Air filtration systems do not reduce the risk of picking up viral infections, according to new research from the University of East Anglia. The latest study published on Monday, November 20, reveals that technologies designed to make social interactions safer indoors are ineffective in the real world.
The team studied technologies, including air filtration, germicidal lights and ionisers. They looked at all the available evidence but found little to support hopes that these technologies can make air safe from respiratory or gastrointestinal infections. The study, 'Effectiveness of filtering or decontaminating air to reduce or prevent respiratory infections: A systematic review' was published in Preventive Medicine journal.
Prof Paul Hunter, from UEA's Norwich Medical School, said, "Air cleaners are designed to filter pollutants or contaminants out of the air that passes through them. When the Covid pandemic hit, many large companies and governments, including the NHS, the British military, and New York City and regional German governments, investigated installing this type of technology to reduce airborne virus particles in buildings and small spaces. However, air treatment technologies can be expensive. So it's reasonable to weigh the benefits against costs and understand the current capabilities of such technologies."
Research team studied whether air-cleaning technologies make people safe
The research team studied evidence about whether air cleaning technologies make people safe from catching airborne respiratory or gastrointestinal infections.
They analysed evidence about microbial infections or symptoms in people exposed or not to air treatment technologies in 32 studies, all conducted in real-world settings like schools or care homes. So far, none of the studies of air treatment started during the Covid era have been published.
Researcher found no strong evidence against technologies
Lead researcher Dr Julii Brainard, also from UEA's Norwich Medical School, said, "The technologies that we considered included filtration, germicidal lights, ionisers and any other way of safely removing or deactivating viruses in breathable air. In short, we found no strong evidence that air treatment technologies will likely protect people in real-world settings."
"There is much evidence that several air treatment strategies can reduce environmental and surface contamination, especially germicidal lights and high-efficiency particulate air filtration (HEPA). But the combined evidence was that these technologies don't stop or reduce illness. There was some weak evidence that the air treatment reduced the likelihood of infection, but this evidence seems biased and imbalanced," Dr Brainard continued.
"We strongly suspect that there were some relevant studies with very minor or no effect, but these were never published. Our findings are disappointing, but it is vital that public health decision-makers have a full picture," Dr Brainard added.
"Hopefully, those studies that have been done during Covid will be published soon, and we can make a more informed judgement about the value of air treatment during the pandemic."
Research team included
This research was led by the University of East Anglia with collaborators at University College London, the University of Essex, the Norfolk and Norwich University Hospital Trust, and the University of Surrey.
It was funded by the National Institute for Health and Care Research Health Protection Unit in Emergency Preparedness and Response, led by Kings College London and UEA in collaboration with the UK Health Security Agency.
