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Home-made face masks likely need at least 2 layers to curb COVID-19 spread:
Home-made cloth face masks likely need a minimum of two layers, and preferably three, to prevent the dispersal of viral droplets from the nose and mouth that are associated with the spread of COVID-19, indicates a video case study published online in the journal Thorax.
[...] A team of Australian researchers therefore compared the effectiveness of single and double-layer cloth face coverings (175 g/m² cotton fabric, with a thread count of 170/ inch) with a 3-ply surgical face mask (Bao Thach) at reducing droplet spread.
[...] The video recording showed that the 3-ply surgical face mask was the most effective at reducing airborne droplet dispersal, although even a single layer cloth face covering reduced the droplet spread from speaking.
But a double layer covering was better than a single layer in reducing the droplet spread from coughing and sneezing, the recording showed.
This is just one case, added to which several other factors contribute to the effectiveness of cloth face masks, note the researchers. These include the type of material used, design and fit, as well as the frequency of washing.
Nevertheless, based on their observations, a home made cloth mask with at least two layers is preferable to a single layer mask, they say, adding: "Guidelines on home-made cloth masks should stipulate multiple layers."
And they emphasise: "There is a need for more evidence to inform safer cloth mask design, and countries should ensure adequate manufacturing or procurement of surgical masks."
Journal Reference:
Prateek Bahl, Shovon Bhattacharjee, Charitha de Silva, et al. Face coverings and mask to minimise droplet dispersion and aerosolisation: a video case study [$], Thorax (DOI: 10.1136/thoraxjnl-2020-215748)
(Score: 4, Interesting) by DeathMonkey on Monday July 27 2020, @03:37PM (8 children)
The masks I made already have 2 layers because I followed the CDC instructions:
How to Make Cloth Face Coverings [cdc.gov]
(Score: 0) by Anonymous Coward on Monday July 27 2020, @03:47PM
Same here, made a few for myself several months ago, didn't take long with a sewing machine.
Used old "tea towels" (kitchen towels) for the material and sewed in a stiff piece of wire to bend over my nose. Put the softer towel toward my face to minimize irritation--because for one test lab I visit I have to wear the mask for the better part of two shifts in a row.
(Score: 5, Informative) by c0lo on Monday July 27 2020, @05:32PM (3 children)
3 layers works better - use a "with pocket" pattern - if I'm wearing a mask at least I can give myself a chance to the best protection still reasonable.
Outer layer - synthetic, as hydrophobic as possible - keep the bigger droplets on the surface
Replaceable filter in the "pocket" in between - a cotton non-woven fabric - after 1-2 washes, if becomes to non-uniform in thickness to trust it, discard
Inside layer - thickish fluffy flannel
No stitches except for the edges, don't want any perforation the from one side to the other anywhere close to nostrils/mouth. It also helps if the mask sticks to the face on edges only and uses the entire surface for air filtering - larger surface means one can breath easier and the speed of in/out air currents is smaller (keeps the penetration lower). The model I use is adapted from this [suzyquilts.com].
In any case, the house rules are:
1. no more that 2 hours exposure
2. come back home, throw the mask in the water+detergent (until you have enough to justify a machine wash)
3. wash hands.
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 3, Interesting) by fyngyrz on Monday July 27 2020, @07:06PM (2 children)
To which I would add:
Also, build a habit of observing careful control over where one puts one's hands during all out-of-home activities, particularly WRT your vehicle, if used, and WRT entry into your domicile, so as to make these prophylactic actions both effective and easy to prosecute.
Keep well clear of those who aren't wearing masks.
If you or yours do contract the virus, these things will tend to reduce the viral load, tend to reduce the severity of the resulting symptoms and follow-on effects, and tend to reduce further transmission (R0.)
--
I feel like I'm in season 5 of my life and the writers are
making ridiculous stuff happen to keep it interesting.
(Score: 3, Funny) by HiThere on Monday July 27 2020, @11:23PM (1 child)
Another step you should follow is to rinse your mouth with 20 proof alcohol. Stronger if you prefer. Add water or tonic if you feel like repeating.
Well, the medics don't recommend this step, but it reduces tension after all the others.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 0) by Anonymous Coward on Tuesday July 28 2020, @07:01AM
20 Proof? That's like 10%. Red or white wine.
Brandy, rum, vodka, or whiskey, would be better, they are all 35 to 45%. (stated in my order of preference :) )
(Score: 2) by tizan on Monday July 27 2020, @05:38PM
Indeed and i have a slit ion one side and i put a sheet of coffee filter paper in between which i replace every time i wash it....that makes it 3 layers.
Some people use the vacuum bag filter paper ...
(Score: 2) by edIII on Monday July 27 2020, @06:09PM (1 child)
Like Colo said, go with three.
My family's design is really nice. It is form fitting under the chin, wide enough to reach back almost all the way to the ears, and form fitting on the nose. Something like paper clips, but more resilient, are used in the bridge of the nose to allow you make it perfectly form fitting for your nose. This results in a full seal, unlike those piece of shit medical masks where from the side you can literally see somebody's pie hole while they are speaking. The chin is sealed super well, and the sides of my cheeks and my nose form the rest of the seal.
Outer layer is at least 200 thread count, along with innermost layer. Inside the pocket we put HEPA filters that are cut to fit into the pocket perfectly with zero missed area inside. So the HEPA filter is well past the point on my face where the seal is, providing full coverage for breathing.
They take a little more effort to breathe through, but not as bad as an N95 mask. I'll put my masks up against the piece of shit medical ones any day of the week to compare how well they seal. If somebody absolutely insists I use the medical ones, I can take that peice of shit and just put it inside the pocket too.
Technically, lunchtime is at any moment. It's just a wave function.
(Score: 2) by c0lo on Monday July 27 2020, @06:34PM
I'm using manilla fasteners [okschoolandoffice.com.au] in an insert slot on top of the mask.
Cheap enough to discard, soft enough to bend them around the contour of the nose.
https://www.youtube.com/watch?v=aoFiw2jMy-0