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Niu Y, Wang F, Luo D, Shu Z, Huang J, Zhang Y, Liu C, Qian H. Vertical transmission of infectious aerosols through building toilet drainage system: An experimental study. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 343:123284. [PMID: 38163630 DOI: 10.1016/j.envpol.2023.123284] [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: 07/06/2023] [Revised: 12/23/2023] [Accepted: 12/30/2023] [Indexed: 01/03/2024]
Abstract
The building's toilet drainage system has been identified as a potential route for the transmission of SARS-CoV-2 during outbreaks. This study employed agar-fluorescein sodium semi-solid as trace particles to investigate the possibility of vertical transmission of the SARS-CoV-2 in drainage system. In both scenarios, where floor drains were all properly sealed or dried out, simulated faeces containing fluorescein sodium were flushed into the toilet bowl. Air sampling was conducted in each restroom, and differential pressure measurements at the floor drain locations were taken. The experimental results showed that when all floor drains were properly sealed, the differential pressure at each floor drain was 0. The fluorescein sodium-traced aerosol did not transmit through the drainage system to various floors, which significantly reduced the risk of infection for users through this route. However, when all floor drains dried out, toilet users above the neutral pressure layer (NPL) were at a high risk of virus infection. Due to the increasing maximum negative pressure at the floor drain above the NPL with ascending floor levels, users on each floor above the NPL faced an elevated infection risk in restrooms. Specifically, users on the top floor were exposed to infectious aerosols roughly 1.6 times that of the first floor above the NPL. Conversely, owing to the increasing maximum positive pressure at the floor drain below the NPL with descending floor levels, users below the NPL experienced a comparatively lower infection risk. This finding has important implications for understanding the vertical transmission dynamics of SARS-CoV-2 in residential or public building and can inform the development of effective control measures.
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Affiliation(s)
- Yuanyuan Niu
- School of Energy and Environment, Southeast University, Nanjing, 210096, China
| | - Fang Wang
- School of Energy and Power Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Danting Luo
- School of Energy and Environment, Southeast University, Nanjing, 210096, China
| | - Zhiyong Shu
- School of Energy and Environment, Southeast University, Nanjing, 210096, China
| | - Jiayu Huang
- School of Energy and Environment, Southeast University, Nanjing, 210096, China
| | - Yongpeng Zhang
- School of Energy and Power Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Cong Liu
- School of Energy and Environment, Southeast University, Nanjing, 210096, China
| | - Hua Qian
- School of Energy and Environment, Southeast University, Nanjing, 210096, China.
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Guo Y, Li X, Luby S, Jiang G. Vertical outbreak of COVID-19 in high-rise buildings: The role of sewer stacks and prevention measures. CURRENT OPINION IN ENVIRONMENTAL SCIENCE & HEALTH 2022; 29:100379. [PMID: 35856009 PMCID: PMC9279164 DOI: 10.1016/j.coesh.2022.100379] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 06/27/2022] [Accepted: 07/04/2022] [Indexed: 05/25/2023]
Abstract
COVID-19 outbreaks in high-rise buildings suggested the transmission route of fecal-aerosol-inhalation due to the involvement of viral aerosols in sewer stacks. The vertical transmission is likely due to the failure of water traps that allow viral aerosols to spread through sewer stacks. This process can be further facilitated by the chimney effect in vent stack, extract ventilation in bathrooms, or wind-induced air pressure fluctuations. To eliminate the risk of such vertical disease spread, the installation of protective devices is highly encouraged in high-rise buildings. Although the mechanism of vertical pathogen spread through drainage pipeline has been illustrated by tracer gas or microbial experiments and numerical modeling, more research is needed to support the update of regulatory and design standards for sewerage facilities.
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Affiliation(s)
- Ying Guo
- School of Civil, Mining, Environmental and Architectural Engineering, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Xuan Li
- School of Civil, Mining, Environmental and Architectural Engineering, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Stephen Luby
- Division of Infectious Diseases and Geographic Medicine, Stanford University, Stanford, CA 94305, USA
| | - Guangming Jiang
- School of Civil, Mining, Environmental and Architectural Engineering, University of Wollongong, Wollongong, NSW 2522, Australia
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia
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Zhang Y, Hui FKP, Duffield C, Saeed AM. A review of facilities management interventions to mitigate respiratory infections in existing buildings. BUILDING AND ENVIRONMENT 2022; 221:109347. [PMID: 35782231 PMCID: PMC9238148 DOI: 10.1016/j.buildenv.2022.109347] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 05/01/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
The Covid-19 pandemic reveals that the hazard of the respiratory virus was a secondary consideration in the design, development, construction, and management of public and commercial buildings. Retrofitting such buildings poses a significant challenge for building owners and facilities managers. This article reviews current research and practices in building operations interventions for indoor respiratory infection control from the perspective of facilities managers to assess the effectiveness of available solutions. This review systematically selects and synthesises eighty-six articles identified through the PRISMA process plus supplementary articles identified as part of the review process, that deal with facilities' operations and maintenance (O&M) interventions. The paper reviewed the context, interventions, mechanisms, and outcomes discussed in these articles, concluding that interventions for respiratory virus transmission in existing buildings fall into three categories under the Facilities Management (FM) discipline: Hard services (HVAC and drainage system controls) to prevent aerosol transmissions, Soft Services (cleaning and disinfection) to prevent fomite transmissions, and space management (space planning and occupancy controls) to eliminate droplet transmissions. Additionally, the research emphasised the need for FM intervention studies that examine occupant behaviours with integrated intervention results and guide FM intervention decision-making. This review expands the knowledge of FM for infection control and highlights future research opportunities.
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Affiliation(s)
- Yan Zhang
- Department of Infrastructure Engineering, University of Melbourne, Level 6, Building 290, 700 Swanston Street, Carlton, Victoria, Australia
| | - Felix Kin Peng Hui
- Department of Infrastructure Engineering, University of Melbourne, Australia
| | - Colin Duffield
- Department of Infrastructure Engineering, University of Melbourne, Australia
| | - Ali Mohammed Saeed
- Department of Jobs, Regions and Precincts, Level 13, 1 Spring Street, Melbourne, Victoria, Australia
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Tang H, Pan Z, Li C. Tempo-spatial infection risk assessment of airborne virus via CO 2 concentration field monitoring in built environment. BUILDING AND ENVIRONMENT 2022; 217:109067. [PMID: 35464750 PMCID: PMC9013429 DOI: 10.1016/j.buildenv.2022.109067] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/10/2022] [Accepted: 04/03/2022] [Indexed: 05/14/2023]
Abstract
The aerosol transmission was academically recognized as a possible transmission route of Coronavirus disease 2019 (COVID-19). We established an approach to assess the indoor tempo-spatial airborne-disease infection risks through aerosol transmission via real-time CO2 field measurement and occupancy monitoring. Compared to former studies, the proposed method can evaluate real-time airborne disease infection risks through aerosol transmission routes. The approach was utilized in a university office. The accumulated infection risk was calculated for three occupants with practical working schedules (from occupancy recording) and one hypothesis occupant with a typical working schedule. COVID-19 was used as an example. Results demonstrated that the individual infection risks diversified with different dwell times and working places in the office. For the three occupants with a practical working schedule, their 3-day accumulated infection risks were respectively 0.050%, 0.035%, 0.027% and 0.041% due to 11.6, 9.0 and 13.8 h exposure with an initial infector percentage of 1%. The results demonstrate that location and dwell time are both important factors influencing the infection risk of certain occupant in built environment, whereas existing literature seldom took these two points into consideration simultaneously. On the contrary, our proposed approach treated the infection risks as place-by-place, time-by-time and person-by-person diversified in the built environment. The risk assessment results can provide early warning for building occupants and contribute to the transmission control of air-borne disease.
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Affiliation(s)
- Haida Tang
- School of Architecture and Urban Planning, Shenzhen University, Shenzhen, 518060, China
| | - Zhenyu Pan
- School of Architecture and Urban Planning, Shenzhen University, Shenzhen, 518060, China
| | - Chunying Li
- School of Architecture and Urban Planning, Shenzhen University, Shenzhen, 518060, China
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