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Lai J, Coleman KK, Tai SHS, German J, Hong F, Albert B, Esparza Y, Rastogi D, Srikakulapu A, Kalliomäki P, Schanz M, Smith AA, Sierra Maldonado I, Oertel M, Fadul N, Gold TL, McPhaul K, Ma T, Cowling BJ, Milton DK. Relative efficacy of masks and respirators as source control for viral aerosol shedding from people infected with SARS-CoV-2: a controlled human exhaled breath aerosol experimental study. EBioMedicine 2024; 104:105157. [PMID: 38821778 PMCID: PMC11245760 DOI: 10.1016/j.ebiom.2024.105157] [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: 12/11/2023] [Revised: 05/03/2024] [Accepted: 05/04/2024] [Indexed: 06/02/2024] Open
Abstract
BACKGROUND Tight-fitting masks and respirators, in manikin studies, improved aerosol source control compared to loose-fitting masks. Whether this translates to humans is not known. METHODS We compared efficacy of masks (cloth and surgical) and respirators (KN95 and N95) as source control for SARS-CoV-2 viral load in exhaled breath of volunteers with COVID-19 using a controlled human experimental study. Volunteers (N = 44, 43% female) provided paired unmasked and masked breath samples allowing computation of source-control factors. FINDINGS All masks and respirators significantly reduced exhaled viral load, without fit tests or training. A duckbill N95 reduced exhaled viral load by 98% (95% CI: 97%-99%), and significantly outperformed a KN95 (p < 0.001) as well as cloth and surgical masks. Cloth masks outperformed a surgical mask (p = 0.027) and the tested KN95 (p = 0.014). INTERPRETATION These results suggest that N95 respirators could be the standard of care in nursing homes and healthcare settings when respiratory viral infections are prevalent in the community and healthcare-associated transmission risk is elevated. FUNDING Defense Advanced Research Projects Agency, National Institute of Allergy and Infectious Diseases, Centers for Disease Control and Prevention, the Bill & Melinda Gates Foundation, and The Flu Lab.
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Affiliation(s)
- Jianyu Lai
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Kristen K Coleman
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - S-H Sheldon Tai
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Jennifer German
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Filbert Hong
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Barbara Albert
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Yi Esparza
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Dewansh Rastogi
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, USA
| | - Aditya Srikakulapu
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Petri Kalliomäki
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Maria Schanz
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Alycia A Smith
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Isabel Sierra Maldonado
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Molly Oertel
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Naja Fadul
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - T Louie Gold
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Kathleen McPhaul
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA
| | - Tianzhou Ma
- Department of Epidemiology and Biostatistics, University of Maryland School of Public Health, College Park, MD, USA
| | - Benjamin J Cowling
- World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Donald K Milton
- Maryland Institute for Applied Environmental Health, University of Maryland School of Public Health, College Park, MD, USA.
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Ho KMA, Baggaley RF, Stone TC, Hogan Á, Kabir Y, Johnson C, Merrifield R, Lovat LB. Face Mask Acceptability for Communal Religious Worship During the COVID-19 Pandemic in the United Kingdom: Results from the CONFESS Study. JOURNAL OF RELIGION AND HEALTH 2023; 62:608-626. [PMID: 36002758 PMCID: PMC9401196 DOI: 10.1007/s10943-022-01641-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/12/2022] [Indexed: 05/07/2023]
Abstract
The COVID-19 pandemic has led to restrictions such as social distancing and mandatory wearing of face masks. Singing and religious gatherings have been linked to infection clusters, and between 2020 and 2021 indoor congregational singing and chanting were prohibited in the United Kingdom. We evaluated attitudes to face mask use and their acceptability as well as changes within places of worship since their reopening in July up to autumn 2020. In this cross-sectional study, participants were recruited using convenience sampling through selective targeting of religious organisations and social media. Participants self-enrolled and completed an online questionnaire, which included open and closed questions. We used multivariable logistic regression to identify factors associated with face mask acceptability. We performed thematic analysis to evaluate responses to open questions. A total of 939 participants were included in the analysis. Median age was 52.7 years and 66.1% were female, while 80.7% identified as Christian. A majority (672/861; 78.0%) of participants would find it acceptable to wear a face mask and reduce their singing or chanting volume if required, even though 428/681 (49.1%) found face masks to be uncomfortable. Multivariable regression found that younger age was associated with a higher acceptability of face masks (adjusted OR (aOR): 0.98 (95% confidence interval (95% CI) 0.96-1.00), p = 0.0218). The majority of respondents stated that religious services had become shorter, attended by fewer people and with reduced singing or chanting. Most (869/893, 97.3%) stated their place of worship complied with government guidelines, with 803/887 (90.5%) reported that their place of worship enforced face mask wearing and 793/887 (89.4%) at least moderately happy with precaution measures. Our study demonstrates the significant impact of COVID-19 in places of worship but a high degree of compliance with guidelines. Face masks, despite practical difficulties, appeared to be more acceptable if there was an incentive of being able to sing and chant.
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Affiliation(s)
- Kai Man Alexander Ho
- Division of Surgery and Interventional Science, University College London, Charles Bell House, 43-45 Foley Street, London, W1W 7TY, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), University College London, Charles Bell House, 43-45 Foley Street, London, W1W 7TY, UK
| | - Rebecca F Baggaley
- Department of Respiratory Sciences, University of Leicester, University Road, Leicester, LE1 7RH, UK
| | - Timothy C Stone
- Division of Surgery and Interventional Science, University College London, Charles Bell House, 43-45 Foley Street, London, W1W 7TY, UK
| | - Áine Hogan
- Division of Surgery and Interventional Science, University College London, Charles Bell House, 43-45 Foley Street, London, W1W 7TY, UK
| | - Yusuf Kabir
- Division of Surgery and Interventional Science, University College London, Charles Bell House, 43-45 Foley Street, London, W1W 7TY, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), University College London, Charles Bell House, 43-45 Foley Street, London, W1W 7TY, UK
| | | | | | - Laurence B Lovat
- Division of Surgery and Interventional Science, University College London, Charles Bell House, 43-45 Foley Street, London, W1W 7TY, UK.
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), University College London, Charles Bell House, 43-45 Foley Street, London, W1W 7TY, UK.
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Salmonsmith J, Ducci A, Balachandran R, Guo L, Torii R, Houlihan C, Epstein R, Rubin J, Tiwari MK, Lovat LB. Use of portable air purifiers to reduce aerosols in hospital settings and cut down the clinical backlog. Epidemiol Infect 2023; 151:e21. [PMID: 36650731 PMCID: PMC9990385 DOI: 10.1017/s0950268823000092] [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: 08/24/2022] [Revised: 12/13/2022] [Accepted: 01/12/2023] [Indexed: 01/19/2023] Open
Abstract
SARS-CoV-2 has severely affected capacity in the National Health Service (NHS), and waiting lists are markedly increasing due to downtime of up to 50 min between patient consultations/procedures, to reduce the risk of infection. Ventilation accelerates this air cleaning, but retroactively installing built-in mechanical ventilation is often cost-prohibitive. We investigated the effect of using portable air cleaners (PAC), a low-energy and low-cost alternative, to reduce the concentration of aerosols in typical patient consultation/procedure environments. The experimental setup consisted of an aerosol generator, which mimicked the subject affected by SARS-CoV-19, and an aerosol detector, representing a subject who could potentially contract SARS-CoV-19. Experiments of aerosol dispersion and clearing were undertaken in situ in a variety of rooms with two different types of PAC in various combinations and positions. Correct use of PAC can reduce the clearance half-life of aerosols by 82% compared to the same indoor-environment without any ventilation, and at a broadly equivalent rate to built-in mechanical ventilation. In addition, the highest level of aerosol concentration measured when using PAC remains at least 46% lower than that when no mitigation is used, even if the PAC's operation is impeded due to placement under a table. The use of PAC leads to significant reductions in the level of aerosol concentration, associated with transmission of droplet-based airborne diseases. This could enable NHS departments to reduce the downtime between consultations/procedures.
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Affiliation(s)
- Jacob Salmonsmith
- Department of Mechanical Engineering, University College London, London, UK
| | - Andrea Ducci
- Department of Mechanical Engineering, University College London, London, UK
| | | | - Liwei Guo
- Department of Mechanical Engineering, University College London, London, UK
| | - Ryo Torii
- Department of Mechanical Engineering, University College London, London, UK
| | - Catherine Houlihan
- Rare and Imported Pathogens Laboratory, UK Health Security Agency, London, UK
- Department of Infection and Immunity, University College London, London, UK
| | - Ruth Epstein
- Department of Otolaryngology, Royal National Ear Nose and Throat and Eastman Dental Hospital, University College London Hospitals NHS Foundation Trust, London, UK
- Division of Surgery & Interventional Science, University College London, London, UK
| | - John Rubin
- Department of Otolaryngology, Royal National Ear Nose and Throat and Eastman Dental Hospital, University College London Hospitals NHS Foundation Trust, London, UK
| | - Manish K. Tiwari
- Department of Mechanical Engineering, University College London, London, UK
- Wellcome/EPSRC Centre for Interventional & Surgical Sciences (WEISS), University College London, London, UK
| | - Laurence B. Lovat
- Division of Surgery & Interventional Science, University College London, London, UK
- Wellcome/EPSRC Centre for Interventional & Surgical Sciences (WEISS), University College London, London, UK
- Gastrointestinal Services, University College London Hospital, London, UK
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