title: Wind-driven roof turbines: a novel way to improve ventilation for TB infection control in health facilities.
abstract: OBJECTIVE
  Tuberculosis transmission in healthcare facilities contributes significantly to the TB epidemic, particularly in high HIV settings. Although improving ventilation may reduce transmission, there is a lack of evidence to support low-cost practical interventions. We assessed the efficacy of wind-driven roof turbines to achieve recommended ventilation rates, compared to current recommended practices for natural ventilation (opening windows), in primary care clinic rooms in Khayelitsha, South Africa.
  
  
  METHODS
  Room ventilation was assessed (CO₂ gas tracer technique) in 4 rooms where roof turbines and air-intake grates were installed, across three scenarios: turbine, grate and window closed, only window open, and only turbine and grate open, with concurrent wind speed measurement. 332 measurements were conducted over 24 months.
  
  
  RESULTS
  For all 4 rooms combined, median air changes per hour (ACH) increased with wind speed quartiles across all scenarios. Higher median ACH were recorded with open roof turbines and grates, compared to open windows across all wind speed quartiles. Ventilation with open turbine and grate exceeded WHO-recommended levels (60 Litres/second/patient) for 95% or more of measurements in 3 of the 4 rooms; 47% in the remaining room, where wind speeds were lower and a smaller diameter turbine was installed.
  
  
  CONCLUSIONS
  High room ventilation rates, meeting recommended thresholds, may be achieved using wind-driven roof turbines and grates, even at low wind speeds. Roof turbines and air-intake grates are not easily closed by staff, allowing continued ventilation through colder periods. This simple, low-cost technology represents an important addition to our tools for TB infection control.
authors.affiliation: Médecins Sans Frontières, Cape Town, South Africa. hcox@burnet.edu.au
authors.forename: Helen
authors.initials: H
authors.lastname: Cox
authors.forename: Rod
authors.initials: R
authors.lastname: Escombe
authors.forename: Cheryl
authors.initials: C
authors.lastname: McDermid
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Mtshemla
authors.forename: Tim
authors.initials: T
authors.lastname: Spelman
authors.forename: Virginia
authors.initials: V
authors.lastname: Azevedo
authors.forename: Leslie
authors.initials: L
authors.lastname: London
mesh_terms: D003252:Construction Materials; D006268:Health Facilities; D006801:Humans; D017053:Infection Control / Q000379:methods*; D014376:Tuberculosis / Q000517:prevention & control*; D014691:Ventilation / Q000295:instrumentation* / Q000379:methods*; D014919:Wind; D014944:World Health Organization