Portable air filters do not reduce respiratory infections in older people’s care homes, according to the largest real-world trial of the technology to date.
The study, led by researchers at the University of Bristol and published in JAMA Internal Medicine, found that high-efficiency particulate air (HEPA) filters made no difference to rates of coughs, colds, flu or Covid-19 among care home residents. They also failed to reduce other common infections, including gastrointestinal, urinary and skin infections.
The finding suggest that care homes should continue to rely on established infection control measures, such as vaccination, hand hygiene and regular cleaning, rather than investing in portable air filtration systems.
Respiratory infections remain a major threat in care homes, where even relatively mild illnesses can quickly become serious in older people. While HEPA filters are widely used to improve air quality and are known to remove airborne particles in laboratory settings, evidence of their effectiveness in everyday care settings has been limited.
To address that gap, researchers recruited 91 care homes across England between 2021 and 2024, involving 1,158 residents. Around half of the homes were randomly assigned portable HEPA filters, which were installed in communal areas and residents’ bedrooms and operated continuously throughout the winter months. The remaining homes continued with their usual infection prevention practices without air filters.
At the end of the study, there was no meaningful difference between the two groups.
Researchers found that the filters did not reduce the number of respiratory infections or other common infections. They also found no differences in hospital admissions, antibiotic prescriptions, residents’ physical health, falls or near falls, or staff sickness absence.
Importantly, the findings were not explained by poor use of the devices. Care homes followed manufacturers’ guidance on where the filters should be placed and kept them running as instructed throughout the trial. No safety concerns or harmful effects were reported.
Professor Alastair Hay, a GP and Professor of Primary Care at the University of Bristol, who led the study, said the results provide clear evidence that portable HEPA filters should not be relied upon to prevent infections in care homes.
“Our study has clearly shown that HEPA filters do not prevent respiratory infections, like coughs, colds, flu or Covid-19, when used in older people’s care homes,’ he said. ‘It is important, therefore, that care homes continue with standard infection control methods, including vaccinations, regular cleaning and hand washing.’
The researchers estimate that avoiding unnecessary purchases of portable HEPA filters could save care homes in England around £30 million each year.
Co-author Professor Ruth Kipping said: ‘This is the first robust trial of HEPA filter use in care homes. In the light of our findings, we recommend that care home managers, residents and local authorities do not invest in portable HEPA filters for the purpose of reducing infections in care homes.
‘Further research is needed in other health care settings and with other age groups before we can be sure that portable HEPA filters are universally ineffective for infection control. More research will become necessary if manufacturers develop air filters that can operate at higher flow rates that are acceptable to staff and residents.’
The full research can be read here
Photo: Jsme MILA
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