A study of eight hospitals in Peru has shown that opening windows and doors provided ventilation more than double that of mechanically ventilated negative-pressure rooms and 18 times that of rooms with windows and doors closed.
The researchers, led by Rod Escombe from Imperial College London, compared the airflow in 70 naturally ventilated clinical rooms such as respiratory isolation rooms, TB wards, respiratory wards, general medical wards, outpatient consulting rooms, waiting rooms, and emergency departments with 12 mechanically ventilated negative-pressure respiratory isolation rooms built after 2000.
Even at the lowest of wind speeds, natural ventilation exceeded mechanical ventilation. Facilities built more than 50 years ago, characterized by large windows and high ceilings, had greater ventilation than modern naturally ventilated rooms. The authors went on to calculate what these results might mean for transmission of infection and estimated that in mechanically ventilated rooms 39% of susceptible individuals would become infected following 24 h of exposure to untreated TB patients compared with 33% in modern and 11% in pre-1950 naturally ventilated facilities with windows and doors open.
The authors conclude that opening windows and doors maximizes natural ventilation and that the risk of airborne contagion is lower than with mechanical ventilation systems. Old-fashioned clinical areas with high ceilings and large windows provided the greatest protection.
In a related perspective article Peter Wilson, from University College London, concludes that although “natural ventilation is not an easy solution for patients in countries where winters are cold … the current practice of sealing in the local environment is probably the wrong route for hospital wards”.
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Citation: Escombe AR, Oeser CC, Gilman RH, Navincopa M, Ticona E, et al. (2007) Natural ventilation for the prevention of airborne contagion. PLoS Med 4(2): e68.
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- Caption: MDRTB ward in a Lima hospital (Photographer: Rod Escombe)
CONTACT:
Dr. Rod Escombe
Imperial College London
Infectious Diseases & Immunity
Commonwealth Building, Hammersmith Hospital,
Du Cane Road
London W12 ONN, United Kingdom
+ 447941942189 (UK contact number)
+ 51192299097 (Peru contact number)
rod.escombe@imperial.ac.uk
Related PLoS Medicine Perspective article:
Citation: Wilson P (2007) Is natural ventilation a useful tool to prevent the airborne spread of TB? PLoS Med 4(2): e77.
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http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0040077
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Related image for press use: http://www.plos.org/press/plme-04-02-wilson.jpg
- Caption: Los Angeles Sanatorium, Duarte, California, United States (Photo: City of Hope)
CONTACT:
Peter Wilson
University College London
Windeyer Institute of Medical Sciences
Room 231, Clinical Microbiology
46 Cleveland Street
London, W1T 4JF, United Kingdom
+44 845 155 5000 ext 4516 or +44 207 380 9913 (Secretary)
+44 207 636 6482 (fax)
peter.wilson@uclh.nhs.uk
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PLoS Medicine