1/ All masks are not the same, and it's hard to tell which ones work better, but this article provides some insights.
First, "paper" surgical masks are really very very good.
advances.sciencemag.org/content/early/…
First, "paper" surgical masks are really very very good.
advances.sciencemag.org/content/early/…
2/ The disposable surgical masks (nonwoven, 3-layer) may seem flimsy, but they are engineered to do this job, and they are available now at around 50c each.
If you want to be extra safe, add a face shield
That's what doctors do when they aren't dealing w a high risk covid case
If you want to be extra safe, add a face shield
That's what doctors do when they aren't dealing w a high risk covid case
3/ an interesting finding: valved N95 masks were significantly worse than fitted, nonvalved n95 masks for preventing the spread of droplets
Makes sense- valve lets out breath. These may be better at protecting the wearer, but not as good as surgical masks for preventing spread.
Makes sense- valve lets out breath. These may be better at protecting the wearer, but not as good as surgical masks for preventing spread.
4/ Cotton is hit or miss.
More layers generally better.
Different materials in different layers (cotton/polypro blend) seems to be better.
What's pretty important is how well it fits, and whether there are big gaps
More layers generally better.
Different materials in different layers (cotton/polypro blend) seems to be better.
What's pretty important is how well it fits, and whether there are big gaps
5/ as shown in the graph to the right, bandanna only cuts down by about half, and stretches out the period of droplet transmission.
(You can barely see the other low squiggly lines on the bottom which are better masks)
(You can barely see the other low squiggly lines on the bottom which are better masks)
6/ fleece is terrible!
The authors speculate that fleece may actually chop up large particles into smaller ones instead of blocking, which is exactly what you don't want!
The authors speculate that fleece may actually chop up large particles into smaller ones instead of blocking, which is exactly what you don't want!
7/ But the bottom line here is that almost all of these masks cut down droplet spread by 80% or more
That is huge.
Simple version: If we all wore effective masks and wore them well, then the reproductive number could fall from 2.5 to less than 1.0, and outbreak would extinguish
That is huge.
Simple version: If we all wore effective masks and wore them well, then the reproductive number could fall from 2.5 to less than 1.0, and outbreak would extinguish
8/ there are a fair number of questions about whether "surgical masks" found online are good enough.
Don't look for "FDA approved"
FDA has issued broad regulatory flexibilities for mask makers unless they claim liquid resistance (which you don't need)
fda.gov/medical-device…
Don't look for "FDA approved"
FDA has issued broad regulatory flexibilities for mask makers unless they claim liquid resistance (which you don't need)
fda.gov/medical-device…
9/ But more experienced medical manufacturers will often have data on performance viz "ASTM" standards.
F2299 (particulate filtering) is probably most relevant, but if the box has any info on ASTM testing, I think you're good.
astm.org/standardizatio…
F2299 (particulate filtering) is probably most relevant, but if the box has any info on ASTM testing, I think you're good.
astm.org/standardizatio…
10/ Maybe a good use of executive authority/ DPA would be to ship a few boxes of good surgical masks to every household in America.
Would cost one thousandth of what's being debated on economic stimulus. (when what we need to reboot the economy is control of the outbreak)
Would cost one thousandth of what's being debated on economic stimulus. (when what we need to reboot the economy is control of the outbreak)
