In response to what Clare Snyder <
cl...@snyder.on.ca> wrote :
>> D I Y masks are not about protecting the wearer -
>>it's about keeping the wearer's spit drops off of things.
>>How many microns in a spit drop ? sneeze drop ..
>> John T.
> 5 to 15, generally speaking - for aerosolized sneeze - so still not
> very effective. Might reduce the range by a few percent though - - - -
The virus itself, is huge for a virus, but still pretty tiny, around 100nm,
or about 0.1um (approximately, to round numbers).
But what matters is the "spit" size, which, if it's 5um to 15um, then
that's what we need to filter "in" when we're at close quarters.
One problem, as noted prior, is whether it's at all useful shielding "most"
of the particles, where it could be like machine-gun bullets, where only
one needs to get out to infect someone else.
Still, the news is abuzz with home-made DIY mask designs, such as this:
o *How to make a non-medical coronavirus face mask ĄV no sewing required*
<
https://www.theguardian.com/us-news/2020/apr/06/how-to-make-no-sew-face-mask-coronavirus>
In that article, sans sewing, they make a mask out of an old T-shirt,
with a paper towel as the absorbent central material.
This (clickbait?) news article says an unpublished paper reports:
"QuiltersĄŚ cotton, a tightly woven high-thread-count fabric, can filter
out some 70% to 79% of small particles including viruses... '
That's better than surgical masks, which Segal said filter out only
65% of particles. (N95 masks offer the highest level of protection
filtering out 95% of air particles.)
o So what materials do come out on top?
<
https://www.marketwatch.com/story/some-fabrics-are-more-effective-than-others-for-making-diy-face-masks-heres-which-ones-are-best-2020-04-07>
"Vacuum cleaner bags ranked higher than tea towels,
but theyĄŚre considerably more difficult to breathe through"
And yet:
"Tea towels are better to use for a mask than T-shirts or pillowcases"
o *Addressing COVID-19 Face Mask Shortages* (Stanford Medicine)
<
https://stanfordmedicine.app.box.com/v/covid19-PPE-1-1?mod=article_inline>
There's another simple design in MarketWatch over here:
o *When you canĄŚt buy a mask, make it yourself*
<
https://www.marketwatch.com/story/this-might-be-the-simplest-no-sew-diy-coronavirus-mask-2020-04-03>
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