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A comment on Why is Japan still a coronavirus outlier?. Parent comment

Re:Why is Japan still a coronavirus outlier? by barry-cotter on Saturday March 21, 2020 @09:06PM (#22651728)
Scarves are about the least effective makeshift masks, catching less than 50% of virus sized particles. A tea towel/dish cloth catches over 70% and a vacuum cleaner bag is over 80%, almost as good as a surgical mask.

> Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2440799/

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Re:Why is Japan still a coronavirus outlier? by Jedd on Saturday March 21, 2020 @09:21PM (#22651805)
> ... catching less than 50% of virus sized particles.

This is true but irrelevant.

You want to catch larger globs that carry virus-sized particles, and almost any material will help to some extent with this.

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Re:Why is Japan still a coronavirus outlier? by barry-cotter on Saturday March 21, 2020 @09:29PM (#22651855)
Not discouraging it, just pointing out that there are much better alternative materials.
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Re:Why is Japan still a coronavirus outlier? by mirimir on Saturday March 21, 2020 @09:36PM (#22651899)
But breathing through a vacuum cleaner bag is too hard.

Still, it might work if you did a radical pleat. I'll try it.

As I recall, two layers of cotton t-shirt is the best option.

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Re:Why is Japan still a coronavirus outlier? by lonelappde on Sunday March 22, 2020 @09:40AM (#22654865)
That would be awesome but I think you meant a "radial" pleat.
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Re:Why is Japan still a coronavirus outlier? by mirimir on Sunday March 22, 2020 @03:18PM (#22657707)
Huh. I meant radical in the sense of large surface area. And I was thinking ~cylindrical.

But radial is a great idea. And as soon as I started playing with paper, the ancient muscle memory of folding filter paper came back to me.

Edit: OK, I used filter paper from a shop vac, 20 cm wide by 30 cm high, with six faces triangular faces on the top and bottom, and eight faces on the sides. The ends of the faces on each side are sewed together, with an elastic strap connecting them. So the base is a diamond, ~18 cm wide and ~12 high. There's cloth edging on the top and bottom, and a cloth-wrapped 1 cm x 5 cm strip of aluminum edging to seal the top of the nose.

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