【Scientific Reports】不完全なシーリングにより、呼気エアロゾル粒子がサージカルマスクから逃げる(2021.6.16作成) 「咳より会話の方が漏れやすい」

gene @momotar37156452

「全体的なマスク効率[漏れを含む]・・ マスク貫通ろ過効率と比較して、会話の場合は93〜70％に低下する。咳の場合は94〜90％にすぎない」 「不完全なシーリングにより、呼気エアロゾル粒子がサージカルマスクから逃げる」 nature.com/articles/s4159… 日本語 translatetheweb.com/?ref=TVert&fro… pic.twitter.com/YDAVuavgpd

拡大

Hiroshi Tsuji, MD, PhD, MPH🌏産業医 @Hiroshi_Tsuji

サージカルマスク着用時の飛沫は咳より会話の方が漏れやすいとの結果。マスクを通過+脇から漏れた気流の両方を考慮したマスク全体の効率を調査。マスクを通過したろ過効率に比べて、会話時は93-70％に減少に対して、咳の時は94-90％に減少のみ。12人の被験者から推定。nature.com/articles/s4159…

chris cappa @CappaSnappa

Excited to finally see our work on how the "leaks" from surgical masks influence the overall mask efficacy for respiratory aerosol emission out in the world! (short 🧵) nature.com/articles/s4159…

chris cappa @CappaSnappa

We know that facemasks can help reduce emission of respiratory aerosols when people breath, talk, cough, etc. However, we also know that unless you're wearing a properly fit respirator, such as an N95, that some air escapes out the sides.

chris cappa @CappaSnappa

This is why glasses sometimes fog up with facemask wearing. But, how does this air escape influence the effectiveness of the mask for reducing aerosol emission? And how does this vary between people?

chris cappa @CappaSnappa

To test this, we had volunteers speak a passage while wearing a surgical facemask and then measured the number of aerosols that passed through the mask or escaped in the different directions (top, sides, bottom), and compared with no mask wearing

chris cappa @CappaSnappa

As expected, most aerosols are removed from the air that passes through the mask material. However, we also found that even for air that escapes out the sides the number of aerosols is substantially reduced, especially for larger aerosols.

chris cappa @CappaSnappa

When we added all this together, we found that even after accounting for aerosol escape the surgical mask still led to, on average, a total reduction in aerosol emission of 70%, although with notable person-to-person variability

chris cappa @CappaSnappa

All this is to say, even though some air escapes out the edges, mask wearing still provides substantial protection to those around you by reducing your aerosol emission.

chris cappa @CappaSnappa

And when both sources (e.g., a person speaking) and receivers (e.g., a person listening) wear masks the benefits compound!

chris cappa @CappaSnappa

So, wear a mask when you're feeling even the slightest bit sick and help protect others. This goes for any respiratory disease (e.g. the flu), not just COVID.

chris cappa @CappaSnappa

And thanks to my awesome coauthors @ucdavis and Mt. Sinai. And to all the volunteers. ucdavis.edu/news/facemasks…

Emily Burns😊 DMs welcome #TeamReality @EmilyVBurns

1/ In today’s installment of “how to lie with science” a nature article purporting to show that even w/gaps, surgical masks 70%+ effective. Let’s take it apart. First, look at the experimental set-up & how the air would actually flow (cigarette smoke) nature.com/articles/s4159… pic.twitter.com/B5HCH8Fohk

拡大

Emily Burns😊 DMs welcome #TeamReality @EmilyVBurns

2/ Comparing the jets of cigarette smoke, in truth, the exhalation would be rocketing past the apparatus. This is reflected in the incredibly low particle numbers—10/sec @ max. The actual # is 1000 - 10K particles/sec--which excludes <0.5 micron. pnas.org/content/117/22… pic.twitter.com/0oJkQOAAgf

拡大

Emily Burns😊 DMs welcome #TeamReality @EmilyVBurns

3/ The study notes that it does not include particles under 0.5 microns—the vast majority of aerosols, as seen below. Though it is clear from the measured particles/second, that the apparatus is missing 99.9% to 99.99% of the particles emitted. pic.twitter.com/WsFSlG03TB

拡大

Emily Burns😊 DMs welcome #TeamReality @EmilyVBurns

4/ The particles captured, are surely the largest. Unfortunately, studies keep showing that not only are particles >5 microns a tiny fraction of respiratory aerosols, when they contain virus, it is not infectious. medrxiv.org/content/10.110… pnas.org/content/pnas/1… pic.twitter.com/NLqly3eZ0v

拡大

Emily Burns😊 DMs welcome #TeamReality @EmilyVBurns

5/ The graph below shows the particles emitted via each mode. There is no statistical difference between no-mask, and the exhalation out the top. The authors note that there is some when comparing individuals. Ok, maybe. pic.twitter.com/nWvw67Uctj

拡大

Emily Burns😊 DMs welcome #TeamReality @EmilyVBurns

6/ What is really interesting, is, if you add up the particles captured from top, bottom and sides (x2) they would be very close--or higher--than the “no-mask” scenario. Showing just what a big science lie, we got earlier from Bill Nye. twitter.com/Emily_Burns_V/…

Emily Burns😊 DMs welcome #TeamReality @Emily_Burns_V

3/ And yet, we have this kind of dishonesty from people like Bill Nye. He talks about “stopping the flow of air.” Yet he, just as everyone else who has worn a mask, must have felt the air escaping out the top of the mask--fluttering his eye lashes--during this demonstration. pic.twitter.com/gwX6xtJ07i

2021-05-28 06:08:31

Emily Burns😊 DMs welcome #TeamReality @EmilyVBurns

7/ This makes sense given other research showing that with a 3.2% gap, a surgical mask is 100% ineffective. Another study looking at PROTECTION, found that even with a mask GLUED to a mannequin, protection was only 50% for 0.5 micron. 3-20% w/gaps. tandfonline.com/doi/full/10.10… pic.twitter.com/MX2PVFZyig

拡大

Emily Burns😊 DMs welcome #TeamReality @EmilyVBurns

8/ The flaws in this study are not unique to it—this one just happens to combine all of the scientific sleights of hand used to claim that masks work, in the face of the overwhelming evidence that they do not. medrxiv.org/content/10.110… pic.twitter.com/f2gVh0Inrq

拡大

Emily Burns😊 DMs welcome #TeamReality @EmilyVBurns

9/ For more detail on this I put together this 60-tweet thread. Don’t stop at 31. twitter.com/Emily_Burns_V/…

Emily Burns😊 DMs welcome #TeamReality @Emily_Burns_V

1/ It's now acknowledged that COVID-19 is primarily transmitted by tiny aerosols generated through NORMAL breathing—not coughing, or flying spit globules. Based on what we already KNEW about these respiratory aerosols, this should have meant MASKS OUT. thesmileproject.global/post/airborne-… pic.twitter.com/HQtraAGf2a

2021-05-28 06:04:56

Emily Burns😊 DMs welcome #TeamReality @EmilyVBurns

10/ Or, just listen to Dr. Osterholm explain it back in June of 2020. Yes, as he always does when he says something true, he walked it back. But it doesn’t render it less true, it only renders him more craven. Start at 1:00 youtu.be/3CglBhn0znM

拡大

Linsey Marr https://www.threads.net/@linseycmarr @linseymarr

Surgical masks aren't too terrible for source control. "The overall mask efficiency [including leakage]...is reduced compared to the through-mask filtration efficiency, from 93 to 70% for talking, but from only 94–90% for coughing." nature.com/articles/s4159… by @CappaSnappa