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: -1, Offtopic) by Anonymous Coward on Monday July 27 2020, @04:14PM (5 children)
Masks are inferior. People should be wearing closed-circuit rebreathers.
(Score: 2, Funny) by Anonymous Coward on Monday July 27 2020, @04:17PM (4 children)
I haul around a scuba tank on a little dolley and hope to GOD I don't run out of air because there is only so far I can drive while holding my breath before I get home!!
(Score: 0) by Anonymous Coward on Monday July 27 2020, @05:29PM
Have you tried one of those snorkels with the ping-pong ball on the end?
(Score: 2) by DeathMonkey on Monday July 27 2020, @06:50PM (2 children)
The U in SCUBA stands for "underwater."
What you're looking for is SCBA, the tank will be "upside down" compared to SCUBA gear so you can access the valves inside your class A PPE.
(Score: 0) by Anonymous Coward on Monday July 27 2020, @09:02PM (1 child)
Oh my God, now I am expected to wear a HAZMAT suit too? This is the deadliest virus ever!
(Score: 2) by DeathMonkey on Monday July 27 2020, @09:32PM
Well, if you just enjoy hauling compressed air cylinders around then go for it.
But if you actually want that air to protect you from anything it needs to be inside an enclose with a slightly higher air pressure inside than outside.