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Saccani C, Guzzini A, Vocale C, Gori D, Pellegrini M, Fantini MP, Primavera A. Experimental testing of air filter efficiency against the SARS-CoV-2 virus: The role of droplet and airborne transmission. BUILDING AND ENVIRONMENT 2022; 210:108728. [PMID: 34975206 PMCID: PMC8710432 DOI: 10.1016/j.buildenv.2021.108728] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 12/08/2021] [Accepted: 12/22/2021] [Indexed: 06/14/2023]
Abstract
Verifying the capacity of different types of air filters to stop the propagation of the SARS-CoV-2 virus has become a strategic element to contain viral spreading in enclosed spaces. This paper shows the results of experimental tests about the capacity of different commercial filter grades to stop SARS-CoV-2 propagation using inactivated virions. In the first test, the obtained results showed that the F8 filter blocks SARS-CoV-2 propagation if it encounters a flow devoid of liquid phase, i.e., a biphasic flow that can wet the filtering material. On the contrary, as shown in the second test, the SARS-CoV-2 virus propagates through the F8 filter if the droplet content in the air flow is enough to wet it. In these operational conditions, i.e., when the filter is wet by a flow with a high droplet content, the absolute H14 filter was also shown to fail to stop the transmission of the SARS-CoV-2 virus. Lastly, in the third test, the viral load was shown to be stopped when the pathway of the infected droplet is blocked.
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Affiliation(s)
- Cesare Saccani
- Department of Industrial Engineering (DIN), University of Bologna, Viale del Risorgimento 2, 40136, Bologna, Italy
| | - Alessandro Guzzini
- Department of Industrial Engineering (DIN), University of Bologna, Viale del Risorgimento 2, 40136, Bologna, Italy
| | - Caterina Vocale
- Regional Reference Center for Microbiological Emergencies (CRREM), Microbiology Unit, IRCCS, Azienda Ospedaliero-Universitaria di Bologna, Via Albertoni 15, 40138, Bologna, Italy
| | - Davide Gori
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, via San Giacomo 12, 40126, Bologna, Italy
| | - Marco Pellegrini
- Department of Industrial Engineering (DIN), University of Bologna, Viale del Risorgimento 2, 40136, Bologna, Italy
| | - Maria Pia Fantini
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, via San Giacomo 12, 40126, Bologna, Italy
| | - Alessandra Primavera
- Regional Reference Center for Microbiological Emergencies (CRREM), Microbiology Unit, IRCCS, Azienda Ospedaliero-Universitaria di Bologna, Via Albertoni 15, 40138, Bologna, Italy
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Wen Z, Yang W, Li N, Wang J, Hu L, Li J, Yin Z, Zhang K, Dong X. Assessment of the risk of infectious aerosols leaking to the environment from BSL-3 laboratory HEPA air filtration systems using model bacterial aerosols. PARTICUOLOGY 2014; 13:82-87. [PMID: 38620193 PMCID: PMC7148691 DOI: 10.1016/j.partic.2012.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 09/14/2012] [Accepted: 11/21/2012] [Indexed: 06/10/2023]
Abstract
To assess the risk of infectious bacterial aerosols leaking to the environment, the filtration efficiency of a biosafety level 3 (BSL-3) laboratory high-efficiency particulate (HEPA) filter was investigated using the aerosolized bacteria Serratia marcescens. The aerosol size was measured using an Andersen sampler. Eight first stage HEPA filters (numbered 1-8) were distributed in contaminated labs and exhausts from each of the first stage HEPA filters were aggregated and filtered through one second stage HEPA filter before being released to the environment. In total, 8 first-stage and 1 second-stage HEPA filters from the BSL-3 air purification system were analyzed. No S. marcescens was detected in first stage filters 1, 2, 4, 5, 7 and 8 and the second stage HEPA filter. The filtration efficiencies against aerosolized S. marcescens were >99.9999%. First stage filter numbers 3 and 6 had filtration efficiencies of 99.9825% and 99.9906%, respectively. When filter number 3 was replaced by a new filter and the bracket for filter number 6 was sealed, no aerosolized S. marcescens was detected in the filtered air. Our work suggests that the BSL-3 laboratory HEPA filter air purification system is effective against bacterial aerosols, with little to no bacterial leakage into the environment.
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Affiliation(s)
- Zhanbo Wen
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Wenhui Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Na Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Jie Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Lingfei Hu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Jinsong Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Zhe Yin
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Ke Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Xiaokai Dong
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
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