SORA

Advancing, promoting and sharing knowledge of health through excellence in teaching, clinical practice and research into the prevention and treatment of illness

Natural ventilation for the prevention of airborne contagion.

Escombe, AR; Oeser, CC; Gilman, RH; Navincopa, M; Ticona, E; Pan, W; Martínez, C; Chacaltana, J; Rodríguez, R; Moore, DAJ; et al. Escombe, AR; Oeser, CC; Gilman, RH; Navincopa, M; Ticona, E; Pan, W; Martínez, C; Chacaltana, J; Rodríguez, R; Moore, DAJ; Friedland, JS; Evans, CA (2007) Natural ventilation for the prevention of airborne contagion. PLoS Med, 4 (2). e68. ISSN 1549-1676 https://doi.org/10.1371/journal.pmed.0040068
SGUL Authors: Friedland, Jonathan Samuel

[img]
Preview
PDF Published Version
Available under License Creative Commons Attribution.

Download (707kB) | Preview

Abstract

BACKGROUND: Institutional transmission of airborne infections such as tuberculosis (TB) is an important public health problem, especially in resource-limited settings where protective measures such as negative-pressure isolation rooms are difficult to implement. Natural ventilation may offer a low-cost alternative. Our objective was to investigate the rates, determinants, and effects of natural ventilation in health care settings. METHODS AND FINDINGS: The study was carried out in eight hospitals in Lima, Peru; five were hospitals of "old-fashioned" design built pre-1950, and three of "modern" design, built 1970-1990. In these hospitals 70 naturally ventilated clinical rooms where infectious patients are likely to be encountered were studied. These included respiratory isolation rooms, TB wards, respiratory wards, general medical wards, outpatient consulting rooms, waiting rooms, and emergency departments. These rooms were compared with 12 mechanically ventilated negative-pressure respiratory isolation rooms built post-2000. Ventilation was measured using a carbon dioxide tracer gas technique in 368 experiments. Architectural and environmental variables were measured. For each experiment, infection risk was estimated for TB exposure using the Wells-Riley model of airborne infection. We found that opening windows and doors provided median ventilation of 28 air changes/hour (ACH), more than double that of mechanically ventilated negative-pressure rooms ventilated at the 12 ACH recommended for high-risk areas, and 18 times that with windows and doors closed (p < 0.001). Facilities built more than 50 years ago, characterised by large windows and high ceilings, had greater ventilation than modern naturally ventilated rooms (40 versus 17 ACH; p < 0.001). Even within the lowest quartile of wind speeds, natural ventilation exceeded mechanical (p < 0.001). The Wells-Riley airborne infection model predicted that in mechanically ventilated rooms 39% of susceptible individuals would become infected following 24 h of exposure to untreated TB patients of infectiousness characterised in a well-documented outbreak. This infection rate compared with 33% in modern and 11% in pre-1950 naturally ventilated facilities with windows and doors open. CONCLUSIONS: Opening windows and doors maximises natural ventilation so that the risk of airborne contagion is much lower than with costly, maintenance-requiring mechanical ventilation systems. Old-fashioned clinical areas with high ceilings and large windows provide greatest protection. Natural ventilation costs little and is maintenance free, and is particularly suited to limited-resource settings and tropical climates, where the burden of TB and institutional TB transmission is highest. In settings where respiratory isolation is difficult and climate permits, windows and doors should be opened to reduce the risk of airborne contagion.

Item Type: Article
Additional Information: © 2007 Escombe 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.
Keywords: Air Microbiology, Cross Infection, Hospital Design and Construction, Hospitals, Humans, Peru, Tuberculosis, Ventilation, Humans, Tuberculosis, Cross Infection, Air Microbiology, Ventilation, Hospital Design and Construction, Hospitals, Peru, Science & Technology, Life Sciences & Biomedicine, Medicine, General & Internal, General & Internal Medicine, HEALTH-CARE WORKERS, RESISTANT MYCOBACTERIUM-TUBERCULOSIS, NOSOCOMIAL TUBERCULOSIS, RESPIRATORY ISOLATION, INFECTED PATIENTS, LONGITUDINAL DATA, OUTBREAK, TRANSMISSION, MODELS, RISK, Science & Technology, Life Sciences & Biomedicine, Medicine, General & Internal, General & Internal Medicine, MEDICINE, GENERAL & INTERNAL, HEALTH-CARE WORKERS, RESISTANT MYCOBACTERIUM-TUBERCULOSIS, NOSOCOMIAL TUBERCULOSIS, RESPIRATORY ISOLATION, INFECTED PATIENTS, LONGITUDINAL DATA, OUTBREAK, TRANSMISSION, MODELS, RISK, 11 Medical And Health Sciences, General & Internal Medicine
Journal or Publication Title: PLoS Med
ISSN: 1549-1676
Language: eng
Dates:
DateEvent
27 February 2007Published
4 January 2007Accepted
Publisher License: Creative Commons: Attribution 4.0
Projects:
Project IDFunderFunder ID
UNSPECIFIEDWellcome Trusthttp://dx.doi.org/10.13039/100004440
T35A107646PHS HHSUNSPECIFIED
#HRN-5986-A-00-6006-00United States Agency for International Developmenthttp://dx.doi.org/10.13039/100000200
GHS-A-00-03-00019–00United States Agency for International Developmenthttp://dx.doi.org/10.13039/100000200
PubMed ID: 17326709
Web of Science ID: WOS:000244711800024
Go to PubMed abstract
URI: http://openaccess.sgul.ac.uk/id/eprint/110665
Publisher's version: https://doi.org/10.1371/journal.pmed.0040068

Actions (login required)

Edit Item Edit Item