Most air cleaning devices have not been tested on people − and little is known about their potential harms, new study finds

Some portable air cleaners generate chemicals such as ozone, formaldehyde and hydroxyl radicals to kill microbes. ArtistGNDphotography/E+ via Getty Images

Portable air cleaners aimed at curbing indoor spread of infections are rarely tested for how well they protect people – and very few studies evaluate their potentially harmful effects. That’s the upshot of a detailed review of nearly 700 studies that we co-authored in the journal Annals of Internal Medicine.

Many respiratory viruses, such as COVID-19 and influenza, can spread through indoor air. Technologies such as HEPA filters, ultraviolet light and special ventilation designs – collectively known as engineering infection controls – are intended to clean indoor air and prevent viruses and other disease-causing pathogens from spreading.