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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: 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