Direct estimates of absolute ventilation and estimated Mycobacterium tuberculosis transmission risk in clinics in South Africa

Bibliographic Data

ID19591690
AuthorsPeter G Beckwith (0000-0003-3206-5696, University of Cape Town), Aaron S Karat (0000-0001-9643-664X, University of Cape Town), Indira Govender (0000-0003-0598-7388, London School of Hygiene & Tropical Medicine), Arminder Deol (0000-0002-7154-5505, London School of Hygiene & Tropical Medicine), Nicky McCreesh (0000-0003-1409-8531, London School of Hygiene & Tropical Medicine), Karina Kielmann (0000-0001-5519-1658, Queen Margaret University), Kathy Baisley (0000-0003-1849-6625, London School of Hygiene & Tropical Medicine), Anne D Grant (0000-0002-2437-5195, London School of Hygiene & Tropical Medicine), Tom Yates (0000-0002-6081-1767, University College London, corresponding author), Tom A Yates
EditorsRehab Hosny El-Sokkary
Year2022
Volume2
Issue11
Pagese0000603
Publication date2022-11-02
Open AccessYes
TypeARTICLE
VenuePLOS Global Public Health (JOURNAL)
Journal identifiersISSN: 2767-3375 • E-ISSN: 2767-3375
PublisherPublic Library of Science (PLoS) (PUBLISHER)
DOI10.1371/journal.pgph.0000603
PMID36962521
OpenAlexW4307931641
LanguageEN
Citations received1
References cited40

Healthcare 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 m 3 /hr, range 338–4815 m 3 /hr) than in consultation rooms (median 197 m 3 /hr, range 0–1451 m 3 /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

Airborne transmission · Biology · Disease · Doors · Environmental health · Geography · Indoor bioaerosol · Meteorology · Mycobacterium tuberculosis · Natural Ventilation · Pathology · Telecommunications · Tuberculosis · Veterinary medicine · Engineering · Infection Control and Ventilation · Infection Control in Healthcare · Medicine · Nosocomial Infections in ICU · Ecology · Emergency Medicine · Internal Medicine

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