False hope
University of East Anglia
A new study published today reveals that technologies
designed to make social interactions safer in indoor spaces are not effective
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.
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 in a bid to reduce airborne virus particles in buildings and small spaces.
"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 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.
Lead researcher Dr Julii Brainard, also from UEA's
Norwich Medical School, said: "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.
"In short, we found no strong evidence that air
treatment technologies are likely to protect people in real world settings.
"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.
"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.
"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."
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.