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 today in the freely available 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, including respiratory isolation rooms, TB wards, respiratory wards, general medical wards, outpatient consulting rooms, waiting rooms, and emergency departments. 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. Even at the lowest wind speeds, natural ventilation exceeded mechanical ventilation.
"We were surprised by how effective simply opening windows and doors was at generating high rates of ventilation, which would theoretically reduce the risk of transmission," says Dr Escombe. "Using an airborne infection model to predict the effect of natural ventilation on TB transmission, we estimated that in mechanically-ventilated rooms, 39% of susceptible individuals would become infected following 24 hours of exposure to untreated TB patients. This compared with 33% in modern and 11% in pre-1950 naturally ventilated facilities with windows and doors open."
Facilities built more than 50 years ago, characterized by large windows and high ceilings, had greater ventilation than modern naturally ventilated rooms. Some of these older facilities had been built especially for TB patients, along the design principles of TB sanatoria when fresh air was part of the treatment for TB in the pre-antibiotic era.
"We concluded that opening windows and doors provides high rates of ventilation and may therefore provide the most effective protection against airborne infection in low resource settings," says Dr Escombe. "Old-fashioned clinical areas with high ceilings and large windows provided the greatest protection. Mechanically ventilated negative-pressure isolation rooms are very expensive to install and maintain, and are limited to certain high risk areas such as TB isolation rooms. In contrast, natural ventilation is a low-cost, low-tech intervention that can be applied in many different areas, including waiting rooms, out-patient clinics and emergency departments, where many infectious patients are found. Whilst not suited to cold climates, natural ventilation offers an important infection control measure in the tropics, where the greatest burden of TB is found."
Craig Brierley | EurekAlert!
Europe’s Demographic Future. Where the Regions Are Heading after a Decade of Crises
10.08.2017 | Berlin-Institut für Bevölkerung und Entwicklung
Scientists reveal source of human heartbeat in 3-D
07.08.2017 | University of Manchester
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).
The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
16.08.2017 | Physics and Astronomy
16.08.2017 | Materials Sciences
16.08.2017 | Interdisciplinary Research