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Paddy EN, Afolabi OOD, Sohail M. Exploring toilet plume bioaerosol exposure dynamics in public toilets using a Design of Experiments approach. Sci Rep 2024; 14:10665. [PMID: 38724540 PMCID: PMC11082142 DOI: 10.1038/s41598-024-61039-w] [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: 01/11/2024] [Accepted: 04/30/2024] [Indexed: 05/12/2024] Open
Abstract
Bioaerosols generated during toilet flushing can contribute to the spread of airborne pathogens and cross-contamination in indoor environments. This presents an increased risk of fomite-mediated or aerosol disease transmission. This study systematically investigated the factors contributing to increased bioaerosol exposure following toilet flushing and developed an empirical model for predicting the exposure-relevant bioaerosol concentration. Air in a toilet cubicle was sampled by impaction after seeding with Clostridium difficile spores. Design of Experiments (DoE) main effects screening and full factorial design approaches were then employed to investigate the significant factors that heighten the risk of exposure to bioaerosols post-flush. Our findings reveal that the inoculated bacterial concentration (C), time elapsed after flushing (t), lateral distance (d), and mechanical ventilation (v) are significant predictors of bioaerosol concentration, with p-values < 0.05. The interaction term, C × d showed a marked increase in bioaerosol concentration up to 232 CFU/m3 at the closest proximity and highest pathogen load. The interplay of C and t (C × t) demonstrated a time-dependent attenuation of bioaerosol viability, with concentrations peaking at 241 CFU/m3 immediately post-flush and notably diminishing over time. The lateral distance and time post-flush (d × t) interaction also revealed a gradual decrease in bioaerosol concentration, highlighting the effectiveness of spatial and temporal dilution in mitigating bioaerosol exposure risks. Furthermore, there is an immediate rise in relative humidity levels post-flush, impacting the air quality in the toilet environment. This study not only advances our understanding of exposure pathways in determining bioaerosol exposure, but also offers pivotal insights for designing targeted interventions to reduce bioaerosol exposure. Recommendations include designing public toilets with antimicrobial surfaces, optimizing ventilation, and initiating timely disinfection protocols to prioritise surfaces closest to the toilet bowl during peak exposure periods, thereby promoting healthier indoor environments and safeguarding public health in high-traffic toilet settings.
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Affiliation(s)
- Elizabeth N Paddy
- School of Architecture, Building and Civil Engineering, Loughborough University, Loughborough, Leicestershire, UK.
| | - Oluwasola O D Afolabi
- School of Architecture, Building and Civil Engineering, Loughborough University, Loughborough, Leicestershire, UK
| | - M Sohail
- School of Architecture, Building and Civil Engineering, Loughborough University, Loughborough, Leicestershire, UK
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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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Eisenberg S, Walton A, Connor TH. The Occupational and Environmental Hazards of Uncovered Toilets. Am J Nurs 2024; 124:55-60. [PMID: 38511713 DOI: 10.1097/01.naj.0001010592.45177.43] [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: 03/22/2024]
Abstract
ABSTRACT Substantial evidence demonstrates that plumes from uncovered toilets potentially expose nurses and other health care workers to aerosols containing infectious agents and hazardous drugs, including antineoplastic drugs. Most hospitals in the United States utilize flushometer-type toilets, which operate under high pressure and do not have a permanently attached closure or lid, which is known to reduce the aerosols generated by flushing. This article aims to raise awareness among nurses of the potential exposure risks associated with toilet plume aerosols, so they can educate other health care workers and take part in initiatives to address these risks.
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Affiliation(s)
- Seth Eisenberg
- Seth Eisenberg is an oncology nursing consultant and the former professional practice coordinator of infusion services at the Fred Hutchinson Cancer Center, Seattle. AnnMarie Walton is an associate professor at the Duke University School of Nursing, Durham, NC. Thomas Harry Connor is a retired hazardous drug researcher for the National Institute for Occupational Safety and Health and a former associate professor at the University of Texas Health Science Center at Houston. Contact author: Thomas Harry Connor, . The authors have disclosed no potential conflicts of interest, financial or otherwise
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Tan M, Tian Y, Zhang D, Wang Q, Gao Z. Aerosol Transmission of Norovirus. Viruses 2024; 16:151. [PMID: 38275961 PMCID: PMC10818780 DOI: 10.3390/v16010151] [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: 12/26/2023] [Revised: 01/16/2024] [Accepted: 01/18/2024] [Indexed: 01/27/2024] Open
Abstract
Norovirus (NoV) is a major cause of acute gastroenteritis outbreaks worldwide. A comprehensive understanding of the transmission mode is of great significance for the prevention and control of the NoV infection. Currently, the transmission modes of NoV include contact, food-borne, water-borne and aerosol transmission. The first three modes are more common, while aerosol transmission is seldom reported. In this paper, the source, generation mechanism, infectivity, sampling and related outbreaks of NoV aerosol are summarized and discussed.
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Affiliation(s)
- Mengdi Tan
- School of Public Health, China Medical University, Shenyang 110122, China
| | - Yi Tian
- Institute for the Control of Infectious and Endemic Diseases, Beijing Center for Disease Prevention and Control, Beijing 100013, China
| | - Daitao Zhang
- Institute for the Control of Infectious and Endemic Diseases, Beijing Center for Disease Prevention and Control, Beijing 100013, China
| | - Quanyi Wang
- Institute for the Control of Infectious and Endemic Diseases, Beijing Center for Disease Prevention and Control, Beijing 100013, China
| | - Zhiyong Gao
- School of Public Health, China Medical University, Shenyang 110122, China
- Institute for the Control of Infectious and Endemic Diseases, Beijing Center for Disease Prevention and Control, Beijing 100013, China
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5
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Valzano F, Coda ARD, Liso A, Arena F. Multidrug-Resistant Bacteria Contaminating Plumbing Components and Sanitary Installations of Hospital Restrooms. Microorganisms 2024; 12:136. [PMID: 38257963 PMCID: PMC10818725 DOI: 10.3390/microorganisms12010136] [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: 11/20/2023] [Revised: 12/05/2023] [Accepted: 01/08/2024] [Indexed: 01/24/2024] Open
Abstract
Antimicrobial resistance (AMR) poses several issues concerning the management of hospital-acquired infections, leading to increasing morbidity and mortality rates and higher costs of care. Multidrug-resistant (MDR) bacteria can spread in the healthcare setting by different ways. The most important are direct contact transmission occurring when an individual comes into physical contact with an infected or colonized patient (which can involve healthcare workers, patients, or visitors) and indirect contact transmission occurring when a person touches contaminated objects or surfaces in the hospital environment. Furthermore, in recent years, toilets in hospital settings have been increasingly recognised as a hidden source of MDR bacteria. Different sites in restrooms, from toilets and hoppers to drains and siphons, can become contaminated with MDR bacteria that can persist there for long time periods. Therefore, shared toilets may play an important role in the transmission of nosocomial infections since they could represent a reservoir for MDR bacteria. Such pathogens can be further disseminated by bioaerosol and/or droplets potentially produced during toilet use or flushing and be transmitted by inhalation and contact with contaminated fomites. In this review, we summarize available evidence regarding the molecular features of MDR bacteria contaminating toilets of healthcare environments, with a particular focus on plumbing components and sanitary installation. The presence of bacteria with specific molecular traits in different toilet sites should be considered when adopting effective managing and containing interventions against nosocomial infections potentially due to environmental contamination. Finally, here we provide an overview of traditional and new approaches to reduce the spreading of such infections.
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Affiliation(s)
- Felice Valzano
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 20, 71122 Foggia, Italy; (F.V.); (F.A.)
| | - Anna Rita Daniela Coda
- Department of Medical and Surgical Sciences, University of Foggia, Via Napoli 20, 71122 Foggia, Italy;
| | - Arcangelo Liso
- Department of Medical and Surgical Sciences, University of Foggia, Via Napoli 20, 71122 Foggia, Italy;
| | - Fabio Arena
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 20, 71122 Foggia, Italy; (F.V.); (F.A.)
- IRCCS Don Carlo Gnocchi Foundation, Via di Scandicci 269, 50143 Florence, Italy
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Goforth MP, Boone SA, Clark J, Valenzuela PB, McKinney J, Ijaz MK, Gerba CP. Impacts of lid closure during toilet flushing and of toilet bowl cleaning on viral contamination of surfaces in United States restrooms. Am J Infect Control 2023; 52:S0196-6553(23)00820-9. [PMID: 38276944 DOI: 10.1016/j.ajic.2023.11.020] [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: 07/20/2023] [Revised: 11/25/2023] [Accepted: 11/27/2023] [Indexed: 01/27/2024]
Abstract
BACKGROUND Viral aerosols generated during toilet flushing represent a potential route of pathogen transmission. The goal of this study was to determine the impact of toilet lid closure prior to flushing on the generation of viral aerosols and cross-contamination of restroom fomites. METHODS A surrogate for human enteric viruses (bacteriophage MS2) was added to household and public toilet bowls and flushed. The resulting viral contamination of the toilet and other restroom surfaces was then determined. RESULTS After flushing the inoculated toilets, toilet seat bottoms averaged >107 PFU/100 cm2. Viral contamination of restroom surfaces did not depend on toilet lid position (up or down). After toilet bowls were cleaned using a bowl brush with or without a commercial product (hydrochloric acid), a >4 log10 (>99.99%) reduction in contamination of the toilet bowl water was observed versus no product. Bowl brush contamination was reduced by 1.6 log10 (97.64%) when the product was used versus no product. CONCLUSIONS These results demonstrate that closing the toilet lid prior to flushing does not mitigate the risk of contaminating bathroom surfaces and that disinfection of all restroom surfaces (ie, toilet rim, floors) may be necessary after flushing or after toilet brush used for the reduction of virus cross-contamination.
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Affiliation(s)
- Madison P Goforth
- Department of Environmental Science, University of Arizona, Tucson, AZ
| | - Stephanie A Boone
- Department of Environmental Science, University of Arizona, Tucson, AZ.
| | - Justin Clark
- Department of Environmental Science, University of Arizona, Tucson, AZ
| | | | - Julie McKinney
- Global Research and Development for Lysol and Dettol, Reckitt Benckiser LLC, Montvale, NJ
| | - M Khalid Ijaz
- Global Research and Development for Lysol and Dettol, Reckitt Benckiser LLC, Montvale, NJ
| | - Charles P Gerba
- Department of Environmental Science, University of Arizona, Tucson, AZ
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7
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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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8
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Paddy EN, Afolabi OOD, Sohail M. Toilet plume bioaerosols in health care and hospitality settings: A systematic review. Am J Infect Control 2023; 51:324-333. [PMID: 35870658 DOI: 10.1016/j.ajic.2022.07.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 07/07/2022] [Accepted: 07/08/2022] [Indexed: 11/30/2022]
Abstract
BACKGROUND The spread of some respiratory and gastro-intestinal infections has been linked to the exposure to infectious bioaerosols released after toilet flushing. This represents a health hazard and infection risk for immunocompromised patients, health workers and the public, particularly within the health care and hospitality settings. This systematic review provides current knowledge and identifies gaps in the evidence regarding toilet plume bioaerosols and the potential contributory role in spreading infections in health care and hospitality settings. METHODS The PRISMA guidelines were used. Searches were run in PubMed, Scopus, and Google Scholar from 1950 to 30th June 2021. Searches of global and regional reports and updates from relevant international and governmental organizations were also conducted. RESULTS AND CONCLUSION The search yielded 712 results, and 37 studies were finally selected for this review. There is a lack of national and international bioaerosol sampling and exposure standards for health care and hospitality settings. Toilet plume bioaerosols are complex in nature, thus, measured bioaerosol concentrations in these settings depend on many variables and may differ for every pathogen responsible for a particular infectious disease. The contact and airborne transmission risks posed by toilet plume bioaerosols also remain unquantified. They are an important pathway that can increase the exposure to enteric and airborne pathogens. Hence, quantitative risk assessment and related research are needed to investigate these transmission risks.
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Affiliation(s)
- Elizabeth N Paddy
- School of Architecture, Building and Civil Engineering, Loughborough University, Loughborough, Leicestershire, United Kingdom.
| | - Oluwasola O D Afolabi
- School of Architecture, Building and Civil Engineering, Loughborough University, Loughborough, Leicestershire, United Kingdom
| | - M Sohail
- School of Architecture, Building and Civil Engineering, Loughborough University, Loughborough, Leicestershire, United Kingdom
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9
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Luo D, Huang J, Zheng X, Liu F, Li Y, Wang Y, Qian H. Spread of flushing-generated fecal aerosols in a squat toilet cubicle: Implication for infection risk. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 859:160212. [PMID: 36395842 DOI: 10.1016/j.scitotenv.2022.160212] [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: 08/20/2022] [Revised: 10/27/2022] [Accepted: 11/12/2022] [Indexed: 06/16/2023]
Abstract
Toilet flushing generates and spread fecal aerosols, potentially leading to infection transmission risk. Squat toilets are widely used in public restrooms in some Asian countries including China and India, and remain to be studied. Aerosol dispersion while flushing squat toilet in cubicle was visualized, while the aerosol concentrations were measured on different surfaces by monitoring fluorescence intensity through seeding simulated fluorescence feces. Flushing-generated fecal aerosols could spread to the breathing zone, deposit on floor, and partitions in squat toilet cubicles, and spread even beyond to the restroom lobby. A total of 0.24 % and 0.17 % of seeded fecal waste deposits on the floor and partition (lower than 0.20 m) for each flush. Aerosol concentration decays rapidly, with 86.8 ± 2.2 % reduction in the second minute after a previous flush compared to that in the first minute. Public toilet users are recommended to wait for 2 min after the early flush before entering the cubicle.
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Affiliation(s)
- Danting Luo
- School of Energy and Environment, Southeast University, Nanjing, China; Engineering Research Center for Building Energy Environments & Equipments, Ministry of Education, China; Hubei Engineering Center for Infectious Disease Prevention, Control and Treatment, Wuhan, China
| | - Jiayu Huang
- School of Energy and Environment, Southeast University, Nanjing, China; Engineering Research Center for Building Energy Environments & Equipments, Ministry of Education, China
| | - Xiaohong Zheng
- School of Energy and Environment, Southeast University, Nanjing, China; Engineering Research Center for Building Energy Environments & Equipments, Ministry of Education, China
| | - Fan Liu
- School of Energy and Environment, Southeast University, Nanjing, China; University of Shanghai for Science and Technology, Shanghai, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Ying Wang
- Hubei Engineering Center for Infectious Disease Prevention, Control and Treatment, Wuhan, China; Department of infection management, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China
| | - Hua Qian
- School of Energy and Environment, Southeast University, Nanjing, China; Engineering Research Center for Building Energy Environments & Equipments, Ministry of Education, China; Hubei Engineering Center for Infectious Disease Prevention, Control and Treatment, Wuhan, China.
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10
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Dubitsky L, McRae O, Bird JC. Enrichment of Scavenged Particles in Jet Drops Determined by Bubble Size and Particle Position. PHYSICAL REVIEW LETTERS 2023; 130:054001. [PMID: 36800466 DOI: 10.1103/physrevlett.130.054001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 11/04/2022] [Accepted: 01/06/2023] [Indexed: 06/18/2023]
Abstract
When small bubbles rupture in a contaminated water source, the resulting liquid jet breaks up into droplets that can aerosolize solid particulates such as bacteria, viruses, and microplastics. Particles collected on the bubble surface have the potential to become highly concentrated in the jet drops, dramatically increasing their impact. It has been assumed that only particles small enough to fit within a thin microlayer surrounding the bubble can be transported into its influential top jet drop. Yet here, we demonstrate that not only can larger particles be transported into this jet drop, but also that these particles can exceed previous enrichment measurements. Through experiments and simulations, we identify the prerupture location of the liquid that develops into the top jet drop and model how interfacial rearrangement combines with the bubble size, particle size, and the angular distribution of particles on the bubble surface to set the particle enrichment.
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Affiliation(s)
- Lena Dubitsky
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Oliver McRae
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - James C Bird
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
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Succar A, Lefebvre X, Prévost M, Bédard E, Robert E. Characterization of the aerosol produced from an aerated jet. WATER RESEARCH 2023; 229:119432. [PMID: 36495852 DOI: 10.1016/j.watres.2022.119432] [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: 09/17/2022] [Revised: 11/15/2022] [Accepted: 11/25/2022] [Indexed: 06/17/2023]
Abstract
Faucet aerators that form aerated water jets generate aerosols, which can constitute a risk of infection if the water is contaminated, particularly for vulnerable individuals near the sink. In this study, we characterize the size and trajectory of water droplets produced from an aerated jet. The detected particle diameter ranged from 3 to 150μm. The concentration of droplets in the air varied from near-zero to a maximum of 2×1011particles/m3, depending on the location relative to the jet. We found four relevant categories of droplets based on their trajectories following their emission at the jet's free surface: particles with inertia high enough to escape the immediate vicinity of the jet (category 1), particles moving towards the jet (category 2), particles drawn into the aerator, which only included particles with a diameter smaller than 50μm (category 3), and particles with a near-vertical trajectory (category 4). Tracing category 1 particles to their generation location on the water interface shows a higher emission rate near the aerator. Finally, we employ a numerical model to compute the subsequent trajectories of droplets detected at the limits of the sampled domain. We find that particles whose diameter is smaller than 55μm completely dry and become airborne. Larger droplets deposit within a radius of 7cm around the jet, assuming a surface is located 20cm below the aerator tip. These results increase the fundamental understanding of the emission mechanisms of droplets in aerated jets and their fate in the sink environment.
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Affiliation(s)
- Antonella Succar
- Department of Mechanical Engineering, Polytechnique Montréal, Montréal, QC, Canada.
| | - Xavier Lefebvre
- Department of Mechanical Engineering, Polytechnique Montréal, Montréal, QC, Canada
| | - Michèle Prévost
- Industrial Chair on Drinking Water, Department of Civil, Geological and Mining Engineering, Polytechnique Montréal, Montréal, QC, Canada
| | - Emilie Bédard
- Department of Civil, Geological and Mining Engineering, Polytechnique Montréal, Montréal, QC, Canada
| | - Etienne Robert
- Department of Mechanical Engineering, Polytechnique Montréal, Montréal, QC, Canada
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Nazari A, Hong J, Taghizadeh-Hesary F, Taghizadeh-Hesary F. Reducing Virus Transmission from Heating, Ventilation, and Air Conditioning Systems of Urban Subways. TOXICS 2022; 10:796. [PMID: 36548629 PMCID: PMC9784553 DOI: 10.3390/toxics10120796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/13/2022] [Accepted: 12/15/2022] [Indexed: 06/17/2023]
Abstract
Aerosols carrying the virus inside enclosed spaces is an important mode of transmission for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as supported by growing evidence. Urban subways are one of the most frequented enclosed spaces. The subway is a utilitarian and low-cost transit system in modern society. However, studies are yet to demonstrate patterns of viral transmission in subway heating, ventilation, and air conditioning (HVAC) systems. To fill this gap, we performed a computational investigation of the airflow (and associated aerosol transmission) in an urban subway cabin equipped with an HVAC system. We employed a transport equation for aerosol concentration, which was added to the basic buoyant solver to resolve the aerosol transmission inside the subway cabin. This was achieved by considering the thermal, turbulent, and induced ventilation flow effects. Using the probability of encountering aerosols on sampling surfaces crossing the passenger breathing zones, we detected the highest infection risk zones inside the urban subway under different settings. We proposed a novel HVAC system that can impede aerosol spread, both vertically and horizontally, inside the cabin. In the conventional model, the maximum probability of encountering aerosols from the breathing of infected individuals near the fresh-air ducts was equal to 51.2%. This decreased to 3.5% in the proposed HVAC model. Overall, using the proposed HVAC system for urban subways led to a decrease in the mean value of the probability of encountering the aerosol by approximately 84% compared with that of the conventional system.
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Affiliation(s)
- Ata Nazari
- Department of Mechanical Engineering, University of Tabriz, Tabriz 51666-16471, Iran
| | - Jiarong Hong
- Mechanical Engineering & Saint Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN 55455, USA
| | - Farzad Taghizadeh-Hesary
- ENT and Head and Neck Research Center and Department, The Five Sense Health Institute, School of Medicine, Iran University of Medical Sciences, Tehran 14535, Iran
| | - Farhad Taghizadeh-Hesary
- TOKAI Research Institute for Environment and Sustainability (TRIES), Tokai University, Hiratsuka-shi 259-1292, Kanagawa-ken, Japan
- School of Global Studies, Tokai University, Hiratsuka-shi 259-1292, Kanagawa-ken, Japan
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13
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Commercial toilets emit energetic and rapidly spreading aerosol plumes. Sci Rep 2022; 12:20493. [PMID: 36481924 PMCID: PMC9732293 DOI: 10.1038/s41598-022-24686-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/18/2022] [Indexed: 12/13/2022] Open
Abstract
Aerosols can transmit infectious diseases including SARS-CoV-2, influenza and norovirus. Flushed toilets emit aerosols that spread pathogens contained in feces, but little is known about the spatiotemporal evolution of these plumes or the velocity fields that transport them. Using laser light to illuminate ejected aerosols we quantify the kinematics of plumes emanating from a commercial flushometer-type toilet, and use the motion of aerosol particles to compute velocity fields of the associated flow. The toilet flush produces a strong chaotic jet with velocities exceeding 2 m/s; this jet transports aerosols to heights reaching 1.5 m within 8 seconds of initiating a flush. Quantifying toilet plumes and associated flow velocities provides a foundation for future design strategies to mitigate plume formation or to disinfect pathogens within it.
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14
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Zhang T(T, Yao L, Gao Z, Wang F. Particle exposure risk to a lavatory user after flushing a squat toilet. Sci Rep 2022; 12:21088. [PMID: 36473899 PMCID: PMC9726816 DOI: 10.1038/s41598-022-25106-4] [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: 08/15/2022] [Accepted: 11/24/2022] [Indexed: 12/12/2022] Open
Abstract
Squat toilets are widely used in developing countries due to local customs and low costs. The flushing of a squat toilet can entrain strong airflow and produce aerosols. This investigation constructed a lavatory mock-up with a squat toilet. The flushing-induced airflow was both visualized and quantitatively measured by particle image velocimetry. The maximum height of the impacted airflow was identified by an ultrasonic anemometer. For inference of the particle emission rate, the toilet bowl was covered by an enclosed box for particle concentration measurement. The risks from skin contact of the deposited particles on the flushing button and the door handle and the possible inhalation of the released aerosols were evaluated. The results revealed that flushing a squat toilet can drive toilet plume to rise up to 0.9 m above the toilet bowl. A single flushing process can produce 0.29 million particles with diameters greater than 0.3 μm, among which 90% of the particles are submicron-sized. The flushing may cause particles to deposit on the flushing button and lavatory door handle as well as inhalation exposure even remaining in the lavatory for half a minute after flushing, especially for those lavatory users whose respiratory zones are below 1.0 m.
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Affiliation(s)
- Tengfei (Tim) Zhang
- grid.30055.330000 0000 9247 7930School of Civil Engineering, Dalian University of Technology, Dalian, China
| | - Lifang Yao
- grid.30055.330000 0000 9247 7930School of Civil Engineering, Dalian University of Technology, Dalian, China
| | - Zilong Gao
- grid.30055.330000 0000 9247 7930School of Civil Engineering, Dalian University of Technology, Dalian, China
| | - Feng Wang
- grid.33763.320000 0004 1761 2484Tianjin Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
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15
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Wang JX, Wu Z, Wang H, Zhong M, Mao Y, Li Y, Wang M, Yao S. Ventilation reconstruction in bathrooms for restraining hazardous plume: Mitigate COVID-19 and beyond. JOURNAL OF HAZARDOUS MATERIALS 2022; 439:129697. [PMID: 36104926 PMCID: PMC9335364 DOI: 10.1016/j.jhazmat.2022.129697] [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: 05/20/2022] [Revised: 07/11/2022] [Accepted: 07/27/2022] [Indexed: 05/20/2023]
Abstract
Converging evidence reports that the probability of vertical transmission patterns via shared drainage systems, may be responsible for the huge contactless community outbreak in high-rise buildings. Publications indicate that a faulty bathroom exhaust fan system is ineffective in removing lifted hazardous virus-laden aerosols from the toilet bowl space. Common strategies (boosting ventilation capability and applying disinfection tablets) seem unsustainable and remain to date untested. Using combined simulation and experimental approaches, we compared three ventilation schemes in a family bathroom including the traditional ceiling fan, floor fan, and side-wall fan. We found that the traditional ceiling fan was barely functional whereby aerosol particles were not being adequately removed. Conversely, a side-wall fan could function efficiently and an enhanced ventilation capability can have increased performance whereby nearly 80.9% of the lifted aerosol particles were removed. There exists a common, and easily-overlooked mistake in the layout of the bathroom, exposing occupants to a contactless vertical pathogen aerosol transmission route. Corrections and dissemination are thus imperative for the reconstruction of these types of family bathrooms. Our findings provide evidence for the bathroom and smart ventilation system upgrade, promoting indoor public health and human hygiene.
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Affiliation(s)
- Ji-Xiang Wang
- College of Electrical, Energy and Power Engineering, Yangzhou University, Yangzhou 225009, PR China; Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China.
| | - Zhe Wu
- College of Electrical, Energy and Power Engineering, Yangzhou University, Yangzhou 225009, PR China
| | - Hongmei Wang
- College of Electrical, Energy and Power Engineering, Yangzhou University, Yangzhou 225009, PR China
| | - Mingliang Zhong
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, PR China
| | - Yufeng Mao
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, PR China
| | - Yunyun Li
- School of Energy and Environment, Southeast University, Nanjing 210096, PR China
| | - Mengxiao Wang
- Department of Traditional Chinese Medicine, Tianjin Medical University General Hospital, Tianjin 300052, PR China
| | - Shuhuai Yao
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China; Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China.
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16
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Oksanen LAH, Virtanen J, Sanmark E, Rantanen N, Venkat V, Sofieva S, Aaltonen K, Kivistö I, Svirskaite J, Pérez AD, Kuula J, Levanov L, Hyvärinen A, Maunula L, Atanasova NS, Laitinen S, Anttila V, Lehtonen L, Lappalainen M, Geneid A, Sironen T. SARS-CoV-2 indoor environment contamination with epidemiological and experimental investigations. INDOOR AIR 2022; 32:e13118. [PMID: 36305066 PMCID: PMC9828560 DOI: 10.1111/ina.13118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 08/25/2022] [Accepted: 09/06/2022] [Indexed: 05/02/2023]
Abstract
SARS-CoV-2 has been detected both in air and on surfaces, but questions remain about the patient-specific and environmental factors affecting virus transmission. Additionally, more detailed information on viral sampling of the air is needed. This prospective cohort study (N = 56) presents results from 258 air and 252 surface samples from the surroundings of 23 hospitalized and eight home-treated COVID-19 index patients between July 2020 and March 2021 and compares the results between the measured environments and patient factors. Additionally, epidemiological and experimental investigations were performed. The proportions of qRT-PCR-positive air (10.7% hospital/17.6% homes) and surface samples (8.8%/12.9%) showed statistical similarity in hospital and homes. Significant SARS-CoV-2 air contamination was observed in a large (655.25 m3 ) mechanically ventilated (1.67 air changes per hour, 32.4-421 L/s/patient) patient hall even with only two patients present. All positive air samples were obtained in the absence of aerosol-generating procedures. In four cases, positive environmental samples were detected after the patients had developed a neutralizing IgG response. SARS-CoV-2 RNA was detected in the following particle sizes: 0.65-4.7 μm, 7.0-12.0 μm, >10 μm, and <100 μm. Appropriate infection control against airborne and surface transmission routes is needed in both environments, even after antibody production has begun.
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Affiliation(s)
- Lotta‐Maria A. H. Oksanen
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Department of Otorhinolaryngology and Phoniatrics – Head and Neck SurgeryHelsinki University HospitalHelsinkiFinland
| | - Jenni Virtanen
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Faculty of Veterinary MedicineUniversity of HelsinkiHelsinkiFinland
| | - Enni Sanmark
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Department of Otorhinolaryngology and Phoniatrics – Head and Neck SurgeryHelsinki University HospitalHelsinkiFinland
| | - Noora Rantanen
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Department of Otorhinolaryngology and Phoniatrics – Head and Neck SurgeryHelsinki University HospitalHelsinkiFinland
| | - Vinaya Venkat
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Faculty of Veterinary MedicineUniversity of HelsinkiHelsinkiFinland
| | - Svetlana Sofieva
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
- Finnish Meteorological InstituteHelsinkiFinland
| | - Kirsi Aaltonen
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Faculty of Veterinary MedicineUniversity of HelsinkiHelsinkiFinland
| | - Ilkka Kivistö
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Faculty of Veterinary MedicineUniversity of HelsinkiHelsinkiFinland
| | - Julija Svirskaite
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
| | | | - Joel Kuula
- Finnish Meteorological InstituteHelsinkiFinland
| | - Lev Levanov
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | | | - Leena Maunula
- Faculty of Veterinary MedicineUniversity of HelsinkiHelsinkiFinland
| | - Nina S. Atanasova
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
- Finnish Meteorological InstituteHelsinkiFinland
| | | | - Veli‐Jukka Anttila
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- HUS Inflammation CenterHelsinki University HospitalHelsinkiFinland
| | - Lasse Lehtonen
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- HUS Diagnostic Center, HUSLABHelsinki University HospitalHelsinkiFinland
| | - Maija Lappalainen
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- HUS Diagnostic Center, HUSLABHelsinki University HospitalHelsinkiFinland
| | - Ahmed Geneid
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Department of Otorhinolaryngology and Phoniatrics – Head and Neck SurgeryHelsinki University HospitalHelsinkiFinland
| | - Tarja Sironen
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Faculty of Veterinary MedicineUniversity of HelsinkiHelsinkiFinland
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17
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Stiehl B, Shrestha R, Schroeder S, Delgado J, Bazzi A, Reyes J, Kinzel M, Ahmed K. The effect of relative air humidity on the evaporation timescales of a human sneeze. AIP ADVANCES 2022; 12:075210. [PMID: 35989720 PMCID: PMC9386616 DOI: 10.1063/5.0102078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
The present paper investigates droplet and aerosol emission from the human respiratory function by numerical and experimental methods, which is analyzed at the worst-case scenario, a violent sneeze without a face covering. The research findings develop the understanding of airborne disease transmission relevant to COVID-19, its recent variants, and other airborne pathogens. A human sneeze is studied using a multiphase Computational Fluid Dynamics (CFD) model using detached eddy simulation coupled to the emission of droplets that break up, evaporate, and disperse. The model provides one of the first experimental benchmarks of CFD predictions of a human sneeze event. The experiments optically capture aerosols and droplets and are processed to provide spatiotemporal data to validate the CFD model. Under the context of large random uncertainty, the studies indicate the reasonable correlation of CFD prediction with experimental measurements using velocity profiles and exposure levels, indicating that the model captures the salient details relevant to pathogen dispersion. Second, the CFD model was extended to study the effect of relative humidity with respect to the Wells curve, providing additional insight into the complexities of evaporation and sedimentation characteristics in the context of turbulent and elevated humidity conditions associated with the sneeze. The CFD results indicated correlation with the Wells curve with additional insight into features, leading to non-conservative aspects associated with increased suspension time. These factors are found to be associated with the combination of evaporation and fluid-structure-induced suspension. This effect is studied for various ambient air humidity levels and peaks for lower humidity levels, indicating that the Wells curve may need a buffer in dry climates. Specifically, we find that the increased risk in dry climates may be up to 50% higher than would be predicted using the underlying assumptions in Wells' model.
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Affiliation(s)
| | | | | | | | | | | | | | - Kareem Ahmed
- Author to whom correspondence should be addressed: . Tel.: (407) 823-5710
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18
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Massicotte R, Assanta MA, Rosette KM. Importance of the Precautionary Principle With Regard to the Risk of Exposure to Aerosols Containing Viral Loads of SARS-CoV-2 Present in Feces: In Perspective. Front Public Health 2022; 10:892290. [PMID: 35692325 PMCID: PMC9174678 DOI: 10.3389/fpubh.2022.892290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/20/2022] [Indexed: 11/13/2022] Open
Abstract
In COVID-19 infection, the emissions of droplets and aerosols produced by the respiratory tract of contaminated subjects may represent a high risk of spreading the SARS-COV-2 virus in the environment. Thus, studies have shown that there is, at least, another source of droplets and aerosols in which viral particles of SARS-COV-2 can be found. It happens after flushing of toilet to dispose of the stools of a patient who has contracted COVID-19. The presence of viral particles of SARS-COV-2 in the stool could be linked to the concentration of angiotensin-converting enzyme 2 (ACE2) found on the surface of intestinal cells. Therefore, there is a reason to wonder whether the emission of viral particles by activating a toilet flush could represent an important potential risk of contamination for health care workers. To investigate this hypothesis, we have correlated different studies on the production of droplets and aerosols as well as the presence of viral particles following flush of toilet. This pooling of these studies led to the following conclusion: the precautionary principle should be applied with regard to the potential risk represented by viral particles of SARV-COV-2 in the stool when flushing the toilet.
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Affiliation(s)
- Richard Massicotte
- Laboratory of Innovation and Analysis of Bioperformance, Ecole Polytechnique de Montreal, Montreal, QC, Canada
| | - Mafu Akier Assanta
- Food Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Hyacinthe, QC, Canada
| | - Kakese Mukosa Rosette
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Département de Pathologie et Microbiologie, Faculté de Médecine Vétérinaire, Centre de Recherche d'Infectiologie Porcine et Avicole, Université de Montréal, Saint-Hyacinthe, QC, Canada
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19
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Cai C, Kim P, Connor TH, Liu Y, Floyd EL. Reducing the particles generated by flushing institutional toilets. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2022; 19:318-326. [PMID: 35293854 DOI: 10.1080/15459624.2022.2053693] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Airborne particles play a significant role in the transmission of SARS-CoV-2, the virus that causes COVID-19. A previous study reported that institutional flush-O-meter (FOM) toilets can generate 3-12 times as many droplets as other toilets by splashing (large droplets) and bubble bursting (fine droplets). In this study, an aerosol suppression lid was evaluated to measure the reduction of particles by size using three metrics; number, surface area, and mass concentrations. To quantify toilet flush aerosol over time, detailed particle size distributions (from 0.016-19.81 µm across 152 size bins) were measured from a FOM toilet in a controlled-environment test chamber, without ventilation, with and without use of the suppression lid. Prior to each flushing trial, the toilet bowl water was seeded with 480 mL fluorescein at 10 mg/mL. A high-speed camera was used to record the large droplet movements after flushing. An ultraviolet-visible spectrophotometer was used to analyze the wipe samples to evaluate the contamination on the lid. The particle number, surface area, and mass concentrations without a lid were elevated compared to a lid in the first 90 sec. Overall, the lid reduced 48% of total number concentration, 76% of total surface area concentration, and 66% of total mass concentration, respectively. Depending on the particle size, the number concentration reduction percentage ranged from 48-100% for particles larger than 0.1 µm. Large droplets created by splashing were captured by the high-speed camera. Similar studies can be used for future particle aerodynamic studies. The fluorescein droplets deposited on the lid back sections, which were closer to the FOM accounted for 82% of the total fluorescein. Based on two-way ANOVA analysis, there were significant differences among both the experimental flushes (p = 0.0185) and the sections on the lid (p = 0.0146). Future work should explore the aerosolization produced by flushing and the performance of the lid in real restroom environments, where feces and urine exist in the bowl water and the indoor ventilation system is in operation.
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Affiliation(s)
- Changjie Cai
- Department of Occupational and Environmental Health, Hudson College of Public Health, The University of Oklahoma Health Sciences Center, The University of Oklahoma, Oklahoma City, Oklahoma
| | - Peter Kim
- Department of Occupational and Environmental Health, Hudson College of Public Health, The University of Oklahoma Health Sciences Center, The University of Oklahoma, Oklahoma City, Oklahoma
| | - Thomas H Connor
- Applied Research and Technology, National Institute for Occupational Safety and Health (Retired), Washington, District of Columbia
| | - Yingtao Liu
- Department of Aerospace and Mechanical Engineering, Gallogly College of Engineering, The University of Oklahoma, Norman, Oklahoma
| | - Evan L Floyd
- Department of Occupational and Environmental Health, Hudson College of Public Health, The University of Oklahoma Health Sciences Center, The University of Oklahoma, Oklahoma City, Oklahoma
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20
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Vardoulakis S, Espinoza Oyarce DA, Donner E. Transmission of COVID-19 and other infectious diseases in public washrooms: A systematic review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 803:149932. [PMID: 34525681 PMCID: PMC8390098 DOI: 10.1016/j.scitotenv.2021.149932] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/13/2021] [Accepted: 08/23/2021] [Indexed: 05/03/2023]
Abstract
BACKGROUND The risk of infectious disease transmission in public washrooms causes concern particularly in the context of the COVID-19 pandemic. This systematic review aims to assess the risk of transmission of viral or bacterial infections through inhalation, surface contact, and faecal-oral routes in public washrooms in healthcare and non-healthcare environments. METHODS We systematically reviewed environmental sampling, laboratory, and epidemiological studies on viral and bacterial infection transmission in washrooms using PubMed and Scopus. The review focused on indoor, publicly accessible washrooms. RESULTS Thirty-eight studies from 13 countries were identified, including 14 studies carried out in healthcare settings, 10 in laboratories or experimental chambers, and 14 studies in restaurants, workplaces, commercial and academic environments. Thirty-three studies involved surface sampling, 15 air sampling, 8 water sampling, and 5 studies were risk assessments or outbreak investigations. Infectious disease transmission was studied in relation with: (a) toilets with flushing mechanisms; (b) hand drying systems; and (c) water taps, sinks and drains. A wide range of enteric, skin and soil bacteria and enteric and respiratory viruses were identified in public washrooms, potentially posing a risk of infection transmission. Studies on COVID-19 transmission only examined washroom contamination in healthcare settings. CONCLUSION Open-lid toilet flushing, ineffective handwashing or hand drying, substandard or infrequent surface cleaning, blocked drains, and uncovered rubbish bins can result in widespread bacterial and/or viral contamination in washrooms. However, only a few cases of infectious diseases mostly related to faecal-oral transmission originating from washrooms in restaurants were reported. Although there is a risk of microbial aerosolisation from toilet flushing and the use of hand drying systems, we found no evidence of airborne transmission of enteric or respiratory pathogens, including COVID-19, in public washrooms. Appropriate hand hygiene, surface cleaning and disinfection, and washroom maintenance and ventilation are likely to minimise the risk of infectious disease transmission.
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Affiliation(s)
- Sotiris Vardoulakis
- National Centre for Epidemiology and Population Health, Research School of Population Health, Australian National University, Canberra, ACT 2601, Australia.
| | - Daniela A Espinoza Oyarce
- National Centre for Epidemiology and Population Health, Research School of Population Health, Australian National University, Canberra, ACT 2601, Australia
| | - Erica Donner
- Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
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21
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Peña-Monferrer C, Antao S, Manson-Sawko R. Numerical investigation of droplets in a cross-ventilated space with sitting passengers under asymptomatic virus transmission conditions. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:123314. [PMID: 35002204 PMCID: PMC8728630 DOI: 10.1063/5.0070625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 11/05/2021] [Indexed: 06/14/2023]
Abstract
Asymptomatic virus transmission in public transportation is a complex process that is difficult to analyze computationally and experimentally. We present a high-resolution computational study for investigating droplet dynamics under a speech-like exhalation mode. A large eddy simulation coupled with Lagrangian tracking of drops was used to model a rectangular space with sitting thermal bodies and cross-ventilated with a multislot diffuser. Release of drops from different seat positions was evaluated to analyze the decontamination performance of the ventilation system. The results showed an overall good performance, with an average of 24.1% of droplets removed through the exhaust in the first 40 s. The droplets' distribution revealed that higher concentrations were less prevalent along the center of the domain where the passengers sit. Longitudinal contamination between rows was noted, which is a negative aspect for containing the risk of infection in a given row but has the benefit of diluting the concentration of infectious droplets. Droplets from the window seat raised more vertically and invaded the space of other passengers to a lesser extent. In contrast, droplets released from the middle seat contaminated more the aisle passenger's space, indicating that downward flow from personal ventilation could move down droplets to its breathing region. Droplets released from the aisle were dragged down by the ventilation system immediately. The distance of drops to the mouth of the passengers showed that the majority passed at a relatively safe distance. However, a few of them passed at a close distance of the order of magnitude of 1 cm.
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Affiliation(s)
- C Peña-Monferrer
- IBM Research Europe, The Hartree Centre, Warrington WA4 4AD, United Kingdom
| | - S Antao
- IBM Research Europe, The Hartree Centre, Warrington WA4 4AD, United Kingdom
| | - R Manson-Sawko
- IBM Research Europe, The Hartree Centre, Warrington WA4 4AD, United Kingdom
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22
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Wang Q, Liu L. On the Critical Role of Human Feces and Public Toilets in the Transmission of COVID-19: Evidence from China. SUSTAINABLE CITIES AND SOCIETY 2021; 75:103350. [PMID: 34540563 PMCID: PMC8433098 DOI: 10.1016/j.scs.2021.103350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 09/08/2021] [Accepted: 09/08/2021] [Indexed: 05/05/2023]
Abstract
The surprising spread speed of the COVID-19 pandemic creates an urgent need for investigating the transmission chain or transmission pattern of COVID-19 beyond the traditional respiratory channels. This study therefore examines whether human feces and public toilets play a critical role in the transmission of COVID-19. First, it develops a theoretical model that simulates the transmission chain of COVID-19 through public restrooms. Second, it uses stabilized epidemic data from China to empirically examine this theory, conducting an empirical estimation using a two-stage least squares (2SLS) model with appropriate instrumental variables (IVs). This study confirms that the wastewater directly promotes the transmission of COVID-19 within a city. However, the role of garbage in this transmission chain is more indirect in the sense that garbage has a complex relationship with public toilets, and it promotes the transmission of COVID-19 within a city through interaction with public toilets and, hence, human feces. These findings have very strong policy implications in the sense that if we can somehow use the ratio of public toilets as a policy instrument, then we can find a way to minimize the total number of infections in a region. As shown in this study, pushing the ratio of public toilets (against open defecation) to the local population in a city to its optimal level would help to reduce the total infection in a region.
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Affiliation(s)
- Qiuyun Wang
- School of Economics, Southwestern University of Finance and Economics, P.R China
| | - Lu Liu
- School of Economics, Southwestern University of Finance and Economics, P.R China
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23
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Mojtahedzadeh N, Neumann FA, Rohwer E, Nienhaus A, Augustin M, Harth V, Zyriax BC, Mache S. The Health Behaviour of German Outpatient Caregivers in Relation to the COVID-19 Pandemic: A Mixed-Methods Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:8213. [PMID: 34360505 PMCID: PMC8346166 DOI: 10.3390/ijerph18158213] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 12/23/2022]
Abstract
The COVID-19 pandemic has affected outpatient caregivers in a particular way. While the German population becomes increasingly older, the number of people in need of care has also increased. The health and, thus, the health behaviour of employees in the outpatient care become relevant to maintain working capacity and performance in the long term. The aims of the study were (1) to examine the health behaviour and (2) to explore pandemic-related perceived change of health behaviour among outpatient caregivers during the COVID-19 pandemic. In a mixed-methods study, 15 problem-centred interviews and a web-based cross-sectional survey (N = 171) were conducted with outpatient caregivers working in Northern Germany. Interviewees reported partially poorer eating behaviour, higher coffee consumption, lower physical activity, skipping breaks more often and less sleep duration and quality during the pandemic. Some quantitative findings indicate the same tendencies. A majority of participants were smokers and reported higher stress perception due to the pandemic. Preventive behaviour, such as wearing PPE or hand hygiene, was increased among interviewees compared to the pre-pandemic period. Our findings indicate that the COVID-19 pandemic could negatively affect outpatient caregivers' health behaviour, e.g., eating/drinking behaviour and physical activity. Therefore, employers in outpatient care should develop workplace health promotion measures to support their employees in conducting more health-promoting behaviours during the COVID-19 pandemic.
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Affiliation(s)
- Natascha Mojtahedzadeh
- Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany; (N.M.); (E.R.); (V.H.)
| | - Felix Alexander Neumann
- Midwifery Science—Health Services Research and Prevention, Institute for Health Service Research in Dermatology and Nursing (IVDP), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany; (F.A.N.); (B.-C.Z.)
| | - Elisabeth Rohwer
- Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany; (N.M.); (E.R.); (V.H.)
- Midwifery Science—Health Services Research and Prevention, Institute for Health Service Research in Dermatology and Nursing (IVDP), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany; (F.A.N.); (B.-C.Z.)
| | - Albert Nienhaus
- Department of Occupational Medicine, Hazardous Substances and Public Health, Institution for Statutory Accident Insurance and Prevention in the Health and Welfare Services (BGW), 22089 Hamburg, Germany;
- Competence Center for Epidemiology and Health Services Research for Healthcare Professionals (CVcare), Institute for Health Services Research in Dermatology and Nursing (IVDP), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Matthias Augustin
- Competence Center for Health Services Research in Vascular Diseases (CVvasc), Institute for Health Services Research in Dermatology and Nursing (IVDP), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany;
| | - Volker Harth
- Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany; (N.M.); (E.R.); (V.H.)
| | - Birgit-Christiane Zyriax
- Midwifery Science—Health Services Research and Prevention, Institute for Health Service Research in Dermatology and Nursing (IVDP), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany; (F.A.N.); (B.-C.Z.)
| | - Stefanie Mache
- Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany; (N.M.); (E.R.); (V.H.)
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24
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Peña-Monferrer C, Antao S, Manson-Sawko R. Numerical investigation of respiratory drops dynamics released during vocalization. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:083321. [PMID: 34471339 PMCID: PMC8404381 DOI: 10.1063/5.0059419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/01/2021] [Indexed: 05/14/2023]
Abstract
Release of drops from a human body has been the focus of many recent investigations because of the current COVID-19 pandemic. Indirect virus transmission from asymptomatic individuals has been proved to be one of the major infectious routes and difficult to quantify, detect, and mitigate. We show in this work a detailed and novel numerical investigation of drops released during vocalization from a thermal manikin using a large eddy simulation coupled with Lagrangian tracking of drops. The vocalization experiment was modeled using existing data from the literature for modeling exhaled airflow, emission rate, and size distribution. Particular focus was on the definition of the boundary conditions for the exhalation process. Turbulence was compared with experimental data for the near mouth region for 75 exhalation breathing cycles and showed the sensitivity of different modeling assumptions at the mouth inlet. The results provide insights of special interest for understanding drop dynamics in speech-like exhalation modes, modeling the mouth inlet boundary conditions, and providing data for verifying other more simplified models.
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Affiliation(s)
- C. Peña-Monferrer
- IBM Research Europe, The Hartree Centre, Warrington WA4 4Ad, United Kingdom
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Chatterjee S, Murallidharan JS, Agrawal A, Bhardwaj R. How coronavirus survives for hours in aerosols. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:081708. [PMID: 34471334 PMCID: PMC8404379 DOI: 10.1063/5.0059908] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 08/01/2021] [Indexed: 05/10/2023]
Abstract
COVID (CoronaVirus Disease)-19, caused by severe acute respiratory syndrome-CoronaVirus-2 (SARS-CoV-2) virus, predominantly transmits via airborne route, as highlighted by recent studies. Furthermore, recently published titer measurements of SARS-CoV-2 in aerosols have disclosed that the coronavirus can survive for hours. A consolidated knowledge on the physical mechanism and governing rules behind the significantly long survival of coronavirus in aerosols is lacking, which is the subject of the present investigation. We model the evaporation of aerosolized droplets of diameter ≤ 5 μ m. The conventional diffusion-limited evaporation is not valid to model the evaporation of small size (μm-nm) droplets since it predicts drying time on the order of milliseconds. Also, the sedimentation timescale of desiccated droplets is on the order of days and overpredicts the virus survival time; hence, it does not corroborate with the above-mentioned titer-decay timescale. We attribute the virus survival timescale to the fact that the drying of small ( ∼ μ m-nm) droplets is governed, in principle, by the excess internal pressure within the droplet, which stems from the disjoining pressure due to the cohesive intermolecular interaction between the liquid molecules and the Laplace-pressure. The model predictions for the temporal reduction in the aerosolized droplet number density agree well with the temporal decay of virus titer. The findings, therefore, provide insight on the survival of coronavirus in aerosols, which is particularly important to mitigate the spread of COVID-19 from indoors.
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Affiliation(s)
- Sanghamitro Chatterjee
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | | | - Amit Agrawal
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Rajneesh Bhardwaj
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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Islam MS, Larpruenrudee P, Saha SC, Pourmehran O, Paul AR, Gemci T, Collins R, Paul G, Gu Y. How severe acute respiratory syndrome coronavirus-2 aerosol propagates through the age-specific upper airways. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:081911. [PMID: 34552312 PMCID: PMC8450910 DOI: 10.1063/5.0061627] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 07/24/2021] [Indexed: 05/22/2023]
Abstract
The recent outbreak of the COVID-19 causes significant respirational health problems, including high mortality rates worldwide. The deadly corona virus-containing aerosol enters the atmospheric air through sneezing, exhalation, or talking, assembling with the particulate matter, and subsequently transferring to the respiratory system. This recent outbreak illustrates that the severe acute respiratory syndrome (SARS) coronavirus-2 is deadlier for aged people than for other age groups. It is evident that the airway diameter reduces with age, and an accurate understanding of SARS aerosol transport through different elderly people's airways could potentially help the overall respiratory health assessment, which is currently lacking in the literature. This first-ever study investigates SARS COVID-2 aerosol transport in age-specific airway systems. A highly asymmetric age-specific airway model and fluent solver (ANSYS 19.2) are used for the investigation. The computational fluid dynamics measurement predicts higher SARS COVID-2 aerosol concentration in the airway wall for older adults than for younger people. The numerical study reports that the smaller SARS coronavirus-2 aerosol deposition rate in the right lung is higher than that in the left lung, and the opposite scenario occurs for the larger SARS coronavirus-2 aerosol rate. The numerical results show a fluctuating trend of pressure at different generations of the age-specific model. The findings of this study would improve the knowledge of SARS coronavirus-2 aerosol transportation to the upper airways which would thus ameliorate the targeted aerosol drug delivery system.
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Affiliation(s)
- Mohammad S. Islam
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney (UTS), 15 Broadway, Ultimo, New South Wales 2007, Australia
- Authors to whom correspondence should be addressed: and
| | - Puchanee Larpruenrudee
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney (UTS), 15 Broadway, Ultimo, New South Wales 2007, Australia
| | - Suvash C. Saha
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney (UTS), 15 Broadway, Ultimo, New South Wales 2007, Australia
- Authors to whom correspondence should be addressed: and
| | - Oveis Pourmehran
- School of Mechanical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia and Department of Surgery—Otolaryngology Head and Neck Surgery, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Akshoy Ranjan Paul
- Department of Applied Mechanics, Motilal Nehru National Institute of Technology Allahabad, Prayagraj 211004, Uttar Pradesh, India
| | | | - Richard Collins
- Biomechanics International, Cranberry Township, Pennsylvania 16066, USA
| | - Gunther Paul
- James Cook University, Australian Institute of Tropical Health and Medicine, Townsville, Queensland 4810, Australia
| | - Yuantong Gu
- School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, Brisbane 4000, Australia
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Abney SE, Bright KR, McKinney J, Ijaz MK, Gerba CP. Toilet hygiene-review and research needs. J Appl Microbiol 2021; 131:2705-2714. [PMID: 33899991 PMCID: PMC9292268 DOI: 10.1111/jam.15121] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 03/26/2021] [Accepted: 04/21/2021] [Indexed: 11/26/2022]
Abstract
The goal of good toilet hygiene is minimizing the potential for pathogen transmission. Control of odours is also socially important and believed to be a societal measure of cleanliness. Understanding the need for good cleaning and disinfecting is even more important today considering the potential spread of emerging pathogens such as SARS‐CoV‐2 virus. While the flush toilet was a major advancement in achieving these objectives, exposure to pathogens can occur from failure to clean and disinfect areas within a restroom, as well as poor hand hygiene. The build‐up of biofilm within a toilet bowl/urinal including sink can result in the persistence of pathogens and odours. During flushing, pathogens can be ejected from the toilet bowl/urinal/sink and be transmitted by inhalation and contaminated fomites. Use of automatic toilet bowl cleaners can reduce the number of microorganisms ejected during a flush. Salmonella bacteria can colonize the underside of the rim of toilets and persist up to 50 days. Pathogenic enteric bacteria appear in greater numbers in the biofilm found in toilets than in the water. Source tracking of bacteria in homes has demonstrated that during cleaning enteric bacteria are transferred from the toilet to the bathroom sinks and that these same bacteria colonize cleaning tools used in the restroom. Quantitative microbial risk assessment has shown that significant risks exist from both aerosols and fomites in restrooms. Cleaning with soaps and detergents without the use of disinfectants in public restrooms may spread bacteria and viruses throughout the restroom. Odours in restrooms are largely controlled by ventilation and flushing volume in toilet/urinals. However, this results in increased energy and water usage. Contamination of both the air and surfaces in restrooms is well documented. Better quantification of the risks of infection are needed as this will help determine what interventions will minimize these risks.
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Affiliation(s)
- S E Abney
- Department of Environmental Science, University of Arizona, Tucson, AZ, USA
| | - K R Bright
- Department of Environmental Science, University of Arizona, Tucson, AZ, USA
| | - J McKinney
- Global Research and Development for Lysol and Dettol, Reckitt Benckiser LLC, Montvale, NJ, USA
| | - M Khalid Ijaz
- Global Research and Development for Lysol and Dettol, Reckitt Benckiser LLC, Montvale, NJ, USA.,Department of Biology, Medgar Evers College of the City University of New York (CUNY), Brooklyn, NY, USA
| | - C P Gerba
- Department of Environmental Science, University of Arizona, Tucson, AZ, USA
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