Most air purifier claims lack real-life testing, warn researchers

United News of India

a day ago

New Delhi, Aug 17 (UNI) Planning to purchase that sleek air purifier for your home or office? You may want to think twice. While these devices---from sleek designer models to compact plug-and-play gadgets--- are widely marketed as solutions for cleaner, healthier indoor air, new research suggests that many of them lack real-world evidence to support their claims.
In fact, some may even produce harmful byproducts like ozone, raising fresh concerns about their long-term safety and effectiveness, as has been found by researchers at the University of Colorado Anschutz Medical Campus and the National Institute for Occupational Safety and Health (NIOSH) — part of the U.S. Centres for Disease Control and Prevention (CDC).
The study, published in the latest Annals of Internal Medicine, analysed nearly 700 studies conducted between 1929 and 2024 on various air-cleaning methods such as HEPA filters, ultraviolet (UV) light systems, ionisers, and advanced ventilation designs. Strikingly, only 9% of these studies actually assessed whether the devices reduced illness in humans.
'We were surprised to find that most of the research tested air cleaning devices in lab chambers, not in real-world settings where people live, work or go to school,' said Dr. Lisa Bero, professor of internal medicine and co-author of the study.
'We need stronger studies that look at actual health outcomes, whether people are actually exposed to fewer pathogens or get sick less often — and not just measurements of particles in the air.'
Most studies examined indirect indicators — such as reductions in dust, harmless microbes, or tracer gases — rather than tracking actual viral or bacterial infection rates. Very few evaluated whether people got sick less often after using these devices.
'Many of these technologies look promising on paper, but we just don't know if they work in the real world,' said Dr. Amiran Baduashvili, associate professor of medicine and the paper's lead author.
'People are buying and installing these systems in homes and schools hoping to protect themselves and their families — but the science hasn't caught up to the marketing.'
It's not only about their effectiveness. The researchers also raised concerns about potential harms from certain air-cleaning devices. Technologies like ionisers, plasma-based systems, and some ultraviolet light purifiers can produce ozone, a gas known to irritate the lungs and aggravate respiratory conditions.
'Ozone and other chemicals created by some air-cleaning devices can actually harm the respiratory system, especially in children or people with chronic respiratory illnesses,' said Louis Leslie, co-author of the study and senior professional in the Department of Ophthalmology at the University of Colorado School of Medicine.
The study found that only a small portion of existing research even examined such risks, despite their potential public health implications.
'It may be worth checking whether the manufacturer provides data on any potentially harmful emissions from a device and what can be done to minimise them,' added Bero.
'Being more aware of possible risks is an important part of making informed decisions, especially as more people and organisations spend money on these technologies and bring them into clinics, schools and homes.'
While advanced filtration systems and new technologies may play a role, experts stress that simple, low-cost interventions are still the foundation of healthy indoor air.
'We're not saying these technologies don't work - we're saying we don't know enough yet,' Bero said, adding, 'Public health decisions should be based on solid, independent evidence.'
Until that evidence is stronger, researchers advise people to prioritise natural ventilation, open windows regularly, and clean frequently. These everyday practices remain some of the most effective ways to reduce airborne contaminants and limit the spread of infection indoors.
'This study highlights the urgent need for better science to guide how we make our indoor environments safer — especially as respiratory infections continue to pose a serious public health threat,' said Bero.
UNI AJ ARN