing evolution of new variants of concern.
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Affiliation(s)
- Ernest R. Chan
- Institute for Computational Biology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Lucas D. Jones
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Marlin Linger
- The Center for Global Health & Diseases, Pathology Department, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Jeffrey D. Kovach
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America
- The Center for Global Health & Diseases, Pathology Department, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Maria M. Torres-Teran
- Pathology Department, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Audric Wertz
- Biology Department, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Curtis J. Donskey
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Geriatric Research, Education, and Clinical Center, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, United States of America
| | - Peter A. Zimmerman
- The Center for Global Health & Diseases, Pathology Department, Case Western Reserve University, Cleveland, Ohio, United States of America
- Master of Public Health Program, Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America
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If you can’t measure it, you can’t improve it: Practical tools to assess ventilation and airflow patterns to reduce the risk for transmission of severe acute respiratory syndrome coronavirus 2 and other airborne pathogens. Infect Control Hosp Epidemiol 2022; 43:915-917. [PMID: 35379373 PMCID: PMC9021581 DOI: 10.1017/ice.2022.103] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Numerical Investigation on the Droplet Dispersion inside a Bus and the Infection Risk Prediction. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12125909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
COVID-19 can be easily transmitted to passengers by inhaling exhaled droplets from the infected person in a bus. Therefore, studying droplet dispersion would provide further insight into the mechanism of virus transmission and predict the risk of infection among passengers on a bus. In this research, a bus equipped with air-conditioning was employed as the research object. To determine the dispersion path, concentration distribution, and escape time of the droplets, computational fluid dynamic (CFD) was applied to simulate the flow field and the droplets’ dispersion. The effect of the air supply rate, the location of vents, and the location of infected persons on the dispersion were discussed. Based on the distribution of droplets in the cabin calculated by CFD, a superposition method was used to determine the number of virus particles inhaled by every individual passenger over a four-hour journey. Then, infection risk was assessed by the Wells-Riley equation for all the passengers in the cabin after the whole journey. The results show that the distribution of droplets in the cabin is greatly influenced by the location of the infected person, and the airflow pattern is highly associated with the air supply rate and the location of vents. The infection risk of passengers located at the droplet dispersion path and the distance from the infected persons less than 2.2 m is over 10%. The increase in the air supply rate could speed up the spread of the droplets but at the same time, it could reduce the infection risk.
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Cadnum JL, Jencson AL, Alhmidi H, Zabarsky TF, Donskey CJ. Airflow Patterns in Double-Occupancy Patient Rooms May Contribute to Roommate-to-Roommate Transmission of Severe Acute Respiratory Syndrome Coronavirus 2. Clin Infect Dis 2022; 75:2128-2134. [PMID: 35476020 PMCID: PMC9129113 DOI: 10.1093/cid/ciac334] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 04/15/2022] [Accepted: 04/25/2022] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Hospitalized patients are at risk to acquire severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from roommates with unrecognized coronavirus disease 2019 (COVID-19). We hypothesized that airflow patterns might contribute to SARS-CoV-2 transmission in double-occupancy patient rooms. METHODS A device emitting condensed moisture was used to identify airflow patterns in double-occupancy patient rooms. Simulations were conducted to assess transfer of fluorescent microspheres, 5% sodium chloride aerosol, and aerosolized bacteriophage MS2 between patient beds 3 meters apart and to assess the effectiveness of privacy curtains and portable air cleaners in reducing transfer. RESULTS Air flowed from inlet vents in the center of the room to an outlet vent near the door, resulting in air currents flowing toward the bed adjacent to the outlet vent. Fluorescent microspheres (212-250-µm diameter), 5% sodium chloride aerosol, and aerosolized bacteriophage MS2 released from the inner bed were carried on air currents toward the bed adjacent to the outlet vent. Closing curtains between the patient beds reduced transfer of each of the particles. Operation of a portable air cleaner reduced aerosol transfer to the bed adjacent to the outlet vent but did not offer a benefit over closing the curtains alone, and in some situations, resulted in an increase in aerosol exposure. CONCLUSIONS Airflow patterns in double-occupancy patient rooms may contribute to risk for transmission of SARS-CoV-2 between roommates. Keeping curtains closed between beds may be beneficial in reducing risk.
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Affiliation(s)
- Jennifer L. Cadnum
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, USA
| | - Annette L. Jencson
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, USA
| | - Heba Alhmidi
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, USA
| | - Trina F. Zabarsky
- Infection Control Department, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, USA
| | - Curtis J. Donskey
- Geriatric Research, Education, and Clinical Center, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, USA,Case Western Reserve University School of Medicine, Cleveland, Ohio, USA,Corresponding author: Curtis J. Donskey, Infectious Diseases Section 1110W, Louis Stokes Cleveland VA Medical Center, 10701 East Boulevard, Cleveland, Ohio 44106, USA;
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Cadnum JL, Alhmidi H, Donskey CJ. Planes, Trains, and Automobiles: Use of Carbon Dioxide Monitoring to Assess Ventilation During Travel. Pathog Immun 2022; 7:31-40. [PMID: 35316971 PMCID: PMC8932639 DOI: 10.20411/pai.v7i1.495] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/16/2022] [Indexed: 11/23/2022] Open
Abstract
Background: Travel poses a risk for transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other respiratory viruses. Poorly ventilated indoor settings pose a particularly high risk for transmission.
Methods: We used carbon dioxide measurements to assess adequacy of ventilation during 5 trips that included air travel. During selected parts of each trip that involved indoor settings, we monitored carbon dioxide levels every 1 minute and recorded peak levels and the number of people present. Carbon dioxide readings above 800 parts per million (ppm) were considered an indicator of suboptimal ventilation.
Results: Carbon dioxide levels remained below 800 ppm during train rides to and from the airport and inside airports except in a crowded boarding area with ~300 people present. Carbon dioxide levels exceeded 800 ppm inside the airplanes, but the air was filtered with high efficiency particulate air filters. Carbon dioxide levels remained below 800 ppm in common areas of a hotel but exceeded 800 ppm in a hotel room with 2 to 3 occupants and in a fitness center with 3 people exercising. In restaurants, carbon dioxide levels increased above 800 ppm during crowded conditions with 24 or more people present and 75% or more seat occupancy.
Conclusion: Our results suggest that ventilation may be sufficient to minimize the risk for airborne transmission in many situations during travel. However, ventilation may be suboptimal in some areas or under certain conditions such as in hotel rooms or when restaurants, fitness centers, or airplane boarding areas are crowded. There is a need for larger scale studies to assess the quality of ventilation in a wide range of community settings.
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Affiliation(s)
- Jennifer L. Cadnum
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
| | - Heba Alhmidi
- Geriatric Research, Education, and Clinical Center, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
| | - Curtis J. Donskey
- Geriatric Research, Education, and Clinical Center, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
- Case Western Reserve University School of Medicine, Cleveland, Ohio
- CORRESPONDING AUTHOR Curtis J. Donskey, Infectious Diseases Section 1110W, Louis Stokes Cleveland VA Medical Center 10701 East Boulevard, Cleveland, Ohio 44106; Phone: 216-791-3800 ext. 64788; Fax: 216-229-8509;
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Modeling Transport of SARS-CoV-2 Inside a Charlotte Area Transit System (CATS) Bus. FLUIDS 2022. [DOI: 10.3390/fluids7020080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We present in this paper a model of the transport of human respiratory particles on a Charlotte Area Transit System (CATS) bus to examine the efficacy of interventions to limit exposure to SARS-CoV-2, the virus that causes COVID-19. The methods discussed here utilize a commercial Navier–Stokes flow solver, RavenCFD, using a massively parallel supercomputer to model the flow of air through the bus under varying conditions, such as windows being open or the HVAC flow settings. Lagrangian particles are injected into the RavenCFD predicted flow fields to simulate the respiratory droplets from speaking, coughing, or sneezing. These particles are then traced over time and space until they interact with a surface or are removed via the HVAC system. Finally, a volumetric Viral Mean Exposure Time (VMET) is computed to quantify the risk of exposure to the SARS-CoV-2 under various environmental and occupancy scenarios. Comparing the VMET under varying conditions should help identify viable methods to reduce the risk of viral exposure of CATS bus passengers during the COVID-19 pandemic.
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Haq MF, Cadnum JL, Carlisle M, Hecker MT, Donskey CJ. SARS in Cars: Carbon Dioxide Levels Provide a Simple Means to Assess Ventilation in Motor Vehicles. Pathog Immun 2022; 7:19-30. [PMID: 35178491 PMCID: PMC8843085 DOI: 10.20411/pai.v7i1.493] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 01/14/2022] [Indexed: 11/25/2022] Open
Abstract
Background: Poorly ventilated enclosed spaces pose a risk for airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other respiratory viruses. Limited information is available on ventilation in motor vehicles under differing driving conditions. Methods: We conducted carbon dioxide measurements to assess ventilation in motor vehicles under varying driving conditions with 2 to 3 vehicle occupants. During routine driving, carbon dioxide produced by the breathing of vehicle occupants was measured inside 5 cars and a van under a variety of driving conditions with or without the ventilation fan on and with windows open or closed. Carbon dioxide readings above 800 parts per million (ppm) were considered an indicator of suboptimal ventilation. Results: Carbon dioxide levels remained below 800 ppm in all vehicles if the ventilation fan was on and/or the windows were open while parked or during city or highway driving. With the ventilation system set on non-recirculation mode, carbon dioxide levels rose above 800 ppm in all vehicles when the fan was off and the windows were closed while parked and during city driving, and in 2 of the 6 vehicles during highway driving. With the ventilation system set on recirculation mode, carbon dioxide rose above 800 ppm within 10 minutes in all vehicles tested. Conclusion: Carbon dioxide measurements could provide a practical and rapid method to assess ventilation in motor vehicles. Simple measures such as opening windows, turning on the fan, and avoiding the recirculation mode greatly improve ventilation.
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Affiliation(s)
- Muhammed F. Haq
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
| | - Jennifer L. Cadnum
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
| | - Matthew Carlisle
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
| | - Michelle T. Hecker
- Department of Infectious Diseases, MetroHealth Medical Center, Cleveland, Ohio
- Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Curtis J. Donskey
- Case Western Reserve University School of Medicine, Cleveland, Ohio
- Research, Education, and Clinical Center, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
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Ha W, Zabarsky TF, Eckstein EC, Alhmidi H, Jencson AL, Cadnum JL, Donskey CJ. Use of carbon dioxide measurements to assess ventilation in an acute care hospital. Am J Infect Control 2022; 50:229-232. [PMID: 34848292 PMCID: PMC8627286 DOI: 10.1016/j.ajic.2021.11.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/14/2021] [Accepted: 11/18/2021] [Indexed: 11/01/2022]
Abstract
Poorly ventilated indoor spaces pose a risk for airborne transmission of SARS-CoV-2. We measured carbon dioxide levels in a multiple areas in an acute care hospital to assess the adequacy of ventilation. Carbon dioxide levels remained below 800 parts per million in most areas but exceeded this level in a small conference room with 8 occupants, an office with 3 occupants, and a bathroom with 2 occupants. Measuring carbon dioxide levels could provide a simple means for healthcare facilities to assess the adequacy of ventilation.
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17
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Klompas M. New Insights into the Prevention of Hospital-Acquired Pneumonia/Ventilator-Associated Pneumonia Caused by Viruses. Semin Respir Crit Care Med 2022; 43:295-303. [PMID: 35042261 DOI: 10.1055/s-0041-1740582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
A fifth or more of hospital-acquired pneumonias may be attributable to respiratory viruses. The SARS-CoV-2 pandemic has clearly demonstrated the potential morbidity and mortality of respiratory viruses and the constant threat of nosocomial transmission and hospital-based clusters. Data from before the pandemic suggest the same can be true of influenza, respiratory syncytial virus, and other respiratory viruses. The pandemic has also helped clarify the primary mechanisms and risk factors for viral transmission. Respiratory viruses are primarily transmitted by respiratory aerosols that are routinely emitted when people exhale, talk, and cough. Labored breathing and coughing increase aerosol generation to a much greater extent than intubation, extubation, positive pressure ventilation, and other so-called aerosol-generating procedures. Transmission risk is proportional to the amount of viral exposure. Most transmissions take place over short distances because respiratory emissions are densest immediately adjacent to the source but then rapidly dilute and diffuse with distance leading to less viral exposure. The primary risk factors for transmission then are high viral loads, proximity, sustained exposure, and poor ventilation as these all increase net viral exposure. Poor ventilation increases the risk of long-distance transmission by allowing aerosol-borne viruses to accumulate over time leading to higher levels of exposure throughout an enclosed space. Surgical and procedural masks reduce viral exposure but do not eradicate it and thus lower but do not eliminate transmission risk. Most hospital-based clusters have been attributed to delayed diagnoses, transmission between roommates, and staff-to-patient infections. Strategies to prevent nosocomial respiratory viral infections include testing all patients upon admission, preventing healthcare providers from working while sick, assuring adequate ventilation, universal masking, and vaccinating both patients and healthcare workers.
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Affiliation(s)
- Michael Klompas
- Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Healthcare Institute, Boston, Massachusetts.,Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts
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18
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Yang Y, Wang Y, Tian L, Su C, Chen Z, Huang Y. Effects of purifiers on the airborne transmission of droplets inside a bus. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2022; 34:017108. [PMID: 35340683 PMCID: PMC8939553 DOI: 10.1063/5.0081230] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 12/28/2021] [Indexed: 05/25/2023]
Abstract
During an airborne infectious disease outbreak, bus passengers can be easily infected by the dispersion of exhaled droplets from an infected passenger. Therefore, measures to control the transport of droplets are necessary, such as a mask or purifier. The current research examined aerosol transport in a bus with air-conditioning. To determine the dispersion path, deposition distribution, and droplet escape time, the computational fluid dynamics were used to predict the flow field and the dispersion of droplets considering the effects of droplet size, location of the infected person, and purifier type. In addition, based on the viability and the number of virus particles in a droplet, the total number of virus particles inhaled by passengers over a 4-h journey was obtained by the superposition method. The Wells-Riley equation was then used to assess the infection risk of the passengers in the bus cabin. The results showed that droplets with a size of 1-20 μm have essentially the same deposition characteristics, and the location of the infected passenger affects the distribution of droplets' transport and the effectiveness of a purifier in removing droplets. A purifier can effectively remove droplets from passengers' coughs and reduce the infection risk of passengers. The performance of the smaller purifiers is not as stable as that of the larger purifiers, and the performance is influenced by the airflow structure where the infected passenger is located.
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Affiliation(s)
| | | | - Linli Tian
- Author to whom correspondence should be addressed:. Tel.: 0086-13317136217
| | | | - Zhixin Chen
- Hubei Key Laboratory of Advanced Technology for Automotive Components, Wuhan University of Technology, Wuhan, Hubei 430070, China
| | - Yuanyi Huang
- SAIC GM Wuling Automobile Co., Ltd, Liuzhou, Guangxi 545000, China
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19
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Kriegel M, Hartmann A, Buchholz U, Seifried J, Baumgarte S, Gastmeier P. SARS-CoV-2 Aerosol Transmission Indoors: A Closer Look at Viral Load, Infectivity, the Effectiveness of Preventive Measures and a Simple Approach for Practical Recommendations. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 19:220. [PMID: 35010484 PMCID: PMC8750733 DOI: 10.3390/ijerph19010220] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 12/12/2022]
Abstract
There is uncertainty about the viral loads of infectious individuals required to transmit COVID-19 via aerosol. In addition, there is a lack of both quantification of the influencing parameters on airborne transmission and simple-to-use models for assessing the risk of infection in practice, which furthermore quantify the influence of non-medical preventive measures. In this study, a dose-response model was adopted to analyze 25 documented outbreaks at infection rates of 4-100%. We show that infection was only possible if the viral load was higher than 108 viral copies/mL. Based on mathematical simplifications of our approach to predict the probable situational attack rate (PARs) of a group of persons in a room, and valid assumptions, we provide simplified equations to calculate, among others, the maximum possible number of persons and the person-related virus-free air supply flow necessary to keep the number of newly infected persons to less than one. A comparison of different preventive measures revealed that testing contributes the most to the joint protective effect, besides wearing masks and increasing ventilation. In addition, we conclude that absolute volume flow rate or person-related volume flow rate are more intuitive parameters for evaluating ventilation for infection prevention than air exchange rate.
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Affiliation(s)
- Martin Kriegel
- Hermann-Rietschel-Institut, Technical University of Berlin, 10623 Berlin, Germany;
| | - Anne Hartmann
- Hermann-Rietschel-Institut, Technical University of Berlin, 10623 Berlin, Germany;
| | - Udo Buchholz
- Department for Infectious Disease Epidemiology, Robert Koch Institute, 13353 Berlin, Germany; (U.B.); (J.S.)
| | - Janna Seifried
- Department for Infectious Disease Epidemiology, Robert Koch Institute, 13353 Berlin, Germany; (U.B.); (J.S.)
| | | | - Petra Gastmeier
- Institute for Hygiene and Environmental Medicine, Charité-University Medicine Berlin, 12203 Berlin, Germany;
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20
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Do plexiglass barriers reduce the risk for transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)? Infect Control Hosp Epidemiol 2021:1-4. [PMID: 34726150 DOI: 10.1017/ice.2021.383] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Barriers are commonly installed in workplace situations where physical distancing cannot be maintained, but their effectiveness in decreasing viral transmission is unknown. In simulations, physical barriers with no openings were effective in reducing contamination with an aerosolized benign virus or fluorescent microspheres, but barriers with openings were not.
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21
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Klompas M, Ye S, Vaidya V, Ochoa A, Baker MA, Hopcia K, Hashimoto D, Wang R, Rhee C. Association between Airborne Infection Isolation Room Utilization Rates and Healthcare Worker COVID-19 Infections in Two Academic Hospitals. Clin Infect Dis 2021; 74:2230-2233. [PMID: 34599821 PMCID: PMC8500060 DOI: 10.1093/cid/ciab849] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Indexed: 12/12/2022] Open
Abstract
We compared healthcare worker SARS-CoV-2 infection rates between March-August 2020 in two similar hospitals with high versus low airborne infection isolation room utilization rates but otherwise identical infection control policies. We found no difference in healthcare worker infection rates between the two hospitals nor between patient-facing vs non-patient-facing providers.
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Affiliation(s)
- Michael Klompas
- Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, USA.,Infection Control Department, Brigham and Women's Hospital, Boston, MA, USA
| | - Shangyuan Ye
- Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, USA
| | - Vineeta Vaidya
- Infection Control Department, Brigham and Women's Hospital, Boston, MA, USA
| | - Aileen Ochoa
- Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, USA.,Infection Control Department, Brigham and Women's Hospital, Boston, MA, USA
| | - Meghan A Baker
- Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, USA.,Infection Control Department, Brigham and Women's Hospital, Boston, MA, USA
| | - Karen Hopcia
- Occupational Health Services, Mass General Brigham, Boston, MA, USA
| | - Dean Hashimoto
- Occupational Health Services, Mass General Brigham, Boston, MA, USA
| | - Rui Wang
- Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, USA
| | - Chanu Rhee
- Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, USA.,Infection Control Department, Brigham and Women's Hospital, Boston, MA, USA
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