Effective re-usable face-masks

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Effective re-usable face-masks

Post by Pucksoppet » Sun Apr 05, 2020 7:31 pm

Has anyone come up with a design that:

(a) Meets a formal standard for filtering their air (like N95, but less stringent, perhaps)
(b) Can be machine-washed a reasonable number of times to sanitise the mask to an acceptable level

There is a somewhat equivocal Cochrane review of the use of surgical masks for preventing wound infection during surgery:

Disposable surgical face masks for preventing surgical wound infection in clean surgery
Cochrane Systematic Review - Intervention Version published: 26 April 2016
https://doi.org/10.1002/14651858.CD002929.pub3


Of course, that's very different from preventing transmission of SARS-CoV-2

There is also this review:

Clinical Review State of the Art Review
Facemasks for the prevention of infection in healthcare and community settings
BMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h694 (Published 09 April 2015) Cite this as: BMJ 2015;350:h694


I can understand that the CDC recommendation may well be a source-control recommendation - masks are not there to stop you from being infected by others, but to help prevent an apparently symptomless you infecting others.

I'm a bit concerned that people will get hung up on wearing a mask, when hand hygiene is known to be extremely important.
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Re: Effective re-usable face-masks

Post by Pucksoppet » Sun Apr 05, 2020 8:16 pm

Just to point to three things:

1) CDC advice
CDC: Use of Cloth Face Coverings to Help Slow the Spread of COVID-19
CDC: Recommendation Regarding the Use of Cloth Face Coverings, Especially in Areas of Significant Community-Based Transmission
CDC: Cloth Face Coverings: Questions and Answers

2) A supplier of reusable face masks: https://reusablefacemasks.com/breathe-h ... ifications

3) Two Israeli companies looking to produce reusable masks
- one that claims "(Anti-bacterial) Effectiveness lasts for up to 100 washes at 75°C (167°F) or 65 washes at 92°C (197°F)".
- the other claims "An independent lab found that CottonX remains effective against Staph and E. coli bacteria for 50 industrial washings or 100 home washings."
Both point out their masks have not been tested with SAR-CoV-2
https://www.israel21c.org/new-antiviral ... dly-virus/

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Re: Effective re-usable face-masks

Post by dyqik » Mon Apr 06, 2020 1:26 am

Er, antibacterial properties don't seem particularly relevant to a virus.

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Re: Effective re-usable face-masks

Post by Pucksoppet » Mon Apr 06, 2020 8:59 am

dyqik wrote:
Mon Apr 06, 2020 1:26 am
Er, antibacterial properties don't seem particularly relevant to a virus.
Which is why I pointed that out. I didn't want people to get the wrong impression that the stated effectiveness was anti-viral. I should have been clearer. Sorry.

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Re: Effective re-usable face-masks

Post by Squeak » Mon Apr 06, 2020 1:21 pm

I am interested to see whether cloth masks are actually effective for broad public use. My sister has been training her hospital's staff on PPE for COVID and she's pretty adamant that masks are somewhere between a waste of effort and an additional danger to non-medical folks, given how much more they make you want to touch your face and the limited amount of aerosolisation that covid seems prompt outside actively sick patients. She gets quite energetic about the challenges of getting even experienced healthcare workers to put masks on and off safely and to Stop Fiddling With Them.

We obviously don't have much evidence yet on how aerosolised covid tends to get and I can well imagine that studies of mask effectiveness are strongly affected by material, fit, and behaviour of the people wearing the masks. Has anyone seen papers that deal with fabric mask wearing in uncontrolled settings?

I'm not too stressed if they're merely useless (and it would obviously be great if they genuinely help) but if they either act as an additional source of contamination/face touching or they encourage people to be slack about social distancing, that's a bit of a worry.

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Re: Effective re-usable face-masks

Post by jimbob » Mon Apr 06, 2020 7:07 pm

Squeak wrote:
Mon Apr 06, 2020 1:21 pm
I am interested to see whether cloth masks are actually effective for broad public use. My sister has been training her hospital's staff on PPE for COVID and she's pretty adamant that masks are somewhere between a waste of effort and an additional danger to non-medical folks, given how much more they make you want to touch your face and the limited amount of aerosolisation that covid seems prompt outside actively sick patients. She gets quite energetic about the challenges of getting even experienced healthcare workers to put masks on and off safely and to Stop Fiddling With Them.

We obviously don't have much evidence yet on how aerosolised covid tends to get and I can well imagine that studies of mask effectiveness are strongly affected by material, fit, and behaviour of the people wearing the masks. Has anyone seen papers that deal with fabric mask wearing in uncontrolled settings?

I'm not too stressed if they're merely useless (and it would obviously be great if they genuinely help) but if they either act as an additional source of contamination/face touching or they encourage people to be slack about social distancing, that's a bit of a worry.
I've worn masks on occasion in my infrequent visits to our cleanroom. They are very distracting. Just as the visors in the chemical lab make me appreciate how much I really want to scratch my nose or rub my eyes. I'd hate to wear them longer than the maybe half-hour periods at any one time.
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Re: Effective re-usable face-masks

Post by Squeak » Mon Apr 06, 2020 10:05 pm

I'm completely useless at wearing dustmasks when I'm sanding timber and they've always got dusty on the inside too. Probably due to a combination of my crap technique and my face not meeting the assumptions of shape that the manufacturers assume.

I'm genuinely wondering whether the sudden enthusiasm for public mask-wearing will increase the risks.

However, if someone can show that they make a genuine safety improvement in a public setting, I'll get sewing for my family and friends and anyone else I can find who needs one. It would be quite nice to have a Useful Thing To Do.

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Re: Effective re-usable face-masks

Post by dyqik » Mon Apr 06, 2020 10:09 pm

Squeak wrote:
Mon Apr 06, 2020 10:05 pm
I'm completely useless at wearing dustmasks when I'm sanding timber and they've always got dusty on the inside too. Probably due to a combination of my crap technique and my face not meeting the assumptions of shape that the manufacturers assume.

I'm genuinely wondering whether the sudden enthusiasm for public mask-wearing will increase the risks.

However, if someone can show that they make a genuine safety improvement in a public setting, I'll get sewing for my family and friends and anyone else I can find who needs one. It would be quite nice to have a Useful Thing To Do.
MikeH shared a rapid review that shows they they have little to no effect, and should not be recommended if that will lead to any reduction in availability for healthcare workers.

https://www.medrxiv.org/content/10.1101 ... 20049528v1

But if others think you should be wearing them, then it's probably a good idea to. A safety improvement might come from not getting the backs of less informed members of the public up..

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Re: Effective re-usable face-masks

Post by EACLucifer » Tue Apr 07, 2020 8:13 am

I note the study MikeH posted focusses on the reduction in risk of catching it, whereas much of the argument for public mask wearing is about preventing those infected spreading it, or rather, reducing the rate at which they do so. Actual surgical masks look to have a pretty significant effect on viral shedding

Respiratory virus shedding in exhaled breath and efficacy of face masks

On the pro-mask side of things, I found this relatively persuasive, however, I have not been able to access all the sources used re: efficacy of cloth masks. The key here is not about protecting individuals from catching it, it is a community wide intervention to reduce transmission rates.

The Case for Universal Cloth Mask Adoption &Policies to Increase the Supply of Medical Masks for Health WorkersApril 1 2020

As for face touching, etc, a cloth mask is a radically different beast to the sort of cheap dust mask used for DIY. I test wore the first one I made for several hours without incident, and if anything it served as a reminder not to touch my face, not a reason to do so. One can compare and contrast with the British Government's preferred approach - pushing the use of tissues via "Catch it, Bin it, Kill it" messaging, which seem much more likely to encourage face touching, and spread of droplets from infected people's mouths and noses to their hands, and thence to doorhandles etc.

As for people forgetting social distancing, masks are at least potentially a damn good reminder things are not normal, and should thus act accordingly.

Any effort to promote community wide mask wearing must be done carefully. Emphasis needs to be placed on protection of supply for healthcare and other key workers, and it must be made clear that masks are an adjunct to other methods, not a substitute. That said, community mass mask wearing based on - initially at least - washable cloth masks is one more tool we can bring to bear to slow transmission, and as it is not a costly intervention, nor one in conflict with any other, it probably ought to be promoted.

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Re: Effective re-usable face-masks

Post by MartinDurkin » Tue Apr 07, 2020 8:22 am


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Re: Effective re-usable face-masks

Post by shpalman » Tue Apr 07, 2020 8:38 am

EACLucifer wrote:
Tue Apr 07, 2020 8:13 am
I note the study MikeH posted focusses on the reduction in risk of catching it, whereas much of the argument for public mask wearing is about preventing those infected spreading it, or rather, reducing the rate at which they do so. Actual surgical masks look to have a pretty significant effect on viral shedding

Respiratory virus shedding in exhaled breath and efficacy of face masks

On the pro-mask side of things, I found this relatively persuasive, however, I have not been able to access all the sources used re: efficacy of cloth masks. The key here is not about protecting individuals from catching it, it is a community wide intervention to reduce transmission rates.

The Case for Universal Cloth Mask Adoption &Policies to Increase the Supply of Medical Masks for Health WorkersApril 1 2020

As for face touching, etc, a cloth mask is a radically different beast to the sort of cheap dust mask used for DIY. I test wore the first one I made for several hours without incident, and if anything it served as a reminder not to touch my face, not a reason to do so.
I don't know if you'll be able to see this post on my facebook featuring the mayor of Rapallo, who made masks mandatory for everyone in his city a few days before the Lombardy-wide decree (which Tuscany has now joined in with).

Last week when I went to the supermarket most people were already wearing some sort of mask anyway.

EACL's point about viral shedding is the important one - working on the hypothesis that there are 10 times more incubating/mild/asymptomatic cases in the population as compared to the official numbers (as much true of the UK as of Italy, given the infection curve and the CFR) means that everyone personally has to behave as if they are infectious and everyone around them is susceptible.

I note the difference between a usual surgical mask, which is indeed mainly intended to avoid that a medical professional spits bacteria into a patient, and the kind of PPE required by medical professionals trying to avoid contracting pathogens from highly infectious patients. Most of us when we go outside will not require the latter because we will not be surrounded by a high viral load all day every day.

ETA: getting the f.cking url for my own f.cking facebook post is a f.cking pain in the arse.
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Re: Effective re-usable face-masks

Post by Gfamily » Tue Apr 07, 2020 9:00 am

On my phone, so I can't find a link to it, but I've seen a Cochrane paper based on behaviours in Korea during either the SARS or the MERS epidemic, which found that the most significant correlation with not getting infected was the use of a mask.

I started out being sceptical of 'masks as infection preventers' but now I'm not so sure.
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Re: Effective re-usable face-masks

Post by shpalman » Tue Apr 07, 2020 9:29 am

The Chinese medical professionals who arrived in Lombardy immediately asked "why are there still so many people outside?" and "why aren't they all wearing masks?"
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Re: Effective re-usable face-masks

Post by Gfamily » Tue Apr 07, 2020 9:59 am

Gfamily wrote:
Tue Apr 07, 2020 9:00 am
On my phone, so I can't find a link to it, but I've seen a Cochrane paper based on behaviours in Korea during either the SARS or the MERS epidemic, which found that the most significant correlation with not getting infected was the use of a mask.

I started out being sceptical of 'masks as infection preventers' but now I'm not so sure.
Back on laptop
Here's the Cochrane Review
Physical interventions to interrupt or reduce the spread of respiratory viruses
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Re: Effective re-usable face-masks

Post by EACLucifer » Tue Apr 07, 2020 2:19 pm


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Re: Effective re-usable face-masks

Post by raven » Tue Apr 07, 2020 10:00 pm

That guide is really good, EACLucifer.
shpalman wrote:
Tue Apr 07, 2020 8:38 am
I don't know if you'll be able to see this post on my facebook featuring the mayor of Rapallo
Watching that, it struck me that masks don't fit well on the noble Roman nose. He needs one of those nose clips people used to wear for swimming to peg it to his hooter, then he wouldn't need to keep adjusting it.

I'd probably need one too.

ETA: Hayfever season is almost upon us. I sneeze quite a bit with mine, so perhaps I should start thinking about a washable mask just in case I'm contagious at some point.

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Re: Effective re-usable face-masks

Post by Millennie Al » Thu Apr 09, 2020 3:22 am

dyqik wrote:
Mon Apr 06, 2020 10:09 pm
MikeH shared a rapid review that shows they they have little to no effect, and should not be recommended if that will lead to any reduction in availability for healthcare workers.

https://www.medrxiv.org/content/10.1101 ... 20049528v1

But if others think you should be wearing them, then it's probably a good idea to. A safety improvement might come from not getting the backs of less informed members of the public up..
That study suggests that wearing a mask does very little to prevent you getting infected, but having the infectious person wear a mask does help (when sharing a house - so very prolonged exposure).

This: Respiratory virus shedding in exhaled breath and efficacy of face masks suggests that it is well worth while for an infectious person to wear a mask to protect others against coronavirus or flu, but not rhinovirus (possibly because rhinoviruses are smaller). TNo coronavirus or flu was detected in the 30-minute detection period for mask wearers. It also found:
Among the samples collected without a face mask, we found that the majority of participants with influenza virus and coronavirus infection did not shed detectable virus in respiratory droplets or aerosols,
which is very interesting as infection was verified by nasal and throat swabs. It seems odd that people are exhaling through an infected airway and not spreading infection. Maybe people vary in their potential to infect others, or maybe it's mainly due to some action (such as coughing or speaking) which might not have occured for some participants in the observation period.

Of course currently there is a desperate shortage of PPE, so it's probably much better to reserve supplies for medics who are at much higher risk than the general population.
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Re: Effective re-usable face-masks

Post by Squeak » Thu Apr 09, 2020 7:56 am

Thanks for all those papers. It looks as though there's a clear benefit to mask wearing in a home with a sick person, and for the sick person to wear one while unavoidably out and about (hopefully they're out to get medical help rather than to pop to the shops). And I note that these articles are about various kinds of surgical masks, rather than fabric ones. Which is about what my understanding was before.

So, I'll continue to be dubious about the additional benefits of cloth masks for people following social distancing guidelines. There will presumably be at least some reduction in the number of droplets/aerosols hitting the air from a given sneeze. But I'll also acknowledge that I'm approaching this from a very privileged position in a currently low-risk community and with good health. I could see it being very tempting to do *something* that feels protective, even where the evidence is weak. I just hope that everyone going down that path is doing a good job of washing their masks regularly and keeping their hands busy with something other than said mask.

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Re: Effective re-usable face-masks

Post by Brightonian » Thu Apr 09, 2020 8:00 am

EACLucifer wrote:
Tue Apr 07, 2020 8:13 am
As for people forgetting social distancing, masks are at least potentially a damn good reminder things are not normal, and should thus act accordingly.
Out for a rare walk yesterday, most people were unmasked, including one chap with his shopping bags wheezing across the road directly towards me and I had to take evasive action sharpish so I want to have a mask if only to nudge others into shame.

Hence today I will be trying to follow yours and/or others' instructions on mask-making (am not handy at this sort of thing, so many t-shirts and pillowcases may die in vain).

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Re: Effective re-usable face-masks

Post by Pucksoppet » Thu Apr 09, 2020 8:53 am

EACLucifer wrote:
Tue Apr 07, 2020 8:13 am
As for people forgetting social distancing, masks are at least potentially a damn good reminder things are not normal, and should thus act accordingly.
Would you believe there's an XKCD for that?

Homemade Masks

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Re: Effective re-usable face-masks

Post by Pucksoppet » Thu Apr 09, 2020 1:50 pm

Interesting article on the use of masks, and the disagreement amongst experts over at ScienceAlert:

ScienceAlert: Should We All Be Wearing Face Masks? Here's Why Experts Are So Conflicted PAUL GLASZIOU & CHRIS DEL MAR, THE CONVERSATION 9 APRIL 2020
Should members of the public be wearing face masks during the COVID-19 pandemic? It's a controversial question, with different countries and authorities giving different advice.

We have reviewed the results of more than a dozen randomised trials of face masks and transmission of respiratory illnesses. We found the current best evidence suggests wearing a mask to avoid viral respiratory infections such as COVID-19 offers minimal protection, if any.
...
A recent Hong Kong laboratory study found some evidence masks may prevent the spread of viruses from the wearer.
...
Mask wearing for the possibly infected, to prevent spreading the infection, warrants rigorous and rapid investigation. It could be an alternative or a supplement to social distancing, hand hygiene, testing, and lockdowns.

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Re: Effective re-usable face-masks

Post by dyqik » Thu Apr 09, 2020 2:33 pm

Pucksoppet wrote:
Thu Apr 09, 2020 8:53 am
EACLucifer wrote:
Tue Apr 07, 2020 8:13 am
As for people forgetting social distancing, masks are at least potentially a damn good reminder things are not normal, and should thus act accordingly.
Would you believe there's an XKCD for that?

Homemade Masks
This is pretty much my take on it as well. The non-medical grade masks make a marginal, but useful difference to spreading from yourself to others, and are a good indicator for what the other person wearing them would like you to do re: distancing, precautions etc.

So to the extent that home-made masks are not reducing availability to healthcare professionals, they are useful as part of social distancing etc. and are probably helping people manage anxiety and social cues etc. I'll wear one in enclosed spaces like shops when my wife has finished sewing them, but for walking in the nearly empty woods, I won't bother.

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Re: Effective re-usable face-masks

Post by Bird on a Fire » Thu Apr 09, 2020 3:03 pm

I have a couple of buffs that I can use to cover my nose and mouth, but they do get a bit warm. I might start using them though.

Yesterday a neighbour's kid was chatting to me at close range, and they definitely haven't been isolating effectively - the whole family is always sat out in the street all day, even though they've got a courtyard, and some of them have been off caravanning.
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Re: Effective re-usable face-masks

Post by EACLucifer » Thu Apr 09, 2020 4:37 pm

Squeak wrote:
Thu Apr 09, 2020 7:56 am
Thanks for all those papers. It looks as though there's a clear benefit to mask wearing in a home with a sick person, and for the sick person to wear one while unavoidably out and about (hopefully they're out to get medical help rather than to pop to the shops). And I note that these articles are about various kinds of surgical masks, rather than fabric ones. Which is about what my understanding was before.
I posted an article talking largely about cloth masks, actually.

"We estimate that the benefits of each additional cloth maskworn by the public are conservatively in the $3,000-$6,000 range due to their impact in slowing the spread of the virus"

Meanwhile, using the same model for weighing up the value of different interventions, they were reckoning the value of an N95 on a frontline healthcare worker as in the region of a million dollars.

The study they cited for the effectiveness of cloth masks had surgical masks three times as effective as home made ones, but home made ones were still effective. It is worth remembering that masks aren't being recommended as an alternative to other measures, but an addition to them. Annoyingly, I lost the tab I had open comparing handwashing to masks during the original SARS outbreak, but masks were probably a fraction better, but both was rather better than either intervention alone.

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Re: Effective re-usable face-masks

Post by Herainestold » Thu Apr 09, 2020 6:33 pm

shpalman wrote:
Tue Apr 07, 2020 9:29 am
The Chinese medical professionals who arrived in Lombardy immediately asked "why are there still so many people outside?" and "why aren't they all wearing masks?"
Slight derail here but as China has pretty much effectively dealt with their crisis, why aren't we importing loads of Chinese public health experts and getting them to help us implement the measures they used. Maybe they could bring some masks with them.

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