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Pei G, Azimi P, Rim D, Allen JG. A CFD study on the effect of portable air cleaner placement on airborne infection control in a classroom. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2024; 26:1476-1488. [PMID: 38973672 PMCID: PMC11410509 DOI: 10.1039/d4em00114a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
The utilization of portable air cleaners (PACs) is a recommended supplemental approach to help remove airborne pathogens and mitigate disease transmission in learning environments. To improve PAC effectiveness, science-based information is needed to optimize their implementation strategies such as the deployment location, height, and number of PACs. In this study, we developed a Computational Fluid Dynamics (CFD) model to assess how PACs perform in occupied classrooms equipped with displacement and mixing ventilation systems. The results show that PACs with a flow rate of 2.6 h-1 reduce the mean aerosol intake of all students by up to 66%. A key benefit of using PACs is to facilitate air mixing and movement in indoor environments with inadequate ventilation, thereby effectively reducing high aerosol concentrations near the infector. Furthermore, our results highlight the impact of PAC location on its performance. PACs achieve the best effectiveness when placed closed to the infector (within a distance <3 m). In the absence of knowing who is infected, deploying a PAC at the center of the room is recommended. Moreover, adjusting PAC flow discharge height to the breathing height of occupants (e.g., 0.9-1.2 m for seated people) can enhance their effectiveness in spaces with poor air mixing.
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Affiliation(s)
- Gen Pei
- Environmental Health Department, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA.
| | - Parham Azimi
- Environmental Health Department, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA.
| | - Donghyun Rim
- Architectural Engineering Department, Pennsylvania State University, University Park, PA 16802, USA
| | - Joseph G Allen
- Environmental Health Department, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA.
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2
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Alqarni Z, Rezgui Y, Petri I, Ghoroghi A. Viral infection transmission and indoor air quality: A systematic review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 923:171308. [PMID: 38432379 DOI: 10.1016/j.scitotenv.2024.171308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/03/2024] [Accepted: 02/25/2024] [Indexed: 03/05/2024]
Abstract
Respiratory disease transmission in indoor environments presents persistent challenges for health authorities, as exemplified by the recent COVID-19 pandemic. This underscores the urgent necessity to investigate the dynamics of viral infection transmission within indoor environments. This systematic review delves into the methodologies of respiratory infection transmission in indoor settings and explores how the quality of indoor air (IAQ) can be controlled to alleviate this risk while considering the imperative of sustainability. Among the 2722 articles reviewed, 178 were retained based on their focus on respiratory viral infection transmission and IAQ. Fifty eight articles delved into SARS-CoV-2 transmission, 21 papers evaluated IAQ in contexts of other pandemics, 53 papers assessed IAQ during the SARS-CoV-2 pandemic, and 46 papers examined control strategies to mitigate infectious transmission. Furthermore, of the 46 papers investigating control strategies, only nine considered energy consumption. These findings highlight clear gaps in current research, such as analyzing indoor air and surface samples for specific indoor environments, oversight of indoor and outdoor parameters (e.g., temperature, relative humidity (RH), and building orientation), neglect of occupancy schedules, and the absence of considerations for energy consumption while enhancing IAQ. This study distinctly identifies the indoor environmental conditions conducive to the thriving of each respiratory virus, offering IAQ trade-offs to mitigate the risk of dominant viruses at any given time. This study argues that future research should involve digital twins in conjunction with machine learning (ML) techniques. This approach aims to enhance IAQ by analyzing the transmission patterns of various respiratory viruses while considering energy consumption.
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Affiliation(s)
- Zahi Alqarni
- School of Engineering, Cardiff University, Cardiff CF24 3AA, UK; School of Computer Science, King Khalid University, Abha 62529, Saudi Arabia.
| | - Yacine Rezgui
- School of Engineering, Cardiff University, Cardiff CF24 3AA, UK
| | - Ioan Petri
- School of Engineering, Cardiff University, Cardiff CF24 3AA, UK
| | - Ali Ghoroghi
- School of Engineering, Cardiff University, Cardiff CF24 3AA, UK
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3
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Dacunto P, Nam S, Hirn M, Rodriguez A, Owkes M, Benson M. Classroom aerosol dispersion modeling: experimental assessment of a low-cost flow simulation tool. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:2157-2166. [PMID: 37966351 DOI: 10.1039/d3em00356f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
The purpose of this study was to assess the utility of a low-cost flow simulation tool for an indoor air modeling application by comparing its outputs with the results of a physical experiment, as well as those from a more advanced computational fluid dynamics (CFD) software package. Five aerosol dispersion tests were performed in two different classrooms by releasing a CO2 tracer gas from six student locations. Resultant steady-state concentrations were monitored at 13 locations around the periphery of the room. Subsequently, the experiments were modeled using both a low-cost tool (SolidWorks Flow Simulation) and a more sophisticated tool (STAR-CCM+). Models were evaluated based on their ability to predict the experimentally measured concentrations at the 13 monitoring locations by calculating four performance parameters commonly used in the evaluation of dispersion models: fractional mean bias (FB), normalized mean-square error (NMSE), fraction of predicted value within a factor of two (FAC2), and normalized absolute difference (NAD). The more sophisticated model performed better in 15 of the 20 possible cases (five tests at four parameters each), with parameters meeting acceptance criteria in 19 of 20 cases. However, the lower-cost tool was only slightly worse, with parameters meeting acceptance criteria in 18 of 20 cases, and it performed better than the other tool in 3 of 20 cases. Because it provides useful results at a fraction of the monetary and training cost and is already widely accessible to many institutions, such a tool may be worthwhile for many indoor aerosol dispersion applications, especially for students or researchers just beginning CFD modeling.
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Affiliation(s)
- P Dacunto
- United States Military Academy, Department of Geography and Environmental Engineering, West Point NY 10996, USA.
| | - S Nam
- United States Military Academy, Department of Geography and Environmental Engineering, West Point NY 10996, USA.
| | - M Hirn
- United States Military Academy, Department of Geography and Environmental Engineering, West Point NY 10996, USA.
| | - A Rodriguez
- United States Military Academy, Department of Civil and Mechanical Engineering, West Point NY 10996, USA
| | - M Owkes
- Montana State University, Department of Mechanical and Industrial Engineering, Bozeman MT 59717, USA
| | - M Benson
- United States Military Academy, Department of Civil and Mechanical Engineering, West Point NY 10996, USA
- Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
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Castellini JE, Faulkner CA, Zuo W, Sohn MD. Quantifying spatiotemporal variability in occupant exposure to an indoor airborne contaminant with an uncertain source location. BUILDING SIMULATION 2023; 16:889-913. [PMID: 37192915 PMCID: PMC9986047 DOI: 10.1007/s12273-022-0971-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 11/10/2022] [Accepted: 11/28/2022] [Indexed: 05/18/2023]
Abstract
Well-mixed zone models are often employed to compute indoor air quality and occupant exposures. While effective, a potential downside to assuming instantaneous, perfect mixing is underpredicting exposures to high intermittent concentrations within a room. When such cases are of concern, more spatially resolved models, like computational-fluid dynamics methods, are used for some or all of the zones. But, these models have higher computational costs and require more input information. A preferred compromise would be to continue with a multi-zone modeling approach for all rooms, but with a better assessment of the spatial variability within a room. To do so, we present a quantitative method for estimating a room's spatiotemporal variability, based on influential room parameters. Our proposed method disaggregates variability into the variability in a room's average concentration, and the spatial variability within the room relative to that average. This enables a detailed assessment of how variability in particular room parameters impacts the uncertain occupant exposures. To demonstrate the utility of this method, we simulate contaminant dispersion for a variety of possible source locations. We compute breathing-zone exposure during the releasing (source is active) and decaying (source is removed) periods. Using CFD methods, we found after a 30 minutes release the average standard deviation in the spatial distribution of exposure was approximately 28% of the source average exposure, whereas variability in the different average exposures was lower, only 10% of the total average. We also find that although uncertainty in the source location leads to variability in the average magnitude of transient exposure, it does not have a particularly large influence on the spatial distribution during the decaying period, or on the average contaminant removal rate. By systematically characterizing a room's average concentration, its variability, and the spatial variability within the room important insights can be gained as to how much uncertainty is introduced into occupant exposure predictions by assuming a uniform in-room contaminant concentration. We discuss how the results of these characterizations can improve our understanding of the uncertainty in occupant exposures relative to well-mixed models.
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Affiliation(s)
- John E. Castellini
- Department of Mechanical Engineering, University of Colorado Boulder, UCB 427, Boulder, CO 80309 USA
| | - Cary A. Faulkner
- Department of Mechanical Engineering, University of Colorado Boulder, UCB 427, Boulder, CO 80309 USA
| | - Wangda Zuo
- Department Architectural Engineering, The Pennsylvania State University, University Park, PA 16802 USA
- National Renewable Energy National Laboratory, Golden, CO 80401 USA
| | - Michael D. Sohn
- Energy Analysis and Environmental Impacts Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 USA
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de Crane D’Heysselaer S, Parisi G, Lisson M, Bruyère O, Donneau AF, Fontaine S, Gillet L, Bureau F, Darcis G, Thiry E, Ducatez M, Snoeck CJ, Zientara S, Haddad N, Humblet MF, Ludwig-Begall LF, Daube G, Thiry D, Misset B, Lambermont B, Tandjaoui-Lambiotte Y, Zahar JR, Sartor K, Noël C, Saegerman C, Haubruge E. Systematic Review of the Key Factors Influencing the Indoor Airborne Spread of SARS-CoV-2. Pathogens 2023; 12:382. [PMID: 36986304 PMCID: PMC10053454 DOI: 10.3390/pathogens12030382] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 02/19/2023] [Accepted: 02/20/2023] [Indexed: 03/06/2023] Open
Abstract
The COVID-19 pandemic due to the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been plaguing the world since late 2019/early 2020 and has changed the way we function as a society, halting both economic and social activities worldwide. Classrooms, offices, restaurants, public transport, and other enclosed spaces that typically gather large groups of people indoors, and are considered focal points for the spread of the virus. For society to be able to go "back to normal", it is crucial to keep these places open and functioning. An understanding of the transmission modes occurring in these contexts is essential to set up effective infection control strategies. This understanding was made using a systematic review, according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement (PRISMA) 2020 guidelines. We analyze the different parameters influencing airborne transmission indoors, the mathematical models proposed to understand it, and discuss how we can act on these parameters. Methods to judge infection risks through the analysis of the indoor air quality are described. Various mitigation measures are listed, and their efficiency, feasibility, and acceptability are ranked by a panel of experts in the field. Thus, effective ventilation procedures controlled by CO2-monitoring, continued mask wearing, and a strategic control of room occupancy, among other measures, are put forth to enable a safe return to these essential places.
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Affiliation(s)
| | - Gianni Parisi
- Research Unit in Epidemiology and Risk Analysis Applied to Veterinary Sciences (UREAR-ULiege), FARAH Research Centre, Faculty of Veterinary Medicine, University of Liege, 4000 Liege, Belgium
| | - Maxime Lisson
- TERRA Research Centre, Gembloux Agro-Bio Tech, University of Liège, 5030 Gembloux, Belgium
| | - Olivier Bruyère
- Division of Public Health, Epidemiology and Health Economics, Faculty of Medicine, University of Liège, 4000 Liège, Belgium
| | | | - Sebastien Fontaine
- Institute for Research in Social Sciences (IRSS), Faculty of Social Sciences, University of Liege, 4000 Liège, Belgium
| | - Laurent Gillet
- Immunology-Vaccinology Laboratory, FARAH Research Center, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium
| | - Fabrice Bureau
- Laboratory of Cellular and Molecular Immunology, GIGA Institute, University of Liege, 4000 Liège, Belgium
| | - Gilles Darcis
- Infectious Diseases Department, Centre Hospitalier Universitaire de Liège, 4000 Liège, Belgium
| | - Etienne Thiry
- Veterinary Virology and Animal Viral Diseases, FARAH Research Centre, Department of Infectious and Parasitic Diseases, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium
| | - Mariette Ducatez
- IHAP, Université de Toulouse, INRAE, ENVT, 31000 Toulouse, France
| | - Chantal J. Snoeck
- Clinical and Applied Virology Group, Department of Infection and Immunity, Luxembourg Institute of Health, 4354 Esch-sur-Alzette, Luxembourg
| | - Stéphan Zientara
- UMR1161 Virologie, INRAE, Ecole Nationale Vétérinaire d’Alfort, Anses, Université Paris-Est, F-94700 Maisons-Alfort, France
| | - Nadia Haddad
- UMR BIPAR 956, Anses, INRAE, Ecole Nationale Vétérinaire d’Alfort, Université Paris-Est, 94700 Maisons-Alfort, France
| | - Marie-France Humblet
- Department of Occupational Safety and Health, University of Liege, 4000 Liege, Belgium
| | - Louisa F. Ludwig-Begall
- Veterinary Virology and Animal Viral Diseases, FARAH Research Centre, Department of Infectious and Parasitic Diseases, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium
| | - Georges Daube
- Laboratoire de Microbiologie des Denrées Alimentaires, FARAH Research Center, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium
| | - Damien Thiry
- Bacteriology, FARAH Research Center, Faculty of Veterinary Medicine, University of Liege, 4000 Liège, Belgium
| | - Benoît Misset
- Service des Soins Intensifs, CHU Sart Tilman, Department des Sciences Cliniques, University of Liège, 4000 Liege, Belgium
| | - Bernard Lambermont
- Service des Soins Intensifs, CHU Sart Tilman, Department des Sciences Cliniques, University of Liège, 4000 Liege, Belgium
| | - Yacine Tandjaoui-Lambiotte
- Laboratoire Hypoxie and Poumon INSERM U1272, Service de Réanimation Médico-Chirurgicale, CHU Avicenne, Assistance Publique-Hôpitaux de Paris, 93000 Bobigny, France
| | | | - Kevin Sartor
- Planification: Energie—Environnement, Département d’Aérospatiale et Mécanique, Systèmes Énergétiques, University of Liège, 4000 Liège, Belgium
| | - Catherine Noël
- Department of Occupational Safety and Health, University of Liege, 4000 Liege, Belgium
| | - Claude Saegerman
- Research Unit in Epidemiology and Risk Analysis Applied to Veterinary Sciences (UREAR-ULiege), FARAH Research Centre, Faculty of Veterinary Medicine, University of Liege, 4000 Liege, Belgium
| | - Eric Haubruge
- TERRA Research Centre, Gembloux Agro-Bio Tech, University of Liège, 5030 Gembloux, Belgium
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Kumar P, Rawat N, Tiwari A. Micro-characteristics of a naturally ventilated classroom air quality under varying air purifier placements. ENVIRONMENTAL RESEARCH 2023; 217:114849. [PMID: 36414109 DOI: 10.1016/j.envres.2022.114849] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 11/14/2022] [Accepted: 11/16/2022] [Indexed: 06/16/2023]
Abstract
A naturally-ventilated operational classroom was instrumented at 18 locations to assess spatial variations of classroom air pollution (CRAP), thermal comfort and ventilation indicators under 10 different scenarios (base scenario without air purifier (AP); three single AP scenarios; three scenarios with two APs at same locations; three scenarios with two APs at different locations). Unlike PM2.5, monitored PM10 and CO2 concentrations followed the diurnal occupancy profile. Highest vertical variation (38%) in CO2 was at the classroom entry zone at 40-300 cm height. CO2 increased until 225 cm before stratifying further. PM10 increased to highest levels at children sitting height (100 cm) before decreasing to adult breathing height (150 cm). Highest horizontal variations in CO2 (PM10) were 29% (22%) at 40 cm height between the entry and occupied zones. Teachers' exposure to CO2 (PM10) in breathing zone varied by up to 6% (3%); the corresponding variations across monitored locations were up to 14% (19%). Teachers' exposure to CO2 was up to 13% higher than that of children and 18% lower for PM10. Traffic emissions (PM2.5 and NOx), secondary pollutants (VOCs and O3), thermal comfort parameters and noise level in the classroom varied insignificantly among scenarios. PM10 reduction was not doubled by using two air purifiers, which were most effective when placed within the highest PM concentration zone. Cross-comparisons of scenarios showed: use of AP reduced classroom's spatial average PM10 up to 14%; PM10 was reduced by increasing the AP's filtration capacity; and AP had insignificant impact on spatial average CO2. PM10 showed a maximum reduction of 46% (teacher zone), 62% (occupied zone) and 50% (entry zone) at children's breathing height, depending on usage scenario. This study produced high-resolution data for validating the detailed numerical models for classrooms and informing decision-making on AP's placement to minimise children's exposure to CRAP and re-breathed CO2.
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Affiliation(s)
- Prashant Kumar
- Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, Surrey, United Kingdom; Institute for Sustainability, University of Surrey, Guildford GU2 7XH, Surrey, United Kingdom.
| | - Nidhi Rawat
- Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, Surrey, United Kingdom
| | - Arvind Tiwari
- Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, Surrey, United Kingdom
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Cheung T, Li J, Goh J, Sekhar C, Cheong D, Tham KW. Evaluation of aerosol transmission risk during home quarantine under different operating scenarios: A pilot study. BUILDING AND ENVIRONMENT 2022; 225:109640. [PMID: 36210963 PMCID: PMC9528801 DOI: 10.1016/j.buildenv.2022.109640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/22/2022] [Accepted: 09/24/2022] [Indexed: 06/09/2023]
Abstract
SARS-CoV-2 has been recognized to be airborne transmissible. With the large number of reported positive cases in the community, home quarantine is recommended for the infectors who are not severely ill. However, the risks of household aerosol transmission associated with the quarantine room operating methods are under-explored. We used tracer gas technique to simulate the exhaled virus laden aerosols from a patient under home quarantine situation inside a residential testbed. The Sulphur hexafluoride (SF6) concentration was measured both inside and outside the quarantine room under different operating settings including, air-conditioning and natural ventilation, presence of an exhaust fan, and the air movement generated by ceiling or pedestal fan. We calculated the outside-to-inside SF6 concentration to indicate potential exposure of occupants in the same household. In-room concentration with air-conditioning was 4 times higher than in natural ventilation settings. Exhaust fan operation substantially reduced in-room SF6 concentration and leakage rate in most of the ventilation scenarios, except for natural ventilation setting with ceiling fan. The exception is attributable to the different airflow patterns between ceiling fan (recirculates air vertically) and pedestal fan (moves air horizontally). These airflow variations also led to differences in SF6 concentration at two sampling heights (0.1 m and 1.7 m) and SF6 leakage rates when the quarantine room door was opened momentarily. Use of natural ventilation rather than air-conditioning, and operating exhaust fan when using air-conditioning are recommended to lower exposure risk for home quarantine. A more holistic experiment will be conducted to address the limitations reflected in this study.
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Affiliation(s)
- Toby Cheung
- Department of the Built Environment, National University of Singapore, Singapore
| | - Jiayu Li
- Berkeley Education Alliance for Research in Singapore (BEARS), Singapore
| | - Jiamin Goh
- Department of the Built Environment, National University of Singapore, Singapore
| | - Chandra Sekhar
- Department of the Built Environment, National University of Singapore, Singapore
| | - David Cheong
- Department of the Built Environment, National University of Singapore, Singapore
| | - Kwok Wai Tham
- Department of the Built Environment, National University of Singapore, Singapore
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Field Experiments to Identify and Eliminate Recirculation Zones to Improve Indoor Ventilation: Comparison with CFD. TRANSACTIONS OF THE INDIAN NATIONAL ACADEMY OF ENGINEERING 2022; 7:911-926. [PMID: 35836614 PMCID: PMC9098795 DOI: 10.1007/s41403-022-00335-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 04/15/2022] [Indexed: 11/28/2022]
Abstract
Ventilation of shared indoor spaces is crucial for mitigating air-borne infection spread among its occupants. Replacing the air in a room with fresh air is key to minimize the concentration of potentially infectious aerosol generated in the room. Recirculating air flow present at corners and around obstacles can trap air and infectious aerosol. This can significantly delay their evacuation by the ventilation system. Knowing the location and extent of such recirculation zones is, therefore, important. In this work, we present flow visualization experiments to identify recirculation zones in an enclosed space. It is based on the deflection of the smoke streak generated by an incense stick. We use particle image velocimetry (PIV) post-processing to quantify the deflection of the smoke streak and use it as an indicator of the direction of local air flow. Positive deflection, defined as the deflection towards the exit location, is associated with primary flow present in well-ventilated regions of the room. On the other hand, negative deflection indicates reversed flow in recirculation zones, where the smoke streak is defined away from the exit location. The technique is applied to a public shared washroom, where the toilet seat is found to be in a well-ventilated region, while the washbasin is in a large recirculation zone. We compare the experimental point measurements with flow field solution obtained using computational fluid dynamics (CFD). We also explore geometry modifications as a strategy to eliminate the recirculation zone over the washbasin.
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Ferrari S, Blázquez T, Cardelli R, Puglisi G, Suárez R, Mazzarella L. Ventilation strategies to reduce airborne transmission of viruses in classrooms: A systematic review of scientific literature. BUILDING AND ENVIRONMENT 2022; 222:109366. [PMID: 35818484 PMCID: PMC9259197 DOI: 10.1016/j.buildenv.2022.109366] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 06/20/2022] [Accepted: 07/02/2022] [Indexed: 06/15/2023]
Abstract
The recent pandemic due to SARS-CoV-2 has brought to light the need for strategies to mitigate contagion between human beings. Apart from hygiene measures and social distancing, air ventilation highly prevents airborne transmission within enclosed spaces. Among others, educational environments become critical in strategic planning to control the spread of pathogens and viruses amongst the population, mainly in cold conditions. In the event of a virus outbreak - such as COVID or influenza - many school classrooms still lack the means to guarantee secure and healthy environments. The present review examines school contexts that implement air ventilation strategies to reduce the risk of contagion between students. The analysed articles present past experiences that use either natural or mechanical systems assessed through mathematical models, numerical models, or full-scale experiments. For naturally ventilated classrooms, the studies highlight the importance of the architectural design of educational spaces and propose strategies for aeration control such as CO2-based control and risk-infection control. When it comes to implementing mechanical ventilation in classrooms, different systems with different airflow patterns are assessed based on their ability to remove airborne pathogens considering parameters like the age of air and the generation of airflow streamlines. Moreover, studies report that programmed mechanical ventilation systems can reduce risk-infection during pandemic events. In addition to providing a systematic picture of scientific studies in the field, the findings of this review can be a valuable reference for school administrators and policymakers to implement the best strategies in their classroom settings towards reducing infection risks.
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Affiliation(s)
- S Ferrari
- Dept. of Architecture, Built Environment and Construction Engineering, Politecnico di Milano, Milano, Italy
| | - T Blázquez
- Dept. of Architecture, Built Environment and Construction Engineering, Politecnico di Milano, Milano, Italy
| | - R Cardelli
- Dept. of Architecture, Built Environment and Construction Engineering, Politecnico di Milano, Milano, Italy
| | - G Puglisi
- Dept. of Energy Efficiency Department, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Rome, Italy
| | - R Suárez
- Instituto Universitario de Arquitectura y Ciencias de la Construcción, Escuela Técnica Superior de Arquitectura, Universidad de Sevilla, Sevilla, Spain
| | - L Mazzarella
- Dept. of Energy, Politecnico di Milano, Milano, Italy
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