Opening windows ‘reduces transmission of TB’

Open windows provide valuable ventilation in clinics Copyright: SXC

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[LIMA] The risk of catching tuberculosis (TB) and other airborne diseases may be reduced simply by opening windows and doors, according to a study in Peru.

The World Health Organization recommends opening doors and windows in healthcare settings to prevent TB transmission and provide ventilation to patient rooms, but this is the first time that the practice has received scientific validation.

The research was published in PLoS Medicine this week (27 February).

“Natural ventilation provides an important infection control method in the tropics, where the greatest number of TB patients are located,” said lead researcher Rod Escombe, of Imperial College London, United Kingdom.

He said the method is already being implemented in nine hospitals and eight prisons in Peru, which has a large number of patients who have both TB and HIV/AIDS.

Escombe and colleagues studied eight hospitals in Lima, Peru for three years.

They compared the ventilation of 12 air-conditioned isolation rooms with 70 public areas with open windows and doors providing natural ventilation. These included consultation, waiting and emergency rooms, which, Escombe says, often have the “highest risk of infection” due to overcrowding and poor ventilation — a consequence of the high cost of installing air-conditioning or extractor fans.

Measurements showed that every hour twice as much fresh air passed through naturally ventilated areas than in the air-conditioned rooms.

The researchers estimated that in air-conditioned rooms, 39 per cent of individuals — mainly health workers — would become infected following 24 hours of exposure to untreated TB patients.

In rooms with natural ventilation, the infection rate was reduced to 11 per cent.

“Those facilities are characterised by large windows and high ceilings,” Escombe told SciDev.Net. He added that these rooms, built before 1950, were specially designed for TB patients following the guidelines of the pre-antibiotic era when fresh air was considered an important component of treatment.

Link to full paper in PloS Medicine

Reference:  PLoS Medicine doi:10.1371/journal.pmed.0040068 (2007)