1
|
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.
Collapse
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
| |
Collapse
|
2
|
Luo Q, Liu W, Liao J, Gu Z, Fan X, Luo Z, Zhang X, Hang J, Ou C. COVID-19 transmission and control in land public transport: A literature review. FUNDAMENTAL RESEARCH 2024; 4:417-429. [PMID: 38933205 PMCID: PMC11197583 DOI: 10.1016/j.fmre.2023.10.013] [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: 09/30/2022] [Revised: 10/18/2023] [Accepted: 10/20/2023] [Indexed: 06/28/2024] Open
Abstract
Land public transport is an important link within and between cities, and how to control the transmission of COVID-19 in land public transport is a critical issue in our daily lives. However, there are still many inconsistent opinions and views about the spread of SARS-CoV-2 in land public transport, which limits our ability to implement effective interventions. The purpose of this review is to overview the literature on transmission characteristics and routes of the epidemic in land public transport, as well as to investigate factors affecting its spread and provide feasible measures to mitigate the infection risk of passengers. We obtained 898 papers by searching the Web of Science, Pubmed, and WHO global COVID database by keywords, and finally selected 45 papers that can address the purpose of this review. Land public transport is a high outbreak area for COVID-19 due to characteristics like crowding, inadequate ventilation, long exposure time, and environmental closure. Different from surface touch transmission and drop spray transmission, aerosol inhalation transmission can occur not only in short distances but also in long distances. Insufficient ventilation is the most important factor influencing long-distance aerosol transmission. Other transmission factors (e.g., interpersonal distance, relative orientation, and ambient conditions) should be noticed as well, which have been summarized in this paper. To address various influencing factors, it is essential to suggest practical and efficient preventive measures. Among these, increased ventilation, particularly the fresh air (i.e., natural ventilation), has proven to effectively reduce indoor infection risk. Many preventive measures are also effective, such as enlarging social distance, avoiding face-to-face orientation, setting up physical partitions, disinfection, avoiding talking, and so on. As research on the epidemic has intensified, people have broken down many perceived barriers, but more comprehensive studies on monitoring systems and prevention measures in land public transport are still needed.
Collapse
Affiliation(s)
- Qiqi Luo
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
- Key Laboratory of Urban Meteorology, China Meteorological Administration, Beijing 100089, China
- China Meteorological Administration Xiong'an Atmospheric Boundary Layer Key Laboratory, Xiong'an 070001, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai 519000, China
| | - Wenbing Liu
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
| | - Jiayuan Liao
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
| | - Zhongli Gu
- Guangdong Fans-tech Agro Co., Ltd, Yunfu 527300, China
| | - Xiaodan Fan
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
| | - Zhiwen Luo
- Welsh School of Architecture, Cardiff University, Cardiff CF10 3XQ, United Kingdom
| | - Xuelin Zhang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
| | - Jian Hang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
- Key Laboratory of Urban Meteorology, China Meteorological Administration, Beijing 100089, China
- China Meteorological Administration Xiong'an Atmospheric Boundary Layer Key Laboratory, Xiong'an 070001, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai 519000, China
| | - Cuiyun Ou
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
| |
Collapse
|
3
|
Wilson NM, Calabria C, Warren A, Finlay A, O'Donovan A, Passerello GL, Ribaric NL, Ward P, Gillespie R, Farrel R, McNarry AF, Pan D. Quantifying hospital environmental ventilation using carbon dioxide monitoring - a multicentre study. Anaesthesia 2024; 79:147-155. [PMID: 38059394 DOI: 10.1111/anae.16124] [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] [Accepted: 08/17/2023] [Indexed: 12/08/2023]
Abstract
The COVID-19 pandemic has highlighted the importance of environmental ventilation in reducing airborne pathogen transmission. Carbon dioxide monitoring is recommended in the community to ensure adequate ventilation. Dynamic measurements of ventilation quantifying human exhaled waste gas accumulation are not conducted routinely in hospitals. Instead, environmental ventilation is allocated using static hourly air change rates. These vary according to the degree of perceived hazard, with the highest change rates reserved for locations where aerosol-generating procedures are performed, where medical/anaesthetic gases are used and where a small number of high-risk infective or immunocompromised patients may be isolated to reduce cross-infection. We aimed to quantify the quality and distribution of ventilation in hospital by measuring carbon dioxide levels in a two-phased prospective observational study. First, under controlled conditions, we validated our method and the relationship between human occupancy, ventilation and carbon dioxide levels using non-dispersive infrared carbon dioxide monitors. We then assessed ventilation quality in patient-occupied (clinical) and staff break and office (non-clinical) areas across two hospitals in Scotland. We selected acute medical and respiratory wards in which patients with COVID-19 are cared for routinely, as well as ICUs and operating theatres where aerosol-generating procedures are performed routinely. Between November and December 2022, 127,680 carbon dioxide measurements were obtained across 32 areas over 8 weeks. Carbon dioxide levels breached the 800 ppm threshold for 14% of the time in non-clinical areas vs. 7% in clinical areas (p < 0.001). In non-clinical areas, carbon dioxide levels were > 800 ppm for 20% of the time in both ICUs and wards, vs. 1% in operating theatres (p < 0.001). In clinical areas, carbon dioxide was > 800 ppm for 16% of the time in wards, vs. 0% in ICUs and operating theatres (p < 0.001). We conclude that staff break, office and clinical areas on acute medical and respiratory wards frequently had inadequate ventilation, potentially increasing the risks of airborne pathogen transmission to staff and patients. Conversely, ventilation was consistently high in the ICU and operating theatre clinical environments. Carbon dioxide monitoring could be used to measure and guide improvements in hospital ventilation.
Collapse
Affiliation(s)
- N M Wilson
- Department of Anaesthesia and Critical Care, Royal Infirmary of Edinburgh, Edinburgh, UK
- Usher Institute, University of Edinburgh, Edinburgh, UK
| | - C Calabria
- Department of Anaesthesia and Critical Care, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - A Warren
- Department of Anaesthesia and Critical Care, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - A Finlay
- Department of Anaesthesia and Critical Care, Victoria Hospital, Kirkcaldy, UK
| | - A O'Donovan
- Department of Process, Energy and Transport Engineering, MeSSO Research Group, Munster Technological University, Cork, Ireland
| | - G L Passerello
- Department of Anaesthesia and Critical Care, Victoria Hospital, Kirkcaldy, UK
| | - N L Ribaric
- Faculty of Medicine, University Medical Centre Hamburg-Eppendorf, University of Hamburg, Hamburg, Germany
| | - P Ward
- Department of Anaesthesia, St John's Hospital, Livingston, UK
| | - R Gillespie
- Department of Anaesthesia and Critical Care, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - R Farrel
- Department of Anaesthesia and Critical Care, Victoria Hospital, Kirkcaldy, UK
| | - A F McNarry
- Department of Anaesthesia, Western General Hospital, UK
| | - D Pan
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
- Department of Infectious Diseases and HIV Medicine, University Hospitals of Leicester NHS Trust, Leicester, UK
| |
Collapse
|
4
|
Lordly K, Kober L, Jadidi M, Antoun S, Dworkin SB, Karataş AE. Understanding lifetime and dispersion of cough-emitted droplets in air. INDOOR + BUILT ENVIRONMENT : THE JOURNAL OF THE INTERNATIONAL SOCIETY OF THE BUILT ENVIRONMENT 2023; 32:1929-1948. [PMID: 38023440 PMCID: PMC10657780 DOI: 10.1177/1420326x221098753] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 04/19/2022] [Indexed: 12/01/2023]
Abstract
To understand the exact transmission routes of SARS-CoV-2 and to explore effects of time, space and indoor environment on the dynamics of droplets and aerosols, rigorous testing and observation must be conducted. In the current work, the spatial and temporal dispersions of aerosol droplets from a simulated cough were comprehensively examined over a long duration (70 min). An artificial cough generator was constructed to generate reliably repeatable respiratory ejecta. The measurements were performed at different locations in front (along the axial direction and off-axis) and behind the source in a sealed experimental enclosure. Aerosols of 0.3-10 µm (around 20% of the maximum nuclei count) were shown to persist for a very long time in a still environment, and this has a substantial implication for airborne disease transmission. The experiments demonstrated that a ventilation system could reduce the total aerosol volume and the droplet lifetime significantly. To explain the experimental observations in more detail and to understand the droplet in-air behaviour at various ambient temperatures and relative humidity, numerical simulations were performed using the Eulerian-Lagrangian approach. The simulations show that many of the small droplets remain suspended in the air over time instead of falling to the ground.
Collapse
Affiliation(s)
- Kai Lordly
- Department of Aerospace Engineering, Toronto Metropolitan University, Toronto, ON, Canada
| | - Leya Kober
- Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada
| | - Mehdi Jadidi
- Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada
| | - Sylvie Antoun
- Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada
| | - Seth B Dworkin
- Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada
| | - Ahmet E Karataş
- Department of Aerospace Engineering, Toronto Metropolitan University, Toronto, ON, Canada
| |
Collapse
|
5
|
Ijaz MK, Sattar SA, Nims RW, Boone SA, McKinney J, Gerba CP. Environmental dissemination of respiratory viruses: dynamic interdependencies of respiratory droplets, aerosols, aerial particulates, environmental surfaces, and contribution of viral re-aerosolization. PeerJ 2023; 11:e16420. [PMID: 38025703 PMCID: PMC10680453 DOI: 10.7717/peerj.16420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 10/17/2023] [Indexed: 12/01/2023] Open
Abstract
During the recent pandemic of COVID-19 (SARS-CoV-2), influential public health agencies such as the World Health Organization (WHO) and the U.S. Centers for Disease Control and Prevention (CDC) have favored the view that SARS CoV-2 spreads predominantly via droplets. Many experts in aerobiology have openly opposed that stance, forcing a vigorous debate on the topic. In this review, we discuss the various proposed modes of viral transmission, stressing the interdependencies between droplet, aerosol, and fomite spread. Relative humidity and temperature prevailing determine the rates at which respiratory aerosols and droplets emitted from an expiratory event (sneezing, coughing, etc.) evaporate to form smaller droplets or aerosols, or experience hygroscopic growth. Gravitational settling of droplets may result in contamination of environmental surfaces (fomites). Depending upon human, animal and mechanical activities in the occupied space indoors, viruses deposited on environmental surfaces may be re-aerosolized (re-suspended) to contribute to aerosols, and can be conveyed on aerial particulate matter such as dust and allergens. The transmission of respiratory viruses may then best be viewed as resulting from dynamic virus spread from infected individuals to susceptible individuals by various physical states of active respiratory emissions, instead of the current paradigm that emphasizes separate dissemination by respiratory droplets, aerosols or by contaminated fomites. To achieve the optimum outcome in terms of risk mitigation and infection prevention and control (IPAC) during seasonal infection peaks, outbreaks, and pandemics, this holistic view emphasizes the importance of dealing with all interdependent transmission modalities, rather than focusing on one modality.
Collapse
Affiliation(s)
- M. Khalid Ijaz
- Global Research & Development for Lysol and Dettol, Reckitt Benckiser LLC, Montvale, NJ, United States of America
| | - Syed A. Sattar
- Department of Biochemistry, Microbiology & Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | | | - Stephanie A. Boone
- Water & Energy Sustainable Technology Center, University of Arizona, Tucson, AZ, United States of America
| | - Julie McKinney
- Global Research & Development for Lysol and Dettol, Reckitt Benckiser LLC, Montvale, NJ, United States of America
| | - Charles P. Gerba
- Water & Energy Sustainable Technology Center, University of Arizona, Tucson, AZ, United States of America
| |
Collapse
|
6
|
Guo Y, Dou Z, Zhang N, Liu X, Su B, Li Y, Zhang Y. Student close contact behavior and COVID-19 transmission in China's classrooms. PNAS NEXUS 2023; 2:pgad142. [PMID: 37228510 PMCID: PMC10205473 DOI: 10.1093/pnasnexus/pgad142] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 04/10/2023] [Accepted: 04/14/2023] [Indexed: 05/27/2023]
Abstract
Classrooms are high-risk indoor environments, so analysis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission in classrooms is important for determining optimal interventions. Due to the absence of human behavior data, it is challenging to accurately determine virus exposure in classrooms. A wearable device for close contact behavior detection was developed, and we recorded >250,000 data points of close contact behaviors of students from grades 1 to 12. Combined with a survey on students' behaviors, we analyzed virus transmission in classrooms. Close contact rates for students were 37 ± 11% during classes and 48 ± 13% during breaks. Students in lower grades had higher close contact rates and virus transmission potential. The long-range airborne transmission route is dominant, accounting for 90 ± 3.6% and 75 ± 7.7% with and without mask wearing, respectively. During breaks, the short-range airborne route became more important, contributing 48 ± 3.1% in grades 1 to 9 (without wearing masks). Ventilation alone cannot always meet the demands of COVID-19 control; 30 m3/h/person is suggested as the threshold outdoor air ventilation rate in a classroom. This study provides scientific support for COVID-19 prevention and control in classrooms, and our proposed human behavior detection and analysis methods offer a powerful tool to understand virus transmission characteristics and can be employed in various indoor environments.
Collapse
Affiliation(s)
- Yong Guo
- Department of Building Science, Tsinghua University, Beijing 100084, China
- Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Beijing 100084, China
| | - Zhiyang Dou
- Department of Computer Science, The University of Hong Kong, Beijing 999077, China
| | - Nan Zhang
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing 100124, China
| | - Xiyue Liu
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing 100124, China
| | - Boni Su
- Clean Energy Research Institute, China Electric Power Planning and Engineering Institute, Beijing 100120, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR 999077, China
| | - Yinping Zhang
- Department of Building Science, Tsinghua University, Beijing 100084, China
- Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Beijing 100084, China
| |
Collapse
|
7
|
Wang Y, Wei J, Gao CX, Jin T, Liu L. Tracing the origin of large respiratory droplets by their deposition characteristics inside the respiratory tract during speech. BUILDING SIMULATION 2023; 16:781-794. [PMID: 37101943 PMCID: PMC10009356 DOI: 10.1007/s12273-022-0982-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 12/12/2022] [Accepted: 12/22/2022] [Indexed: 05/28/2023]
Abstract
Origin of differently sized respiratory droplets is fundamental for clarifying their viral loads and the sequential transmission mechanism of SARS-CoV-2 in indoor environments. Transient talking activities characterized by low (0.2 L/s), medium (0.9 L/s), and high (1.6 L/s) airflow rates of monosyllabic and successive syllabic vocalizations were investigated by computational fluid dynamics (CFD) simulations based on a real human airway model. SST k-ω model was chosen to predict the airflow field, and the discrete phase model (DPM) was used to calculate the trajectories of droplets within the respiratory tract. The results showed that flow field in the respiratory tract during speech is characterized by a significant laryngeal jet, and bronchi, larynx, and pharynx-larynx junction were main deposition sites for droplets released from the lower respiratory tract or around the vocal cords, and among which, over 90% of droplets over 5 µm released from vocal cords deposited at the larynx and pharynx-larynx junction. Generally, droplets' deposition fraction increased with their size, and the maximum size of droplets that were able to escape into external environment decreased with the airflow rate. This threshold size for droplets released from the vocal folds was 10-20 µm, while that for droplets released from the bronchi was 5-20 µm under various airflow rates. Besides, successive syllables pronounced at low airflow rates promoted the escape of small droplets, but do not significantly affect the droplet threshold diameter. This study indicates that droplets larger than 20 µm may entirely originate from the oral cavity, where viral loads are lower; it provides a reference for evaluating the relative importance of large-droplet spray and airborne transmission route of COVID-19 and other respiratory infections.
Collapse
Affiliation(s)
- Yihan Wang
- Institute of Refrigeration and Cryogenics, Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Zhejiang University, Hangzhou, 310000 China
| | - Jianjian Wei
- Institute of Refrigeration and Cryogenics, Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Zhejiang University, Hangzhou, 310000 China
| | - Caroline X. Gao
- Public Health and Preventive Medicine, Monash University, Melbourne, VIC 3004 Australia
| | - Tao Jin
- Institute of Refrigeration and Cryogenics, Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Zhejiang University, Hangzhou, 310000 China
| | - Li Liu
- Department of Building Science, Tsinghua University, Beijing, 100084 China
| |
Collapse
|
8
|
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.
Collapse
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.
| |
Collapse
|
9
|
Brosseau LM, Jones RM, Gardner K, Williams SC, Henry KP, Sanders D. Health and Safety Regulations for COVID-19: A Policy Analysis. Ann Work Expo Health 2023; 67:21-35. [PMID: 36511485 DOI: 10.1093/annweh/wxac084] [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: 09/25/2022] [Accepted: 11/16/2022] [Indexed: 12/15/2022] Open
Abstract
The COVID-19 pandemic spurred some regulators in the USA to require occupational health and safety programs to prevent COVID-19 transmission in workplaces. The objective of this study was to describe such state and federal regulations enacted between January 2020 and January 2022. Regulations, including emergency temporary standards (ETS) and permanent standards, were identified through a search of Nexis Uni and Bloomberg Law and review of US OSHA websites and the Federal Register. Full texts were reviewed for regulatory scope, hazard and exposure definitions, determination of exposure or risk levels, and control strategies. Four state (California, Michigan, Virginia, and Oregon) and two federal regulations were identified. All regulations described respiratory aerosols as the primary source of SARS-CoV-2 and recognized person-to-person transmission by droplet, airborne, and contact routes. Only the US OSHA ETS for healthcare explicitly stated that inhalation of respiratory particles was the most likely method of COVID-19 transmission. The Virginia, Michigan, and Oregon regulations described different categories of risk defined by exposure frequency and duration or specific workplace activities. California described exposure as places and times when employees come into contact or congregate with other people. The US OSHA ETS for healthcare described exposure as involving close contact with suspected or confirmed COVID-19 patients. While all of the state regulations required strategies from across the hierarchy, only the Virginia regulations specifically incorporated the hierarchy of controls. Only the California and Virginia regulations explicitly linked control strategies to the transmission route, while Virginia demarcated control strategies by risk level. Oregon linked risk level to occupancy levels and physical distancing requirements and referred to the use of a layered approach for transmission control. The US OSHA ETS for healthcare defined droplet and airborne precautions but made no mention of the hierarchy of controls or risk levels. Respirators were discussed in most of the regulations. The first Michigan regulation explicitly required respirators appropriate to exposure risk. The California regulations noted that respirators protect the wearer while face coverings protect people around the wearer. These regulations offer insights for a permanent US OSHA infectious disease regulation, such as the need to consider a range of transmission modes including near- and far-range aerosol inhalation, endemic and novel pathogens, workplaces beyond healthcare settings, factors that contribute to exposure and risk, the hierarchy of controls, the role of vaccination, and the importance of written exposure assessment and infection prevention plans.
Collapse
Affiliation(s)
- Lisa M Brosseau
- Center for Infectious Disease Research and Policy, University of Minnesota, 420 Delaware St SE, Minneapolis, MN 55455, USA
| | - Rachael M Jones
- Department of Environmental Health Sciences, Fielding School of Public Health, University of California, 50 Charles E Young Dr S, Los Angeles, CA 90095, USA.,Department of Family and Preventive Medicine, Spencer Fox Eccles School of Medicine, University of Utah, 375 Chipeta Way Suite A, Salt Lake City, UT 84108, USA
| | - Kate Gardner
- Department of Family and Preventive Medicine, Spencer Fox Eccles School of Medicine, University of Utah, 375 Chipeta Way Suite A, Salt Lake City, UT 84108, USA
| | - Spencer C Williams
- Department of Family and Preventive Medicine, Spencer Fox Eccles School of Medicine, University of Utah, 375 Chipeta Way Suite A, Salt Lake City, UT 84108, USA
| | | | - Denali Sanders
- Department of Environmental Health and Radiological Health Sciences, Colorado State University, 122A Environmental Health Building, Fort Collins, CO 80523, USA
| |
Collapse
|
10
|
Zhang S, Niu D, Lin Z. Occupancy-aided ventilation for airborne infection risk control: Continuously or intermittently reduced occupancies? BUILDING SIMULATION 2022; 16:733-747. [PMID: 36373145 PMCID: PMC9638348 DOI: 10.1007/s12273-022-0951-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/24/2022] [Accepted: 10/09/2022] [Indexed: 05/25/2023]
Abstract
Ventilation is an important engineering measure to control the airborne infection risk of acute respiratory diseases, e.g., Corona Virus Disease 2019 (COVID-19). Occupancy-aided ventilation methods can effectively improve the airborne infection risk control performance with a sacrifice of decreasing working productivity because of the reduced occupancy. This study evaluates the effectiveness of two occupancy-aided ventilation methods, i.e., the continuously reduced occupancy method and the intermittently reduced occupancy method. The continuously reduced occupancy method is determined by the steady equation of the mass conservation law of the indoor contaminant, and the intermittently reduced occupancy method is determined by a genetic algorithm-based optimization. A two-scenarios-based evaluation framework is developed, i.e., one with targeted airborne infection risk control performance (indicated by the mean rebreathed fraction) and the other with targeted working productivity (indicated by the accumulated occupancy). The results show that the improvement in the airborne infection risk control performance linearly and quadratically increases with the reduction in the working productivity for the continuously reduced occupancy method and the intermittently reduced occupancy method respectively. At a given targeted airborne infection risk control performance, the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the working productivity by up to 92%. At a given targeted working productivity, the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the airborne infection risk control performance by up to 38%.
Collapse
Affiliation(s)
- Sheng Zhang
- School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an, China
| | - Dun Niu
- School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an, China
| | - Zhang Lin
- Division of Building Science and Technology, City University of Hong Kong, Hong Kong, China
| |
Collapse
|
11
|
Nunayon SS, Wang M, Zhang HH, Lai ACK. Evaluating the efficacy of a rotating upper-room UVC-LED irradiation device in inactivating aerosolized Escherichia coli under different disinfection ranges, air mixing, and irradiation conditions. JOURNAL OF HAZARDOUS MATERIALS 2022; 440:129791. [PMID: 36027747 DOI: 10.1016/j.jhazmat.2022.129791] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 08/09/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
Cost-effective and safe air disinfection methods are urgently needed in various environmental public settings. A novel UVC-based disinfection system was designed and tested to provide a promising solution because of its effective inactivation of indoor bioaerosols at a low cost. UVC light-emitting diodes (UVC-LEDs) were utilized as the irradiation source. This system has the unique feature of rotating the UVC-LEDs to generate a "scanning irradiation" zone. Escherichia coli was aerosolized into an experimental chamber, exposed to UVC-LEDs, and sampled using an impactor. Effects of air mixing (well-mixed vs. poorly-mixed), transmission range (short vs. long), and irradiation mode (stationary vs. rotating) were evaluated. The system performs significantly well under the poorly-mixed condition. The results obtained from the short disinfection range indicate that the rotating UVC was approximately 70.5 % more effective than the stationary UVC for the poorly-mixed case. Further, we evaluated the performance of the long disinfection range under a poorly-mixed situation, and the disinfection efficacy was 84.6 % higher for the rotating irradiation than that of the stationary. About 0.59-1.34 J/m2 UV dose can be used to obtain one-log inactivation of E. coli. In conclusion, the novel rotating upper-room UVC-LED system is effective in reducing indoor pathogen transmission, and our findings are highly significant to a growing field where LEDs are applied for disinfection.
Collapse
Affiliation(s)
- Sunday S Nunayon
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Minghao Wang
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Hui H Zhang
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Alvin C K Lai
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
| |
Collapse
|
12
|
Wu J, Geng J, Fu M, Weng W. Multi-person movement-induced airflow and the effects on virus-laden expiratory droplet dispersion in indoor environments. INDOOR AIR 2022; 32:e13119. [PMID: 36168216 DOI: 10.1111/ina.13119] [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: 07/18/2022] [Revised: 09/11/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
The multi-person movement might cause complex induced airflow and affect the virus-laden expiratory droplet transmission in indoor environments. Using the dynamic mesh model in computational fluid dynamics, the multi-person movement with different personnel location distributions was realized. The induced airflow patterns, virus-laden droplet dispersion, and concentration distribution were investigated in detail. The results show that multi-person movement might intensify inter-regional convection, which has been rarely found in single-person movement conditions. Side-by-side distribution and ladder distribution of moving persons could cause a connected low-pressure area behind the moving persons, which might enhance lateral virus transport, especially where droplets might suspend at the height of the breathing zone. Not only 1-10 μm aerosols but also some 20-50 μm droplets are carried by the multi-person movement-induced airflow to over 3 m. Since the width of induced airflow is about 0.6-1.0 m, moving persons should keep enough horizontal distance (>1.0 m) to limit the air mixing and virus-laden droplet transmission. This paper could provide a detailed reference for the numerical study of multi-person movement-induced airflow patterns, droplet dispersion, and indoor infection control.
Collapse
Affiliation(s)
- Jialin Wu
- Department of Engineering Physics, Tsinghua University, Institute of Public Safety Research, Beijing, China
- Beijing Key Laboratory of City Integrated Emergency Response Science, Tsinghua University, Beijing, China
| | - Jing Geng
- Department of Engineering Physics, Tsinghua University, Institute of Public Safety Research, Beijing, China
- Beijing Key Laboratory of City Integrated Emergency Response Science, Tsinghua University, Beijing, China
| | - Ming Fu
- Hefei Institute for Public Safety Research, Tsinghua University, Hefei, Anhui Province, China
- Anhui Province Key Laboratory of Human Safety, Hefei, Anhui Province, China
| | - Wenguo Weng
- Department of Engineering Physics, Tsinghua University, Institute of Public Safety Research, Beijing, China
- Beijing Key Laboratory of City Integrated Emergency Response Science, Tsinghua University, Beijing, China
| |
Collapse
|
13
|
Habibi N, Uddin S, Behbehani M, Al Salameen F, Razzack NA, Zakir F, Shajan A, Alam F. Bacterial and fungal communities in indoor aerosols from two Kuwaiti hospitals. Front Microbiol 2022; 13:955913. [PMID: 35966680 PMCID: PMC9366136 DOI: 10.3389/fmicb.2022.955913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 07/04/2022] [Indexed: 11/16/2022] Open
Abstract
The airborne transmission of COVID-19 has drawn immense attention to bioaerosols. The topic is highly relevant in the indoor hospital environment where vulnerable patients are treated and healthcare workers are exposed to various pathogenic and non-pathogenic microbes. Knowledge of the microbial communities in such settings will enable precautionary measures to prevent any hospital-mediated outbreak and better assess occupational exposure of the healthcare workers. This study presents a baseline of the bacterial and fungal population of two major hospitals in Kuwait dealing with COVID patients, and in a non-hospital setting through targeted amplicon sequencing. The predominant bacteria of bioaerosols were Variovorax (9.44%), Parvibaculum (8.27%), Pseudonocardia (8.04%), Taonella (5.74%), Arthrospira (4.58%), Comamonas (3.84%), Methylibium (3.13%), Sphingobium (4.46%), Zoogloea (2.20%), and Sphingopyxis (2.56%). ESKAPEE pathogens, such as Pseudomonas, Acinetobacter, Staphylococcus, Enterococcus, and Escherichia, were also found in lower abundances. The fungi were represented by Wilcoxinia rehmii (64.38%), Aspergillus ruber (9.11%), Penicillium desertorum (3.89%), Leptobacillium leptobactrum (3.20%), Humicola grisea (2.99%), Ganoderma sichuanense (1.42%), Malassezia restricta (0.74%), Heterophoma sylvatica (0.49%), Fusarium proliferatum (0.46%), and Saccharomyces cerevisiae (0.23%). Some common and unique operational taxonomic units (OTUs) of bacteria and fungi were also recorded at each site; this inter-site variability shows that exhaled air can be a source of this variation. The alpha-diversity indices suggested variance in species richness and abundance in hospitals than in non-hospital sites. The community structure of bacteria varied spatially (ANOSIM r 2 = 0.181-0.243; p < 0.05) between the hospital and non-hospital sites, whereas fungi were more or less homogenous. Key taxa specific to the hospitals were Defluvicoccales, fungi, Ganodermataceae, Heterophoma, and H. sylvatica compared to Actinobacteria, Leptobacillium, L. leptobacillium, and Cordycipitaceae at the non-hospital site (LefSe, FDR q ≤ 0.05). The hospital/non-hospital MD index > 1 indicated shifts in the microbial communities of indoor air in hospitals. These findings highlight the need for regular surveillance of indoor hospital environments to prevent future outbreaks.
Collapse
Affiliation(s)
| | - Saif Uddin
- Environment and Life Science Research Centre, Kuwait Institute for Scientific Research, Kuwait City, Kuwait
| | | | | | | | | | | | | |
Collapse
|
14
|
Mikszewski A, Stabile L, Buonanno G, Morawska L. Increased close proximity airborne transmission of the SARS-CoV-2 Delta variant. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 816:151499. [PMID: 34752865 PMCID: PMC8571125 DOI: 10.1016/j.scitotenv.2021.151499] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/14/2021] [Accepted: 11/03/2021] [Indexed: 05/04/2023]
Abstract
The Delta variant of SARS-CoV-2 causes higher viral loads in infected hosts, increasing the risk of close proximity airborne transmission through breathing, speaking and coughing. We performed a Monte Carlo simulation using a social contact network and exponential dose-response model to quantify the close proximity reproduction number of both wild-type SARS-CoV-2 and the Delta variant. We estimate more than twice as many Delta variant cases will reproduce infection in their close proximity contacts (64%) versus the wild-type SARS-CoV-2 (29%). Occupational health guidelines must consider close proximity airborne transmission and recommend improved personal respiratory protection for high-risk workers.
Collapse
Affiliation(s)
- Alex Mikszewski
- International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Qld, Australia; CIUS Building Performance Lab, The City University of New York, New York 10001, NY, USA
| | - Luca Stabile
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, FR, Italy
| | - Giorgio Buonanno
- International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Qld, Australia; Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, FR, Italy
| | - Lidia Morawska
- International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Qld, Australia; Global Centre for Clean Air Research (GCARE), Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, United Kingdom..
| |
Collapse
|
15
|
Kong M, Li L, Eilts SM, Li L, Hogan CJ, Pope ZC. Localized and Whole-Room Effects of Portable Air Filtration Units on Aerosol Particle Deposition and Concentration in a Classroom Environment. ACS ES&T ENGINEERING 2022; 2:653-669. [PMID: 37552723 PMCID: PMC8864773 DOI: 10.1021/acsestengg.1c00321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 05/14/2023]
Abstract
In indoor environments with limited ventilation, recirculating portable air filtration (PAF) units may reduce COVID-19 infection risk via not only the direct aerosol route (i.e., inhalation) but also via an indirect aerosol route (i.e., contact with the surface where aerosol particles deposited). We systematically investigated the impact of PAF units in a mock classroom, as a supplement to background ventilation, on localized and whole-room surface deposition and particle concentration. Fluorescently tagged particles with a volumetric mean diameter near 2 μm were continuously introduced into the classroom environment via a breathing simulator with a prescribed inhalation-exhalation waveform. Deposition velocities were inferred on >50 horizontal and vertical surfaces throughout the classroom, while aerosol concentrations were spatially monitored via optical particle spectrometry. Results revealed a particle decay rate consistent with expectations based upon the reported clean air delivery rates of the PAF units. Additionally, the PAF units reduced peak concentrations by a factor of around 2.5 compared to the highest concentrations observed and led to a statistically significant reduction in deposition velocities for horizontal surfaces >2.5 m from the aerosol source. Our results not only confirm that PAF units can reduce particle concentrations but also demonstrate that they may lead to reduced particle deposition throughout an indoor environment when properly positioned with respect to the location of the particle source(s) within the room (e.g., where the largest group of students sit) and the predominant air distribution profile of the room.
Collapse
Affiliation(s)
- Meng Kong
- Well Living Lab, Rochester,
Minnesota 55902, United States
| | - Linhao Li
- Well Living Lab, Rochester,
Minnesota 55902, United States
| | - Stephanie M. Eilts
- Department of Mechanical Engineering,
University of Minnesota, Minneapolis, Minnesota 55455,
United States
| | - Li Li
- Department of Mechanical Engineering,
University of Minnesota, Minneapolis, Minnesota 55455,
United States
| | - Christopher J. Hogan
- Department of Mechanical Engineering,
University of Minnesota, Minneapolis, Minnesota 55455,
United States
| | - Zachary C. Pope
- Well Living Lab, Rochester,
Minnesota 55902, United States
- Mayo Clinic, Department of Physiology and
Biomedical Engineering, Rochester, Minnesota 55905, United
States
| |
Collapse
|
16
|
Ezzatpanah H, Gómez-López VM, Koutchma T, Lavafpour F, Moerman F, Mohammadi M, Raheem D. Risks and new challenges in the food chain: Viral contamination and decontamination from a global perspective, guidelines, and cleaning. Compr Rev Food Sci Food Saf 2022; 21:868-903. [PMID: 35142438 DOI: 10.1111/1541-4337.12899] [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: 04/08/2021] [Revised: 11/10/2021] [Accepted: 12/08/2021] [Indexed: 11/27/2022]
Abstract
Even during the continuing world pandemic of severe acute respiratory syndrome coronavirus 2 (SARS CoV-2), consumers remain exposed to the risk of getting infected by existing, emerging, or re-emerging foodborne and waterborne viruses. SARS-CoV-2 is different in that it is transmitted directly via the airborne route (droplets and aerosols) or indirect contact (surfaces contaminated with SARS-CoV-2). International food and health organizations and national regulatory bodies have provided guidance to protect individuals active in food premises from potential occupational exposure to SARS-CoV-2, and have recommended chemicals effective in controlling the virus. Additionally, to exclude transmission of foodborne and waterborne viruses, hygiene practices to remove viral contaminants from surfaces are applied in different stages of the food chain (e.g., food plants, food distribution, storage, retail sector, etc.), while new and enhanced measures effective in the control of all types of viruses are under development. This comprehensive review aims to analyze and compare efficacies of existing cleaning practices currently used in the food industry to remove pathogenic viruses from air, nonfood, and food contact surfaces, as well as from food surfaces. In addition, the classification, modes of transmission, and survival of food and waterborne viruses, as well as SARS-CoV-2 will be presented. The international guidelines and national regulations are summarized in terms of virucidal chemical agents and their applications.
Collapse
Affiliation(s)
- Hamid Ezzatpanah
- Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | | | - Tatiana Koutchma
- Guelph Research and Development Center, Agriculture and Agri-Food Canada, Guelph, Ontario, Canada
| | | | - Frank Moerman
- Department of Chemistry, Catholic University of Leuven - KU Leuven, Leuven, Belgium
| | | | - Dele Raheem
- Arctic Centre (NIEM), University of Lapland, Rovaniemi, Finland
| |
Collapse
|
17
|
Chen W, Qian H, Zhang N, Liu F, Liu L, Li Y. Extended short-range airborne transmission of respiratory infections. JOURNAL OF HAZARDOUS MATERIALS 2022; 422:126837. [PMID: 34399209 PMCID: PMC8342890 DOI: 10.1016/j.jhazmat.2021.126837] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 05/09/2023]
Abstract
Debate and scientific inquiries regarding airborne transmission of respiratory infections such as COVID-19 and influenza continue. Health authorities including the WHO and the US CDC have recognized the airborne transmission of COVID-19 in specific settings, although the ventilation requirements remain to be determined. In this work we consider the long-range airborne transmission as an extended short-range airborne route, which reconciles the link between short- and long-range airborne routes. The effective short-range distance is defined as the distance in short range at which long-range route has the same volumetric exposure value as that due to short-range route. Our data show that a decrease in ventilation rate or room volume per person, or an increase in the ratio of the number of infected to susceptible people reduces the effective short-range distance. In a normal breathing scenario with one out of five people infected and a room volume of 12 m3 per person to ensure an effective short-range distance of 1.5 m, a ventilation rate of 10 L/s per person is needed for a duration of 2 h. Our results suggest that effective environmental prevention strategies for respiratory infections require appropriate increases in the ventilation rate while maintaining a sufficiently low occupancy. PRACTICAL IMPLICATIONS: Demonstration of the long-range airborne route as an extended short-range airborne route suggests the significant role played by building ventilation in respiratory infection exposure. The reconciliation of short- and long-range airborne transmission suggests that the commonly observed dominance of close-contact transmission is a probable evidence of short-range airborne transmission, following a separate earlier study that revealed the relative insignificance of large droplet transmission in comparison with the short-range airborne-route. Existing ventilation standards do not account for respiratory infection control, and this study presents a possible approach to account for infection under new ventilation standards.
Collapse
Affiliation(s)
- Wenzhao Chen
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Hua Qian
- School of Energy and Environment, Southeast University, Nanjing, China
| | - Nan Zhang
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Fan Liu
- School of Energy and Environment, Southeast University, Nanjing, China
| | - Li Liu
- School of Architecture, Tsinghua University, Beijing, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
| |
Collapse
|
18
|
Turkyilmazoglu M. Indoor transmission of airborne viral aerosol with a simplistic reaction-diffusion model. THE EUROPEAN PHYSICAL JOURNAL. SPECIAL TOPICS 2022; 231:3591-3601. [PMID: 35669449 PMCID: PMC9148948 DOI: 10.1140/epjs/s11734-022-00614-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 05/24/2022] [Indexed: 05/06/2023]
Abstract
A simplistic reaction-diffusion model is undertaken in the present work to mathematically explore the spatio-temporal development of concentration of indoor aerosols containing infectious COVID-19 respiratory virus nuclei. Extracting exact solutions of concentration field under the influence of several physical parameters is preferred rather than adopting a more realistic complex model requiring time-consuming numerical simulations. Even though the proposed model is not sophisticated, the analytical solutions can provide quick prediction of the probability of contracting the virus in a ventilated closed room. Moreover, from the obtained elementary solutions of the viral concentration field, it is easy to analyze its spatio-temporal evolution and final equilibrium state. Formulae enable us to estimate the time to get infected and the risk of getting infected within an elapsed time under various physical operative situations involving a uniform infectious particle mixture ejection into the medium, wearing a face mask with a well-defined efficiency parameter and taking into account a localized source of infection. One of the essential conclusion from the current research is that less aerosols carrying COVID-19 particles are as a result of good indoor ventilation conditions, of removing the medium air through windows (or other exits) and of wearing masks of high efficiency. Moreover, the risk and probability of being caught by the indoor COVID-19 disease increases in time, particularly in the downstream of a localized infectious person. The results can be beneficial to understand and take necessary safety considerations against the infection risk in closed public or governmental environments.
Collapse
Affiliation(s)
- Mustafa Turkyilmazoglu
- Department of Mathematics, Hacettepe University, 06532 Beytepe, Ankara Turkey
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
| |
Collapse
|
19
|
Ribaric NL, Vincent C, Jonitz G, Hellinger A, Ribaric G. Hidden hazards of SARS-CoV-2 transmission in hospitals: A systematic review. INDOOR AIR 2022; 32:e12968. [PMID: 34862811 DOI: 10.1111/ina.12968] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 09/17/2021] [Accepted: 11/19/2021] [Indexed: 05/04/2023]
Abstract
Despite their considerable prevalence, dynamics of hospital-associated COVID-19 are still not well understood. We assessed the nature and extent of air- and surface-borne SARS-CoV-2 contamination in hospitals to identify hazards of viral dispersal and enable more precise targeting of infection prevention and control. PubMed, ScienceDirect, Web of Science, Medrxiv, and Biorxiv were searched for relevant articles until June 1, 2021. In total, 51 observational cross-sectional studies comprising 6258 samples were included. SARS-CoV-2 RNA was detected in one in six air and surface samples throughout the hospital and up to 7.62 m away from the nearest patients. The highest detection rates and viral concentrations were reported from patient areas. The most frequently and heavily contaminated types of surfaces comprised air outlets and hospital floors. Viable virus was recovered from the air and fomites. Among size-fractionated air samples, only fine aerosols contained viable virus. Aerosol-generating procedures significantly increased (ORair = 2.56 (1.46-4.51); ORsurface = 1.95 (1.27-2.99)), whereas patient masking significantly decreased air- and surface-borne SARS-CoV-2 contamination (ORair = 0.41 (0.25-0.70); ORsurface = 0.45 (0.34-0.61)). The nature and extent of hospital contamination indicate that SARS-CoV-2 is likely dispersed conjointly through several transmission routes, including short- and long-range aerosol, droplet, and fomite transmission.
Collapse
Affiliation(s)
- Noach Leon Ribaric
- Faculty of Medicine, University Medical Center Hamburg-Eppendorf, University of Hamburg, Hamburg, Germany
| | - Charles Vincent
- Department of Experimental Psychology, University of Oxford, Oxford, UK
| | - Günther Jonitz
- German Medical Association, Berlin, Germany
- State Chamber of Physicians Berlin, Berlin, Germany
| | - Achim Hellinger
- Department of General, Visceral, Endocrine and Oncologic Surgery, Fulda Hospital, University Medicine Marburg Campus Fulda, Fulda, Germany
| | - Goran Ribaric
- Johnson & Johnson Institute, Norderstedt, Germany
- MedTech Europe, Antimicrobial Resistance (AMR) and Healthcare Associated Infections (HAI) Sector Group, Brussels, Belgium
| |
Collapse
|
20
|
Zhang N, Liu X, Jin T, Zhao P, Miao D, Lei H, Su B, Xue P, Xie J, Li Y. Weakening personal protective behavior by Chinese university students after COVID-19 vaccination. BUILDING AND ENVIRONMENT 2021; 206:108367. [PMID: 34566244 PMCID: PMC8450227 DOI: 10.1016/j.buildenv.2021.108367] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/14/2021] [Accepted: 09/15/2021] [Indexed: 05/14/2023]
Abstract
Personal protective behaviors and their dynamic change are known to play a major role in the community spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal pathogen of the coronavirus disease 2019 (COVID-19) pandemic. In this study, a total of 3229 students in Chinese universities completed an online survey about their knowledge on transmission and personal protective behavior before and after COVID-19 vaccination. Of the respondents, 87.6% had been vaccinated. Most students believed that the large droplet (97.0%) and short-range airborne (89.3%) routes were the two most likely SARS-CoV-2 transmission routes, whereas only 24.1% considered long-range airborne transmission to be possible. Students who would be expected to possess better knowledge about virus transmission (e.g., students of medicine) reported better personal protective behaviors. Female students reported relatively better personal hygiene practices than male students, so did the confident students than their diffident peers. Students washed their hands on average of 5.76 times per day during the pandemic. Students at universities in southern regions washed their hands more frequently but paid less attention to indoor ventilation than did their northern counterparts. Interestingly, students who are fear of being infected had the bad personal hygiene. University students wore 22% less masks in public indoor environments after vaccination. Chinese university students weakened their personal protective behavior after vaccination and it may increase the potential risk of infection in the new waves of variant virus (e.g. delta).
Collapse
Affiliation(s)
- Nan Zhang
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Xiyue Liu
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Tianyi Jin
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Pengcheng Zhao
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, SAR, China
| | - Doudou Miao
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Hao Lei
- School of Public Health, Zhejiang University, Hangzhou, Zhejiang, China
| | - Boni Su
- China Electric Power Planning & Engineering Institute, Beijing, China
| | - Peng Xue
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Jingchao Xie
- Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, SAR, China
- School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, China
| |
Collapse
|
21
|
Capasso L, D’Alessandro D. Housing and Health: Here We Go Again. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph182212060. [PMID: 34831815 PMCID: PMC8624624 DOI: 10.3390/ijerph182212060] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 11/15/2021] [Indexed: 12/23/2022]
Abstract
Housing is one of the major determinants of human health and the current COVID-19 pandemic has highlighted its relevance. The authors summarize the main issues, including dimensional standards, indoor air quality, safety, accessibility, neighborhoods, and area characteristics. The authors propose an operating scheme in order to implement actions to improve residential wellbeing on a local, national, and international level.
Collapse
Affiliation(s)
- Lorenzo Capasso
- Italian Ministry of Education, USR Abruzzo (Regional Office of Abruzzi), 66100 Chieti, Italy
- Correspondence:
| | - Daniela D’Alessandro
- Department of Civil Building and Environmental Engineering, “Sapienza” University of Rome, 00100 Rome, Italy;
| |
Collapse
|
22
|
Habibi N, Uddin S, Al‐Salameen F, Al‐Amad S, Kumar V, Al‐Otaibi M, Razzack NA, Shajan A, Shirshikar F. SARS-CoV-2, other respiratory viruses and bacteria in aerosols: Report from Kuwait's hospitals. INDOOR AIR 2021; 31:1815-1825. [PMID: 34121237 PMCID: PMC8447393 DOI: 10.1111/ina.12871] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/23/2021] [Accepted: 05/27/2021] [Indexed: 05/08/2023]
Abstract
The role of airborne particles in the spread of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is well explored. The novel coronavirus can survive in aerosol for extended periods, and its interaction with other viral communities can cause additional virulence and infectivity. This baseline study reports concentrations of SARS-CoV-2, other respiratory viruses, and pathogenic bacteria in the indoor air from three major hospitals (Sheikh Jaber, Mubarak Al-Kabeer, and Al-Amiri) in Kuwait dealing with coronavirus disease 2019 (COVID-19) patients. The indoor aerosol samples showed 12-99 copies of SARS-CoV-2 per m3 of air. Two non-SARS-coronavirus (strain HKU1 and NL63), respiratory syncytial virus (RSV), and human bocavirus, human rhinoviruses, Influenza B (FluB), and human enteroviruses were also detected in COVID-positive areas of Mubarak Al Kabeer hospital (MKH). Pathogenic bacteria such as Mycoplasma pneumonia, Streptococcus pneumonia and, Haemophilus influenza were also found in the hospital aerosols. Our results suggest that the existing interventions such as social distancing, use of masks, hand hygiene, surface sanitization, and avoidance of crowded indoor spaces are adequate to prevent the spread of SARS-CoV-2 in enclosed areas. However, increased ventilation can significantly reduce the concentration of SARS-CoV-2 in indoor aerosols. The synergistic or inhibitory effects of other respiratory pathogens in the spread, severity, and complexity of SARS-CoV-2 need further investigation.
Collapse
Affiliation(s)
- N. Habibi
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - S. Uddin
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - F. Al‐Salameen
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - S. Al‐Amad
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - V. Kumar
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - M. Al‐Otaibi
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - N. Abdul Razzack
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - A. Shajan
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - F. Shirshikar
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| |
Collapse
|
23
|
Li Y, Nazaroff WW, Bahnfleth W, Wargocki P, Zhang Y. The COVID-19 pandemic is a global indoor air crisis that should lead to change: A message commemorating 30 years of Indoor Air. INDOOR AIR 2021; 31:1683-1686. [PMID: 34661309 PMCID: PMC8653253 DOI: 10.1111/ina.12928] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 08/20/2021] [Accepted: 08/24/2021] [Indexed: 05/19/2023]
Affiliation(s)
- Yuguo Li
- Department of Mechanical EngineeringThe University of Hong KongHong Kong SARChina
| | | | - William Bahnfleth
- Department of Architectural EngineeringPennsylvania State University (Penn State)University ParkPAUSA
| | - Pawel Wargocki
- Department of Civil EngineeringTechnical University of DenmarkLyngbyDenmark
| | - Yinping Zhang
- Department of Building ScienceTsinghua UniversityBeijingChina
| |
Collapse
|
24
|
Public toilets with insufficient ventilation present high cross infection risk. Sci Rep 2021; 11:20623. [PMID: 34663838 PMCID: PMC8523564 DOI: 10.1038/s41598-021-00166-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/07/2021] [Indexed: 12/28/2022] Open
Abstract
Due to insufficient ventilation, public toilets present high risks for cross-infection. The study investigated 61 public toilets to identify the causes and locations of biological contaminated sources. Airborne and surface bacterial contamination, carbon dioxide concentration, and surface ammonia levels were measured. Both bacterial contamination and CO2 are higher in non-ventilated toilets compared to their ventilated counterparts. Bacteria colony forming units (CFUs) in a public toilet with poor ventilation can reach 5 times the number of CFUs outside of the toilet. This suggests that non-ventilated public toilets present a higher risk of cross-infection. Areas near all kinds of sanitary equipment (toilet bowls, squat toilets and urinals) were highly contaminated, indicating that enhanced cleaning regimes are necessary. Further, lidless trash bins present a higher risk as contaminated matter within the trash bins is not inhibited from being released into the environment. Ventilation and cleaning need to be improved to mitigate the risk of cross-infection in public toilets.
Collapse
|
25
|
Lovec V, Premrov M, Leskovar VŽ. Practical Impact of the COVID-19 Pandemic on Indoor Air Quality and Thermal Comfort in Kindergartens. A Case Study of Slovenia. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18189712. [PMID: 34574634 PMCID: PMC8472386 DOI: 10.3390/ijerph18189712] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/27/2021] [Accepted: 09/10/2021] [Indexed: 11/16/2022]
Abstract
The experimental monitoring of carbon dioxide concentration was carried out in kindergartens in Slovenia, together with indoor air temperature and relative humidity, before and during the COVID-19 pandemic. The aim of the research was to estimate the practical impact of the pandemic on indoor air quality and thermal comfort. The case study sample included buildings with different architectural typology, which are predominantly present in the building stock of Slovenia. The monitoring process lasted for 125 days before and during the COVID-19 pandemic. The results have shown a better indoor air quality in kindergartens during the pandemic, mostly due to ventilation protocols and almost imperceptibly changed indoor air temperature. The COVID-19 pandemic affected air quality in kindergarten classrooms in Slovenia by reducing the average carbon dioxide concentration when children were present in classrooms by 30%.
Collapse
|