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