[vanusa]

Masks are considered useless unless you are infected.

That's not what the guidelines said. They guidelines were referring only to "hygienic masks" a.k.a. generic surgical masks:

The Federal Office of Public Health (FOPH) does not recommend that people who are well wear hygienic masks (surgical masks). If you are in good health, they do not protect you effectively against an infection with respiratory viruses (i.e. self protection). Wearing a mask therefore can give you a false sense of security.

This is a known point. But they did not mention -- nor did they advise against the use of -- properly rated and certified masks (such as N95 masks). Which do provide some protection (albeit with caveats).

Also, just think for minute around the basic logic of what you're saying. If (properly rated and certified) masks provide "no protection" (for unprotected individuals) - then why are the health care workers using them?

[prostheticvamp]

They provide no /self/ protection. As I have said in multiple threads on this topic: we wear astm3 masks to protect /patients/ from /us/. A lot of hospital PPE is oriented towards /patient/ protection.

And N95s are heavy and uncomfortable. No one can wear them for long. But if anyone wants to, they’re welcome to it.

[bootlooped]

I have worn N95 masks for probably hundreds of hours due to having had a job in a factory with poor indoor air quality. Wearing them for 30-60 minutes during high risk activities like riding in a packed subway car would not be a problem for most people.

[kragen]

N95 masks are used in many industries to protect their wearers from particulates, including wet particulates. Many of them have check valves that make them useless for protecting other people from the wearer. We don't yet know how much protection they provide against SARS-CoV-2 infection, because we don't know how essential saliva droplets are to contagion, but they probably provide some.

Although there are different kinds of N95 masks, the most common kind weighs a few grams; this is not uncomfortable.

[prostheticvamp]

Have you worn an N95 for any particular amount of time? Honest question. Because Uou refer to a few grams as “not uncomfortable.”

I find N95 face masks insufferably hot and muggy, with their “few grams” hanging off my nose and ears eventually very annoying. I don’t know if any hc workers that find N95s tolerable for very long.

[petertodd]

I've spent a summer in +30°C heat doing demolition and foam insulation in a house that had been through a fire. I had to wear a heavy half face cartridge respirator the whole time due to both the toxins from the fire, and the toxins from the foam insulation.

I wouldn't say that was fun. But it was tolerable. A N95 mask is fine by comparison - not much worse than a surgical mask.

[prostheticvamp]

That’s funny, because I wear the cartridge respirator outside of work for some hobbyist reno stuff I do, and find it much more tolerable than the N95. To each their own, I suppose.

[vanusa]

Can you please clarify:

(1) Which category of mask are you saying provides "no" self protection -- ASTM 3 and N95? (I've read over your post multiple times, and not entirely clear).

(2) So to be clear - are you saying that N95s provide "no" self protection? Not just that they can be misused; or that protecting against surface droplets is more important; but literally "no" self protection?

(3) And if the answer to (2) is yes, can you provide a source or two we can use for further illumination on this topic?

I'm not trying to waste your time, here. I'd actually really appreciate your input.

[prostheticvamp]

Sorry if I was unclear. ASTM3s do not provide self protection. They are estimated to reduce ambient virion uptake by about 2/3 - which just isn’t enough to make a meaningful difference most of the time, as 1/3 of the usual droplet output is already more than is needed to cause infection.

[vanusa]

Thanks for clarifying.

[pombrand]

N95 masks may only be effective used with eye protection. Surgical masks may not help at all.

Looked for interventional studies testing whether face masks and eye protection work in humans to protect against airborne viral particles. A big issue with many such studies is that medical staff only use masks and/or eye protection at work, opening them to being infected outside of work.

Found a small study [1] getting around this problem by exposing subjects (n = 28, avg age 30.5 years) to monodispersed live attenuated influenza vaccine particles by placing them in front of a vibrating-orifice aerosol generator for 20 minutes, subsequently testing for infection using RT-PCR and culture in nasal washes.

RESULTS

- No precautions: 4 out of 4 infected.

- Ocular exposure only: 4 out of 4 infected.

- Surgical mask only (3M 1818): 5 out of 5 infected.

- Surgical mask with eye protection (Z87 Uvex non-vented): 5 out of 5 infected.

- N95 mask (3M 1860/1860S) only: 3 out of 5 infected.

- N95 mask with eye protection: 1 out of 5 infected.

1. Bischoff WE, Reid T, Russell GB, Peters TR. Transocular entry of seasonal influenza-attenuated virus aerosols and the efficacy of n95 respirators, surgical masks, and eye protection in humans. J Infect Dis. 2011;204(2):193–199.

[aschatten]

Thanks for the great reference. I am tired of people saying how masks are inefficient and all, based only on speculations.

[tyfon]

You can actually increase your odds of infection by different deceases by having a paper mask since they are often uncomfortable or fit poorly and people put their hands to the face to adjust them.

[Keloo]

I've heard the opposite rationale. Having 'any' kind of mask decrease the number of times you touch your mouth or nose..

[fortran77]

I concur. Wearing a mask makes it less likely you'll inadvertently touch your mouth, nose, or eyes.

[endorphone]

This seems like an invented rationalization given that the average person touches their face up to 3000 times a day already (up to. It is trivial to find details of this range). If you adjust a mask a few times, but in return it stops you from touching your nose/mouth constantly, that's an enormous win.

And just to clarify, again people are talking about surgical masks. N95 masks, which are still "cheap paper masks", indisputably work. This is way beyond debate.

[tyfon]

It is what I read by an associate in microbiology and infection control [1]. I tend to listen to experts but maybe he's wrong about the field he is studying, I'm not an expert :)

Translated from Norwegian:

- Does a facemask help against spreading virii?

- No, not when you are using it out among people. The point is that you will scratch your face and get your fingers in contact with your soft tissue. So it is counterproductive to use these regular paper masks, says associate in microbiology and infection control at the University of Southeast Norway, Jörn Klein.

[1] https://www.nettavisen.no/nyheter/smittevernforsker-munnbind...

[whatshisface]

>The point is that you will scratch your face and get your fingers in contact with your soft tissue.

So they're saying that... masks will help if you don't touch your face? Makes sense to me, the PPE that the CDC recommends involve a face shield in addition to a mask.

[vanusa]

Again this is about "regular paper masks" -- not specially rated masks such as N95.

Also, it dodges the question of - "What if, being adults, we train ourselves not to scratch our face (in view of the seriousness of the issue)? Will masks help then?"

[endorphone]

But we already touch our face endlessly. Again, this sounds like he invented this on the spot. This wasn't studied, isn't the result of an analysis, it's just a lazy response. Further, again he was talking about surgical masks.

Surgical masks don't work. Surgical masks are a subset of masks, and it is grossly inaccurate to extrapolate that out to "masks don't work".

[tyfon]

I never claimed all masks don't work, I was talking about cheap paper masks. It might not have been clear enough in the original comment.

[cheerlessbog]

Citation for the 3000 value? That seems to be a meme : I can't find evidence for it. A study [1] found 23 times an hour which is 368 times in a 16 hour day.

https://www.ncbi.nlm.nih.gov/m/pubmed/25637115/

[majos]

Tangent, but 3000 times per day is about once every 20s awake. That seems high?

[tyfon]

The article I refer to in the sibling comment claims 23 times an hour on average so it would mean about 550 times during a day/night if you don't sleep. It sounds a bit more plausible.

[endorphone]

That's the high, though apparently the average is more in the range of 550 times or so.