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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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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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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: 6] [Impact Index Per Article: 3.0] [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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Chang SM, Chen JW, Tsai CS, Ko WC, Scaria J, Wang JL. Antimicrobial-Resistant Escherichia coli Distribution and Whole-Genome Analysis of Sequence Type 131 Escherichia coli Isolates in Public Restrooms in Taiwan. Front Microbiol 2022; 13:864209. [PMID: 35495726 PMCID: PMC9044074 DOI: 10.3389/fmicb.2022.864209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 02/28/2022] [Indexed: 11/15/2022] Open
Abstract
The threat of antibiotic-resistant bacteria to public health may originate from public restrooms. To better understand the community burden of antimicrobial-resistant Escherichia coli and sequence type complex 131 E. coli (STc131) in the public restroom, we performed a surveillance in public restrooms in southern Taiwan. Swabs were sampled from randomly selected public restrooms in Tainan, Taiwan in 2019. Antimicrobial susceptibility, phylogenetic grouping, and multiplex PCR were performed for the major ST complex in the B2 phylogenetic group. If STc131 isolates were identified, the whole-genome sequencing was performed. A total of 613 collection sites found 132 sites (21.5%) positive for E. coli. The most common phylogenetic group was A (30.9%) followed by B2 (30.3%). Ceftriaxone-resistant E. coli and extended-spectrum β-lactamases–producing E. coli were found in 2.4 and 1.0% of total public restrooms, respectively. The isolates in rural areas had higher ceftriaxone non-susceptibility than those in the city centers (3.9 vs. 1.2%, P = 0.038). Nine STc131 isolates were found in public restrooms, and most (77.8%) belonged to the subtype fimH41, whereas 22.2% belonged to fimH30. With the inclusion of STc131 isolates from human and dog fecal colonization in Taiwan, whole-genome sequencing was performed in 35 isolates. A large cluster of fimH41 in SNP-tree and GrapeTree was found from different sources (human, dog, and environment) and geographical areas. In conclusion, our surveillance of antimicrobial-resistant E. coli showed a higher prevalence of E. coli detected in public restrooms in the rural areas compared to those in city centers. The whole-genome sequence implies that fimH41 STc131 strains are successfully circulated in the community in Taiwan.
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Affiliation(s)
- Szu-Min Chang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jenn-Wei Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chin-Shiang Tsai
- Department of Internal Medicine, National Cheng Kung University Hospital, Dou-Liou Branch, College of Medicine, National Cheng Kung University, Yunlin, Taiwan.,Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Wen-Chien Ko
- Department of Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Joy Scaria
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, United States
| | - Jiun-Ling Wang
- Department of Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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