This study investigating air filtration, germicidal lights, and ionizers reveals that the technologies that were designed to make social interactions safer are not effective at preventing illness in real-world settings. The researchers analyzed evidence about microbial infections or symptoms in people exposed or not exposed to air treatment technologies in 32 studies that were conducted in real-world settings such as schools or care homes. According to the researchers, they looked at all of the available evidence but found little support that these technologies can make air safe from respiratory or gastrointestinal infections. However, none of the studies of air treatment started during the pandemic have been published at the time of this study.
“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 in a bid to reduce airborne virus particles in buildings and small spaces,” said Prof Paul Hunter, from UEA’s Norwich Medical School. “But air treatment technologies can be expensive. So it’s reasonable to weigh up the benefits against costs, and to understand the current capabilities of such technologies.”
“The kinds of technologies that we considered included filtration, germicidal lights, ionisers, and any other way of safely removing viruses or deactivating them in breathable air,” said Lead researcher Dr. Julii Brainard, also from UEA’s Norwich Medical School.” There is a lot of existing evidence that environmental and surface contamination can be reduced by several air treatment strategies, 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 methods reduced likelihood of infection, but this evidence seems biased and imbalanced,” said Brainard. “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,” added Brainard. “Hopefully those studies that have been done during Covid will be published soon and we can make a more informed judgement about what the value of air treatment may have been during the pandemic.”
