OT: Face masks do seem to be a worthwhile defense agaisnt Covid-19

Today's edition of the Proceedings of the (US) National Academy of Science had an interesting paper on the subject.

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Face masks do seem to help slow the spread of the disease. They are only part of the solution, but do seem to help enough be worth the effort.

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Bill Sloman, Sydney
Reply to
Bill Sloman
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e had an interesting paper on the subject.

part of the solution, but do seem to help enough be worth the effort.

Yes, it's pretty obvious. One of the posters here from Norway talks about the trust in the Norwegian politicians so that the populace listens to thei r advice resulting in low infection rates and low death counts.

In the US there seem to be a fair number of people who don't think masks an d distance are important. I think a lot of people here are getting "accust omed" to living with the virus and the improving numbers make them feel les s vulnerable. So now our infection rates are turning around and the death rates in many states are increasing as well.

The federal government can only do so much since it is the local government s that need to do contact tracing and impose quarantines. The few, but imp ortant things the federal government could do were not done or not done wel l or not done until it was too late. A perfect example is the way Trump an d Pence refused to wear masks in public settings, even when EVERYONE else w as wearing them. Now, finally when the infection is bad enough that Pence is genuinely concerned about his personal safety we find him wearing a mask and recommending that others do it. I guess he hadn't heard that masks we re a good idea until just now. I have to blame that on Fauci. Bad Fauci!

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  Rick C. 

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Reply to
Ricketty C

It isn't really so surprising.

Cultures like the Far East where a face mask is commonly worn when you have a cold (but still go to work) had a much slower rise in infections.

Conversely continental cultures where the common greeting is to hug and kiss on both cheeks had an extremely rapid rate of transmission.

Stopping shaking hands was about the first sign in the West that things were changing. Even CEOs of pharma companies found it hard to stop greeting visitors this way. Several unshaken hands proffered at various meetings I am aware of in the period immediately prior to UK lockdown.

Where things go wrong with public using face mask PPE is that they don't treat them with respect and put them down in places and in ways where the inner safe side gets contaminated by the environment or their hands.

PPE is a double edged sword - used incorrectly it can provide the illusion of safety but without the benefit. Mostly wearing a mask prevents those who are actively shedding virus from contaminating quite so much of the environment around them. Definitely a benefit to society in reducing transmission but not necessarily for the careless wearer.

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Regards, 
Martin Brown
Reply to
Martin Brown

Of course. They always have been. It's "common sense", but that has been substantially lacking in our UK government's scientific advisers for months. Their extraordinarily negative, and inaccurate, comments in early March about the effectiveness of masks will indirectly have been responsible for thousands of infections. But will they admit they got it wrong? How strange that a few weeks ago they made wearing "face coverings" compulsory for public transport!

I researched this in February and early March; there was enough info online to confirm that it made sense to wear a mask. Have a look at this page, and note the date of the article: .

Yes, it's a commercial business selling masks, but they reference the information they provide. There were other papers around that time referring to the effectiveness of N95/P3 masks in remove flu virus particles.

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Jeff
Reply to
Jeff Layman

That would be me. (The trust is not complete, of course, and we currently have too many people, especially young adults, ignoring the distancing rules.)

Our current case rate is too low for face masks to be of any relevance (except, of course, if you are in quarantine, at higher risk of getting infected, or in contact with vulnerable people). So we don't have any general requirements for face masks.

When your numbers are as high as they are in some parts of the USA at the moment, there is a significant chance for someone to have the virus without knowing it - and thus face masks are important to help protect other people.

Social distancing and hygiene are always important - they protect /you/ as well as protecting others in case you have the virus and don't know it. They are vital to keeping our numbers low.

Yes. A proportion of people here (again, mainly teenagers and young adults - the most irresponsible age groups) feel the epidemic is over in this country and they can party and socialise as before. While it is true that there is almost no virus here (we are at 3 cases per day per million people), it is not over - and it is social distancing that keeps the numbers low.

People everywhere are - naturally enough - getting fed up with the whole thing, and it is harder to motivate them to keep fighting this pandemic. Once they see some optimistic figures (like the lower death rates in the USA), they pounce on that as a sign of relief and a return to normality.

One thing that seems hard for most people to understand is how precautions work if they don't have something to compare it to. You can look at figures of road deaths before seat belts were commonly used, and figures afterwards, and understand that seat belts prevent death. But if a Norwegian looks at the virus figures in this country, it's very easy to think there wasn't really a big problem, it's all a panic for nothing and all the restrictions were unnecessary because very few people got ill and died. (People had that reaction to mass vaccinations for the swine flu, or all the fuss about Y2K problems.) Without the before and after comparisons, it's hard to understand that it is only because of the restrictions that the pandemic numbers are not higher. (I guess Norway is lucky that we can look to our neighbour Sweden, and see what you get when you don't follow the rules.)

Another difference between the countries is the social security. In Norway, if you think you might possibly have a symptom of Covid, or might have been in contact with someone who has it, you can (and should) self-isolate without risk to your job or your economy. In the USA, there is much more pressure to turn up to work until it is proven that you are too ill to do the job - or you risk losing that job, your house, your health insurance.

A country's leaders are supposed to set a good example. The USA and the UK (not Scotland) seem to have trouble with that concept.

Reply to
David Brown

I have never seen anyone take off a mask and put it down in that way. Some might take it off by grabbing the front and pulling, but that is more likely to contaminate their hand than the other way round. The problem then is that they /might/ rub their face once the mask is off. The solution? Make it clear people should only take off their mask when they have finished with it, discard it in a bin, and immediately wash their hands.

On the TV news I have seen pictures of people incorrectly wearing masks, but have never seen this when out in the street. They are either not wearing masks or wearing them correctly. I also doubt anyone (other than see the ref in my reply to the OP) has checked how much masks could help prevent infection to the wearer. I don't have any evidence, but although it is true that masks help prevent the outward passage of particles, I believe that the repetitive mantra of lack of prevention for incoming particles has been overdone from the start.

The simple message is that masks or facial coverings of any sort outside the home should have been compulsory from the start. That a few people don't wear them correctly is *their* problem. Just because a few people don't wear seat belts in cars is no reason to say they don't work, so there is no need for /anyone/ to wear them.

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Jeff
Reply to
Jeff Layman

Many of the masks in circulation now are hand made sewn things that neither fit particularly well nor are comfortable to wear. I'd guess no more than 2% of the people on the streets round here are wearing them.

People are forever fiddling with them. I haven't been on public transport since the lockdown began. Most buses I pass are empty.

I have been watching people whilst queuing for the supermarket. The number sucking a finger whilst on their mobile phone or rubbing their eyes without a second thought is quite staggering.

I guess coming from a dangerous chemicals background I am rather sensitive the the risk of touching your face with contaminated hands.

I do have a mask that I would protect me from the virus when combined with the right filter cartridge - a full face respirator that has been fitted to my face with the peardrops test and then CS gas trial. So I that have confidence that it will keep me safe in truly hostile chemical environments. My wife isn't keen for me to wear it in public though...

I think it is a bit more nuanced than that. They were afraid that encouraging everyone to wear masks early on would deprive the NHS staff who really *need* the right PPE to do their job of resources. They were probably right about that since the procurement of junk PPE kit that didn't work was the highest profile historic UK failure early on. Flown in with great fanfare from Turkey and then shown to be worthless tat.

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Regards, 
Martin Brown
Reply to
Martin Brown

...

That matches what I see.

I wear a cheap and nasty mask when shopping for three reasons: - to remind people that there is still a problem (probably ineffective, but worth trying) - to provide some protection to other people (marginal help in that situation) - to remind me not to rub eyes, pick my nose, suck my thumb etc (invaluable :) )

Reply to
Tom Gardner

Every little helps. Quite why our feckless, inept and reckless government hasn't mandated this I don't know. Oh, wait, I've just explained why!

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Cheers 
Clive
Reply to
Clive Arthur

Originally it was probably because they had run down the supplies of PPE (cost cutting or maximising value (sic)), and there wasn't enough even for front-line medics that /really/ needed it.

Nowadays your explanation is probably sufficient. Must have that feelgood factor to revitalise the economy, mustn't we.

Besides, can you see Cummings wearing a mask, except to escape the hoards baying for his blood? (BoJo? Who he?)

Reply to
Tom Gardner

How would that have worked? Where would you get one? I was told the other day that the type of mask I have (only because I worked on making a Greenl and paddle out of cedar) should be tossed after wearing it for 8 hours! Ev en now I don't know that I could find another one with any confidence of it s quality.

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  Rick C. 

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Reply to
Ricketty C

That argument seems to be misunderstanding the purpose of the face masks. Their use for the general population is to reduce the risk of the wearer spreading the disease, not to reduce the risk of /getting/ it.

You don't need a quality face mask. You need one that covers your mouth and nose and significantly reduces the droplets that come out when you breath, cough or sneeze. By reducing the quantity and the speed of the droplets, it greatly reduces the amount of virus particles you spread if you have the disease.

A buff or scarf is fine for the job. So are home-made masks made of cloth folded over appropriately. You wear them when you are out amongst other people, which should be for as short a time as possible, and wash them regularly.

Paper masks, such as used for dust protection, aren't great over time - they'll get soggy, ineffective and uncomfortable. Because they deteriorate with dampness they always have a limited lifetime (whether used as dust masks or as Covid masks).

You are not looking for something that guarantees blocking the virus, either in or out. You are looking for something that gives a solid reduction in the risk of spreading it.

Reply to
David Brown

For those reasons face masks with vents are, at best, of dubious value. At worst they could spread the droplets in a jet in one direction.

Reply to
Tom Gardner

That's more-or-less the point. Nothing short of a full-body NBC suit will /guarantee/ protection against a virus. You are just trying to reduce your chances of infection. If you want to help cut down incoming particles, you could do a *lot* worse than a folded cloth mask which has a cut-off piece of vacuum-cleaner bag (preferably HEPA-rated) inside it. At the end of the day throw away the piece of bag and wash the cloth. What else could be more simple and effective?

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Jeff
Reply to
Jeff Layman

They were in an impossible position. If they had said wear masks back then hoarding would have made the PPE situation for medics even worse. Hell the hoarders are back at loo rolls and dried pasta again even now!

At close quarters I think it makes a difference both ways around. I have lived in Japan where such masks when travelling out and about whilst infective with a cold are commonplace and have been since the 1980's.

It was noticeable how shallow their infection curve was from the outset although it could be partly explained by honne vs tatemae versions of the truth when they were still hoping the 2020 Olympics would go ahead.

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There are all sorts of businesses jumping on the filters and masks bandwagon. Colloidal silver advocates and graphene amongst them.

It is a bit misleading too. You don't need to stop individual virus particles to make a substantial difference to the infectivity. It is stopping fine aerosol particles with a few hundred or thousand virus particles in them that really makes the difference.

Most of the gain from wearing a mask is preventing the wearer spreading their infection and any benefit the wearer gets is a mere side effect.

Although in theory a single virus could get lucky and infect you it is a probabilistic numbers game and our immune system can generally see off a fair proportion of invaders. But if just one gets through then...

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Regards, 
Martin Brown
Reply to
Martin Brown

I tried to explain to people that nothing we do will assure even 99% that w e won't get the virus. The whole 6 foot rule and wearing masks and everyth ing else we do other than staying at home only reduces the spread of the di sease so that the disease infects fewer people rather than increasing every day.

I realize that people are tired of treating the world like we are in the Bl ack Plague. I am too. But going out to buy groceries is one thing, spendi ng the weekend mingling with the world at large is another. I had to run u p to Maryland and stopped to visit a friend. We had dinner outside with pl enty of space around us. While dining we watched so many people go by with out masks and obviously not worrying about spreading or catching the virus.

It's hard to keep focused on the goal. That's why it is important to have leaders who provide direction and support, rather than pretending this dise ase will magically disappear.

I wish we didn't have to wait until January to get a new cleaning crew in. This one certainly is not up to the job. I really don't know if we can la st that long in this country.

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  Rick C. 

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Reply to
Ricketty C

No need to toss it or wash it unless it is disgusting. Have two and alternate. 24 hours of sitting should be enough time for the viruses to have become inactive.

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  Rick C. 

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Reply to
Ricketty C

Just to add that the term officially prefered here is 'face covering' to distinguish from a 'proper' mask, though of course most people use the shorter word.

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Cheers 
Clive
Reply to
Clive Arthur

The face masks for general population are not about protection from the virus. They are not there to cut down on incoming particles. You wear them to reduce /outgoing/ particles. They are not for /your/ protection from others - they are to protect others from /you/.

I don't know if it is possible to make that point any clearer, but it seems to have escaped you so far.

Reply to
David Brown

Washing& drying is helpful, so is exposure to microwave or infrared heat to raise the temperature above some small threshold and also evaporate any moisture at the same time which can incubate bacterial growth.

Activated Carbon filters work better in combination as long as the restrictive pressure is not excessive for weak lung diaphragms by having a fan-folded filter or high-quality vent.

Like any RLC filter, the attenuation depends on the stray leakage, spectral impedance and passthru of certain particle wavelengths.

Reply to
Tony Stewart

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