Most Air Purifiers Haven’t Been Tested on Humans. That’s a Problem
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 kno