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Comment by panarky | Hacker News Reader

> The effectiveness of masks, however, is still under debate

Effective for the mask wearer, or effective for others in the vicinity of the mask wearer?

It's well established that cheap cloth masks and procedure masks don't protect the mask wearer very much.

The rationale for cheap masks is that they drastically reduce the spread of particles from the wearer to everyone else nearby.

If your goal is to protect yourself, wear an N95 or better.

If your goal is to protect a population, and N95s aren't available, then the cheap mask help a lot when people wear them.

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Except there is no convincing evidence that they actually do help others, and the whole theoretical mechanism is centered around catching large respiratory droplets which is at odd with the totality of evidence pointing towards aerosol being the dominant mode. I would add if droplet transmission is the dominant mode, which I very much doubt, then masks would still fail in a real-world setting when you look at the fact they make conversational partners stand closer or speak louder, and the massive cross contamination that happens to almost everybody wearing these pieces of cloth over their faces (hands touch mask, mask touches hands, etc)

People touch their faces all the time, mask or not. And some non-physical effects of masks may be useful. If nothing else, fumbling around with masks is repeated reminder for all other measures.

It may feel silly to wear a mask if you belief that this is the only effect. But you cannot deny that it is a causal effect, e.g. it would not happen without wearing the masks.

> no convincing evidence

This MIT study [0] was pretty convincing.

They conclude that "face masks can be an extremely effective indoor safety measure".

For example:

If an infected person was riding on a commercial airline with 100 other people, other passengers would be at risk of infection within 70 minutes. If all of the passengers wore masks, however, that space could be safe for up to 54 hours.

[0] https://www.pnas.org/content/118/17/e2018995118

Basically all convincing evidence for mask use is models (like the linked article) and in vitro unrealistic tests; whereas in real world data, the best I could find wrt covid is 2% reduction.

Bacteria are a different matter, and possibly other viruses. But real world data about covid is that masks make very little difference either way, and are possibly harmful.

How can a model be convincing if it hasn't been extensively tested in the real world?

The model of wearing masks has been extensively tested in Asia. Meanwhile US doctors were telling me that putting on a mask would actually cause you to get infected faster because you'd do it wrong. (Then the CDC announced mask orders the next day and they mumbled something about new evidence to me.)

And we can see who's done better in the last year.

It's looking more and more like a whole bunch of Asian countries just got lucky. Singapore, Taiwan and Vietnam have all currently got uncontrolled community spread again (possibly China too), and whilst the Taiwan outbreak could maybe be blamed on them getting sloppy Singapore has been aggressively enforcing mask wearing the whole time.

There was already good reason to suspect this was the case over a year ago too. The early outbreaks mostly seemed to be a gradient emanating outwards from Italy, with genetic testing suggesting that even the US had done reasonably well at halting spread from China and its big outbreaks came from Europe; Asia is obviously a long way from Italy and it was suspicious that a bunch of countries that in reality had widely varying policies on things like masks, testing, etc showed such similar results. Including countries like Australia and New Zealand that were more or less western in terms of culture but were geographically close to the rest.

I wear "n95" masks while sanding drywall, obviously trying to make the fit as good as possible, and still my boogers end up with tons of plaster in them. I would assume these particles to be bigger than any virion.

A properly fit N95 should block out all dust. If you are getting plaster in your nose, try different types of masks (folding), or a half-face respirator.

One of the justification for not advising N95s to the public was the fact that most people don't know how to properly wear one. As if they couldn't be trained in a few weeks, or duration of the pandemic.

Also, N95s filter out particles smaller than .3 microns (the 95% part). You can look it up, but it has something to do with the electrostatic media and physics. It definitely does not work like a sieve. (https://www.usatoday.com/story/news/factcheck/2020/06/11/fac...)

Actually it DOES work like a sieve on larger particles. The electrostatic mechanism works on smaller particles, while the larger ones are indeed filtered "mechanically".

The 0.3 micron size is used in the specification because it's the "worst" case... too large for maximum electrostatic attraction, too small for mechanical filtration...it's the worst case.

You are here talking specifically of N95 masks, not cloth masks, and this is only true for the very few that properly use masks. Doctors are required to not touch N95 mask and dispose of them after each use. Viruses can live for up to 24hrs on a mask and spread from you touching the mask then another surface.

Covid survives for 30 seconds in sunlight, so wearing a mask outside is bad on balance as you breathe in your own CO2 and reduce oxygen intake which both have negative health effects (especially during exercise).

Unless you have a valve, and hardly breath at all, exhaling pushes the N95 away from your face enough to let some unfiltered air in. There’s a similar (though smaller) effect with the thin paper valves, but regardless of how good the fit is, you need a much better valve than that to actually filter all air through the fabric.

Are there N95's without a valve? Cause all I've owned before the pandemic had a valve.

Yes.

I’ve had both with and without valves since 2015. Would never buy one without a valve again if I can find one with a valve (in the last year at some times could only find valveless)

Fwiw, in Israel it was illegal to use a valved mask without covering the valve with cloth/paper/surgical mask. The official statement was that the pressure out of the valve disperses virions much farther, and is thus more dangerous to people around you if you are presymptomatic than having no mask at all.

When wearing a mask in a hospital setting I had to have a fitting done. A test was run and a machine measured particles getting through. Properly fitted, nothing got though down to a very small size (which I don't recall).

An earlier version of the test saw some particle released into the room and a properly fitted mask wouldn't let it though. If people could smell the chemical, the fit was poor.

And I assume you were also trained in how to use the masks properly so that they didn't increase chance of virus spread and only used N95 masks? E.g. don't touch mask and dispose/clean the mask after each use.

Almost nobody does this, and many use cloth masks.

Yep, what most people forget when talking about N95 and similar is how a "standardized" fit test is performed, basically the 95% is theory and only IF the mask is properly fitted.

You will have deep signs on your face after wearing a fitted N95 a feww hours.

Previous posts with some more details and link to a US Department of labour video: https://news.ycombinator.com/item?id=27129984 https://news.ycombinator.com/item?id=23957506

> I would assume these particles to be bigger than any virion.

The masks aren't expected to stop individual virus particles. They are supposed to catch salivary droplets containing the virus.

These are probably bigger than particles of drywall dust.

> then the cheap mask help a lot when people wear them.

Are there any reliable and conclusive studies supporting this?

There are not even any reliable studies showing that surgical masks help during surgery. The problem with public health agencies is that, apparently, if they don't have an RCT they immediately jump to make the worst possible decisions. So try not to do the same thing.

> There are not even any reliable studies showing that surgical masks help during surgery.

That's fine, because I am not a surgeon and I don't care.

I do care about fogging up my glasses and having to speak up without any proper evidence that wearing a mask helps significantly against covid.

The kind with a bendable bar or tape at the top for your nose don't affect my glasses.

Anyway, you're going to run into the same problem doctors' advice has, where everything not required is forbidden. If a 100-year problem like a pandemic comes up, try some unproven precautions, it's better than not doing anything until it's mandated.

> The rationale for cheap masks is that they drastically reduce the spread of particles from the wearer to everyone else nearby.

If so, why does states with the highest mask use (CA, NYC) have much higher covid rates than states with some of the lowest mask use (Florida, Texas)?

> If so, why does states with the highest mask use (CA, NYC) have much higher covid rates than states with some of the lowest mask use (Florida, Texas)?

They...don’t (leaving out NYC because the other three things are large, diverse states and NYC is a single large city):

California 3.7M cumulative cases & 1,336 case/day current 7-day average vs. 39.5M population

Florida 2.3M cumulative cases & 3,007 case/day 7-day average vs 21.5M population.

Texas 2.9M cumulative case & 2,034 case/day current 7-day average vs. 29M population.

FL and TX are worse on per capita cumulative cases, and much worse on current per capita new cases than California.

(case numbers from usafacts.org)

Also consider age distribution/population density in areas you compare.

Death rate is exponential in age, so small differences in age distribution gives big differences in relative deaths.

Death rate to confirmed cases is TX 1.7% (51k deaths over 2.9m cases), Florida 1.56% (36k deaths over 2296 cases), CA 1.64% (62k deaths over 3.74m cases) [source: google coronovirus stats]. So data does not confirm your conclusion.

Without stats on the age distribution of confirmed cases (even before considering the absence of analysis of confounding factors, liking case timing within the pandemic, etc.), I’m not sure how you can say the data doesn’t confirm the conclusion since you don’t have data on the proposed independent variable at all.

Yes, age distribution matters as older people are at higher risk. As some signal for this Florida is USAs old people home, so you would expect that if masks had a large positive mitigatory effect then Florida with its low mask use would do worse than CA and NY that has low mask use. However, we do not see this.

> As some signal for this Florida is USAs old people home, so you would expect that if masks had a large positive mitigatory effect then Florida with its low mask use would do worse than CA and NY that has low mask use.

Again, this has a problem of failing to address case timing and distribution, with CA and NY being hard hit and having COVID into the community before there was much awareness or any policy response (e.g., targeted control measures directed at elder facilities) or personal behavior response or evolution in treatment protocols, which radically changes the dynamic vs. states that weren't hit until after public awareness and health care competence was more advannced.

And presumbaly, you mean “CA and NY with high mask use”, otherwise this argument is nonsense. OTOH, no one has cited any data supporting the “CA and NY are representative of high mask use states while FL (and TX, as claimed in other posts) are representative of low mask use” argument, which seems to be based on stereotyping based on dominant political parties in each state and leanings of political leaders of each party on mask mandates. What data there is on this doesn’t seem to support that this stereotyping accurately reflects mask use, OTOH; i.e., a study on mask use with self-reported data for May through August of last year had mask use as:

AUG: CA 74.6% > FL 71.6% > NY 69.6% > TX 69.1%

JUL: NY 80.6% > CA 74.3% > FL 66.9% > TX 66%

JUN: NY 56.4% > CA 48.7% > FL 45.1% > TX 42.4%

MAY: NY 46.1% > CA 45.2% > TX 43.8% > FL 43.5%

APR: CA 38.1% > NY 36.1% > FL 35.0% > TX 32.4%

And, notably, all four states were in the top half of the country in mask use in all 5 months with data.

https://journals.plos.org/plosone/article?id=10.1371/journal...

I tend to trust state policy and political leanings more as an indicator then a self reported study. Can you please dig into why you trust this self reported study on the politically charged mask use question? Especially when the study is performed by academics that is perceived to be too often left-wing activists by republicans and many libertarians? (And according to Haidt have a provably largely left leaning bias)

Self reported results are prone to preference falsification and hidden bias in whom answers. (“Yes, mom, I did my homework” ;) )

Self reported results of politically charged questions are effectively polls. To indicate the problem you can observed how inaccurate polls around politically charged choices has become when compared to actual choices.

The normal problems with self reported results are probably aggravated by how academics, major authorities, media, and tech companies have openly without cover used force to promote the “right” answer and suppressed the “wrong”. The use of force to enforce specific conclusions had been an extraordinary and very noticeable break from western traditions.

> I tend to trust state policy and political leanings more as an indicator then a self reported study.

I don’t, in the absence of strong enforcement of policy (which did not exist in, e g., California COVID policy), especially on issues of strong partisan posturing; even solid red or blue states tend to be pretty closely balanced in the population; majoritarianism, reinforced by gerrymandering and related mechanisms, produces strong and durable political dominance from slight population imbalances, so “state dominant party” stereotypes and state policy vastly exaggerate differences in distribution of individual belief, preference, and, in the absence of effective compulsion, behavior.

> To indicate the problem you can observed how inaccurate polls around politically charged choices has become when compared to actual choices.

They...haven’t, really, become particularly inaccurate. Poll-based predictions of binary outcomes of things that poll very close to even have become somewhat less reliable than they very briefly were before (they were a fairly new practice compared to just reporting polls without predictions, anyway, so its not like there was a well-established baseline) because when polls are near even, very slight changes in accuracy have an outsize effect on binary predictions.

NY (not NYC) cumulative cases is 2m and population is 19.4m, so about 10.3% of population [source: google coronavius stats].

> California 3.7M cumulative cases & 1,336 case/day current 7-day average vs. 39.5M population

Its 3.77M, so about 9.5% of population.

> Texas 2.9M cumulative case & 2,034 case/day current 7-day average vs. 29M population.

That's 10%.

> Florida 2.3M cumulative cases & 3,007 case/day 7-day average vs 21.5M population.

That's about 10.6%.

> FL and TX are worse on per capita cumulative cases, and much worse on current per capita new cases than California.

With the total cases being about the same so this does not support your conclusion that masks "drastically reduce spread".

> With the total cases being about the same so this does not support your conclusion

I didn’t offer any conclusion except that the upthread claim that California had a much higher rate of COVID cases than FL/TX was bunk. To actually tease out the effects of mask use from jurisdictional case statistics, you’d also have to (1) have stats on mask use, which (despite people making claims about it in coordination with blatantly false claims about cases), I haven’t seen, and (2) have good stats for the other things that would reasonably be expected to contribute to differences in infection spread, (3) either have enough a priori knowledge of the contribution of the items in 2 to control for their effect in 1:1 comparisons, or have data from enough different places to do an analysis that determines the contributions of different factors.

Even with good mask stats, a head to head comparison of a couple states case numbers with mask stats wouldn’t otherwise be useful for anything.

>To actually tease out the effects of mask use from jurisdictional case statistics, you’d also have to (1) have stats on mask use, which (despite people making claims about it in coordination with blatantly false claims about cases), I haven’t seen, and (2) have good stats for the other things that would reasonably be expected to contribute to differences in infection spread, (3) either have enough a priori knowledge of the contribution of the items in 2 to control for their effect in 1:1 comparisons, or have data from enough different places to do an analysis that determines the contributions of different factors.

Absolutely, 100% with you. And effectiveness of a mitigation should be determined before mandating it, and the positives and negatives of the mitigation should be well understood.

> I didn’t offer any conclusion except that the upthread claim that California had a much higher rate of COVID cases than FL/TX was bunk.

I was responding to the parents claim that masks “ drastically reduce the spread” which I think I’ve showed is an unsupported claim, although I stated my initial claim too strongly. There is no significant observable effect on state covid case count or state death to confirmed case count (which would to some degree control for some differences in testing).

> Even with good mask stats, a head to head comparison of a couple states case numbers with mask stats wouldn’t otherwise be useful for anything.

After one year of mandating this mitigation we should be able to see some observable difference to continue mandating that people cover their faces. This is not zero-cost, especially for the ones living alone, as the masks block facial expressions showing emotion and the masks make it harder to breathe which can on aggregate cause health issues. For instance, a large number of dental issues is caused by mask use [1].

[1] https://fineartsdentistry.com/how-face-masks-are-affecting-o...

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