We’ve removed a video from our site and YouTube because it contained incorrect information.
In “Everything an Air Purifier Can and Can’t Do” (published in August 2019), I stated that HEPA filters don’t capture airborne viruses. Although we believed that was true at the time, based on our extensive reporting, we now know that’s wrong. Once this became clear in the early months of the pandemic in 2020, we immediately added a section to our guide to the best air purifiers specifically noting that, yes, HEPA filters do capture free airborne viruses and aerosol droplets containing them.
But YouTube videos are not as easy to update when an error, an omission, or new information comes to light. You can’t change a published YouTube video; you can either take it down entirely or leave it up as is. We decided to leave the video up but added a correction pinned to the top of the comments section of the video’s page on YouTube. However, we’ve heard from many people over time suggesting that this is insufficient. We agree. We recognize that not everyone is paying close attention to the text beneath the video. Also, this text correction doesn’t travel with the video off of YouTube’s website. If someone embeds the video on a different webpage, the correction text is left behind on YouTube. So we’ve concluded that removing the video altogether is the best decision to ensure that no one is confused or misled by this outdated and incorrect assertion about HEPA filters.
To reiterate what we state in our guide, HEPA filters do capture particle-size ranges of 0.01 micron (10 nanometers) and above with great efficiency, which includes the vast majority of airborne viruses. For context, the coronavirus is approximately 0.125 micron (125 nanometers) in diameter.
This article was edited by Harry Sawyers and Jason Chen.