SciDev.net reports on a just-published Peruvian clinical study of tuberculosis risk for health care workers, comparing infection rates in clinical settings with, and without, natural ventilation. Health care infection risk associated with patient contact was modeled and (apparently) verified with Peruvian data to be 33% in the air conditioned buildings, such as are currently the norm in all institutional buildings around the world - the kind without operable windows, compared to 11% in older style (pre-1950 design) buildings with windows that were used to provide high rates of natural ventilation. The original research paper was published in PLoS Medicine. See below the fold for the "Conclusions" statement of the paper. Note that the stretch-headline statement of this post presumes that a health care institution seeking LEED certification would design natural ventilation options in to achieve certification, including air to air heat exchange technology as appropriate, and that the infection control benefits would translate from achievable increases in ventilation. Image credit: Crossbeck Cottager
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.