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Jin L, Ye M, Lin W, Ye Y, Chuang YC, Luo JY, Tang F. Identification of key potential infection processes and risk factors in the computed tomography examination process by FMEA method under COVID-19. BMC Infect Dis 2024; 24:257. [PMID: 38395803 PMCID: PMC10893727 DOI: 10.1186/s12879-024-09136-z] [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: 10/18/2023] [Accepted: 02/13/2024] [Indexed: 02/25/2024] Open
Abstract
PURPOSE To identify the key infection processes and risk factors in Computed Tomography (CT) examination process within the standard prevention and control measures for the COVID-19 epidemic, aiming to mitigate cross-infection occurrences in the hospital. METHOD The case hospital has assembled a team of 30 experts specialized in CT examination. Based on the CT examination process, the potential failure modes were assessed from the perspective of severity (S), occurrence probability (O), and detectability (D); they were then combined with corresponding risk prevention measures. Finally, key infection processes and risk factors were identified according to the risk priority number (RPN) and expert analysis. RESULTS Through the application of RPN and further analysis, four key potential infection processes were identified, including "CT request form (A1)," "during the scan of CT patient (B2)," "CT room and objects disposal (C2)," and "medical waste (garbage) disposal (C3)". In addition, eight key risk factors were also identified, including "cleaning personnel does not wear masks normatively (C32)," "nurse does not select the vein well, resulting in extravasation of the peripheral vein for enhanced CT (B25)," "patient cannot find the CT room (A13)," "patient has obtained a CT request form but does not know the procedure (A12)," "patient is too unwell to continue with the CT scan (B24)," "auxiliary staff (or technician) does not have a good grasp of the sterilization and disinfection standards (C21)," "auxiliary staff (or technician) does not sterilize the CT machine thoroughly (C22)," and "cleaning personnel lacks of knowledge of COVID-19 prevention and control (C33)". CONCLUSION Hospitals can publicize the precautions regarding CT examination through various channels, reducing the incidence of CT examination failure. Hospitals' cleaning services are usually outsourced, and the educational background of the staff employed in these services is generally not high. Therefore, during training and communication, it is more necessary to provide a series of scope and training programs that are aligned with their understanding level. The model developed in this study effectively identifies the key infection prevention process and critical risk factors, enhancing the safety of medical staff and patients. This has significant research implications for the potential epidemic of major infectious diseases.
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Affiliation(s)
- Lingzhi Jin
- Radiology department, Taizhou Central Hospital (Taizhou University Hospital), Taizhou, Zhejiang, China
| | - Meiting Ye
- Radiology department, Taizhou Central Hospital (Taizhou University Hospital), Taizhou, Zhejiang, China
| | - Wenhua Lin
- Radiology department, Taizhou Central Hospital (Taizhou University Hospital), Taizhou, Zhejiang, China
| | - Yong Ye
- Institute of Public Health and Emergency Management, Taizhou University, Taizhou, Zhejiang, China
- Business College, Taizhou University, Taizhou, Zhejiang, China
| | - Yen-Ching Chuang
- Institute of Public Health and Emergency Management, Taizhou University, Taizhou, Zhejiang, China.
- Business College, Taizhou University, Taizhou, Zhejiang, China.
- Key Laboratory of evidence-based Radiology of Taizhou, Linhai, Zhejiang, China.
| | - Jin-Yan Luo
- Institute for Hospital Management, Tsing Hua University, Shenzhen, Guangdong, China.
| | - Fuqin Tang
- Nursing Department, Taizhou Central Hospital (Taizhou University Hospital), Taizhou, China.
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Hao W, Huang YW, Wang Y. Bioaerosol size as a potential determinant of airborne E. coliviability under ultraviolet germicidal irradiation and ozone disinfection. NANOTECHNOLOGY 2024; 35:145702. [PMID: 38086064 DOI: 10.1088/1361-6528/ad14b4] [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: 08/28/2023] [Accepted: 12/12/2023] [Indexed: 01/18/2024]
Abstract
Ultraviolet germicidal irradiation (UVGI) and ozone disinfection are crucial methods for mitigating the airborne transmission of pathogenic microorganisms in high-risk settings, particularly with the emergence of respiratory viral pathogens such as SARS-CoV-2 and avian influenza viruses. This study quantitatively investigates the influence of UVGI and ozone on the viability ofE. coliin bioaerosols, with a particular focus on howE. coliviability depends on the size of the bioaerosols, a critical factor that determines deposition patterns within the human respiratory system and the evolution of bioaerosols in indoor environments. This study used a controlled small-scale laboratory chamber whereE. colisuspensions were aerosolized and subjected to varying levels of UVGI and ozone levels throughout the exposure time (2-6 s). The normalized viability ofE. coliwas found to be significantly reduced by UVGI (60-240μW s cm-2) as the exposure time increased from 2 to 6 s, and the most substantial reduction ofE. colinormalized viability was observed when UVGI and ozone (65-131 ppb) were used in combination. We also found that UVGI reduced the normalized viability ofE. coliin bioaerosols more significantly with smaller sizes (0.25-0.5μm) than with larger sizes (0.5-2.5μm). However, when combining UVGI and ozone, the normalized viability was higher for smaller particle sizes than for the larger ones. The findings provide insights into the development of effective UVGI disinfection engineering methods to control the spread of pathogenic microorganisms in high-risk environments. By understanding the influence of the viability of microorganisms in various bioaerosol sizes, we can optimize UVGI and ozone techniques to reduce the potential risk of airborne transmission of pathogens.
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Affiliation(s)
- Weixing Hao
- Department of Chemical, Environmental and Materials Engineering, University of Miami, Coral Gables, FL 33146, United States of America
| | - Yue-Wern Huang
- Department of Biological Sciences, Missouri University of Science and Technology, Rolla, MO 65409, United States of America
| | - Yang Wang
- Department of Chemical, Environmental and Materials Engineering, University of Miami, Coral Gables, FL 33146, United States of America
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3
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Luo H, Zhang S, Zhong L. Ultraviolet germicidal irradiation: A prediction model to estimate UV-C-induced infectivity loss in single-strand RNA viruses. ENVIRONMENTAL RESEARCH 2024; 241:117704. [PMID: 37984783 DOI: 10.1016/j.envres.2023.117704] [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: 08/31/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 11/22/2023]
Abstract
Ultraviolet germicidal irradiation (UVGI) disinfection technology is effective in inactivating microorganisms. However, its performance can vary against different microorganisms due to their diverse structural and genomic features. Thus, rapid predictions of UV (254 nm) inactivation kinetics are essential, particularly for highly infectious emerging pathogens, such as SARS-CoV-2, during the extemporary COVID-19 pandemic. In this study, aiming at single-strand RNA (ssRNA) viruses, an improved genomic model was introduced to predict the UV inactivation kinetics of viral genomes using genome sequence data. First, the overall virus infectivity loss in an aqueous matrix was estimated as the sum of damage to both the entire genome and the protein capsid. Then, the "UV rate constant ratio of aerosol and liquid" was used to convert the UV rate constant for viruses in a liquid-based matrix to an airborne state. The prediction model underwent both quantitative and qualitative validation using experimental data from this study and the literature. Finally, with the goal of mitigating potential airborne transmission of ssRNA viruses in indoor environments, this paper summarizes existing in-duct UVGI system designs and evaluates their germicidal performance. The prediction model may serve as a preliminary tool to assess the effectiveness of a UVGI system for emerging or unculturable viruses or to estimate the required UV dose when designing such a system.
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Affiliation(s)
- Hao Luo
- Department of Mechanical Engineering, University of Alberta, 9211-116 Street NW, Edmonton, Alberta, T6G 1H9, Canada
| | - Shuce Zhang
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, T6G 2G2, Canada
| | - Lexuan Zhong
- Department of Mechanical Engineering, University of Alberta, 9211-116 Street NW, Edmonton, Alberta, T6G 1H9, Canada.
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4
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Liu H, Liu Z, He J, Hu C, Rong R, Han H, Wang L, Wang D. Reducing airborne transmission of SARS-CoV-2 by an upper-room ultraviolet germicidal irradiation system in a hospital isolation environment. ENVIRONMENTAL RESEARCH 2023; 237:116952. [PMID: 37619635 DOI: 10.1016/j.envres.2023.116952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/08/2023] [Accepted: 08/21/2023] [Indexed: 08/26/2023]
Abstract
Upper-room ultraviolet germicidal irradiation (UVGI) technology can potentially inhibit the transmission of airborne disease pathogens. There is a lack of quantitative evaluation of the performance of the upper-room UVGI for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) airborne transmission under the combined effects of ventilation and UV irradiation. Therefore, this study aimed to explore the performance of the upper-room UVGI system for reducing SARS-CoV-2 virus transmission in a hospital isolation environment. Computational fluid dynamics and virological data on SARS-CoV-2 were integrated to obtain virus aerosol exposure in the hospital isolation environment containing buffer rooms, wards and bathrooms. The UV inactivation model was applied to investigate the effects of ventilation rate, irradiation flux and irradiation height on the upper-room UVGI performance. The results showed that increasing ventilation rate from 8 to 16 air changes per hour (ACH) without UVGI obtained 54.32% and 45.63% virus reduction in the wards and bathrooms, respectively. However, the upper-room UVGI could achieve 90.43% and 99.09% virus disinfection, respectively, with the ventilation rate of 8 ACH and the irradiation flux of 10 μW cm-2. Higher percentage of virus could be inactivated by the upper-room UVGI at a lower ventilation rate; the rate of improvement of UVGI elimination effect slowed down with the increase of irradiation flux. Increase irradiation height at lower ventilation rate was more effective in improving the UVGI performance than the increase in irradiation flux at smaller irradiation height. These results could provide theoretical support for the practical application of UVGI in hospital isolation environments.
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Affiliation(s)
- Haiyang Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Zhijian Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China.
| | - Junzhou He
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Chenxing Hu
- School of Mechanical Engineering, Beijing Institute of Technology, Beijing, 100081, China
| | - Rui Rong
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Hao Han
- State Key Laboratory of NBC Protection for Civilian, Beijing, 100191, China.
| | - Lingyun Wang
- State Key Laboratory of NBC Protection for Civilian, Beijing, 100191, China
| | - Desheng Wang
- State Key Laboratory of NBC Protection for Civilian, Beijing, 100191, China
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Park S, Mistrick R, Sitzabee W, Rim D. Effect of ventilation strategy on performance of upper-room ultraviolet germicidal irradiation (UVGI) system in a learning environment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 899:165454. [PMID: 37467991 DOI: 10.1016/j.scitotenv.2023.165454] [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: 11/20/2022] [Revised: 06/22/2023] [Accepted: 07/08/2023] [Indexed: 07/21/2023]
Abstract
Upper-room ultraviolet germicidal irradiation (UVGI) system is recently in the limelight as a potentially effective method to mitigate the risk of airborne virus infection in indoor environments. However, few studies quantitatively evaluated the relationship between ventilation effectiveness and virus disinfection performance of a UVGI system. The objective of this study is to investigate the effects of ventilation strategy on detailed airflow distributions and UVGI disinfection performance in an occupied classroom. Three-dimensional computational fluid dynamics (CFD) simulations were performed for representative cooling, heating, and ventilation scenarios. The results show that when the ventilation rate is 1.1 h-1 (the minimum ventilation rate based on ASHRAE 62.1), enhancing indoor air circulation with the mixing fan notably improves the UVGI disinfection performance, especially for cooling with displacement ventilation and all-air-heating conditions. However, increasing indoor air mixing yields negligible effect on the disinfection performance for forced-convection cooling condition. The results also reveal that regardless of indoor thermal condition, disinfection effectiveness of a UVGI system increases as ventilation effectiveness is close to unity. Moreover, when the room average air speed is >0.1 m/s, upper-room UVGI system could yield about 90% disinfection effect for the aerosol size of 1 μm-10 μm. The findings of this study imply that upper-room UVGI systems in indoor environments (i.e., classrooms, hospitals) should be designed considering ventilation strategy and occupancy conditions, especially for occupied buildings with insufficient air mixing throughout the space.
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Affiliation(s)
- Seongjun Park
- Department of Architectural Engineering, Pennsylvania State University, United States of America.
| | - Richard Mistrick
- Architectural Engineering Department, Pennsylvania State University, 104 Engineering Unit A, University Park, PA 16802, United States of America.
| | - William Sitzabee
- Pennsylvania State University, 201 Physical Plant Building, University Park, PA 16802, United States of America.
| | - Donghyun Rim
- Architectural Engineering Department, Pennsylvania State University, 222 Engineering Unit A, University Park, PA 16802, United States of America.
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Maubert B, Theillière C, Jany P, Bourlet T, Deschamps J, Pozzetto B, Singh F, Gadea E. Ultrafast inactivation of SARS-CoV-2 by 254-nm UV-C irradiation on porous and non-porous media of medical interest using an omnidirectional chamber. Sci Rep 2023; 13:12648. [PMID: 37542073 PMCID: PMC10403608 DOI: 10.1038/s41598-023-39439-1] [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: 03/01/2023] [Accepted: 07/25/2023] [Indexed: 08/06/2023] Open
Abstract
Covid-19 has spurred a renewed interest in decontamination techniques for air, objects and surfaces. Beginning in 2020, urgent effort was done to permit the reuse of UV-C for inactivating SARS-CoV-2. However, those studies diverged widely on the dose necessary to reach this goal; until today, the real value of the sensitivity of the virus to a 254-nm illumination is not known precisely. In this study, decontamination was performed in an original UV-C large decontamination chamber (UVCab, ON-LIGHT, France) delivering an omnidirectional irradiation with an average dose of 50 mJ/cm2 in 60 s. Viral inactivation was checked by both cell culture and PCR test. SARS-CoV-2 was inactivated by UV-C light within 3 s on both porous (disposable gown) and non-porous (stainless steel and apron) surfaces. For the porous surface, an irradiation of 5 min was needed to achieve a completely negative PCR signal. The Z value estimating the sensitivity of SARS-CoV-2 to UV-C in the experimental conditions of our cabinet was shown to be > 0.5820 m2/J. These results illustrate the ability of this apparatus to inactivate rapidly and definitively high loads of SARS-CoV-2 deposited on porous or non-porous supports and opens new perspectives on material decontamination using UV-C.
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Affiliation(s)
- Bertrand Maubert
- Laboratoire de Biologie, Centre Hospitalier Emile Roux, 43000, Le Puy en Velay, France
| | - Camille Theillière
- Unité de Recherche Clinique, Centre Hospitalier Emile Roux, 43000, Le Puy en Velay, France
- CIRI, Centre International de Recherche en Infectiologie, GIMAP Team, Univ St-Etienne, INSERM U1111, CNRS UMR5308, ENS de Lyon, UCBL1, Univ Lyon, 42023, Saint-Etienne, France
| | - Prescillia Jany
- Unité de Recherche Clinique, Centre Hospitalier Emile Roux, 43000, Le Puy en Velay, France
| | - Thomas Bourlet
- CIRI, Centre International de Recherche en Infectiologie, GIMAP Team, Univ St-Etienne, INSERM U1111, CNRS UMR5308, ENS de Lyon, UCBL1, Univ Lyon, 42023, Saint-Etienne, France
- Service des Agents Infectieux, Centre Hospitalier Universitaire de Saint-Étienne, 42055, Saint-Etienne, France
| | - Jérôme Deschamps
- ON-LIGHT SAS, SMO Biopole Clermont-Limagne, 63360, Saint Beauzire, France
| | - Bruno Pozzetto
- CIRI, Centre International de Recherche en Infectiologie, GIMAP Team, Univ St-Etienne, INSERM U1111, CNRS UMR5308, ENS de Lyon, UCBL1, Univ Lyon, 42023, Saint-Etienne, France
- Service des Agents Infectieux, Centre Hospitalier Universitaire de Saint-Étienne, 42055, Saint-Etienne, France
| | - Fateh Singh
- ON-LIGHT SAS, SMO Biopole Clermont-Limagne, 63360, Saint Beauzire, France
| | - Emilie Gadea
- Unité de Recherche Clinique, Centre Hospitalier Emile Roux, 43000, Le Puy en Velay, France.
- U1059, Equipe DVH, Mines Saint-Etienne, Univ Lyon, Univ St-Etienne, 42000, Saint-Etienne, France.
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Butler MJ, Sloof D, Peters C, Conway Morris A, Gouliouris T, Thaxter R, Keevil VL, Beggs CB. Impact of supplementary air filtration on aerosols and particulate matter in a UK hospital ward: a case study. J Hosp Infect 2023; 135:81-89. [PMID: 36842537 PMCID: PMC9957342 DOI: 10.1016/j.jhin.2023.02.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/15/2023] [Accepted: 02/16/2023] [Indexed: 02/28/2023]
Abstract
BACKGROUND Aerosol spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a major problem in hospitals, leading to an increase in supplementary high-efficiency particulate air filtration aimed at reducing nosocomial transmission. This article reports a natural experiment that occurred when an air cleaning unit (ACU) on a medicine for older people ward was switched off accidentally while being commissioned. AIM To assess aerosol transport within the ward and determine whether the ACU reduced airborne particulate matter (PM) levels. METHODS An ACU was placed in a ward comprising two six-bedded bays plus three single-bed isolation rooms which had previously experienced several outbreaks of coronavirus disease 2019. During commissioning, real-time measurements of key indoor air quality parameters (PM1-10, CO2, temperature and humidity) were collected from multiple sensors over 2 days. During this period, the ACU was switched off accidentally for approximately 7 h, allowing the impact of the intervention on PM to be assessed. FINDINGS The ACU reduced the PM counts considerably (e.g. PM1 65.5-78.2%) throughout the ward (P<0.001 all sizes), with positive correlation found for all PM fractions and CO2 (r=0.343-0.817; all P<0.001). PM counts rose/fell simultaneously when the ACU was off, with correlation of PM signals from multiple locations (e.g. r=0.343-0.868; all P<0.001) for particulates <1 μm). CONCLUSION Aerosols migrated rapidly between the various ward subcompartments, suggesting that social distancing alone cannot prevent nosocomial transmission of SARS-CoV-2 as this fails to mitigate longer-range (>2 m) transmission. The ACU reduced PM levels considerably throughout the ward space, indicating its potential as an effective intervention to reduce the risk posed by infectious airborne particles.
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Affiliation(s)
- M J Butler
- Department of Medicine for the Elderly, Cambridge University Hospitals, Cambridge, UK
| | - D Sloof
- AirPurity UK, Ltd, Cambridge, UK
| | - C Peters
- Department of Microbiology, NHS Greater Glasgow and Clyde, Glasgow, UK
| | - A Conway Morris
- John V Farman Intensive Care Unit, Cambridge University Hospitals, Cambridge, UK; Division of Immunology, Department of Pathology, University of Cambridge, Cambridge, UK; Department of Medicine, University of Cambridge, Cambridge, UK
| | - T Gouliouris
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - R Thaxter
- Infection Prevention and Control, Cambridge University Hospitals, Cambridge, UK
| | - V L Keevil
- Department of Medicine for the Elderly, Cambridge University Hospitals, Cambridge, UK; Department of Medicine, University of Cambridge, Cambridge, UK
| | - C B Beggs
- Department of Medicine for the Elderly, Cambridge University Hospitals, Cambridge, UK; Carnegie School of Sport, Leeds Beckett University, Leeds, UK.
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Casini B, Tuvo B, Scarpaci M, Totaro M, Badalucco F, Briani S, Luchini G, Costa AL, Baggiani A. Implementation of an Environmental Cleaning Protocol in Hospital Critical Areas Using a UV-C Disinfection Robot. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:4284. [PMID: 36901293 PMCID: PMC10001687 DOI: 10.3390/ijerph20054284] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 02/24/2023] [Accepted: 02/25/2023] [Indexed: 06/18/2023]
Abstract
Improving the cleaning and disinfection of high-touch surfaces is one of the core components of reducing healthcare-associated infections. The effectiveness of an enhanced protocol applying UV-C irradiation for terminal room disinfection between two successive patients was evaluated. Twenty high-touch surfaces in different critical areas were sampled according to ISO 14698-1, both immediately pre- and post-cleaning and disinfection standard operating protocol (SOP) and after UV-C disinfection (160 sampling sites in each condition, 480 in total). Dosimeters were applied at the sites to assess the dose emitted. A total of 64.3% (103/160) of the sampling sites tested after SOP were positive, whereas only 17.5% (28/160) were positive after UV-C. According to the national hygienic standards for health-care setting, 9.3% (15/160) resulted in being non-compliant after SOP and only 1.2% (2/160) were non-compliant after UV-C disinfection. Operation theaters was the setting that resulted in being less compliant with the standard limit (≤15 colony-forming unit/24 cm2) after SOP (12%, 14/120 sampling sites) and where the UV-C treatment showed the highest effectiveness (1.6%, 2/120). The addition of UV-C disinfection to the standard cleaning and disinfection procedure had effective results in reducing hygiene failures.
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Affiliation(s)
- Beatrice Casini
- Department of Translational Research and the New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Benedetta Tuvo
- Department of Translational Research and the New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Michela Scarpaci
- Department of Translational Research and the New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Michele Totaro
- Department of Translational Research and the New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Federica Badalucco
- Department of Translational Research and the New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Silvia Briani
- Hospital Management, University Hospital of Pisa, 56126 Pisa, Italy
| | - Grazia Luchini
- Hospital Management, University Hospital of Pisa, 56126 Pisa, Italy
| | - Anna Laura Costa
- Department of Translational Research and the New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Angelo Baggiani
- Department of Translational Research and the New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
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Aganovic A, Cao G, Kurnitski J, Wargocki P. New dose-response model and SARS-CoV-2 quanta emission rates for calculating the long-range airborne infection risk. BUILDING AND ENVIRONMENT 2023; 228:109924. [PMID: 36531865 PMCID: PMC9747236 DOI: 10.1016/j.buildenv.2022.109924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
Predictive models for airborne infection risk have been extensively used during the pandemic, but there is yet still no consensus on a common approach, which may create misinterpretation of results among public health experts and engineers designing building ventilation. In this study we applied the latest data on viral load, aerosol droplet sizes and removal mechanisms to improve the Wells Riley model by introducing the following novelties i) a new model to calculate the total volume of respiratory fluid exhaled per unit time ii) developing a novel viral dose-based generation rate model for dehydrated droplets after expiration iii) deriving a novel quanta-RNA relationship for various strains of SARS-CoV-2 iv) proposing a method to account for the incomplete mixing conditions. These new approaches considerably changed previous estimates and allowed to determine more accurate average quanta emission rates including omicron variant. These quanta values for the original strain of 0.13 and 3.8 quanta/h for breathing and speaking and the virus variant multipliers may be used for simple hand calculations of probability of infection or with developed model operating with six size ranges of aerosol droplets to calculate the effect of ventilation and other removal mechanisms. The model developed is made available as an open-source tool.
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Affiliation(s)
- Amar Aganovic
- Department of Automation and Process Engineering, UiT The Arctic University of Norway, Tromsø, Norway
| | - Guangyu Cao
- Department of Energy and Process Engineering, Norwegian University of Science and Technology - NTNU, Trondheim, Norway
| | - Jarek Kurnitski
- REHVA Technology and Research Committee, Tallinn University of Technology, Tallinn, Estonia
| | - Pawel Wargocki
- Department of Civil Engineering, Technical University of Denmark, Copenhagen, Denmark
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10
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Chen CY, Chen PH, Chen JK, Su TC. Recommendations for ventilation of remodeled negative-pressure isolation wards for COVID-19 patients: A comparison of international guidelines. J Formos Med Assoc 2022; 122:91-97. [PMID: 36476674 PMCID: PMC9691448 DOI: 10.1016/j.jfma.2022.11.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 11/20/2022] [Indexed: 11/26/2022] Open
Abstract
This mini-review provides the practice guideline recommendations for ventilation of remodeled negative-pressure isolation wards for COVID-19 Patients. Remodeled "quasi-negative-pressure" isolation wards had been proved a feasible, inexpensive, safe, and effective measure to contain nosocomial outbreaks. We should first determine the minimum required ventilation volume of an isolation ward based on the severity of COVID-19 patients. Mechanical ventilation remains the mainstay for achieving the requirement, while the assistance of recirculation is also helpful. Beyond adequate ventilation volume, the "clean to less-clean" directional airflow remains the golden rule for the solution of indoor ventilation. The virus-laden exhaust should be treated with HEPA/UV device or be kept away from living organisms, buildings, and air inlets.
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Affiliation(s)
- Chung-Yen Chen
- Department of Environmental and Occupational Medicine, National Taiwan University Hospital Yunlin Branch, Taiwan,Department of Environmental and Occupational Medicine, National Taiwan University Hospital, Taiwan,Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taiwan
| | - Ping-Hui Chen
- Department of Environmental and Occupational Medicine, National Taiwan University Hospital, Taiwan,Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taiwan,Department of Environmental and Occupational Medicine, National Taiwan University Hospital Hsin-Chu Branch, Taiwan
| | - Jia-Kun Chen
- Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taiwan,Corresponding author. No. 17, Xu-Zhou Road, Taipei 10055, Taiwan. Fax: +886 2 3366-8114
| | - Ta-Chen Su
- Department of Environmental and Occupational Medicine, National Taiwan University Hospital, Taiwan,Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taiwan
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11
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Abkar L, Zimmermann K, Dixit F, Kheyrandish A, Mohseni M. COVID-19 pandemic lesson learned- critical parameters and research needs for UVC inactivation of viral aerosols. JOURNAL OF HAZARDOUS MATERIALS ADVANCES 2022; 8:100183. [PMID: 36619826 PMCID: PMC9553962 DOI: 10.1016/j.hazadv.2022.100183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/28/2022] [Accepted: 10/10/2022] [Indexed: 11/28/2022]
Abstract
The COVID-19 pandemic highlighted public awareness of airborne disease transmission in indoor settings and emphasized the need for reliable air disinfection technologies. This increased awareness will carry in the post-pandemic era along with the ever-emerging SARS-CoV variants, necessitating effective and well-defined protocols, methods, and devices for air disinfection. Ultraviolet (UV)-based air disinfection demonstrated promising results in inactivating viral bioaerosols. However, the reported data diversity on the required UVC doses has hindered determining the best UVC practices and led to confusion among the public and regulators. This article reviews available information on critical parameters influencing the efficacy of a UVC air disinfection system and, consequently, the required dose including the system's components as well as operational and environmental factors. There is a consensus in the literature that the interrelation of humidity and air temperature has a significant impact on the UVC susceptibility, which translate to changing the UVC efficacy of commercialized devices in indoor settings under varying conditions. Sampling and aerosolization techniques reported to have major influence on the result interpretation and it is recommended to use several sampling methods simultaneously to generate comparable and conclusive data. We also considered the safety concerns and the potential safe alternative of UVC, far-UVC. Finally, the gaps in each critical parameter and the future research needs of the field are represented. This paper is the first step to consolidating literature towards developing a standard validation protocol for UVC air disinfection devices which is determined as the one of the research needs.
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Key Words
- Aerosolization of pathogens
- Air sampling methods
- Airborne transmission
- CDC, centre for disease control and prevention (USA)
- CMD, count median diameter
- DNA, deoxyribonucleic acid
- DSB, double strand break
- Far-UVC
- Far-UVC, ultraviolet irradiation in the ‘far’ range of 200–230 nm
- GTC, growth tube collectors
- LED, light emitting diode
- LPUV, low-pressure ultraviolet lamp
- NIOSH, national institute for occupational safety and health
- PBS, phosphate buffered saline
- PRRS, porcine reproductive and respiratory syndrome
- Particle size distribution
- REL, recommended exposure limit
- RH, relative humidity
- RNA, ribonucleic acid
- ROS, reactive oxygen species
- SARS-CoV-2, severe acute respiratory syndrome coronavirus-2
- SSB, single strand break
- Suspending media
- UV, ultraviolet irradiation
- UV-LED, light emitting diode in the ultraviolet range
- UVC, ultraviolet irradiation in the ‘C’, or germicidal, spectrum from 200 to 290 nm
- UVGI, ultraviolet germicidal irradiation
- Viral UVC susceptibility
- dsDNA, double-stranded deoxyribonucleic acid
- ssRNA, single-stranded ribonucleic acid
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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.
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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.
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Zhu S, Lin T, Wang L, Nardell EA, Vincent RL, Srebric J. Ceiling impact on air disinfection performance of Upper-Room Germicidal Ultraviolet (UR-GUV). BUILDING AND ENVIRONMENT 2022; 224:109530. [PMID: 36065253 PMCID: PMC9429126 DOI: 10.1016/j.buildenv.2022.109530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/12/2022] [Accepted: 08/21/2022] [Indexed: 06/15/2023]
Abstract
This study used Computational Fluid Dynamics (CFD) to investigate air disinfection for SARS-CoV-2 by the Upper-Room Germicidal Ultraviolet (UR-GUV), with focus on ceiling impact. The study includes three indoor settings, i.e., low (airport bus), medium (classroom) and high (rehearsal room) ceilings, which were ventilated with 100% clean air (CA case), 80% air-recirculation with a low filtration (LF case), and 80% air-recirculation with a high filtration (HF case). According to the results, using UR-GUV can offset the increased infection risk caused by air recirculation, with viral concentrations in near field (NF) and far field (FF) in the LF case similar to those in the CA case. In the CA case, fraction remaining (FR) was 0.48-0.73 with 25% occupancy rate (OR) and 0.49-0.91 with 45% OR in the bus, 0.41 in NF and 0.11 in FF in the classroom, and 0.18 in NF and 0.09 in FF in the rehearsal room. Obviously, UR-GUV performance in NF can be improved in a room with a high ceiling where FR has a power relationship with UV zone height. As using UR-GUV can only extend the exposure time to get infection risk of 1% (T 1% ) to 8 min in NF in the classroom, and 47 min in NF in the rehearsal room, it is necessary to abide by social distancing in the two rooms. In addition, T 1% in FF was calculated to be 18.3 min with 25% OR and 21.4% with 45% OR in the airport bus, showing the necessity to further wear a mask.
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Affiliation(s)
- Shengwei Zhu
- Department of Mechanical Engineering, University of Maryland, College Park, MD, USA
| | - Tong Lin
- Department of Mechanical Engineering, University of Maryland, College Park, MD, USA
| | - Lingzhe Wang
- Department of Mechanical Engineering, University of Maryland, College Park, MD, USA
| | - Edward A Nardell
- Departments of Environmental Health and Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | | | - Jelena Srebric
- Department of Mechanical Engineering, University of Maryland, College Park, MD, USA
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Fischer RJ, Port JR, Holbrook MG, Yinda KC, Creusen M, ter Stege J, de Samber M, Munster VJ. UV-C Light Completely Blocks Aerosol Transmission of Highly Contagious SARS-CoV-2 Variants WA1 and Delta in Hamsters. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:12424-12430. [PMID: 36001075 PMCID: PMC9437662 DOI: 10.1021/acs.est.2c02822] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 06/15/2023]
Abstract
Behavioral and medical control measures have not been effective in containing the spread of SARS-CoV-2 in large part due to the unwillingness of populations to adhere to "best practices". Ultraviolet light with wavelengths of between 200 and 280 nm (UV-C) and, in particular, germicidal ultraviolet light, which refers to wavelengths around 254 nm, have the potential to unobtrusively reduce the risk of SARS-CoV-2 transmission in enclosed spaces. We investigated the effectiveness of a strategy using UV-C light to prevent airborne transmission of the virus in a hamster model. Treatment of environmental air with 254 nm UV-C light prevented transmission of SARS-CoV-2 between individuals in a model using highly susceptible Syrian golden hamsters. The prevention of transmission of SARS-CoV-2 in a natural system by treating elements of the surrounding environment is one more weapon in the arsenal to combat COVID. The results presented indicate that coupling mitigation strategies utilizing UV-C light, along with current methods to reduce transmission risk, have the potential to allow a return to normal indoor activities.
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Affiliation(s)
- Robert J. Fischer
- Laboratory
of Virology, National Institute of Allergy
and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840 United States
| | - Julia R. Port
- Laboratory
of Virology, National Institute of Allergy
and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840 United States
| | - Myndi G. Holbrook
- Laboratory
of Virology, National Institute of Allergy
and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840 United States
| | - Kwe Claude Yinda
- Laboratory
of Virology, National Institute of Allergy
and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840 United States
| | - Martin Creusen
- Signify, High Tech Campus 48, 5656 AE Eindhoven, The Netherlands
| | - Jeroen ter Stege
- UVConsult
BV, Hoofdstraat 249, 1611 AG Bovenkarspel, The Netherlands
| | - Marc de Samber
- Signify, High Tech Campus 48, 5656 AE Eindhoven, The Netherlands
| | - Vincent J. Munster
- Laboratory
of Virology, National Institute of Allergy
and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840 United States
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Al Huraimel K, Alhosani M, Gopalani H, Kunhabdulla S, Stietiya MH. Elucidating the role of environmental management of forests, air quality, solid waste and wastewater on the dissemination of SARS-CoV-2. HYGIENE AND ENVIRONMENTAL HEALTH ADVANCES 2022; 3:100006. [PMID: 37519421 PMCID: PMC9095661 DOI: 10.1016/j.heha.2022.100006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 04/13/2022] [Accepted: 04/30/2022] [Indexed: 11/29/2022]
Abstract
The increasing frequency of zoonotic diseases is amongst several catastrophic repercussions of inadequate environmental management. Emergence, prevalence, and lethality of zoonotic diseases is intrinsically linked to environmental management which are currently at a destructive level globally. The effects of these links are complicated and interdependent, creating an urgent need of elucidating the role of environmental mismanagement to improve our resilience to future pandemics. This review focused on the pertinent role of forests, outdoor air, indoor air, solid waste and wastewater management in COVID-19 dissemination to analyze the opportunities prevailing to control infectious diseases considering relevant data from previous disease outbreaks. Global forest management is currently detrimental and hotspots of forest fragmentation have demonstrated to result in zoonotic disease emergences. Deforestation is reported to increase susceptibility to COVID-19 due to wildfire induced pollution and loss of forest ecosystem services. Detection of SARS-CoV-2 like viruses in multiple animal species also point to the impacts of biodiversity loss and forest fragmentation in relation to COVID-19. Available literature on air quality and COVID-19 have provided insights into the potential of air pollutants acting as plausible virus carrier and aggravating immune responses and expression of ACE2 receptors. SARS-CoV-2 is detected in outdoor air, indoor air, solid waste, wastewater and shown to prevail on solid surfaces and aerosols for prolonged hours. Furthermore, lack of protection measures and safe disposal options in waste management are evoking concerns especially in underdeveloped countries due to high infectivity of SARS-CoV-2. Inadequate legal framework and non-adherence to environmental regulations were observed to aggravate the postulated risks and vulnerability to future waves of pandemics. Our understanding underlines the urgent need to reinforce the fragile status of global environmental management systems through the development of strict legislative frameworks and enforcement by providing institutional, financial and technical supports.
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Affiliation(s)
- Khaled Al Huraimel
- Division of Consultancy, Research & Innovation (CRI), Sharjah Environment Company - Bee'ah, Sharjah, United Arab Emirates
| | - Mohamed Alhosani
- Division of Consultancy, Research & Innovation (CRI), Sharjah Environment Company - Bee'ah, Sharjah, United Arab Emirates
| | - Hetasha Gopalani
- Division of Consultancy, Research & Innovation (CRI), Sharjah Environment Company - Bee'ah, Sharjah, United Arab Emirates
| | - Shabana Kunhabdulla
- Division of Consultancy, Research & Innovation (CRI), Sharjah Environment Company - Bee'ah, Sharjah, United Arab Emirates
| | - Mohammed Hashem Stietiya
- Division of Consultancy, Research & Innovation (CRI), Sharjah Environment Company - Bee'ah, Sharjah, United Arab Emirates
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16
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Kwan A, Sklar R, Cameron DB, Schell RC, Bertozzi SM, McCoy SI, Williams B, Sears DA. Respiratory pandemic preparedness learnings from the June 2020 COVID-19 outbreak at San Quentin California State Prison. Int J Prison Health 2022; 19:306-321. [PMID: 35678718 PMCID: PMC10231421 DOI: 10.1108/ijph-12-2021-0116] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 03/24/2022] [Accepted: 04/08/2022] [Indexed: 01/04/2023]
Abstract
PURPOSE This study aims to characterize the June 2020 COVID-19 outbreak at San Quentin California State Prison and to describe what made San Quentin so vulnerable to uncontrolled transmission. DESIGN/METHODOLOGY/APPROACH Since its onset, the COVID-19 pandemic has exposed and exacerbated the profound health harms of carceral settings, such that nearly half of state prisons reported COVID-19 infection rates that were four or more times (and up to 15 times) the rate found in the state's general population. Thus, addressing the public health crises and inequities of carceral settings during a respiratory pandemic requires analyzing the myriad factors shaping them. In this study, we reported observations and findings from environmental risk assessments during visits to San Quentin California State Prison. We complemented our assessments with analyses of administrative data. FINDINGS For future respiratory pathogens that cannot be prevented with effective vaccines, this study argues that outbreaks will no doubt occur again without robust implementation of additional levels of preparedness - improved ventilation, air filtration, decarceration with emergency evacuation planning - alongside addressing the vulnerabilities of carceral settings themselves. ORIGINALITY/VALUE This study addresses two critical aspects that are insufficiently covered in the literature: how to prepare processes to safely implement emergency epidemic measures when needed, such as potential evacuation, and how to address unique challenges throughout an evolving pandemic for each carceral setting.
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Affiliation(s)
- Ada Kwan
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California San Francisco, San Francisco, California, USA and Division of Health Policy and Management, School of Public Health, University of California, Berkeley, Berkeley, California, USA
| | - Rachel Sklar
- Program on Reproductive Health and the Environment, University of California San Francisco, San Francisco, California, USA
| | - Drew B. Cameron
- Division of Health Policy and Management, School of Public Health, University of California, Berkeley, Berkeley, California, USA and Department of Health Policy and Management, Yale School of Public Health, Yale University, New Haven, Connecticut, USA
| | - Robert C. Schell
- Division of Health Policy and Management, School of Public Health, University of California, Berkeley, Berkeley, California, USA
| | - Stefano M. Bertozzi
- Division of Health Policy and Management, School of Public Health, University of California, Berkeley, Berkeley, California, USA; School of Public Health, University of Washington, Seattle, Washington, USA and Instituto Nacional de Salud Pública, Cuernavaca, Mexico
| | - Sandra I. McCoy
- Division of Epidemiology, School of Public Health, University of California, Berkeley, Berkeley, California, USA
| | - Brie Williams
- Center for Vulnerable Populations, Department of Medicine, University of California San Francisco, San Francisco, California, USA
| | - David A. Sears
- Division of Infectious Diseases, Department of Medicine, University of California San Francisco, San Francisco, California, USA
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Cortiços ND, Duarte CC. Energy efficiency in large office buildings post-COVID-19 in Europe's top five economies. ENERGY FOR SUSTAINABLE DEVELOPMENT : THE JOURNAL OF THE INTERNATIONAL ENERGY INITIATIVE 2022; 68:410-424. [PMID: 35494620 PMCID: PMC9040500 DOI: 10.1016/j.esd.2022.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 04/04/2022] [Accepted: 04/11/2022] [Indexed: 05/31/2023]
Abstract
Since the World Health Organization announced the COVID-19 pandemic, indoor airflows became a synonym for virus super-spreaders and the focus point for the scientific community and professional associations across the globe, disrupting all daily life dimensions. Europe's quick response to control the disease led the REHVA board to address mitigation guidelines, reassessed by each member association's following national specifics. The present study aims to quantify the energy consumption and CO2 emissions of "large office" buildings in top-five European economies under the COVID-19 guidelines under the post-pandemic telework forecast. Methodology resorted to a standard model under Building Energy Simulation assessment to compare prior and posterior scenarios. The latter displays a tendency to increase energy and CO2 emissions in all locations, in the first form 10.18% (Rome) to 69.48% (Paris); and second 5.80% (Rome) and 120.61% (Paris), which will affect national energy production and imports, urban pollution and business competitiveness. On a different scope, future HVAC guidelines need to address the incoming figures, particularly in highly dense urban areas. Also, to comply with the goals set by the Paris Accord.
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Affiliation(s)
- Nuno D Cortiços
- Building Science, Technology and Sustainability Lab, Research Centre for Architecture, Urbanism and Design, Lisbon School of Architecture, University of Lisbon, Rua Sá Nogueira, Pólo Universitário, Alto da Ajuda, 1349-063 Lisboa, Portugal
| | - Carlos C Duarte
- Building Science, Technology and Sustainability Lab, Research Centre for Architecture, Urbanism and Design, Lisbon School of Architecture, University of Lisbon, Rua Sá Nogueira, Pólo Universitário, Alto da Ajuda, 1349-063 Lisboa, Portugal
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18
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Styczynski A, Hemlock C, Hoque KI, Verma R, LeBoa C, Bhuiyan MOF, Nag A, Harun MGD, Amin MB, Andrews JR. Assessing impact of ventilation on airborne transmission of SARS-CoV-2: a cross-sectional analysis of naturally ventilated healthcare settings in Bangladesh. BMJ Open 2022; 12:e055206. [PMID: 35428628 PMCID: PMC9013789 DOI: 10.1136/bmjopen-2021-055206] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 03/18/2022] [Indexed: 12/23/2022] Open
Abstract
OBJECTIVES To evaluate the risk of exposure to SARS-CoV-2 in naturally ventilated hospital settings by measuring parameters of ventilation and comparing these findings with results of bioaerosol sampling. STUDY DESIGN Cross-sectional study. STUDY SETTING AND STUDY SAMPLE The study sample included nine hospitals in Dhaka, Bangladesh. Ventilation characteristics and air samples were collected from 86 healthcare spaces during October 2020 to February 2021. PRIMARY OUTCOME Risk of cumulative SARS-CoV-2 infection by type of healthcare area. SECONDARY OUTCOMES Ventilation rates by healthcare space; risk of airborne detection of SARS-CoV-2 across healthcare spaces; impact of room characteristics on absolute ventilation; SARS-CoV-2 detection by naturally ventilated versus mechanically ventilated spaces. RESULTS The majority (78.7%) of naturally ventilated patient care rooms had ventilation rates that fell short of the recommended ventilation rate of 60 L/s/p. Using a modified Wells-Riley equation and local COVID-19 case numbers, we found that over a 40-hour exposure period, outpatient departments posed the highest median risk for infection (7.7%). SARS-CoV-2 RNA was most frequently detected in air samples from non-COVID wards (50.0%) followed by outpatient departments (42.9%). Naturally ventilated spaces (22.6%) had higher rates of SARS-CoV-2 detection compared with mechanically ventilated spaces (8.3%), though the difference was not statistically significant (p=0.128). In multivariable linear regression with calculated elasticity, open door area and cross-ventilation were found to have a significant impact on ventilation. CONCLUSION Our findings provide evidence that naturally ventilated healthcare settings may pose a high risk for exposure to SARS-CoV-2, particularly among non-COVID-designated spaces, but improving parameters of ventilation can mitigate this risk.
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Affiliation(s)
- Ashley Styczynski
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Caitlin Hemlock
- Division of Epidemiology and Biostatistics, University of California Berkeley, Berkeley, California, USA
| | - Kazi Injamamul Hoque
- Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Renu Verma
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Chris LeBoa
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Md Omar Faruk Bhuiyan
- Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Auddithio Nag
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Md Golam Dostogir Harun
- Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Mohammed Badrul Amin
- Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Jason R Andrews
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
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19
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Ghaddar N, Ghali K. Ten questions concerning the paradox of minimizing airborne transmission of infectious aerosols in densely occupied spaces via sustainable ventilation and other strategies in hot and humid climates. BUILDING AND ENVIRONMENT 2022; 214:108901. [PMID: 35197667 PMCID: PMC8853966 DOI: 10.1016/j.buildenv.2022.108901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/07/2022] [Accepted: 02/12/2022] [Indexed: 05/14/2023]
Abstract
Airborne disease transmission in indoor spaces and resulting cross-contamination has been a topic of broad concern for years - especially recently with the outbreak of COVID-19. Global recommendations on this matter consist of increasing the outdoor air supply in the aim of diluting the indoor air. Nonetheless, a paradoxical relationship has risen between increasing amount of outdoor air and its impact on increased energy consumption - especially densely occupied spaces. The paradox is more critical in hot and humid climates, where large amounts of energy are required for the conditioning of the outdoor air. Therefore, many literature studies investigated new strategies for the mitigation of cross-contamination with little-to-no additional cost of energy. These strategies mainly consist of the dilution and/or the capture and removal of contaminants at the levels of macroenvironment room air and occupant-adjacent microenvironment. On the macroenvironment level, the dilution occurs by the supply of large amounts of outdoor air in a sustainable way using passive cooling systems, and the removal of contaminants happens via filtering. Similarly, the microenvironment of the occupant can be diluted using localized ventilation techniques, and contaminants can be captured and removed by direct exhaust near the source of contamination. Thus, this work answers ten questions that explore the most prevailing technologies from the above-mentioned fronts that are used to mitigate cross-contamination in densely occupied spaces located in hot and humid climates at minimal energy consumption. The paper establishes a basis for future work and insights for new research directives for macro and microenvironment approaches.
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Affiliation(s)
- Nesreen Ghaddar
- Mechanical Engineering Department, American University of Beirut, P.O. Box 11-0236, Beirut, 1107-2020, Lebanon
| | - Kamel Ghali
- Mechanical Engineering Department, American University of Beirut, P.O. Box 11-0236, Beirut, 1107-2020, Lebanon
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Lane SJ, Sugg M, Spaulding TJ, Hege A, Iyer L. Southeastern United States Predictors of COVID-19 in Nursing Homes. J Appl Gerontol 2022; 41:1641-1650. [PMID: 35412383 PMCID: PMC9098783 DOI: 10.1177/07334648221082022] [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] [Indexed: 11/26/2022] Open
Abstract
This study’s aim was to determine nursing home (NH) and county-level predictors
of COVID-19 outbreaks in nursing homes (NHs) in the southeastern region of the
United States across three time periods. NH-level data compiled from census data
and from NH compare and NH COVID-19 infection datasets provided by the Center
for Medicare and Medicaid Services cover 2951 NHs located in 836 counties in
nine states. A generalized linear mixed-effect model with a random effect was
applied to significant factors identified in the final stepwise regression.
County-level COVID-19 estimates and NHs with more certified beds were predictors
of COVID-19 outbreaks in NHs across all time periods. Predictors of NH cases
varied across the time periods with fewer community and NH variables predicting
COVID-19 in NH during the late period. Future research should investigate
predictors of COVID-19 in NH in other regions of the US from the early periods
through March 2021.
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Affiliation(s)
- Sandi J Lane
- Department of Nutrition and Health Care Management, 1801Appalachian State University, Boone, NC, USA
| | - Maggie Sugg
- Department of Geography and Planning, 1801Appalachian State University, Boone, NC, USA
| | - Trent J Spaulding
- Department of Nutrition and Health Care Management, 1801Appalachian State University, Boone, NC, USA
| | - Adam Hege
- Department of Public Health, 1801Appalachian State University, Boone, NC, USA
| | - Lakshmi Iyer
- Department of Computer Information Systems, 1801Appalachian State University, Boone, NC, USA
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Skudra A, Revalde G, Zajakina A, Mezule L, Spunde K, Juhna T, Rancane K. UV inactivation of Semliki Forest virus and bacteria by alternative light sources. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2022; 10:100120. [PMID: 35437519 PMCID: PMC8994679 DOI: 10.1016/j.jpap.2022.100120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The quick spreading of the SARS-CoV-2 virus, initiating the global pandemic with a significant impact on economics and health, highlighted an urgent need for effective and sustainable restriction mechanisms of pathogenic microorganisms. UV-C radiation, causing inactivation of many viruses and bacteria, is one of the tools for disinfection of different surfaces, liquids, and air; however, mainly mercury 254 nm line is commonly used for it. In this paper, we report our results of the experiments with newly elaborated special type polychromatic non-mercury UV light sources, having spectral lines in the spectral region from 190 nm to 280 nm. Inactivation tests were performed with both Escherichia coli (E.coli) bacteria and Semliki Forest virus (SFV) as a representative of human enveloped RNA viruses. In addition, the effect of prepared lamps on virus samples in liquid and dry form (dried virus-containing solution) was tested. Reduction of 4 log10 of E.coli was obtained after 10 min of irradiation with both thallium-antimony and arsenic high-frequency electrodeless lamps. High reduction results for the arsenic light source demonstrated sensitivity of E. coli to wavelengths below 230 nm, including spectral lines around 200 nm. For the Semliki Forest virus, the thallium-antimony light source showed virus inactivation efficiency with a high virus reduction rate in the range of 3.10 to > 4.99 log10 within 5 min of exposure. Thus, the new thallium-antimony light source showed the most promising disinfection effect in bacteria and viruses, and arsenic light sources for bacteria inactivation, opening doors for many applications in disinfection systems, including for pathogenic human RNA viruses.
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Evaluation of UV-C Radiation Efficiency in the Decontamination of Inanimate Surfaces and Personal Protective Equipment Contaminated with Phage ϕ6. Microorganisms 2022; 10:microorganisms10030593. [PMID: 35336168 PMCID: PMC8954440 DOI: 10.3390/microorganisms10030593] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 02/28/2022] [Accepted: 03/07/2022] [Indexed: 12/23/2022] Open
Abstract
To help halt the global spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), appropriate disinfection techniques are required. Over the last years, the interest in Ultraviolet-C (UV-C) radiation as a method to disinfect inanimate surfaces and personal protective equipment (PPE) has increased, mainly to efficiently disinfect and prevent SARS-CoV-2 from spreading and allow for the safe reuse of said equipment. The bacteriophage ϕ6 (or simply phage ϕ6) is an RNA virus with a phospholipid envelope and is commonly used in environmental studies as a surrogate for human RNA-enveloped viruses, including SARS-CoV-2. The present study investigated the use of two new UV irradiation systems ((2)2.4W and (8)5.5W)) constituted by conventional mercury UV-C lamps with a strong emission peak at ~254 nm to potentially inactivate phage ϕ6 on different surfaces (glass, plastic, stainless steel, and wood) and personal protective equipment, PPE, (surgical and filtering facepiece 2, FFP2, masks, a clear acetate visor, and disposable protective clothing). The results showed that both UV-C systems were effective in inactivating phage ϕ6, but the UV-C sterilizing chamber (8)5.5W had the best disinfection performance on the tested surfaces. The inactivation effectiveness is material-dependent on all surfaces, reaching the detection limit of the method at different times (between 60 and 240 s of irradiation). The glass surface needed less time to reduce the virus (30 s) when compared with plastic, stainless, and wood surfaces (60 s). The virus inactivation was more effective in the disposable surgical and FFP2 masks (60 and 120 s, respectively) than in the disposable vest and clear acetate visor (240 s). Overall, this study suggests that UV-C lamps with peak emission at ~254 nm could provide rapid, efficient, and sustainable sanitization procedures to different materials and surfaces. However, dosage and irradiation time are important parameters to be considered during their implementation as a tool in the fight against human coronaviruses, namely against SARS-CoV-2.
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Allen GR, Benner KJ, Bahnfleth WP. Inactivation of Pathogens in Air Using Ultraviolet Direct Irradiation Below Exposure Limits. JOURNAL OF RESEARCH OF THE NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY 2022; 126:126052. [PMID: 38469440 PMCID: PMC10046823 DOI: 10.6028/jres.126.052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 01/05/2021] [Indexed: 03/13/2024]
Abstract
A method is described for inactivation of pathogens, especially airborne pathogens, using ultraviolet (UV) radiation emitted directly into occupied spaces and exposing occupants to a dose below the accepted actinic exposure limit (EL). This method is referred to as direct irradiation below exposure limits, or DIBEL. It is demonstrated herein that low-intensity UV radiation below exposure limits can achieve high levels of equivalent air changes per hour (ACHeq) and can be an effective component of efforts to combat airborne pathogens such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19). An ACHeq of 4 h-¹ is presently achievable over a continuous 8 h period for the SARS-CoV-2 virus with UV-C light-emitting diodes (LEDs) having peak wavelength at 275 nm, and future improvements in LED technology and optics are anticipated to enable improvements up to 150 h-¹ in the coming decade. For example, the actinic EL is 60 J/m² at 254 nm, and human coronaviruses, including SARS-CoV-2, have a UV dose required for 90 % inactivation of about 5 J/m² at 254 nm. Irradiation by 254 nm UV-C at the EL is expected to provide 90 % inactivation of these organisms in air in about 40 min when the UV-C is delivered at a constant irradiance over 8 h, or in about 5 min if the UV-C is delivered at a constant irradiance over 1 h. Since the irradiation is continuous, the inactivation of initial contaminants accumulates to 99 % and then 99.9 %, and it also immediately begins inactivating any newly introduced (e.g., exhaled) pathogens at the same rate throughout the 8 h period. The efficacy for inactivating airborne pathogens with DIBEL may be expressed in terms of ACHeq, which may be compared with conventional ventilation-based methods for air disinfection. DIBEL may be applied in addition to other disinfection methods, such as upper room UV germicidal irradiation, and mechanical ventilation and filtration. The ACHeq of the separate methods is additive, providing enhanced cumulative disinfection rates. Conventional air disinfection technologies have typical ACHeq values of about 1 h-¹ to 5 h-¹ and maximum practical values of about 20 h-¹. UV-C DIBEL currently provides ACHeq values that are typically about 1 h-¹ to 10 h-¹, thus either complementing, or potentially substituting for, conventional technologies. UV-C DIBEL protocols are forecast herein to evolve to >100 ACHeq in a few years, potentially surpassing conventional technologies. UV-A (315 nm to 400 nm) and/or UV-C (100 nm to 280 nm) DIBEL is also efficacious at inactivating pathogens on surfaces. The relatively simple installation, low acquisition and operating costs, and unobtrusive aesthetic of DIBEL using UV LEDs contribute value in a layered, multi-agent disinfection strategy.
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Affiliation(s)
- Gary R Allen
- Gary Allen Consulting, Inc., Euclid, OH 44119, USA
| | - Kevin J Benner
- GE Current, a Daintree company, East Cleveland, OH 44112, USA
| | - William P Bahnfleth
- Department of Architectural Engineering The Pennsylvania State University State College, PA 16801, USA
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24
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Vlaskin MS. Review of air disinfection approaches and proposal for thermal inactivation of airborne viruses as a life-style and an instrument to fight pandemics. APPLIED THERMAL ENGINEERING 2022; 202:117855. [PMID: 34867067 PMCID: PMC8628600 DOI: 10.1016/j.applthermaleng.2021.117855] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 10/20/2021] [Accepted: 11/24/2021] [Indexed: 05/02/2023]
Abstract
COVID-19 (Coronavirus Disease 2019) pandemic highlighted the importance of air biosecurity because SARS-CoV-2 is mainly transmitted from person to person via airborne droplets. Preventing infectious droplets from entering the body is one of the best ways to protect against infection. This paper reviews the transmission patterns of airborne pathogens and air disinfection methods. A particular emphasis is put on studies devoted to the thermal inactivation of viruses. These reviews reveal that air heat treatment has not been seriously considered as a possible air disinfection approach. Simple calculations show that the energy input required for thermal disinfection of human's air daily consumption is almost the same as for daily water consumption (by heat treatment from room temperature to 100 °C). Moreover, it is possible to organize a continuous heat recovery from the air already heated during disinfection to the inlet air, thus significantly increasing the energy efficiency. Therefore, I propose a solution for the thermal inactivation of airborne pathogens based on air heating and its subsequent cooling in a heat exchanger with heat recovery. Such a solution could be used to create mobile personal and stationary indoor air disinfectors, as well as heating, ventilation, and air conditioning systems. Thermal disinfection of air to breathe might one day be part of people's daily life like thermal disinfection of drinking water. Aside from limiting infectious disease transmission, thermal inactivation might be the basis for developing inhaled vaccines using thermally inactivated whole pathogens.
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Affiliation(s)
- Mikhail S Vlaskin
- Joint Institute for High Temperatures of the Russian Academy of Sciences, 13/2 Izhorskaya St, Moscow 125412, Russia
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25
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Abstract
The COVID-19 pandemic forced the accessibility, social gathering, lifestyle, and working environment to be changed to reduce the infection. Coronavirus spreads between people in several different ways. Small liquid particles (aerosols, respiratory droplets) from an infected person are transmitted through air and surfaces that are in contact with humans. Reducing transmission through modified heating, ventilation, and air conditioning (HVAC) systems and building design are potential solutions. A comprehensive review of the engineering control preventive measures to mitigate COVID-19 spread, healthy building design, and material was carried out. The current state-of-the-art engineering control preventive measures presented include ultraviolet germicidal irradiation (UVGI), bipolar ionization, vertical gardening, and indoor plants. They have potential to improve the indoor air quality. In addition, this article presents building design with materials (e.g., copper alloys, anti-microbial paintings) and smart technologies (e.g., automation, voice control, and artificial intelligence-based facial recognition) to mitigate the infections of communicable diseases.
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Bueno de Mesquita PJ, Delp WW, Chan WR, Bahnfleth WP, Singer BC. Control of airborne infectious disease in buildings: Evidence and research priorities. INDOOR AIR 2022; 32:e12965. [PMID: 34816493 DOI: 10.1111/ina.12965] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 10/07/2021] [Accepted: 11/11/2021] [Indexed: 06/13/2023]
Abstract
The evolution of SARS-CoV-2 virus has resulted in variants likely to be more readily transmitted through respiratory aerosols, underscoring the increased potential for indoor environmental controls to mitigate risk. Use of tight-fitting face masks to trap infectious aerosol in exhaled breath and reduce inhalation exposure to contaminated air is of critical importance for disease control. Administrative controls including the regulation of occupancy and interpersonal spacing are also important, while presenting social and economic challenges. Indoor engineering controls including ventilation, exhaust, air flow control, filtration, and disinfection by germicidal ultraviolet irradiation can reduce reliance on stringent occupancy restrictions. However, the effects of controls-individually and in combination-on reducing infectious aerosol transfer indoors remain to be clearly characterized to the extent needed to support widespread implementation by building operators. We review aerobiologic and epidemiologic evidence of indoor environmental controls against transmission and present a quantitative aerosol transfer scenario illustrating relative differences in exposure at close-interactive, room, and building scales. We identify an overarching need for investment to implement building controls and evaluate their effectiveness on infection in well-characterized and real-world settings, supported by specific, methodological advances. Improved understanding of engineering control effectiveness guides implementation at scale while considering occupant comfort, operational challenges, and energy costs.
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Affiliation(s)
| | - William W Delp
- Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Wanyu R Chan
- Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - William P Bahnfleth
- Department of Architectural Engineering, Pennsylvania State University, State College, Pennsylvania, USA
| | - Brett C Singer
- Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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27
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Michelini Z, Mazzei C, Magurano F, Baggieri M, Marchi A, Andreotti M, Cara A, Gaudino A, Mazzalupi M, Antonelli F, Sommella L, Angeletti S, Razzano E, Runge A, Petrinca P. UltraViolet SANitizing System for Sterilization of Ambulances Fleets and for Real-Time Monitoring of Their Sterilization Level. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 19:331. [PMID: 35010590 PMCID: PMC8750941 DOI: 10.3390/ijerph19010331] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/22/2021] [Accepted: 12/28/2021] [Indexed: 06/04/2023]
Abstract
BACKGROUND The contamination of ambulances with pathogenic agents represents a potential threat for the public health, not only for common pathogens but also for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The aim of this project was to exploits the germicidal effect of the UVC radiation at 254 nm to sanitize the patient's compartment of ambulances with an advanced UltraViolet SANitizing System (UV-SAN) and assess its relevance for avoiding the spread of COVID-19 and other drug resistant pathogens. METHODS The system is equipped with UVC lamps that are activated when the ambulance compartment is empty and sanitize the environment in less than 15 min. An Ozone sensor continuously monitors the gas concentration, ensuring it does not exceed threshold value harmful for patients and operators' health. The system is relying on GNSS data and a satellite communication link, which allow to monitor and record traceability (when, where and what) of all the sanitation operations performed. This information is real-time monitored from a dedicated web-application. RESULTS UVC irradiation efficiently reduced SARS-CoV-2 virus titer (>99.99%), on inanimate surfaces such as plastic, stainless steel or rubber, with doses ranging from 5.5 to 24.8 mJ/cm2 and the UV-SAN system is effective against multi drug resistant (MDR) bacteria up to >99.99%, after 10 to 30 min of irradiation. CONCLUSIONS UV-SAN can provide rapid, efficient and sustainable sanitization procedures of ambulances.
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Affiliation(s)
- Zuleika Michelini
- National Center Global Health, Istituto Superiore di Sanità, 00161 Rome, Italy; (C.M.); (M.A.); (A.C.)
| | - Chiara Mazzei
- National Center Global Health, Istituto Superiore di Sanità, 00161 Rome, Italy; (C.M.); (M.A.); (A.C.)
| | - Fabio Magurano
- Department of Infectious Diseases, Istituto Superiore di Sanità, 00161 Rome, Italy; (F.M.); (M.B.); (A.M.)
| | - Melissa Baggieri
- Department of Infectious Diseases, Istituto Superiore di Sanità, 00161 Rome, Italy; (F.M.); (M.B.); (A.M.)
| | - Antonella Marchi
- Department of Infectious Diseases, Istituto Superiore di Sanità, 00161 Rome, Italy; (F.M.); (M.B.); (A.M.)
| | - Mauro Andreotti
- National Center Global Health, Istituto Superiore di Sanità, 00161 Rome, Italy; (C.M.); (M.A.); (A.C.)
| | - Andrea Cara
- National Center Global Health, Istituto Superiore di Sanità, 00161 Rome, Italy; (C.M.); (M.A.); (A.C.)
| | - Alessandro Gaudino
- Department of Medicine and Surgery, University of Perugia, 06123 Perugia, Italy;
| | | | | | - Lorenzo Sommella
- Department of Clinical Pathology, Università Campus Bio-Medico di Roma, 00128 Rome, Italy; (L.S.); (S.A.)
| | - Silvia Angeletti
- Department of Clinical Pathology, Università Campus Bio-Medico di Roma, 00128 Rome, Italy; (L.S.); (S.A.)
| | - Elena Razzano
- European Space Agency—ECSAT, Harwell Campus, Didcot OX11 0FD, UK;
| | - Arnaud Runge
- European Space Agency—ESTEC, 2201 AZ Noordwijk, The Netherlands;
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28
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Feng Z, Cao SJ, Haghighat F. Removal of SARS-CoV-2 using UV+Filter in built environment. SUSTAINABLE CITIES AND SOCIETY 2021; 74:103226. [PMID: 34367884 PMCID: PMC8329429 DOI: 10.1016/j.scs.2021.103226] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 07/31/2021] [Accepted: 07/31/2021] [Indexed: 05/03/2023]
Abstract
Air cleaning is an effective and reliable method in indoor airborne SARS-CoV-2 (Severe Acute Respiratory Syndrome Corona-Virus 2) control, with ability of aerosol removal or disinfection. However, traditional air cleaning systems (e.g. fibrous filter, electrostatic removal system) have some risks in operation process, including re-aerosolization and electric breakdown. To avoid these risks, the current study proposed an UV+Filter (ultraviolet and fibrous pleated filter) system to efficiently capture airborne SARS-CoV-2 aerosols and deactivate them in filter medium. It is challenging to quantitatively design UV+Filter due to complex characteristics of SARS-CoV-2 aerosols (e.g. aerodynamic size, biological susceptibility) and hybrid filtration/disinfection processes. This study numerically investigated the overall performances of different air cleaning devices (e.g. Fibrous-filter, UV+Filter, two-stage ESP (electrostatic precipitator) et al.) for control of SARS-CoV-2 aerosols and compared them in term of filtration efficiency, energy consumption and secondary pollution. The prediction of developed models was validated with the experimental data from literature. UV+Filter is the most reliable and safest, while its energy consumption is highest. The newly proposed design method of air cleaning systems could provide essential tools for airborne diseases control.
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Affiliation(s)
- Zhuangbo Feng
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
| | - Shi-Jie Cao
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
- Global Centre for Clean Air Research (GCARE), Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, United Kingdom
| | - Fariborz Haghighat
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Canada
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29
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Trmčić A, Demmings E, Kniel K, Wiedmann M, Alcaine S. Food Safety and Employee Health Implications of COVID-19: A Review. J Food Prot 2021; 84:1973-1989. [PMID: 34265068 PMCID: PMC9906301 DOI: 10.4315/jfp-21-201] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/14/2021] [Indexed: 11/11/2022]
Abstract
The COVID-19 pandemic has greatly impacted the U.S. food supply and consumer behavior. Food production and processing are being disrupted as illnesses, proactive quarantines, and government-mandated movement restrictions cause labor shortages. In this environment, the food industry has been required to adopt new, additional practices to minimize the risk of COVID-19 cases and outbreaks among its workforce. Successfully overcoming these challenges requires a comprehensive approach that addresses COVID-19 transmission both within and outside the facility. Possible interventions include strategies (i) to vaccinate employees, (ii) to assure that employees practice social distancing, (iii) to assure that employees wear face coverings, (iv) to screen employees for COVID-19, (v) to assure that employees practice frequent hand washing and avoid touching their faces, (vi) to clean frequently touched surfaces, and (vii) to assure proper ventilation. Compliance with these control strategies must be verified, and an overall COVID-19 control culture must be established to implement an effective program. Despite some public misperceptions about the health risk of severe acute respiratory syndrome coronavirus 2 on foods or food packaging, both the virus biology and epidemiological data clearly support a negligible risk of COVID-19 transmission through food and food packing. However, COVID-19 pandemic-related supply chain and workforce disruptions and the shift in resources to protect food industry employees from COVID-19 may increase the actual food safety risks. The goal of this review was to describe the COVID-19 mitigation practices adopted by the food industry and the potential impact of these practices and COVID-19-related disruptions on the industry's food safety mission. A review of these impacts is necessary to ensure that the food industry is prepared to maintain a safe and nutritious food supply in the face of future global disruptions.
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Affiliation(s)
- Aljoša Trmčić
- Department of Food Science, Cornell University, Ithaca, New York 14850
| | | | - Kalmia Kniel
- Department of Animal and Food Sciences, University of Delaware, Newark, Delaware 19716, USA
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, New York 14850
| | - Sam Alcaine
- Department of Food Science, Cornell University, Ithaca, New York 14850,Author for correspondence. Tel: 607-255-9183; Fax: 607-254-4868
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30
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Cortiços ND, Duarte CC. COVID-19: The impact in US high-rise office buildings energy efficiency. ENERGY AND BUILDINGS 2021; 249:111180. [PMID: 34149152 PMCID: PMC8205289 DOI: 10.1016/j.enbuild.2021.111180] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 05/10/2021] [Accepted: 06/10/2021] [Indexed: 05/02/2023]
Abstract
The COVID-19 pandemic, through stay-at-home orders, forced rapid changes to social human behavior and interrelations, targeting the work environments to protect workers and users. Rapidly, global organizations, US associations, and professionals stepped in to mitigate the virus's spread in buildings' living and work environments. The institutions proposed new HVAC settings without efficiency concerns, as improved flow rates and filtering for irradiation, humidity, and temperature. Current literature consensually predicted an increase in energy consumption due to new measures to control the SARS-CoV-2 spread. The research team assumed the effort of validating the prior published outcomes, applied to US standardized high-rise office buildings, as defined and set by the key entities in the field, by resorting to a methodology based on software energy analysis. The study compares a standard high-rise office building energy consumption, CO2 emissions and operations costs in nine US climate zones - from 0 to 8, south to north latitudes, respectively -, assessed in the most populated cities, between the previous and post COVID-19 scenarios. The outcomes clarify the gathered knowledge, explaining that climate zones above mixed-humid type tend to increase relative energy use intensity by 21.72%, but below that threshold the zones decrease relative energy use intensity by 11.92%.
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Affiliation(s)
- Nuno D Cortiços
- Building Science, Technology and Sustainability Lab, Research Centre for Architecture, Urbanism and Design, Lisbon School of Architecture, University of Lisbon, Rua Sá Nogueira, Pólo Universitário, Alto da Ajuda, 1349-063 Lisboa, Portugal
| | - Carlos C Duarte
- Building Science, Technology and Sustainability Lab, Research Centre for Architecture, Urbanism and Design, Lisbon School of Architecture, University of Lisbon, Rua Sá Nogueira, Pólo Universitário, Alto da Ajuda, 1349-063 Lisboa, Portugal
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31
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Martínez-Antón JC, Brun A, Vázquez D, Moreno S, Fernández-Balbuena AA, Alda J. Determination of the characteristic inactivation fluence for SARS-CoV-2 under UV-C radiation considering light absorption in culture media. Sci Rep 2021; 11:15293. [PMID: 34315976 PMCID: PMC8316444 DOI: 10.1038/s41598-021-94648-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 07/14/2021] [Indexed: 01/21/2023] Open
Abstract
The optical absorption coefficient of culture media is critical for the survival analysis of pathogens under optical irradiation. The quality of the results obtained from experiments relies on the optical analysis of the spatial distribution of fluence which also depends on the geometry of the sample. In this contribution, we consider both the geometrical shape and the culture medium's absorption coefficient to evaluate how the spatial distribution of optical radiation affects pathogens/viruses. In this work, we exposed SARS-CoV-2 to UV-C radiation ([Formula: see text] = 254 nm) and we calculated-considering the influence of the optical absorption of the culture medium-a characteristic inactivation fluence of [Formula: see text] = 4.7 J/m2, or an equivalent 10% survival (D90 dose) of 10.8 J/m2. Experimentally, we diluted the virus into sessile drops of Dulbecco's Modified Eagle Medium to evaluate pathogen activity after controlled doses of UV irradiation. To validate the optical absorption mode, we carried out an additional experiment where we varied droplet size. Our model-including optical absorption and geometrical considerations-provides robust results among a variety of experimental situations, and represents our experimental conditions more accurately. These results will help to evaluate the capability of UV disinfecting strategies applied to a variety of everyday situations, including the case of micro-droplets generated by respiratory functions.
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Affiliation(s)
- Juan Carlos Martínez-Antón
- Applied Optics Complutense Group, Faculty of Optics and Optometry, University Complutense of Madrid, Av. Arcos de Jalón, 118, 28037, Madrid, Spain
| | - Alejandro Brun
- Centro de Investigación en Sanidad Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Carretera Algete-El Casar de Talamanca, Km 8.1, 28130, Valdeolmos, Madrid, Spain
| | - Daniel Vázquez
- Applied Optics Complutense Group, Faculty of Optics and Optometry, University Complutense of Madrid, Av. Arcos de Jalón, 118, 28037, Madrid, Spain
| | - Sandra Moreno
- Centro de Investigación en Sanidad Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Carretera Algete-El Casar de Talamanca, Km 8.1, 28130, Valdeolmos, Madrid, Spain
| | - Antonio A Fernández-Balbuena
- Applied Optics Complutense Group, Faculty of Optics and Optometry, University Complutense of Madrid, Av. Arcos de Jalón, 118, 28037, Madrid, Spain
| | - Javier Alda
- Applied Optics Complutense Group, Faculty of Optics and Optometry, University Complutense of Madrid, Av. Arcos de Jalón, 118, 28037, Madrid, Spain.
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32
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Luo H, Zhong L. Ultraviolet germicidal irradiation (UVGI) for in-duct airborne bioaerosol disinfection: Review and analysis of design factors. BUILDING AND ENVIRONMENT 2021; 197:107852. [PMID: 33846664 PMCID: PMC8021448 DOI: 10.1016/j.buildenv.2021.107852] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 03/11/2021] [Accepted: 03/29/2021] [Indexed: 05/04/2023]
Abstract
The rapid increase in global cases of COVID-19 illness and death requires the implementation of appropriate and efficient engineering controls to improve indoor air quality. This paper focuses on the use of the ultraviolet germicidal irradiation (UVGI) air purification technology in HVAC ducts, which is particularly applicable to buildings where fully shutting down air recirculation is not feasible. Given the poor understanding of the in-duct UVGI system regarding its working mechanisms, designs, and applications, this review has the following key research objectives:•Identifying the critical parameters for designing a UVGI system, including the characterization of lamp output, behavior of the target microbial UV dose-response, and evaluation of the inactivation performance and energy consumption.•Elucidating the effects of environmental factors (air velocity, air temperature, and humidity) on the UVGI system design parameters and optimization of the in-duct UVGI design.•Summarizing existing UVGI system designs in the literature and illustrating their germicidal and energy performance in light of COVID-19 mitigation.
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Affiliation(s)
- Hao Luo
- Department of Mechanical Engineering, University of Alberta, 9211-116 Street NW, Edmonton, AB, T6G 1H9, Canada
| | - Lexuan Zhong
- Department of Mechanical Engineering, University of Alberta, 9211-116 Street NW, Edmonton, AB, T6G 1H9, Canada
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33
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Bellizzi S, Murgia P, Angioi A, Canu G, Panu Napodano CM, Manca A. Severe acute respiratory syndrome coronavirus-2 medical solid waste treatment: A need for efficient and effective strategies in low-resourced settings. WASTE MANAGEMENT & RESEARCH : THE JOURNAL OF THE INTERNATIONAL SOLID WASTES AND PUBLIC CLEANSING ASSOCIATION, ISWA 2021; 39:76-78. [PMID: 33657925 PMCID: PMC7941137 DOI: 10.1177/0734242x21998739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 02/06/2021] [Indexed: 06/12/2023]
Abstract
Understanding infections related to handling healthcare waste products is of critical importance and the application of simple and low-cost strategies remain a priority in low-income and middle-income countries to protect healthcare workers. We examined the potential effect of relative humidity (RH), air temperature and ultraviolet irradiation (UI) to establish an efficient and effective way to facilitate disposal of medical waste. Literature is emerging on the effect of high RH and high temperature, which would increase airborne mass deposition and decrease the viability of viruses in both airborne particles and on surfaces. On the other hand, severe acute respiratory syndrome coronavirus-2 has been proven to be susceptible to UI when suspended in air like other coronaviruses. An innovative approach utilizing environmental conditions might represent an effective and efficient way to ensure better and sustainable protection of the healthcare workers in low-resourced settings.
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Affiliation(s)
- Saverio Bellizzi
- Medical Epidemiologist, Independent
Consultant, Geneva, Switzerland
| | | | | | | | | | - Antonio Manca
- Candiolo Cancer Institute FPO, IRCCS,
Candiolo, Turin, Italy
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34
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Chiappa F, Frascella B, Vigezzi GP, Moro M, Diamanti L, Gentile L, Lago P, Clementi N, Signorelli C, Mancini N, Odone A. The efficacy of ultraviolet light-emitting technology against coronaviruses: a systematic review. J Hosp Infect 2021; 114:63-78. [PMID: 34029626 PMCID: PMC8139389 DOI: 10.1016/j.jhin.2021.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 05/11/2021] [Accepted: 05/13/2021] [Indexed: 12/13/2022]
Abstract
The ongoing pandemic of COVID-19 has underlined the importance of adopting effective infection prevention and control (IPC) measures in hospital and community settings. Ultraviolet (UV)-based technologies represent promising IPC tools: their effective application for sanitation has been extensively evaluated in the past but scant, heterogeneous and inconclusive evidence is available on their effect on SARS-CoV-2 transmission. With the aim of pooling the available evidence on the efficacy of UV technologies against coronaviruses, we conducted a systematic review following PRISMA guidelines, searching Medline, Embase and the Cochrane Library, and the main clinical trials' registries (WHO ICTRP, ClinicalTrials.gov, Cochrane and EU Clinical Trial Register). Quantitative data on studies' interventions were summarized in tables, pooled by different coronavirus species and strain, UV source, characteristics of UV light exposure and outcomes. Eighteen papers met our inclusion criteria, published between 1972 and 2020. Six focused on SARS-CoV-2, four on SARS-CoV-1, one on MERS-CoV, three on seasonal coronaviruses, and four on animal coronaviruses. All were experimental studies. Overall, despite wide heterogenicity within included studies, complete inactivation of coronaviruses on surfaces or aerosolized, including SARS-CoV-2, was reported to take a maximum exposure time of 15 min and to need a maximum distance from the UV emitter of up to 1 m. Advances in UV-based technologies in the field of sanitation and their proved high virucidal potential against SARS-CoV-2 support their use for IPC in hospital and community settings and their contribution towards ending the COVID-19 pandemic. National and international guidelines are to be updated and parameters and conditions of use need to be identified to ensure both efficacy and safety of UV technology application for effective infection prevention and control in both healthcare and non-healthcare settings.
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Affiliation(s)
- F Chiappa
- School of Public Health, University Vita-Salute San Raffaele, Milan, Italy
| | - B Frascella
- School of Public Health, University Vita-Salute San Raffaele, Milan, Italy
| | - G P Vigezzi
- School of Public Health, University Vita-Salute San Raffaele, Milan, Italy
| | - M Moro
- Infection Control Committee, IRCCS San Raffaele Hospital, Milan, Italy
| | - L Diamanti
- Clinical Engineering Unit, IRCCS San Raffaele Hospital, Milan, Italy; HTA Committee, IRCCS San Raffaele Hospital, Milan, Italy
| | - L Gentile
- Clinical Engineering Unit, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - P Lago
- Clinical Engineering Unit, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - N Clementi
- Laboratory of Microbiology and Virology, University Vita-Salute San Raffaele, Milan, Italy
| | - C Signorelli
- School of Medicine, University Vita-Salute San Raffaele, Milan, Italy
| | - N Mancini
- Laboratory of Microbiology and Virology, University Vita-Salute San Raffaele, Milan, Italy
| | - A Odone
- HTA Committee, IRCCS San Raffaele Hospital, Milan, Italy; Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy.
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Gidari A, Sabbatini S, Bastianelli S, Pierucci S, Busti C, Bartolini D, Stabile AM, Monari C, Galli F, Rende M, Cruciani G, Francisci D. SARS-CoV-2 Survival on Surfaces and the Effect of UV-C Light. Viruses 2021; 13:v13030408. [PMID: 33807521 PMCID: PMC7998261 DOI: 10.3390/v13030408] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/24/2021] [Accepted: 03/02/2021] [Indexed: 12/23/2022] Open
Abstract
The aim of this study was to establish the persistence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on inanimate surfaces such as plastic, stainless steel, and glass during UV-C irradiation which is a physical means commonly utilized in sanitization procedures. The viral inactivation rate, virus half-life, and percentage of titer reduction after UV-C irradiation were assessed. Infectivity was maintained on plastic and glass until 120 h and on stainless steel until 72 h. The virus half-life was 5.3, 4.4, and 4.2 h on plastic, stainless steel, and glass, respectively. In all cases, titer decay was >99% after drop drying. UV-C irradiation efficiently reduced virus titer (99.99%), with doses ranging from 10.25 to 23.71 mJ/cm2. Plastic and stainless steel needed higher doses to achieve target reduction. The total inactivation of SARS-CoV-2 on glass was obtained with the lower dose applied. SARS-CoV-2 survival can be long lasting on inanimate surfaces. It is worth recommending efficient disinfection protocols as a measure of prevention of viral spread. UV-C can provide rapid, efficient and sustainable sanitization procedures of different materials and surfaces. The dosages and mode of irradiation are important parameters to consider in their implementation as an important means to fight the SARS-CoV-2 pandemic.
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Affiliation(s)
- Anna Gidari
- Department of Medicine and Surgery, Clinic of Infectious Diseases, “Santa Maria della Misericordia” Hospital, University of Perugia, 06129 Perugia, Italy; (S.B.); (S.P.); (C.B.); (D.F.)
- Correspondence:
| | - Samuele Sabbatini
- Department of Medicine and Surgery, Medical Microbiology Section, University of Perugia, 06129 Perugia, Italy; (S.S.); (C.M.)
| | - Sabrina Bastianelli
- Department of Medicine and Surgery, Clinic of Infectious Diseases, “Santa Maria della Misericordia” Hospital, University of Perugia, 06129 Perugia, Italy; (S.B.); (S.P.); (C.B.); (D.F.)
| | - Sara Pierucci
- Department of Medicine and Surgery, Clinic of Infectious Diseases, “Santa Maria della Misericordia” Hospital, University of Perugia, 06129 Perugia, Italy; (S.B.); (S.P.); (C.B.); (D.F.)
| | - Chiara Busti
- Department of Medicine and Surgery, Clinic of Infectious Diseases, “Santa Maria della Misericordia” Hospital, University of Perugia, 06129 Perugia, Italy; (S.B.); (S.P.); (C.B.); (D.F.)
| | - Desirée Bartolini
- Department of Pharmaceutical Sciences, Unit of Nutrition and Clinical Biochemistry, University of Perugia, 06122 Perugia, Italy; (D.B.); (F.G.)
| | - Anna Maria Stabile
- Department of Medicine and Surgery, Unit of Human, Clinical and Forensic Anatomy, University of Perugia, 06129 Perugia, Italy; (A.M.S.); (M.R.)
| | - Claudia Monari
- Department of Medicine and Surgery, Medical Microbiology Section, University of Perugia, 06129 Perugia, Italy; (S.S.); (C.M.)
| | - Francesco Galli
- Department of Pharmaceutical Sciences, Unit of Nutrition and Clinical Biochemistry, University of Perugia, 06122 Perugia, Italy; (D.B.); (F.G.)
| | - Mario Rende
- Department of Medicine and Surgery, Unit of Human, Clinical and Forensic Anatomy, University of Perugia, 06129 Perugia, Italy; (A.M.S.); (M.R.)
| | - Gabriele Cruciani
- Department of Chemistry, Biology and Biotechnology, University of Perugia, 06123 Perugia, Italy;
| | - Daniela Francisci
- Department of Medicine and Surgery, Clinic of Infectious Diseases, “Santa Maria della Misericordia” Hospital, University of Perugia, 06129 Perugia, Italy; (S.B.); (S.P.); (C.B.); (D.F.)
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36
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Doughty DC, Hill SC, Mackowski DW. Viruses such as SARS-CoV-2 can be partially shielded from UV radiation when in particles generated by sneezing or coughing: Numerical simulations. JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER 2021; 262:107489. [PMID: 33518804 PMCID: PMC7836904 DOI: 10.1016/j.jqsrt.2020.107489] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 12/19/2020] [Accepted: 12/19/2020] [Indexed: 05/29/2023]
Abstract
UV radiation can inactivate viruses such as SARS-CoV-2. However, designing effective UV germicidal irradiation (UVGI) systems can be difficult because the effects of dried respiratory droplets and other fomites on UV light intensities are poorly understood. Numerical modeling of UV intensities inside virus-containing particles on surfaces can increase understanding of these possible reductions in UV intensity. We model UV intensities within spherical approximations of virions randomly positioned within spherical particles. The model virions and dried particles have sizes and optical properties to approximate SARS-CoV-2 and dried particles formed from respiratory droplets, respectively. In 1-, 5- and 9-µm diameter particles on a surface, illuminated by 260-nm UV light from a direction perpendicular to the surface, 0%, 10% and 18% (respectively) of simulated virions are exposed to intensities less than 1/100th of intensities in individually exposed virions (i.e., they are partially shielded). Even for 302-nm light (simulating sunlight), where absorption is small, 0% and 11% of virions in 1- and 9-µm particles have exposures 1/100th those of individually exposed virions. Shielding is small to negligible in sub-micron particles. Results show that shielding of virions in a particle can be reduced by illuminating a particle either from multiple widely separated incident directions, or by illuminating a particle rotating in air for a time sufficient to rotate through enough orientations. Because highly UV-reflective paints and surfaces can increase the angular ranges of illumination and the intensities within particles, they appear likely to be useful for reducing shielding of virions embedded within particles.
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Affiliation(s)
- David C Doughty
- US Army DEVCOM Army Research Laboratory, 2800 Powder Mill Rd., Adelphi, MD, USA
| | - Steven C Hill
- US Army DEVCOM Army Research Laboratory, 2800 Powder Mill Rd., Adelphi, MD, USA
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37
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Burridge HC, Bhagat RK, Stettler MEJ, Kumar P, De Mel I, Demis P, Hart A, Johnson-Llambias Y, King MF, Klymenko O, McMillan A, Morawiecki P, Pennington T, Short M, Sykes D, Trinh PH, Wilson SK, Wong C, Wragg H, Davies Wykes MS, Iddon C, Woods AW, Mingotti N, Bhamidipati N, Woodward H, Beggs C, Davies H, Fitzgerald S, Pain C, Linden PF. The ventilation of buildings and other mitigating measures for COVID-19: a focus on wintertime. Proc Math Phys Eng Sci 2021; 477:20200855. [PMID: 35153550 PMCID: PMC8300604 DOI: 10.1098/rspa.2020.0855] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 02/10/2021] [Indexed: 12/23/2022] Open
Abstract
The year 2020 has seen the emergence of a global pandemic as a result of the disease COVID-19. This report reviews knowledge of the transmission of COVID-19 indoors, examines the evidence for mitigating measures, and considers the implications for wintertime with a focus on ventilation.
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Affiliation(s)
- Henry C. Burridge
- Department of Civil and Environmental Engineering, Imperial College London, Skempton Building, South Kensington Campus, London SW7 2AZ, UK
| | - Rajesh K. Bhagat
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK
| | - Marc E. J. Stettler
- Department of Civil and Environmental Engineering, Imperial College London, Skempton Building, South Kensington Campus, London SW7 2AZ, UK
| | - Prashant Kumar
- Global Centre for Clean Air Research (GCARE), Department of Civil and Environmental Engineering, University of Surrey, Stag Hill, Guildford GU2 7XH, UK
| | - Ishanki De Mel
- Department of Chemical and Process Engineering, University of Surrey, Stag Hill, Guildford GU2 7XH, UK
| | - Panagiotis Demis
- Department of Chemical and Process Engineering, University of Surrey, Stag Hill, Guildford GU2 7XH, UK
| | - Allen Hart
- Department of Mathematical Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | | | | | - Oleksiy Klymenko
- Department of Chemical and Process Engineering, University of Surrey, Stag Hill, Guildford GU2 7XH, UK
| | - Alison McMillan
- Prifysgol Glyndŵr Wrecsam, Ffordd yr Wyddgrug, Wrecsam LL11 2AW: Wrexham Glyndŵr University, Mold Road, Wrexham LL11 2AW, UK
| | - Piotr Morawiecki
- Department of Mathematical Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Thomas Pennington
- Department of Mathematical Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Michael Short
- Department of Chemical and Process Engineering, University of Surrey, Stag Hill, Guildford GU2 7XH, UK
| | - David Sykes
- AEROS Consultancy, 35 Nairn St, Glasgow G3 8SE, UK
| | - Philippe H. Trinh
- Department of Mathematical Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Stephen K. Wilson
- Department of Mathematics and Statistics, University of Strathclyde, Livingstone Tower, 26 Richmond Street, Glasgow G1 1XH, UK
| | - Clint Wong
- Mathematical Institute, University of Oxford, Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford OX2 6GG, UK
| | - Hayley Wragg
- Department of Mathematical Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Megan S. Davies Wykes
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK
| | - Chris Iddon
- Chartered Institution of Building Services Engineers, 222 Balham High Road, London SW12 9BS, UK
| | - Andrew W. Woods
- BP Institute for Multiphase Flow, University of Cambridge, Madingley Rd, Cambridge CB3 0EZ, UK
| | - Nicola Mingotti
- BP Institute for Multiphase Flow, University of Cambridge, Madingley Rd, Cambridge CB3 0EZ, UK
| | - Neeraja Bhamidipati
- BP Institute for Multiphase Flow, University of Cambridge, Madingley Rd, Cambridge CB3 0EZ, UK
| | - Huw Woodward
- Centre for Environmental Policy, Imperial College London, London SW7 2AZ, UK
| | - Clive Beggs
- Carnegie School of Sport, Headingley Campus, Leeds Beckett University, Leeds LS6 3QT, UK
| | - Hywel Davies
- Chartered Institution of Building Services Engineers, 222 Balham High Road, London SW12 9BS, UK
| | - Shaun Fitzgerald
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK
| | - Christopher Pain
- Department of Earth Science and Engineering, Imperial College London, Royal School of Mines, South Kensington Campus, London SW7 2AZ, UK
| | - P. F. Linden
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK
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38
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Davidson BL. Bare-bulb Upper-Room Germicidal Ultraviolet-C (GUV) Indoor Air Disinfection for COVID-19 †. Photochem Photobiol 2021; 97:524-526. [PMID: 33438214 PMCID: PMC8014599 DOI: 10.1111/php.13380] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 01/08/2021] [Indexed: 12/18/2022]
Abstract
Reliable indoor air disinfection could make clinical and other necessary indoor spaces safer during epidemics with airborne transmission like COVID‐19. Low‐dose upper‐room germicidal ultraviolet‐C (GUV 254 nm) is well suited for this because of the SARS‐CoV‐2 virus' sensitivity to GUV inactivation and GUV's relatively easy adaptability to many types of indoor spaces without respect to outside weather conditions. However, most existing upper‐room GUV fixtures are relatively expensive and inefficient at creating an upper‐room disinfection zone due to loss of disinfecting UV‐C photons caused by the casing and louvers designed to protect persons in the occupied space. Presented herein are two moderate‐size restaurant spaces, 900 ft2 (83.6 m2) and 630 ft2 (58.5 m2), respectively, in which low‐cost bare‐bulb GUV fixtures, without exterior casing, were installed with upward‐pulling ceiling fans to provide upper‐room disinfection and lower‐room safety. Proper safety‐tested installations like these are adaptable to hospital emergency department waiting rooms, clinics, nursing home and prison common areas, public libraries, schools and restaurants.
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Affiliation(s)
- Bruce L Davidson
- Pulmonary Medicine, Washington State University Elson S Floyd College of Medicine and Providence Health System, Seattle, WA, USA
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