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Comment by j7ake | Hacker News Reader

Would COVID being airborne mean that one should wear an N95 mask rather than just surgical masks? Analogous to when doctors perform procedures on patients that may produce aerosols?

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Nothing in this is binary, there are few 100% protections, there is only risk reduction.

Surgical masks reduce risk. N95 or FFP2 masks reduce risks more. So, prefer N95 masks. This does not mean that surgical masks or cloth masks are useless, or that N95 masks are perfect.

The empirical results of mandating masks is that virus spread is reduced substantially. But most masks people wear are not N95 type masks and shouldn't be as effective as the empirical results indicate. One article I read suggests that the effectiveness of masks comes not primarily from the filtering out of the virus but from increasing the humidity in the respiratory tract which in turn affects the ability of the virus to transmit disease.

Do you have any sources for that empirical result? I saw a big study result from Africa that came out last week, and it showed that surgical masks were helpful in reducing spread but the p-values were surprisingly weak except in the over-65 group. And cloth masks were very statistically weak in helping anyone.

>increasing the humidity in the respiratory tract which in turn affects the ability of the virus to transmit disease.

Consistent with early studies on mask sterilization techniques, which found that adding moisture to heat accelerated decay of virus particles.

A recent study found that in large populations, cloth masks were useless and surgical masks were only marginally effective.

https://www.poverty-action.org/publication/impact-community-...

But even with masks, over a long period the risk that everyone will eventually be exposed is close to 100%. That's why instead of obsessing over masks we should focus on vaccinating as many vulnerable people as possible.

https://www.businessinsider.com/delta-variant-made-herd-immu...

We need both. Delta is infectious enough that vaccine alone isn't going to stop it. Vaccine + masks can stop it, though, without infecting everyone.

Unfortunately that's simply wrong and there is no scientific basis for your claim. See the article linked I linked above, including the video testimony from Prof. Pollard. Vaccines are effective at preventing most deaths but vaccines and masks will not be sufficient to eradicate the virus. All of us can expect to be exposed multiple times. That is our reality.

But we need not expect to all get sick. Many, maybe most, vaccinated will get infected, and over it in a day or three, and likely not notice.

I don't understand - according to the paper you cite, cloth masks were less effective than surgical masks, (which would be expected) but not useless.

There was no statistically significant difference between the cloth mask intervention group and the control group.

> Would COVID being airborne mean that one should wear an N95 mask rather than just surgical masks?

Yes.

>Studies that have been done show that if an individual might get infected within 15 minutes in a room, by time and concentration of the virus in the room, add a face cloth covering you only get about five more minutes of protection.

On the other hand if you use the n95 respirators and fit them tight to your face, you can actually spend 25 hours in that same room and still be protected.

https://www.pbs.org/wnet/amanpour-and-company/video/do-masks...

Face shields as well. There was an Indian study showing that they reduced infections to nothing in social workers visiting unmasked people. Note that this also means that surgical masks should still prevent infecting others.

Do you mean face shield only? That seems like it would be much worse than mask only, if covid is airborne as the article suggests. Mask plus face shield should be even better than mask only.

No, they were using face shields as well as mask.

Citation for the study? The Indians also used ivermectin to great effect to reduce their wave 2 months ago.

There was a Swedish study showing face shields WITHOUT mask don't do anything. Also a study showing people with eyeglasses get infected less, i.e. it's possible that one can get infected thru eyes, although, I thing, it's pretty rare. Let's not forget that tear ducts drain in your nose!

Sure. That almost became the mandatory policy where I live.

It was the mandatory policy in Bavaria from about January to this week. At this point, I’m so used to the FFP2 mask I found that fits best that I’m still wearing those instead of the surgical masks we can (for) now wear instead - hooking behind the head is key.

My impression is that there are rapidly rising and then diminishing returns on investment.

Going from cloth to any mask with a high filtration layer is a huge improvement. Cloth is <30% of small particles. High filtration layer is >90%. Beyond that, the benefits are questionable.

Some surgical masks include a non-woven layer, and those already do pretty well (but how would you find those? pre-COVID it was easy). From there, genuine (non-counterfeit) KN95 and nanofiber masks are a big step up, and incredibly effective. At least pre-delta, if everyone used those, combined with modest social distancing, there was very little spread.

N95 masks are a modest improvement from there in terms of filtration, but by that point, mask quality (at least pre-delta) no longer appeared to be the dominant risk factor. COVID19 can spread through other mucous membranes (e.g. eyes). While combined with a face shield, used correctly, etc. I'm sure N95 make a difference over KN95, in practical public health use, I doubt there's any difference.

This is a good summary of data:

https://docs.google.com/spreadsheets/d/1M0mdNLpTWEGcluK6hh5L...

https://docs.google.com/spreadsheets/d/1i06OAItoOwIUaMjElr8m...

I don't really distinguish between things with >90% filtration. Unless you've got an excellent seal and are otherwise protected, it doesn't matter much. Note that the measurements are performed at 300nm. There isn't much spread at 300nm (a single virus particle is unlikely to make you sick). A 90% mask at 300nm will have >>>90% at e.g. a micron. A micron particle is unlikely to have more than one or two COVID particles (a micron is 5 COVIDs wide).

I do distinguish based on pressure drop. Lower means more air goes through the mask, rather than around.

I also do distinguish based on technology. The nanofiber ones don't degrade the same way as N95. The N95 nonblown layer will theoretically beat nanofiber for the first couple of hours of use, but once it's moist from your breath, nanofiber beats it. Personally, I use a disposable nanofiber mask, and I consider it a better (e.g. safer) option. I'm not in a controlled cleanroom/hospital setting, and life happens. Masks do get reused, abused, rained on, and generally exposed to life. Nanofiber have much better durability.

I also supply chain. Amazon and eBay are rife with counterfeits. I like masks where I can order direct. Especially 3M tends to be mostly fakes, unless ordered through authorized distributors.

I distinguish on fit. In addition, a well-fitting 90% masks beats a poor-fitting 99% mask, since with a good fit, all the air goes through the mask. Order yourself a variety pack and see what's comfortable and fits.

The biggest thing you can do is limit yourself to settings where everyone uses reasonable precautions. All parties wearing KN95 masks, having reasonable social distancing, favoring outdoors, vaccinated if >12, etc. is pretty safe. If you have a mixture of extreme precautions and no precautions, everyone is at risk.

I’ve been wearing N95s since Day 1 and most clueful people who could get them were doing the same.

It means that cloth fabric does nothing against aerosol. Even N95 masks don’t filter out all virons which can be as small as 1nm and escape the electrostatic charge of the N95. Security theater.

No, this is misinterpretation and too absolute a conclusion. The truth is not found in extremes. Protection is about reducing viral load -- it is useful even without fully eliminating viral load. A cloth facemask does get damp when you breathe through it, ergo some of your exhaled water (= infection carrier) got caught. An N95 mask catches a lot more. You need a bit of viral load to get infected, so whatever reduces viral load will help.

It is dangerous to immediately conclude that aerosol transmission makes masks security theater. They do not, they do help a lot.

I had a hair on my phone, and I tried to blow it off while wearing an N95. Nothing. Even air itself is substantially slowed through an N95. It's the difference between sucking a viral load at full speed into your lungs, and having it crawl through a barrier at extremely low speed.

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