title: Measuring ventilation and modelling M. tuberculosis transmission in indoor congregate settings, rural KwaZulu-Natal.
abstract: Molecular epidemiology suggests that most Mycobacterium tuberculosis transmission in high-burden settings occurs outside the home.
  
  
  
  To estimate the risk of M. tuberculosis transmission inside public buildings in a high TB burden community in KwaZulu-Natal, South Africa.
  
  
  
  Carbon dioxide (CO2) sensors were placed inside eight public buildings. Measurements were used with observations of occupancy to estimate infection risk using an adaptation of the Wells-Riley equation. Ventilation modelling using CONTAM was used to examine the impact of low-cost retrofits on transmission in a health clinic.
  
  
  
  Measurements indicate that infection risk in the church, classroom and clinic waiting room would be high with typical ventilation, occupancy levels and visit durations. For example, we estimated that health care workers in a clinic waiting room had a 16.9-24.5% annual risk of M. tuberculosis infection. Modelling results indicate that the simple addition of two new windows allowing for cross-ventilation, at a cost of US$330, would reduce the annual risk to health care workers by 57%.
  
  
  
  Results indicate that public buildings in this community have a range of ventilation and occupancy characteristics that may influence transmission risks. Simple retrofits may result in dramatic reductions in M. tuberculosis transmission, and intervention studies should therefore be considered.
authors: University College London (UCL) Institute for Environmental Design and Engineering, Bartlett School of Environment, Energy and Resources, UCL, London, UK.
authors: J G
authors: JG
authors: Taylor
authors: Wellcome Trust Africa Centre for Population Health, Mtubatuba, South Africa; Centre for Infectious Disease Epidemiology, Research Department of Infection and Population Health, UCL, London, UK.
authors: T A
authors: TA
authors: Yates
authors: Wellcome Trust Africa Centre for Population Health, Mtubatuba, South Africa.
authors: M
authors: M
authors: Mthethwa
authors: Wellcome Trust Africa Centre for Population Health, Mtubatuba, South Africa; School of Nursing and Public Health, University of KwaZulu-Natal, Durban, South Africa; Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of Kwa-Zulu Natal, Congella, South Africa.
authors: F
authors: F
authors: Tanser
authors: Centre for Infectious Disease Epidemiology, Research Department of Infection and Population Health, UCL, London, UK, Institute for Global Health, UCL, London, UK.
authors: I
authors: I
authors: Abubakar
authors: University College London (UCL) Institute for Environmental Design and Engineering, Bartlett School of Environment, Energy and Resources, UCL, London, UK.
authors: H
authors: H
authors: Altamirano
mesh_terms: D000328:Adult; D016902:Air Pollution, Indoor / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis; D005160:Facility Design and Construction; D006282:Health Personnel; D006801:Humans; D008962:Models, Theoretical; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D016273:Occupational Exposure / Q000517:prevention & control*; D012307:Risk Factors; D012424:Rural Population; D013019:South Africa / Q000453:epidemiology; D014376:Tuberculosis / Q000453:epidemiology* / Q000635:transmission*; D014691:Ventilation
chemical_list: D002245:Carbon Dioxide