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Low-cost measurement of facemask efficacy for filtering expelled droplets

advances.sciencemag.org

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Re: Low-cost measurement of facemask efficacy for filtering expelled droplets

#71

Post by glofish »

Nav_Panel wrote: post #66
glofish wrote: post #56

Earlier quoted context omitted.

not sure what your are getting at with the null hypothesis. Look at the results. Mandatory cloth masks were associated with 3 times as many ILIs (Influenza Like Illnesses). So it is not some tiny statistical variation. It is a huge effect size. As for the second study, it concludes:" The observed mechanisms may lead to more severe symptoms in individuals with impaired capacity for myocardial compensation. " I am talk…

> 3 times as many ILIs Compared to surgical masks . There was no study of unmasked people. I expect it would be 10x. > The observed mechanisms may lead to more severe symptoms in individuals with impaired capacity for myocardial compensation. The study was only on N95 masks! Most people are wearing surgical or cloth, it's irrelevant. > I am talking about how the all sources of information systematically downplay the…

You should give the paper a more careful read, it discusses all that.

The control group was typical use, whatever the staff chose to do, which included not using masks at all.

The use of masks in the control group was about 23%! And that included medical, N95 and possibly cloth masks as well. Whatever they would typically use.

Here is their conclusion:

"Given the obligations to HCW (Healthcare Workers) occupational health and safety, it is important to consider the potential risk of using cloth masks."

Re: Low-cost measurement of facemask efficacy for filtering expelled droplets

#72

Post by prox »

dragontamer wrote: post #48
Kiro wrote: post #44

Earlier quoted context omitted.

Yes, of course but that's the point. That people are unable follow correct mask usage and get sloppy, especially over time.

But why do you think that? The more you practice something, the better you get at it. Assuming people to be 100% noobs at masks for months is a bit pessimistic. It's easier today to use hand sanitizer with masks than months ago. In my experience anyway.

Have you seen people use masks in interviews and so on? They constantly fidget with it. At least 50%.

Most people are not medically skilled or trained. People fidget unconsciously and uncontrolled.

Re: Low-cost measurement of facemask efficacy for filtering expelled droplets

#73

Post by Kiro »

pmachinery wrote: post #57
Kiro wrote: post #52

Earlier quoted context omitted.

Because it's what the state epidemiologists of the Nordic countries are saying, and why they recommend against mask usage. I'm all for masks btw. All I said was that inefficient masks could be counterproductive due to that reason but apparently even that innocent suggestion is heresy here.

It's not heresy, it's just a banality that has been stated countless times before. Not washing your hands properly can be counterproductive. Not being socially distant enough can be counterproductive. If you're not even arguing against masks, what is your point?

Read the whole thread. It was a reply to:

> So...people need to just slap something over their two air exchanging orifices on their faces before leaving the house and contribute to the our greater health.

My point is that if the mask is inefficient it could be counterproductive due to fidgeting. See sibling comment about fleece masks that hopefully makes a better case since you can't agree the slightest that anyone would ever fidget with their mask.

Regardless, I don't agree that it's a banality considering the ECDC lists it as an important caveat when using face masks:

> There is a risk that improper removal of the face mask, handling of a contaminated face mask or an increased tendency to touch the face while wearing a face mask by healthy persons might actually increase the risk of transmission.

https://www.ecdc.europa.eu/sites/default/files/documents/COV...

Re: Low-cost measurement of facemask efficacy for filtering expelled droplets

#74

Post by Kiro »

mdorazio wrote: post #55
Kiro wrote: post #16

Earlier quoted context omitted.

You touch your face more when adjusting the mask so if it's not efficient enough it may be a net negative. Edit: This is one of the main reason the Scandinavian countries recommend against _all_ mask use (including N95) so not sure why I'm getting downvoted for merely saying an inefficient mask could have that problem.

You're getting downvoted because you provided zero evidence to backup a claim that seems pretty absurd. Touching your mask to adjust it is not the same as touching your nose, mouth, or eyes directly. Pretty much every reputable recommendation says to wash your hands after removing your mask, which avoids the contamination problem pretty well. And to your point on Scandinavian countries, where are you getting that inf…

Thanks. I didn't know that they've started to backpedal. As for sources I had no idea it was such a controversial topic and something I thought was obvious (again, my point was just that an inefficient mask could be counterproductive) but here's the European Centre for Disease Prevention and Control saying the same thing:

> There is a risk that improper removal of the face mask, handling of a contaminated face mask or an increased tendency to touch the face while wearing a face mask by healthy persons might actually increase the risk of transmission.

https://www.ecdc.europa.eu/sites/default/files/documents/COV...

Re: Low-cost measurement of facemask efficacy for filtering expelled droplets

#75

Post by Kiro »

lm28469 wrote: post #32
Kiro wrote: post #16

Earlier quoted context omitted.

You touch your face more when adjusting the mask so if it's not efficient enough it may be a net negative. Edit: This is one of the main reason the Scandinavian countries recommend against _all_ mask use (including N95) so not sure why I'm getting downvoted for merely saying an inefficient mask could have that problem.

I find it hard to believe that any experiments would back up that fact. Do people put their fingers in their eyes/nose/mouth when adjusting their masks ? Surely having everyone wear a mask is more efficient than banning masks because a small fraction of mask wearers would catch covid when readjusting their masks.

I don't find it hard to believe at all. I see people fidget with their masks all the time. Here's the European Centre for Disease Prevention and Control saying the same thing:

> There is a risk that improper removal of the face mask, handling of a contaminated face mask or an increased tendency to touch the face while wearing a face mask by healthy persons might actually increase the risk of transmission.

https://www.ecdc.europa.eu/sites/default/files/documents/COV...

Re: Low-cost measurement of facemask efficacy for filtering expelled droplets

#76

Post by anonytrary »

bjackman wrote: post #14
anonytrary wrote: post #7

I have an even better way, albeit a bit dirty. Take a vape pen and simply put your mask on before exhaling; "eyeball" the size and trajectories of the exhaled vapor, select the mask that wins, and call it a day.

I don't think there's any reason to assume vapour from a pen resembles the droplets in your breath. In fact, that one of them is visible and the other is not should suggest that they might behave very differently.

Mask hole size >> size of o2, n2, co2, and pretty much any aromatic molecule, so I doubt it.

Re: Low-cost measurement of facemask efficacy for filtering expelled droplets

#77

Post by pmachinery »

Kiro wrote: post #73
pmachinery wrote: post #57

Earlier quoted context omitted.

It's not heresy, it's just a banality that has been stated countless times before. Not washing your hands properly can be counterproductive. Not being socially distant enough can be counterproductive. If you're not even arguing against masks, what is your point?

Read the whole thread. It was a reply to: > So...people need to just slap something over their two air exchanging orifices on their faces before leaving the house and contribute to the our greater health. My point is that if the mask is inefficient it could be counterproductive due to fidgeting. See sibling comment about fleece masks that hopefully makes a better case since you can't agree the slightest that anyone w…

> Read the whole thread.

Obviously I read the thread, otherwise I wouldn't have commented on what you wrote in it.

> Regardless, I don't agree that it's a banality considering the ECDC lists it as an important caveat when using face masks

It's a banality when in absolutely every thread on this subject at least one person states the totally obvious that doing something incorrectly could might potentially possibly may be worse than not doing it at all.

Re: Low-cost measurement of facemask efficacy for filtering expelled droplets

#78

Post by DanBC »

dragontamer wrote: post #48
Kiro wrote: post #44

Earlier quoted context omitted.

Yes, of course but that's the point. That people are unable follow correct mask usage and get sloppy, especially over time.

But why do you think that? The more you practice something, the better you get at it. Assuming people to be 100% noobs at masks for months is a bit pessimistic. It's easier today to use hand sanitizer with masks than months ago. In my experience anyway.

> Assuming people to be 100% noobs at masks for months is a bit pessimistic.

Or maybe it's realistic. Go read some hospital audits of mask wearing or handwashing. Have a look at any of the research showing that even staff who are trained to use it struggle to do it properly.

Re: Low-cost measurement of facemask efficacy for filtering expelled droplets

#79

Post by glofish »

macintux wrote: post #68
glofish wrote: post #61

Earlier quoted context omitted.

That is exactly right! What the paper says is that masks should be used when necessary and according to the case presented to the medical staff. Not all the time. When you force people to use the masks all the time you are making the problem worse.

When people are violently objecting to wearing a mask for 10 minutes in the store , I’m less worried about studies focusing on long-term mask usage and more worried about the impact of those spreading doubt.

I am concerned because they are about to force children wear masks 8 hours a day in school. What do you think it will happen when it comes out this was damaging to their health?

Re: Low-cost measurement of facemask efficacy for filtering expelled droplets

#80

Post by rstuart4133 »

pat2man wrote: post #3

The market for face masks is probably enormous right now but the information out there on which ones to buy is anemic. I assumed this was because masks were such a commodity that it didn't really matter which ones you bought, but this article shows otherwise. Even just among the cotton ones there is quite a difference.

After looking at the article for a while, my take away was material aside, the fit matters a lot. They got a very different results with the same materials with different fits. I know from using one the peaked N95 has an awesome fit. I guessing the swath was pressed hard to the face, so no leaks which would explain it's good performance. The best of the cotton masks was again the peaked.

Fit being important isn't good news. You can get a good idea of the material from the ad, but judging fit is hard without trying it on.

The values on N95 can work both ways - allowing air to more easily pass in the in or out direction. If it's in I guess it's not protecting you so well. If it's out it's not protecting others. Out is what they tested. Most seem to be out, but I have one that's in (maybe a manufacturing fault - who knows). It's nicer to wear for long periods than out. In the context of slowing down covid, I'm guessing in is more effective.

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