The chance of infection in wards varies dramatically depending on whether nursing staff leave the windows open, researchers have concluded.
A study by the University of Leeds and Bradford Teaching Hospitals Foundation Trust looked at airflow in a disused “Nightingale” ward using tracer gases to simulate the spread of airborne infections.
They found ventilation in the ward was generally good when windows were left open, keeping the danger of airborne infection low. But risks increased fourfold when the windows were closed.
Lead investigator Cath Noakes, from Leeds University, said: “These wards are still in operation and, although they have often been subdivided into smaller areas with six-eight beds, their ventilation and structure is still fundamentally the same.
“People are being told to seal up their buildings to save energy. If you do that without alternative ventilation systems, you could be increasing the airborne infection risk significantly,” she said.
The Department of Health recommends replacing the equivalent volume of air in a ward six times every hour.
The researchers found ventilation rates were either satisfactory or better than the DH standard when windows were left open. When they were closed, exposure to infection was typically four times higher, equivalent to a ventilation rate of only 1.5 air changes an hour.
However, the researchers found that placing small extractor fans beside each bed had a marked positive effect on ventilation.
Dr Noakes said: “Introducing simple mechanical ventilation to supplement the airflow in the winter, could be an effective approach to ensuring good ventilation year-round, without the energy costs of a full air conditioning system.”
The study, published in the journal Building and Environment, was conducted in a disused ward at St Luke’s Hospital in Bradford and used carbon dioxide as a tracer gas to represent potentially infectious exhaled breath.
Carbon dioxide detectors were positioned where beds might be placed in a working ward and the gas was released by popping carbon-dioxide filled balloons.
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