Opening windows can be more effective than using mechanical ventilation at reducing the risk of transmission of airborne diseases such as tuberculosis (TB), according to a study funded by the Wellcome Trust and the Sir Halley Stewart Trust.

The spread of airborne infections in institutional settings such as hospitals, waiting rooms, prisons and homeless shelters is an important public health problem. This is especially true in resource-poor settings, where the prevalence of TB is highest, and where preventive measures such as negative-pressure isolation rooms are hardest to implement.

A study published this week in the journal 'PLoS Medicine', and carried out by researchers from the Department of Infectious Diseases and Immunity and the Wellcome Trust Centre for Clinical Tropical Medicine, Imperial College London, is the first to investigate the role of natural ventilation by opening windows and doors for preventing the transmission of airborne infection. This simple and low-cost measure is recommended by the WHO for preventing TB transmission in healthcare settings, but until now there have been no studies to support these guidelines.

The researchers, led by Dr Rod Escombe from Imperial College London, studied eight hospitals in Lima (Peru) and measured natural ventilation in 70 different rooms where infectious patients are likely to be found. They compared these with 12 modern mechanically ventilated, negative-pressure respiratory isolation rooms.

The study found that natural ventilation when windows and doors were opened was more than double that of mechanically ventilated, negative-pressure rooms functioning at the high rates recommended by guidelines, and 18 times that of rooms with windows and doors closed.

See also

• Press release (27 February 2007)
• Taming TB: New vaccine and diagnostics aid the fight (News, 12 February 2007)

External links

• Natural Ventilation for the Prevention of Airborne Contagion (Full paper, PLoS Medicine)