Masks

[RWebb]

https://aip.scitation.org/doi/10.1063/5.0016018

[island911]

Not bad.

It is evident that while the forward motion of the jet is impeded significantly, there is notable leakage of tracer droplets through the mask material. We also observe a small amount of tracers escaping from the top edge of the mask, where gaps exist between the nose and the cloth material. These droplets remained suspended in the air until they were dispersed by ambient disturbances.

Seems like someone here has been saying that for a while now.

hmmm....

[island911]

Cool pictures of how masks leak...



And that's with visible smoke. Not plumes of little 125nm virus.

[island911]

Oh wait.. Webb, did you intend this to show how masks attenuate forward velocity of particles?

Point taken, but know that I've never questioned that aspect.

A leaky condom will also slow forward velocity. The question is, how much does that matter?

And again, Covid replicates in the lungs, and escapes the lungs in the air.we breathe.

And, as the article says (and as I keep hammering) These droplets remained suspended in the air until they were dispersed by ambient disturbances. (not fall to the floor 3' away.)

[Chocaholic]

It still seems logical that combining a mask and 6’ separation is worthwhile.

[masraum]

Originally Posted by island911

Cool pictures of how masks leak...



And that's with visible smoke. Not plumes of little 125nm virus.

Do virus "cells" float around on their own? Or are they carried in spit particles?

[Rawknees'Turbo]

Originally Posted by Chocaholic

It still seems logical that combining a mask and 6’ separation is worthwhile.

The fact that so many people find it impossible, or are unwilling, to do the 6' distance thing is something that really amazes me; I work in a setting that sees very little foot traffic, but even so, probably 80% of the people that visit find it necessary to get very close when talking, etc., and have to be constantly asked to watch their distance. I've never been one to crowd people I'm talking too, so my sense of personal space is no doubt shaped by that, but I don't understand why some people think it is an unreasonable burden to maintain some space.

[island911]

Originally Posted by masraum

Do virus "cells" float around on their own? Or are they carried in spit particles?

Both.

The thing is, only a small proportion of virus cells get caught up in saliva. This virus does not replicate in the mouth, it replicates in the lungs.

SAR1 was more easily stopped because that one had people showing symptoms prior to transmission. (coughing ...)

This Covid 19 went around the world with very little symptoms. IOW, many carriers simply breathing.

Anyway, back to the particle story... We DO NOT have large droplets of spit-clad Covid WITHOUT having large amounts of very small particles of aerosolized Covid.

Yes yes, I know... the big push to stop projectile looggies.. Sure, a bandana will help stop those.

[Shaun @ Tru6]

That's not a picture of how masks leak. That's a picture of how a folded cotton handkerchief works in a sneeze and cough simulation.

The best DIY face mask material and fit? Quilting cotton beats bandana, new study suggests

Originally Posted by island911

Cool pictures of how masks leak...



And that's with visible smoke. Not plumes of little 125nm virus.

[stormin48061]

lol, i'm with TRU, that's not a mask. It's a mouth and nose covering. That would nvr pass spec for sure. I think it is just to show diffusion and what an improper material mask does or doesn't do.

[Shaun @ Tru6]

^^^. Yes it’s more of what not to do, what doesn’t work more than anything.

[RWebb]

Originally Posted by masraum

Do virus "cells" float around on their own? Or are they carried in spit particles?

virus particles of this type normally "do better" if they are in water

- large droplets of water = droplets

- tiny droplets that stay in the air a long time = aerosol

I won't say that a naked viroid with no water will become inactivated immediately as I've not seen any studies on that...

[RWebb]

This virus can replicate anywhere it finds an ACE2 receptor, not just in the lungs.

[RWebb]

some take home points from the study:

Loosely folded face masks and bandana-style coverings provide minimal stopping-capability for the smallest aerosolized respiratory droplets.

Well-fitted homemade masks with multiple layers of quilting fabric, and off-the-shelf cone style masks, proved to be the most effective in reducing droplet dispersal. These masks were able to curtail the speed and range of the respiratory jets significantly, albeit with some leakage through the mask material and from small gaps along the edges.

Importantly, uncovered emulated coughs were able to travel notably farther than the currently recommended 6-ft distancing guideline.

[pmax]

Originally Posted by tcar

Smoke does not behave like 'droplets'.

I believe they used a fog machine, not "smoke". Speaking of which, I do wonder if smoking can help here.

---------------------------------------------------------------------------------------
We use a recreational fog/smoke machine to generate tracer particles for visualizing the expelled respiratory jets, using a liquid mixture of distilled water (4 parts) and glycerin (1 part).

The resulting “fog” or “smoke” is visible in the right panel of Fig. 1 and is composed of microscopic droplets of the vaporized liquid mixture. These are comparable in size to the smallest droplets expelled in a cough jet (∼1 µm–10 µm). We estimate that the fog droplets are less than 10 µm in diameter, based on Stokes’ law and our observation that they could remain suspended for up to 3 min in completely still air with no perceptible settling. The laser source used to generate the visualization sheet is an off-the-shelf 5 mW green laser pointer with 532 nm wavelength. A plane vertical sheet is created by passing the laser beam through a thin cylindrical rod (diameter 5 mm) made of borosilicate glass.

[GH85Carrera]

[pmax]

Originally Posted by Rawknees'Turbo

The fact that so many people find it impossible, or are unwilling, to do the 6' distance thing is something that really amazes me; I work in a setting that sees very little foot traffic, but even so, probably 80% of the people that visit find it necessary to get very close when talking, etc., and have to be constantly asked to watch their distance. I've never been one to crowd people I'm talking too, so my sense of personal space is no doubt shaped by that, but I don't understand why some people think it is an unreasonable burden to maintain some space.

Raw', couple of suggestions ... improve the airflow, install a plexiglass barrier, wear a face shield wipe it down often.

CDC also agrees masks are not a substitute for social distancing.

[cabmandone]

I can't believe this is even a discussion. Wear a mask. It helps reduce the spread of a virus.

[cabmandone]

Raw, this one is for you!

[cabmandone]

Originally Posted by pmax

Raw', couple of suggestions ... improve the airflow, install a plexiglass barrier, wear a face shield wipe it down often.

CDC also agrees masks are not a substitute for social distancing.

Sure they do. But they also say is social distancing can't be maintained due to the number of people, wear a mask because it helps reduce the spread of COVID-19. They also say that wearing a mask AND social distancing is the best possible preventative we have right now. So why no do it?