Read on Twitter
I first saw this story & thought, "Crap. Guess I need to find an alternative to the Buff." And then I looked at the scientific publication and, well, it's not that clear cut IMO.
So a thread from me (BB)... https://twitter.com/realdumbrunner/status/1292492631058989057
So a thread from me (BB)... https://twitter.com/realdumbrunner/status/1292492631058989057
The publication is a proof-of-principle for a *method* that the group developed, and for that purpose, the results are fine. But public attention is on the data re: mask effectiveness, and frankly the experiments were not designed for solid conclusions on that front.
Issue 1: Descriptions of the masks/materials used are sparse. What we're interpreting as a neck gaiter/Buff is described as a "Gaiter type neck fleece", with no detail about the material's composition.
Issue 2: The number of testers is smallâ4 people tested 3 materials (surgical mask, 1 cotton mask, bandana). But apparently just *1* person tested the other 11 materials, including the fleece/gaiter.
Issue 3: As we might expect, there was a lot of variability in droplet transmission between speakers w/o masks (baseline). Speaker 1, who tested all materials, had much higher counts than the other 3âgreat for detecting differences in signal but maybe not so representative.
Issue 4: There was individual variability in material effectiveness among the speakers. Note the bandana was *more* effective than a cotton mask for 1 person, but the bandana had minimal effect for 2 others, and moderate for another.
Issue 5: The methods lack info about how the masks were donned (eg, how many layers for bandana or fleece) & whether fit was checked. (Issue 4 might arise from such factors.)
Issue 6: Basis of the "worse than nothing" claim is that fleece increased # of droplets. Authors speculate due to breaking larger droplets into smaller onesâunknown effect on viral transmission. But fleece was tested w 1 person & standard deviation (bar) for fleece was large.
Issue 7: (G brought to my attn) As droplet count increases, so does standard deviation. We don't know whether that's more variability in the signal, or whether that's more noise in the measurement of the signal.
To recap: Some researchers came up with a cheaper way to compare mask effectiveness, but their data was about proving the method worksânot the masks.
Worth noting, if your major use of a neck gaiter relates to running outside (like mine), we should remember the risk of transmitting SARS-CoV-2 while outside & not congregated with others is quite low based on the information available to us today.
If you really want to dig into mask use, check out the WHO site, which includes technical guidance on materials & layers: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks
