1
|
Zhang L, Wang K, Wu K, Guo Y, Liu Z, Yang D, Zhang W, Luo H, Fu Y. Air disinfection by nanosecond pulsed DBD plasma. J Hazard Mater 2024; 472:134487. [PMID: 38704906 DOI: 10.1016/j.jhazmat.2024.134487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/27/2024] [Accepted: 04/28/2024] [Indexed: 05/07/2024]
Abstract
Atmospheric pressure dielectric barrier discharge (DBD) plasma is an emerging and promising technique for air disinfection in public environments. Power supply is a crucial factor but it remains unclear about its impacts on the air disinfection performance of plasmas. In this work, a nanosecond (ns) pulsed power supply was applied to drive an in-duct grating-like DBD array to achieve fast single-pass air disinfection. The influence of pulse parameters and environmental factors on both the discharge characteristics and the single-pass bacterial inactivation efficiency were uncovered. At a close relative humidity (RH) level, the efficiency was dominated by the discharge power, namely, specific input energy could serve as the disinfection dose. A higher frequency, shorter pulse rising time, and suitable pulse width are preferred to obtain a higher Z value. The pulsed source was not notably superior to an alternating current source, or even worse at a low voltage frequency at the same discharge power. Airflow humidity was a predominant factor to improve the efficiency and a single-pass efficiency of ∼ 99% and a Z value of 2.2 L/J were achieved under an optimal RH of 50%-60%. This work provides fundamental knowledge of ns-pulsed DBD on discharge characteristics and air disinfection behaviors.
Collapse
Affiliation(s)
- Liyang Zhang
- Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
| | - Kai Wang
- Tsinghua Shenzhen International Graduate School, Shengzhen, Guangdong 518055, China
| | - Kaiyue Wu
- Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
| | - Yuntao Guo
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Zhigang Liu
- Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
| | - Dong Yang
- Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
| | - Wenjin Zhang
- Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
| | - Haiyun Luo
- Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
| | - Yangyang Fu
- Department of Electrical Engineering, Tsinghua University, Beijing 100084, China.
| |
Collapse
|
2
|
Lu YH, Wang RX, Liu HL, Lai ACK. Evaluating the Performance of UV Disinfection across the 222-365 nm Spectrum against Aerosolized Bacteria and Viruses. Environ Sci Technol 2024; 58:6868-6877. [PMID: 38593035 DOI: 10.1021/acs.est.3c08675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Bioaerosols play a significant role in the transmission of many infectious diseases, especially in enclosed indoor environments. Ultraviolet (UV) disinfection has demonstrated a high efficacy in inactivating microorganisms suspended in the air. To develop more effective and efficient UV disinfection protocols, it is necessary to evaluate and optimize the effectiveness of UV disinfection against aerosolized bacteria and viruses across the entire UV spectrum. In this study, we evaluated the performance of UV disinfection across the UV spectrum, ranging from 222 to 365 nm, against aerosolized bacteria and viruses, including Escherichia coli, Staphylococcus epidermidis, Salmonella enterica, MS2, P22, and Phi6. Six commonly available UV sources, including gas discharge tubes and light-emitting diodes with different emission spectra, were utilized, and their performance in terms of inactivation efficacy, action spectrum, and energy efficiency was determined. Among these UV sources, the krypton chloride excilamp emitting at a peak wavelength of 222 nm was the most efficient in inactivating viral bioaerosols. A low-pressure mercury lamp emitting at 254 nm performed well on both inactivation efficacy and energy efficiency. A UV light-emitting diode emitting at 268 nm demonstrated the highest bacterial inactivation efficacy, but required approximately 10 times more energy to achieve an equivalent inactivation level compared with that of the krypton chloride excilamp and low-pressure mercury lamp. This study provides insights into UV inactivation on bioaerosols, which can guide the development of effective wavelength-targeted UV air disinfection technologies and may significantly help reduce bioaerosol transmission in public areas.
Collapse
Affiliation(s)
- Y H Lu
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
| | - R X Wang
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
| | - H L Liu
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
| | - A C K Lai
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
| |
Collapse
|
3
|
Tao C, Tang X, Luo J, Zhang X. Bactericidal efficacy of mobile ultraviolet-C disinfection devices in reducing contamination in biosafety laboratories. J Infect Dev Ctries 2023; 17:1574-1580. [PMID: 38064395 DOI: 10.3855/jidc.18091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 04/11/2023] [Indexed: 12/18/2023] Open
Abstract
INTRODUCTION Biosafety research requires a wide range of microorganisms and thorough disinfection to prevent laboratory infection is often required. Ultraviolet-C (UV-C) exposure reduces bacterial and viral concentrations. Therefore, in this study, we aimed to evaluate the efficacy of a mobile UV-C device as a non-contact disinfection strategy. METHODOLOGY The bactericidal efficacy of the UV-C device was determined based on log10 decreases in the relative abundances of bacterial indicators, including Escherichia coli, Staphylococcus aureus, Staphylococcus albus, and Pseudomonas aeruginosa at 0.5 and 1.0 m after irradiation for 30, 60, and 90 min. Next, the reduction of natural bacteria in air and on surface as a result of the UV-C device exposure in the laboratory were determined. RESULTS Exposure to the UV-C disinfection device resulted in mean log10 decreases in microbial contamination of 3.55 and 5.85 following irradiation for 30 and 90 min, respectively, at a distance of 0.5 m. Further, P. aeruginosa and E. coli were the most and least sensitive to UV-C exposure, respectively. The bacterial load in air decreased by 65.53% after 60 min of irradiation, while those on surfaces decreased by 44.19% and 78.23% after 30 and 60 min of irradiation, respectively. CONCLUSIONS The UV-C device effectively reduced bacterial load after irradiation for over 60 min. Further studies are encouraged to determine the effectiveness of the UV-C disinfection device in frequently occupied institutions, such as primary medical, health, and nursery, and its efficiency in infection control.
Collapse
Affiliation(s)
- Chunai Tao
- Center for Disease Prevention and Control of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China
| | - Xiaolan Tang
- Center for Disease Prevention and Control of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China
| | - Jiayi Luo
- School of Public Health, Guilin Medical University. Guilin, Guangxi, China
| | - Xinbi Zhang
- School of Public Health, Guilin Medical University. Guilin, Guangxi, China
| |
Collapse
|
4
|
Blatchley ER, Cui H. Quantitative Microbial Risk Assessment for Quantification of the Effects of Ultraviolet Germicidal Irradiation on COVID-19 Transmission. Environ Sci Technol 2023; 57:17393-17403. [PMID: 37922235 DOI: 10.1021/acs.est.3c03026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2023]
Abstract
Quantitative microbial risk assessment (QMRA) is presented as a tool for evaluation of the effectiveness of ultraviolet germicidal irradiation (UVGI) systems for the disinfection of indoor air. The QMRA is developed in the context of UVGI system implementation for control of SARS-CoV-2 infection and comprises submodels to address problem formulation, exposure assessment, and health effects assessment, all of which provide input to a risk characterization submodel. The model simulations indicate that UVGI systems can effectively control the risk of infection associated with SARS-CoV-2 for low to moderate virus emission rates. The risk of disease transmission is strongly influenced by the rate of pathogen emission by an infected individual, the output power of UVGI fixtures and their configuration, the source of UV-C radiation implemented in the UVGI fixtures, and the characteristics of the heating, ventilation, and air conditioning (HVAC) system. The QMRA framework provides a quantitative link between UVGI/HVAC system characteristics and changes in the risk of disease transmission. The framework can be adapted to other airborne pathogens and provides a rational basis for the design, testing, and validation of UVGI systems.
Collapse
Affiliation(s)
- Ernest R Blatchley
- Lyles School of Civil Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, Indiana 47907-2051, United States
- Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Haiying Cui
- Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| |
Collapse
|
5
|
Nguyen TT, He C, Carter R, Ballard EL, Smith K, Groth R, Jaatinen E, Kidd TJ, Nguyen TK, Stockwell RE, Tay G, Johnson GR, Bell SC, Knibbs LD. The Effectiveness of Ultraviolet-C (UV-C) Irradiation on the Viability of Airborne Pseudomonas aeruginosa. Int J Environ Res Public Health 2022; 19:ijerph192013706. [PMID: 36294279 PMCID: PMC9602727 DOI: 10.3390/ijerph192013706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/19/2022] [Accepted: 10/20/2022] [Indexed: 05/17/2023]
Abstract
Pseudomonas aeruginosa (Pa) is the predominant bacterial pathogen in people with cystic fibrosis (CF) and can be transmitted by airborne droplet nuclei. Little is known about the ability of ultraviolet band C (UV-C) irradiation to inactivate Pa at doses and conditions relevant to implementation in indoor clinical settings. We assessed the effectiveness of UV-C (265 nm) at up to seven doses on the decay of nebulized Pa aerosols (clonal Pa strain) under a range of experimental conditions. Experiments were done in a 400 L rotating sampling drum. A six-stage Andersen cascade impactor was used to collect aerosols inside the drum and the particle size distribution was characterized by an optical particle counter. UV-C effectiveness was characterized relative to control tests (no UV-C) of the natural decay of Pa. We performed 112 tests in total across all experimental conditions. The addition of UV-C significantly increased the inactivation of Pa compared with natural decay alone at all but one of the UV-C doses assessed. UV-C doses from 246-1968 µW s/cm2 had an estimated effectiveness of approximately 50-90% for airborne Pa. The effectiveness of doses ≥984 µW s/cm2 were not significantly different from each other (p-values: 0.365 to ~1), consistent with a flattening of effectiveness at higher doses. Modelling showed that delivering the highest dose associated with significant improvement in effectiveness (984 µW s/cm2) to the upper air of three clinical rooms would lead to lower room doses from 37-49% of the 8 h occupational limit. Our results suggest that UV-C can expedite the inactivation of nebulized airborne Pa under controlled conditions, at levels that can be delivered safely in occupied settings. These findings need corroboration, but UV-C may have potential applications in locations where people with CF congregate, coupled with other indoor and administrative infection control measures.
Collapse
Affiliation(s)
- Thi Tham Nguyen
- School of Public Health, The University of Queensland, Brisbane, QLD 4006, Australia
- Correspondence:
| | - Congrong He
- International Laboratory for Air Quality & Health, School of Earth and Atmospheric Sciences, Faculty of Science, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia
| | - Robyn Carter
- Centre for Children’s Health Research, Brisbane, QLD 4101, Australia
| | - Emma L. Ballard
- QIMR Berghofer Institute of Medical Research, Brisbane, QLD 4006, Australia
| | - Kim Smith
- Centre for Children’s Health Research, Brisbane, QLD 4101, Australia
| | - Robert Groth
- International Laboratory for Air Quality & Health, School of Earth and Atmospheric Sciences, Faculty of Science, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia
| | - Esa Jaatinen
- School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia
| | - Timothy J. Kidd
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4032, Australia
- Pathology Queensland, Royal Brisbane and Women’s Hospital, Brisbane, QLD 4006, Australia
| | - Thuy-Khanh Nguyen
- QIMR Berghofer Institute of Medical Research, Brisbane, QLD 4006, Australia
| | | | - George Tay
- The Prince Charles Hospital, Brisbane, QLD 4032, Australia
| | - Graham R. Johnson
- International Laboratory for Air Quality & Health, School of Earth and Atmospheric Sciences, Faculty of Science, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia
| | - Scott C. Bell
- Centre for Children’s Health Research, Brisbane, QLD 4101, Australia
- The Prince Charles Hospital, Brisbane, QLD 4032, Australia
- Faculty of Medicine, The University of Queensland, Brisbane, QLD 4006, Australia
- Translational Research Institute, Brisbane, QLD 4102, Australia
| | - Luke D. Knibbs
- Public Health Unit, Sydney Local Health District, Camperdown, NSW 2050, Australia
- Faculty of Medicine and Health, School of Public Health, The University of Sydney, Sydney, NSW 2006, Australia
| |
Collapse
|
6
|
Lin Y, Chen J, Mai Y, Chen L, Chen Z, Wang G, Deng L, Xu P, Yuan C, Jiang L, Huang M. Double-Grafted PET Fiber Material to Remove Airborne Bacteria with High Efficiency. ACS Appl Mater Interfaces 2022; 14:47003-47013. [PMID: 36214495 DOI: 10.1021/acsami.2c13358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Air pollution caused by bacteria and viruses has posed a serious threat to public health. Commercial air purifiers based on dense fibrous filters can remove particulate matter, including airborne pathogens, but do not kill them efficiently. Here, we developed a double-grafted antibacterial fiber material for the high-efficiency capture and inactivation of airborne microorganisms. Tetracarboxyl phthalocyanine zinc, a photosensitizer, was first grafted onto the polyester (PET) fiber, followed by coating with chitosan on the surface of PET fiber to make a double-grafted fiber material. Under the irradiation of light with a specific wavelength (680 nm), double-grafted fiber materials killed up to 99.99% of Gram-positive bacteria and Gram-negative bacteria and had a significant antibacterial effect on drug-resistant bacteria. The double-grafted PET fiber showed broad-spectrum antibacterial activities and was capable to inactivate drug-resistant bacteria. Notably, in filtration experiments for airborne bacteria, this double-grafted PET fiber demonstrated a high bacteria capture efficiency (95.68%) better than the untreated PET fiber (64.87%). Besides, the double-grafted PET fiber was capable of efficiently killing airborne bacteria. This work provides a new idea for the development of air filtration materials that can efficiently kill airborne pathogen and has good biosafety.
Collapse
Affiliation(s)
- Yuxin Lin
- College of Chemistry, Fuzhou University, Fujian350108, China
| | - Jingyi Chen
- College of Chemistry, Fuzhou University, Fujian350108, China
| | - Yuhan Mai
- College of Chemistry, Fuzhou University, Fujian350108, China
| | - Liyun Chen
- College of Chemistry, Fuzhou University, Fujian350108, China
| | - Zheng Chen
- College of Chemistry, Fuzhou University, Fujian350108, China
| | - Guodong Wang
- College of Chemistry, Fuzhou University, Fujian350108, China
| | - Lina Deng
- College of Chemistry, Fuzhou University, Fujian350108, China
| | - Peng Xu
- College of Biological Science and Engineering, Fuzhou University, Fuzhou, Fujian350108, China
| | - Cai Yuan
- College of Biological Science and Engineering, Fuzhou University, Fuzhou, Fujian350108, China
| | - Longguang Jiang
- College of Chemistry, Fuzhou University, Fujian350108, China
| | - Mingdong Huang
- College of Chemistry, Fuzhou University, Fujian350108, China
| |
Collapse
|
7
|
Mahfooz S, Itrat M, Uddin H, Khan TN. Unani medicinal herbs as potential air disinfectants: an evidence-based review. Rev Environ Health 2022; 37:155-168. [PMID: 34384009 DOI: 10.1515/reveh-2021-0087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 07/21/2021] [Indexed: 06/13/2023]
Abstract
OBJECTIVES Indoor air quality has a significant impact on our health and quality of life, as people spends 80-90% of their time indoors. Fumigation of several medicinal herbs has been recommended by Unani scholars to improve air quality, but their efficacy in air purification is still unknown. Hence, this article aims to discuss the applicability of proposed medicinal herbs in the light of current researches. METHODS A manual literature survey of classical Unani texts was conducted to collect information about the herbs recommended for air purification. In addition, research databases such as PubMed, Google Scholar, and ScienceDirect were extensively searched for evidence on the efficacy and mechanism of action of the suggested herbs in air purification. RESULTS In classical Unani texts, authors have found descriptions of 26 herbs that have been recommended for improving air quality. In-vitro studies have confirmed the antimicrobial activity of 19 of these herbs. Moreover, the efficacy of Styrax benzoin, Commiphora myrrha and Acorus calamus fumigation on aerial microbes have also been validated by studies. CONCLUSIONS The findings of the literature review clearly demonstrated that the herbs recommended by Unani scholars for air purification have broad-spectrum antimicrobial activity, indicating that these herbs could be a potential candidate for air disinfectant. Therefore, authors recommend the further researches on proposed herbs to validate their efficiency against airborne pathogens in the vapour phase.
Collapse
Affiliation(s)
- Shaista Mahfooz
- Department of Tahaffuzi wa Samaji Tib (Preventive and Social Medicine), National Institute of Unani Medicine, Bangalore, Karnataka, India
| | - Malik Itrat
- Department of Tahaffuzi wa Samaji Tib (Preventive and Social Medicine), National Institute of Unani Medicine, Bangalore, Karnataka, India
| | - Hamid Uddin
- Department of Ilmul Saidla (Unani Pharmacy), National Institute of Unani Medicine, Bangalore, Karnataka, India
| | - Tariq Nadeem Khan
- Department of Kulliyat-e-Tib (Basic Principles of Unani Medicine), National Institute of Unani Medicine, Bengaluru, Karnataka, India
| |
Collapse
|
8
|
Jin B, Hu Y, Huang L, Cheng X, Zhao J, Yang X, Sun X, Gan T, Lu B. Effectiveness Between Daily and After-Each-Case Room Disinfection of the Endoscopy Unit. Front Public Health 2021; 9:700041. [PMID: 34676191 PMCID: PMC8523938 DOI: 10.3389/fpubh.2021.700041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 08/31/2021] [Indexed: 11/13/2022] Open
Abstract
Background: To evaluate the effectiveness between daily and after-each-case room disinfection in the endoscopy unit. Methods: This study was conducted in an endoscopy unit of the First Affiliation of Zhejiang Chinese Medical University. We cultured samples from the surface of endoscopy unit items, including operation unit air, isolation gown of an endoscopist, control panel buttons, workstation mouse, and the bed head of the patient. All the samples were divided into daily and after-each-case room disinfection groups. In addition, each group was subdivided into sedation and nonsedation gastroscopy with and without ventilation room groups. Results: The qualified rate of bed head samples of the patient were lower in the daily room disinfection group (76.67%) compared with the after-each-case group (100%). The isolation gown, mouse at the workstation, and the bed head of the patient demonstrated the lowest bacterial and fungal load in the after-each-case room disinfection group compared with the daily room disinfection group (p < 0.05). In the subgroup analysis, a higher microbial load was observed for the isolation gown of the endoscopist used during nonsedation gastroscopy in an unventilated room under the after-each-case room disinfection pattern (p < 0.05); a higher microbial load was observed for the control panel buttons used during nonsedation gastroscopy under the after-each-case room disinfection pattern (p < 0.05). Conclusions: For risk-free or low-risk patients, daily room disinfection provides the basic health requirements of the endoscopy procedure. However, it is better to adopt the after-each-case room disinfection for the isolation gown of the endoscopist and bed head of the patient. For the patients with high risk, the after-each-case room disinfection is more suitable for every endoscopy unit (www.ClinicalTrials.gov, NCT04399005).
Collapse
Affiliation(s)
- Bo Jin
- Department of Endoscopy Center, the First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Yue Hu
- Department of Gastroenterology, First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China.,Key Laboratory of Digestive Pathophysiology of Zhejiang Province, First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Liang Huang
- Department of Endoscopy Center, the First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Xiaoyun Cheng
- Department of Endoscopy Center, the First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Jin Zhao
- Department of Gastroenterology, First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China.,Key Laboratory of Digestive Pathophysiology of Zhejiang Province, First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Xuejing Yang
- Department of Clinical Laboratory, First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Xiling Sun
- Department of Clinical Laboratory, First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Tieer Gan
- Department of Hospital-Acquired Infection Control, First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Bin Lu
- Department of Gastroenterology, First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China.,Key Laboratory of Digestive Pathophysiology of Zhejiang Province, First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| |
Collapse
|
9
|
Yi G, Riduan SN, Armugam A, Ong JT, Hon PY, Abdad MY, Vasoo S, Ang BS, Zhang Y. Nanostructured Copper Surface Kills ESKAPE Pathogens and Viruses in Minutes. ChemMedChem 2021; 16:3553-3558. [PMID: 34459159 DOI: 10.1002/cmdc.202100504] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/27/2021] [Indexed: 11/10/2022]
Abstract
In the search for a fast contact-killing antimicrobial surface to break the transmission pathway of lethal pathogens, nanostructured copper surfaces were found to exhibit the desired antimicrobial properties. Compared with plain copper, these nanostructured copper surfaces with Cu(OH)2 nano-sword or CuO nano-foam were found to completely eliminate pathogens at a fast rate, including clinically isolated drug resistant species. Additionally these nanostructured copper surfaces demonstrated potential antiviral properties when assessed against bacteriophages, as a viral surrogate, and murine hepatitis virus, a surrogate for SARS-CoV-2. The multiple modes of killing, physical killing and copper ion mediated killing contribute to the superior and fast kinetics of antimicrobial action against common microbes, and ESKAPE pathogens. Prototypes for air and water cleaning with current nanostructured copper surface have also been demonstrated.
Collapse
Affiliation(s)
- Guangshun Yi
- Institute of Bioengineering and Bioimaging, 31 Biopolis Way, The Nanos, Singapore, 138669
| | - Siti Nurhanna Riduan
- Institute of Bioengineering and Bioimaging, 31 Biopolis Way, The Nanos, Singapore, 138669
| | - Arunmozhiarasi Armugam
- Institute of Bioengineering and Bioimaging, 31 Biopolis Way, The Nanos, Singapore, 138669
| | - Jin Ting Ong
- National Centre for Infectious Diseases, 16 Jalan Tan Tock Seng, Singapore, 308442.,Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433
| | - Pei Yun Hon
- National Centre for Infectious Diseases, 16 Jalan Tan Tock Seng, Singapore, 308442.,Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433
| | - Mohammad Yazid Abdad
- National Centre for Infectious Diseases, 16 Jalan Tan Tock Seng, Singapore, 308442.,Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433
| | - Shawn Vasoo
- National Centre for Infectious Diseases, 16 Jalan Tan Tock Seng, Singapore, 308442.,Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433
| | - Brenda Sp Ang
- National Centre for Infectious Diseases, 16 Jalan Tan Tock Seng, Singapore, 308442.,Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433
| | - Yugen Zhang
- Institute of Bioengineering and Bioimaging, 31 Biopolis Way, The Nanos, Singapore, 138669
| |
Collapse
|
10
|
Abstract
The outbreak of coronavirus disease 2019 (COVID-19) generated a huge pressure on health care systems worldwide and exposed their lack of preparation for a major health crisis. In the times of a respiratory disease pandemic, members of the dental profession, due to having a direct contact with the patients' oral cavity, body fluids and airborne pathogens, are exposed to a great occupational hazard of becoming infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The authors carried out a systematic literature search using the main online databases (PubMed, Google Scholar, MEDLINE, UpToDate, Embase, and Web of Science) with the following keywords: "COVID-19," "2019-nCoV," "coronavirus," "SARS-CoV-2," "dental COVID-19," "dentistry COVID-19," "occupational hazards dentistry," "ventilation," "air disinfection," "airborne transmission," "hydrogen peroxide disinfection," "UV disinfection," "ozone disinfection," "plasma disinfection," and "TiO2 disinfection." They included publications focused on COVID-19 features, occupational hazards for dental staff during COVID-19 pandemic, and methods of air disinfection. They found that due to the work environment conditions, if appropriate measures of infection control are not being implemented, dental offices and dental staff can become a dangerous source of COVID-19 transmission. That is why the work safety protocols in dentistry have to be revised and additional methods of decontamination implemented. The authors specifically advise on the utilization of wildly accepted methods like ultraviolet germicidal irradiation with additional disinfection systems, which have not been introduced in dentistry yet, like vaporized hydrogen peroxide, non-thermal plasma and air filters with photocatalytic disinfection properties. Due to its toxicity, ozone is not the first-choice method for air decontamination of enclosed clinical settings. Med Pr. 2021;72(1):39-48.
Collapse
Affiliation(s)
- Monika Tysiąc-Miśta
- Medical University of Silesia in Katowice, Katowice, Poland (Faculty of Medical Sciences in Zabrze, Department of Dental Materials, Chair of Prosthetics and Dental Materials)
| | - Agnieszka Dubiel
- Medical University of Silesia, Bytom, Poland (Academic Center of Dentistry and Specialist Medicine)
| | - Karolina Brzoza
- Medical University of Silesia, Bytom, Poland (Academic Center of Dentistry and Specialist Medicine)
| | - Martyna Burek
- Medical University of Silesia, Bytom, Poland (Academic Center of Dentistry and Specialist Medicine)
| | - Karolina Pałkiewicz
- Medical University of Silesia, Bytom, Poland (Academic Center of Dentistry and Specialist Medicine)
| |
Collapse
|
11
|
Hakim H, Gilliam C, Tang L, Xu J, Lee LD. Effect of a shielded continuous ultraviolet-C air disinfection device on reduction of air and surface microbial contamination in a pediatric oncology outpatient care unit. Am J Infect Control 2019; 47:1248-54. [PMID: 31053372 DOI: 10.1016/j.ajic.2019.03.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/22/2019] [Accepted: 03/23/2019] [Indexed: 12/17/2022]
Abstract
BACKGROUND For a clean hospital environment, we evaluated whether ultraviolet-C (UV-C) air disinfection reduces airborne and surface microbial contamination in an outpatient pediatric oncology center. METHODS A pre- and post-intervention study compared 6 test locations, where continuous shielded UV-C air disinfection devices were installed, with 10 control locations without UV-C. Pre- and post-intervention air and surface samples were collected for bacterial and fungal cultures. Percent changes in colony forming unit (CFU) counts in the test and control locations were compared. RESULTS Mean bacterial CFU count per cubic meter air and per surface contact plates decreased by 27% (P = .219) and 37% (P = .01), respectively, in test locations compared to 40% (P = .054) and 30% (P = .006) reductions in control locations. Mean fungal CFU count per cubic meter air and per surface contact plates increased by 14% (P = .156) and 19% (P = .048), respectively, in test locations compared to 24% (P = .409) and 2% (P = .34) increases in control locations. CONCLUSIONS There were no consistent statistically significant differences in the air and surface culture results between test locations where UV-C devices were installed and control locations. The effectiveness of UV-C air disinfection in reducing air and surface microbial contamination in outpatient clinical areas where immunocompromised children are encountered was not proven.
Collapse
|
12
|
Totaro M, Costa AL, Casini B, Profeti S, Gallo A, Frendo L, Porretta A, Valentini P, Privitera G, Baggiani A. Microbiological Air Quality in Heating, Ventilation and Air Conditioning Systems of Surgical and Intensive Care Areas: The Application of a Disinfection Procedure for Dehumidification Devices. Pathogens 2019; 8:pathogens8010008. [PMID: 30650590 PMCID: PMC6472009 DOI: 10.3390/pathogens8010008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 01/07/2019] [Accepted: 01/11/2019] [Indexed: 12/17/2022] Open
Abstract
International literature data report that the increase of infectious risk may be due to heating, ventilation and air conditioning (HVAC) systems contaminated by airborne pathogens. Moreover, the presence of complex rotating dehumidification wheels (RDWs) may complicate the cleaning and disinfection procedures of the HVAC systems. We evaluated the efficacy of a disinfection strategy applied to the RDW of two hospitals’ HVAC systems. Hospitals have four RDW systems related to the surgical areas (SA1 and SA2) and to the intensive and sub-intensive care (IC and sIC) units. Microbiological air and surface analyses were performed in HVAC systems, before and after the disinfection treatment. Hydrogen peroxide (12%) with silver ions (10 mg/L) was aerosolized in all the air sampling points, located close to the RDW device. After the air disinfection procedure, reductions of total microbial counts at 22 °C and molds were achieved in SA2 and IC HVAC systems. An Aspergillus fumigatus contamination (6 CFU/500 L), detected in one air sample collected in the IC HVAC system, was eradicated after the disinfection. The surface samples proved to be of good microbiological quality. The results suggest the need for a disinfection procedure to improve the microbiological quality of the complex HVAC systems, mostly in surgical and intensive care areas.
Collapse
Affiliation(s)
- Michele Totaro
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno 35-39, 56123 Pisa, Italy.
| | - Anna Laura Costa
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno 35-39, 56123 Pisa, Italy.
| | - Beatrice Casini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno 35-39, 56123 Pisa, Italy.
| | - Sara Profeti
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno 35-39, 56123 Pisa, Italy.
| | - Antonio Gallo
- Department of Public Health and Hygiene, Azienda USL Toscana Nord Ovest, 56100 Pisa, Italy.
| | - Lorenzo Frendo
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno 35-39, 56123 Pisa, Italy.
| | - Andrea Porretta
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno 35-39, 56123 Pisa, Italy.
| | - Paola Valentini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno 35-39, 56123 Pisa, Italy.
| | - Gaetano Privitera
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno 35-39, 56123 Pisa, Italy.
| | - Angelo Baggiani
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno 35-39, 56123 Pisa, Italy.
| |
Collapse
|
13
|
Yang Y, Zhang H, Nunayon SS, Chan V, Lai AC. Disinfection efficacy of ultraviolet germicidal irradiation on airborne bacteria in ventilation ducts. Indoor Air 2018; 28:806-817. [PMID: 30171727 DOI: 10.1111/ina.12504] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 08/24/2018] [Indexed: 05/05/2023]
Abstract
A full-scale ventilation duct ultraviolet germicidal irradiation (in-duct UVGI) system was designed to investigate its disinfection efficacy on five airborne pathogens: Serratia marcescens, Pseudomonas alcaligenes, Escherichia coli, Salmonella enterica, and Staphylococcus epidermidis, with airflow Reynolds numbers from 4 × 104 to 8 × 104 . By varying the UV intensity, the susceptibility constants (Z-values) of the bacteria were experimentally determined to be 1.2, 1.0, 0.60, 0.39, and 0.37 m2 /J for S. marcescens, P. alcaligenes, E. coli, S. enterica, and S. epidermidis, respectively. The disinfection efficacy was numerically investigated on the basis of the predicted irradiance, which included emissive irradiance and diffuse refection irradiance. The results suggest that it is vital to properly evaluate the UV dose (irradiance intensity) received by airborne bacteria to determine their Z-values. In-duct UVGI inactivated nearly all of the test bacteria with Reynolds numbers of 4 × 104 (inlet velocity = 3 m/s), and the disinfection efficacy decreased as Reynolds numbers increased. The in-duct UVGI system would potentially provide a supplementary solution for improving indoor air quality (IAQ) within mechanical ventilated/air-conditioned environment.
Collapse
Affiliation(s)
- Yi Yang
- School of Mechanical and Power Engineering, Guangdong Ocean University, Zhanjiang, China
- School of Energy Science and Engineering, Central South University, Changsha, China
| | - Huihui Zhang
- Department of Architecture and Civil Engineering, City University of Hong Kong, Kowloon, China
| | - Sunday Segbenu Nunayon
- Department of Architecture and Civil Engineering, City University of Hong Kong, Kowloon, China
| | - Vincent Chan
- Department of Bioengineering, Khalifa University, Abu Dhabi, UAE
| | - Alvin Ck Lai
- Department of Architecture and Civil Engineering, City University of Hong Kong, Kowloon, China
| |
Collapse
|
14
|
Kim DK, Kang DH. UVC LED Irradiation Effectively Inactivates Aerosolized Viruses, Bacteria, and Fungi in a Chamber-Type Air Disinfection System. Appl Environ Microbiol 2018; 84:e00944-18. [PMID: 29959245 DOI: 10.1128/AEM.00944-18] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 06/19/2018] [Indexed: 11/20/2022] Open
Abstract
In this study, the possibility of inactivating viral, bacterial, and fungal aerosols in a chamber-type air disinfection system by using a UVC light-emitting-diode (LED) array was investigated and inactivation rate constants of each microorganism were calculated in fitting curves of surviving populations. UVC LED array treatment effectively inactivated viral infectivity, achieving 5-log reductions within 45 mJ/cm2 for MS2, Qβ, and ϕX174 viruses. UVC LED array effectiveness in inactivating Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, Listeria monocytogenes, and Staphylococcus aureus aerosols achieved 2.5- to 4-log reductions within 1.5 to 4.6 mJ/cm2 Also, 4-log reductions of Aspergillus flavus and Alternaria japonica were achieved at a dosage of 23 mJ/cm2 using UVC LED array irradiation. The highest UV susceptibility, represented by the inactivation rate constant, was calculated for bacteria, followed by fungi and viruses. UVC LED, an innovative technology, can effectively inactivate microorganisms regardless of taxonomic classification and can sufficiently substitute for conventional mercury UV lamps.IMPORTANCE The United Nations Environment Programme (UNEP) convened the Minamata Convention on Mercury in 2013 to ban mercury-containing products in order to ensure human and environmental health. It will be effectuated in 2020 to discontinue use of low-pressure mercury lamps and new UV-emitting sources have to replace this conventional technology. However, the UV germicidal irradiation (UVGI) system still uses conventional UV lamps, and no research has been conducted for air disinfection using UVC LEDs. The research reported here investigated the inactivation effect of aerosolized microorganisms, including viruses, bacteria, and fungi, with an UVC LED module. The results can be utilized as a primary database to replace conventional UV lamps with UVC LEDs, a novel type of UV emitter. Implementation of UVC LED technology is truly expected to significantly reduce the extent of global mercury contamination, and this study provides important baseline data to help ensure a healthier environment and increased health for humanity.
Collapse
|
15
|
Ethington T, Newsome S, Waugh J, Lee LD. Cleaning the air with ultraviolet germicidal irradiation lessened contact infections in a long-term acute care hospital. Am J Infect Control 2018; 46:482-486. [PMID: 29290480 DOI: 10.1016/j.ajic.2017.11.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/07/2017] [Accepted: 11/08/2017] [Indexed: 02/06/2023]
Abstract
BACKGROUND This study was designed to determine whether removing bacteria from the air with ultraviolet germicidal irradiation (UV-C) at the room level would reduce infection rates. METHODS We reviewed infection data for 12 months before and after UV-C installation in the special care unit (SCU) of a long-term acute care hospital. All patients admitted to the SCU during the study time frame were included. Microbiologic impactor air sampling was completed in August 2015. Shielded UV-C units were installed in 16 patient rooms, the hallway, and the biohazard room. Air sampling was repeated 81 days later. RESULTS After UV-C installation, airborne bacteria (colony forming units [CFU] per cubic meter of air) in patient rooms were reduced an average of 42% (175 vs 102 CFU/m3). Common health care-associated infections (HAIs) (Clostridium difficile [8 cases annually vs 1 case, P = .01] and catheter-associated urinary tract infection [20 cases annually vs 9 cases, P = .012]) were reduced significantly as were overall infections, in number of cases (average 8.8 per month vs 3.5, P < .001), and infection rate (average monthly rate 20.3 vs 8.6, P = .001), despite no reported changes to the amount or type of cleaning done, infection control protocols, or reporting procedures. Other infections, traditionally considered contact transmissible (central line-associated bloodstream infection and methicillin-resistant Staphylococcus aureus), also declined noticeably. CONCLUSIONS Continuous shielded UV-C reduced airborne bacteria and may also lower the number of HAIs, including those caused by contact pathogens. Reduced infections result in lessened morbidity and lower costs. Health care facilities might wish to consider continuous shielded UV-C at the room level as a possible addition to their infection prevention and control protocols.
Collapse
|
16
|
Mphaphlele M, Dharmadhikari AS, Jensen PA, Rudnick SN, van Reenen TH, Pagano MA, Leuschner W, Sears TA, Milonova SP, van der Walt M, Stoltz AC, Weyer K, Nardell EA. Institutional Tuberculosis Transmission. Controlled Trial of Upper Room Ultraviolet Air Disinfection: A Basis for New Dosing Guidelines. Am J Respir Crit Care Med 2015; 192:477-84. [PMID: 25928547 PMCID: PMC4595666 DOI: 10.1164/rccm.201501-0060oc] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 04/29/2015] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Transmission is driving the global tuberculosis epidemic, especially in congregate settings. Worldwide, natural ventilation is the most common means of air disinfection, but it is inherently unreliable and of limited use in cold climates. Upper room germicidal ultraviolet (UV) air disinfection with air mixing has been shown to be highly effective, but improved evidence-based dosing guidelines are needed. OBJECTIVES To test the efficacy of upper room germicidal air disinfection with air mixing to reduce tuberculosis transmission under real hospital conditions, and to define the application parameters responsible as a basis for proposed new dosing guidelines. METHODS Over an exposure period of 7 months, 90 guinea pigs breathed only untreated exhaust ward air, and another 90 guinea pigs breathed only air from the same six-bed tuberculosis ward on alternate days when upper room germicidal air disinfection was turned on throughout the ward. MEASUREMENTS AND MAIN RESULTS The tuberculin skin test conversion rates (>6 mm) of the two chambers were compared. The hazard ratio for guinea pigs in the control chamber converting their skin test to positive was 4.9 (95% confidence interval, 2.8-8.6), with an efficacy of approximately 80%. CONCLUSIONS Upper room germicidal UV air disinfection with air mixing was highly effective in reducing tuberculosis transmission under hospital conditions. These data support using either a total fixture output (rather than electrical or UV lamp wattage) of 15-20 mW/m(3) total room volume, or an average whole-room UV irradiance (fluence rate) of 5-7 μW/cm(2), calculated by a lighting computer-assisted design program modified for UV use.
Collapse
Affiliation(s)
| | | | - Paul A. Jensen
- CDC Division of Tuberculosis Elimination, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Atlanta, Georgia
| | - Stephen N. Rudnick
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts
| | | | | | - Wilhelm Leuschner
- Department of Electronic and Computer Engineering, University of Pretoria, Pretoria, South Africa
| | | | - Sonya P. Milonova
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts
| | | | - Anton C. Stoltz
- Division of Infectious Diseases, Internal Medicine, University of Pretoria Medical School, Pretoria, South Africa; and
| | - Karin Weyer
- Global Tuberculosis Programme, World Health Organization, Geneva, Switzerland
| | - Edward A. Nardell
- Division of Pulmonary and Critical Care Medicine and
- Division of Global Health Equity, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts
| |
Collapse
|
17
|
Rahman SF, Rudnick SN, Milonova SP, McDevitt JJ, Nardell EA. Influence of Bioaerosol Source Location and Ceiling Fan Direction on Eggcrate Upper-room Ultraviolet Germicidal Irradiation. ACTA ACUST UNITED AC 2014; 4:3856-3861. [PMID: 26594636 PMCID: PMC4652796 DOI: 10.9734/bjast/2014/11762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Background Eggcrate upper-room ultraviolet germicidal irradiation (UVGI), an engineering control method for reducing the airborne transmission of infectious diseases, was recently developed as an alternative to conventional upper-room UVGI using conventional louvered fixtures. A UV screen, which is composed of open-cell eggcrate panels supported in a frame designed for a conventional suspended ceiling, was used to minimize UV radiation in the lower room. A ceiling fan, which was blowing upward directly above the microbiological source, provided vertical air exchange between the upper and lower room. This system has been shown to be significantly more effective than conventional upper-room UVGI. Study Design In the present study, the microbiological source location and the airflow direction due to the ceiling fan were varied in order to evaluate their impact on germicidal efficacy. Results The test results clearly showed that placing an aerosol source directly underneath an upward blowing ceiling fan produces the maximum efficacy. Conclusions The likely explanation for this outcome is that the fan sucks the microorganisms emitted by the source into the UV beam before being mixed with the air in the room. This is somewhat analogous to local exhaust ventilation in which the contaminant is removed prior to being mixed with the air in the room. Thus, when possible, the ceiling fan should be blowing upward and directly above the source. However, for experimental testing, the source location should be varied in order to access the range of germicidal efficacies that can be expected.
Collapse
Affiliation(s)
- Sumayah F Rahman
- Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA
| | - Stephen N Rudnick
- Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA
| | - Sonya P Milonova
- Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA
| | - James J McDevitt
- Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA
| | - Edward A Nardell
- Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA ; Department of Medicine, Division of Global Health Equity, Brigham and Women's Hospital, Boston, MA, USA ; Department of Global Health and Social Medicine Harvard Medical School, Boston, MA, USA
| |
Collapse
|
18
|
Yang Y, Chan WY, Wu CL, Kong RYC, Lai ACK. Minimizing the exposure of airborne pathogens by upper-room ultraviolet germicidal irradiation: an experimental and numerical study. J R Soc Interface 2012; 9:3184-95. [PMID: 22809847 PMCID: PMC3481576 DOI: 10.1098/rsif.2012.0439] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 06/26/2012] [Indexed: 11/12/2022] Open
Abstract
There has been increasing interest in the use of upper-room ultraviolet germicidal irradiation (UVGI) because of its proven effectiveness in disinfecting airborne pathogens. An improved drift flux mathematical model is developed for optimizing the design of indoor upper-room UVGI systems by predicting the distribution and inactivation of bioaerosols in a ventilation room equipped with a UVGI system. The model takes into account several bacteria removal mechanisms such as convection, turbulent diffusion, deposition and UV inactivation. Before applying the model, the natural die-off rate and susceptibility constants of bioaerosols were measured experimentally. Two bacteria aerosols, Escherichia coli and Serratia marcescens, were tested for this purpose. It was found out that the general decay trend of the bioaerosol concentration predicted by the numerical model agrees well with the experimental measurements. The modelling results agree better with experimental observations for the case when the UVGI inactivation mechanism dominates at the upper-room region than for the case without UVGI. The numerical results also illustrate that the spatial distribution of airborne bacteria was influenced by both air-flow pattern and irradiance distribution. In addition to predicting the local variation of concentration, the model assesses the overall performance of an upper-room UVGI system. This model has great potential for optimizing the design of indoor an upper-room UVGI systems.
Collapse
Affiliation(s)
- Y. Yang
- Engineering College, Guangdong Ocean University, Zhanjiang 524088, People's Republic of China
- Department of Civil and Architectural Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People's Republic of China
| | - W. Y. Chan
- Department of Civil and Architectural Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People's Republic of China
| | - C. L. Wu
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge 70803, LA, USA
| | - R. Y. C. Kong
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People's Republic of China
| | - A. C. K. Lai
- Department of Civil and Architectural Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People's Republic of China
| |
Collapse
|
19
|
Memarzadeh F, Olmsted RN, Bartley JM. Applications of ultraviolet germicidal irradiation disinfection in health care facilities: effective adjunct, but not stand-alone technology. Am J Infect Control 2010; 38:S13-24. [PMID: 20569852 PMCID: PMC7115255 DOI: 10.1016/j.ajic.2010.04.208] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 04/14/2010] [Accepted: 04/14/2010] [Indexed: 11/29/2022]
Abstract
This review evaluates the applicability and relative contribution of ultraviolet germicidal irradiation (UVGI) to disinfection of air in health care facilities. A section addressing the use of UVGI for environmental surfaces is also included. The germicidal susceptibility of biologic agents is addressed, but with emphasis on application in health care facilities. The balance of scientific evidence indicates that UVGI should be considered as a disinfection application in a health care setting only in conjunction with other well-established elements, such as appropriate heating, ventilating, and air-conditioning (HVAC) systems; dynamic removal of contaminants from the air; and preventive maintenance in combination with through cleaning of the care environment. We conclude that although UVGI is microbiocidal, it is not "ready for prime time" as a primary intervention to kill or inactivate infectious microorganisms; rather, it should be considered an adjunct. Other factors, such as careful design of the built environment, installation and effective operation of the HVAC system, and a high level of attention to traditional cleaning and disinfection, must be assessed before a health care facility can decide to rely solely on UVGI to meet indoor air quality requirements for health care facilities. More targeted and multiparameter studies are needed to evaluate the efficacy, safety, and incremental benefit of UVGI for mitigating reservoirs of microorganisms and ultimately preventing cross-transmission of pathogens that lead to health care-associated infections.
Collapse
Affiliation(s)
| | - Russell N. Olmsted
- Infection Prevention and Control Services, St Joseph Mercy Health System, Ann Arbor, MI
| | | |
Collapse
|