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dc.rights.licenseAttribution 4.0 International (CC BY 4.0)
dc.contributoreditor: El-Sokkary, Rehab Hosny
dc.contributor.authorBeckwith, Peter G.
dc.contributor.authorKarat, Aaron S.
dc.contributor.authorGovender, Indira
dc.contributor.authorDeol, Arminder K.
dc.contributor.authorMcCreesh, Nicky
dc.contributor.authorKielmann, Karina
dc.contributor.authorBaisley, Kathy
dc.contributor.authorGrant, Alison D.
dc.contributor.authorYates, Tom A.
dc.identifierdoi: 10.1371/journal.pgph.0000603
dc.identifierpublisher-id: pgph-d-22-00132
dc.identifier.citationBeckwith, P.G., Karat, A.S., Govender, I., Deol, A.K., McCreesh, N., Kielmann, K., Baisley, K., Grant, A.D. and Yates, T.A. (2022) ‘Direct estimates of absolute ventilation and estimated Mycobacterium tuberculosis transmission risk in clinics in South Africa’, PLOS Global Public Health. Edited by R.H. El-Sokkary, 2(11), p. e0000603. Available at:
dc.descriptionFrom PLOS via Jisc Publications Router
dc.descriptionHistory: collection 2022, received 2022-01-26, accepted 2022-10-03, epub 2022-11-02
dc.descriptionAcknowledgements: We are grateful to the clinical and management staff at 10 clinics where we obtained ventilation measurements. We thank Thomas Murray, Harriet Gliddon, and Sinethemba Mabuyakhulu who assisted us with ventilation measurements in KZN. We are grateful to Rod Escombe, Ed Nardell, Jon Taylor, Don Milton, and Toby van Reenen for useful discussions about various aspects of ventilation science–they take no responsibility for the content of this manuscript.
dc.descriptionPublication status: Published
dc.descriptionFunder: Economic and Social Research Council; funder-id:; Grant(s): ES/P008011/1
dc.descriptionFunder: Wellcome Trust; funder-id:; Grant(s): 218261/Z/19/Z
dc.descriptionFunder: National Institute for Health Research; funder-id:
dc.descriptionAaron S. Karat - ORCID: 0000-0001-9643-664X
dc.descriptionData Availability Statement: The data from this paper are available via https://datacompass.lshtm. Analysis of the tracer gas release experiments was undertaken in Stata version 14.2 (StataCorp, College Station, Texas, USA). This Stata code is available on GitHub (https://github. com/tayates/uo_ventilation). Analysis of paired indoor-outdoor CO2 measurements was carried out using R version 3.6.0 [29].This R code is also available on GitHub (URL: ArminderD/ventilation.git).
dc.description.abstractHealthcare facilities are important sites for the transmission of pathogens spread via bioaerosols, such as Mycobacterium tuberculosis. Natural ventilation can play an important role in reducing this transmission. We aimed to measure rates of natural ventilation in clinics in KwaZulu-Natal and Western Cape provinces, South Africa, then use these measurements to estimate Mycobacterium tuberculosis transmission risk. We measured ventilation in clinic spaces using a tracer-gas release method. In spaces where this was not possible, we estimated ventilation using data on indoor and outdoor carbon dioxide levels. Ventilation was measured i) under usual conditions and ii) with all windows and doors fully open. Under various assumptions about infectiousness and duration of exposure, measured absolute ventilation rates were related to risk of Mycobacterium tuberculosis transmission using the Wells-Riley Equation. In 2019, we obtained ventilation measurements in 33 clinical spaces in 10 clinics: 13 consultation rooms, 16 waiting areas and 4 other clinical spaces. Under usual conditions, the absolute ventilation rate was much higher in waiting rooms (median 1769 m3/hr, range 338–4815 m3/hr) than in consultation rooms (median 197 m3/hr, range 0–1451 m3/hr). When compared with usual conditions, fully opening existing doors and windows resulted in a median two-fold increase in ventilation. Using standard assumptions about infectiousness, we estimated that a health worker would have a 24.8% annual risk of becoming infected with Mycobacterium tuberculosis, and that a patient would have an 0.1% risk of becoming infected per visit. Opening existing doors and windows and rearranging patient pathways to preferentially use better ventilated clinic spaces result in important reductions in Mycobacterium tuberculosis transmission risk. However, unless combined with other tuberculosis infection prevention and control interventions, these changes are insufficient to reduce risk to health workers, and other highly exposed individuals, to acceptable levels.en
dc.publisherPublic Library of Science
dc.rightsLicence for this article:
dc.rightsCopyright: © 2022 Beckwith et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en
dc.sourceeissn: 2767-3375
dc.subjectResearch Article
dc.subjectMedicine and health sciences
dc.subjectBiology and life sciences
dc.subjectEarth sciences
dc.subjectPeople and places
dc.subjectPhysical sciences
dc.titleDirect estimates of absolute ventilation and estimated Mycobacterium tuberculosis transmission risk in clinics in South Africa
qmu.authorKarat, Aaron S.
qmu.authorKielmann, Karina

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