
The effectiveness of cloth masks has been misrepresented - martingoodson
https://rssdss.design.blog/2020/04/24/the-effectiveness-of-cloth-masks-has-been-misrepresented-by-masks4all/
======
toomim
I'm part of a mask-providing charity. [1] This article is misleading in three
ways:

1) It acts as if a single person speaks for #Masks4All. But #Masks4All is a
hashtag, not a person.

2) It says that #Masks4All claims cloth masks are 96% effective. I've never
heard that. We always claim cloth masks are 30% effective, surgical masks are
60-80%, and N95 masks are 95% effective.

3) It says that cloth masks are 70% effective, and then exaggerates this to
say that cloth masks are "not effective."

Who in their right mind would say that "70% effective" means "not effective?"

[1] [https://maskedprotectors.org/](https://maskedprotectors.org/)

~~~
bambax
> _It says that cloth masks are 70% effective, and then exaggerates this to
> say that cloth masks are "not effective."_

No. It says that the main South Korean study "found" that masks were 70%
effective, but that that study is not significant, because it was based on
only 4 people, " _one of whom could not produce detectable virus particles
even without a mask_ " \-- so really, 3 people.

It also says that a much more important study [1], based on 1607 hospital
workers found that _penetration of cloth masks by particles was almost 97%_.

That other study was made in 2015, so before covid, but there is no reason to
believe its results would be different with the covid virus; it's certainly
not disproved by a study based on 3 people.

[1]
[https://bmjopen.bmj.com/content/5/4/e006577](https://bmjopen.bmj.com/content/5/4/e006577)

~~~
DanBC
Also, the 4 person South Korean study was very clear in their conclusion:

[https://annals.org/aim/fullarticle/2764367/effectiveness-
sur...](https://annals.org/aim/fullarticle/2764367/effectiveness-surgical-
cotton-masks-blocking-sars-cov-2-controlled-comparison)

> In conclusion, both surgical and cotton masks seem to be ineffective in
> preventing the dissemination of SARS–CoV-2 from the coughs of patients with
> COVID-19 to the environment and external mask surface.

~~~
jnbiche
First, each patient coughed _directly upon_ a petri dish 20 cm away, not once
but _5 times_.

I don't think anyone would rationally believe that a non-fitted mask would
have a high probability of providing protection to a person directly coughed
on by an infectious mask-wearer, all at a distance of 20cm. If they were going
to test under those conditions, they should have used an N95 mask. Doing it
with a surgical mask under such conditions was a waste of time and no surprise
at all.

The argument has never been that non-fitted masks prevent 100% of all viral
particles emitted by an infectious person from escaping into the environment
(which is what that tests, since it only takes a few virions to start a colony
in a culture).

The argument has been that wearing a non-fitted mask can significant decrease
the amount of virus-laden droplets floating around in the air, and falling
onto surfaces.

The more we find out about asymptomatic carriers, the more this makes sense.
These carriers aren't going around coughing their lungs out, they transmitting
disease by talking and breathing. A mask likely helps a lot with that.

I've really like to see the same experiment repeated, but with the patient
wearing the mask and talking, and the petri disk held ~2 meters away. These
are the conditions under which the disease is being transmitted now, outside
of households and healthcare facilities.

------
Loughla
I get the importance of following science in weird times like these.

But, if the author of articles agrees people should still wear masks, what is
the end game of this article?

The people who want to open back up economies using masks instead of
appropriate other precautions, will not read this. The people who will read
this and understand it will not change their views. The people who will read
this and misunderstand it will just add to the negativity and confusion by
claiming that no one should wear masks.

Maybe I'm just going into a depression spiral, but what's the point?

~~~
sct202
This is how I feel at work sometimes; like someone will say something kind of
wrong but mostly right or their rationale for something is a little bit off.
Is it really worth derailing a meeting over?

~~~
marcosdumay
This is the worst. If you correct them you'll derail the meeting for a short
time and look bad. If you don't correct them, there is a risk somebody will
follow their premises into some conclusion that leads to very bad actions, and
you won't be able to explain why, derailing much more than a meeting.

------
blakesterz
So _IF_ I read this correctly, cloth masks still do a pretty good job? The
post ends with...

"I have reanalysed the Korean data using the suggested replacement value of
half the LOD and the results don’t change very much, suggesting a reduction of
70% of virus particles when using cloth masks."

And it starts with...

"His key claim is that “cotton masks reduce virus emitted duringcoughing by
96%”, citing a recent South Korean study."

So 70% isn't as good as 96%, but it seems like that's still a decent number.
Or am I reading this wrong?

~~~
shamino
When giving out numbers scientifically, it's important to be precise, or have
the uncertainty known. In that case, 96% is widely different than 70%. As Andy
Slavitt says in his April 22 podcast, when someone claims to know something
too precisely in regards to this pandemic, and they don't say "we don't know"
enough, run the other direction.

~~~
shamino
You also want to have someone doing a scientific study to be as unbiased as
possible. As I understand it, (most of?) his family is immunocompromised. This
doesn't mean he shouldn't do it, nor that what he's doing is not saving
millions of lives, but it's a little easier to question the "salesmanship"
aspect of it when he hasn't spent a lot of time in the field.

------
salmonellaeater
> The researchers found that 97% of particles penetrated through cotton masks.
> Why would a ‘review of the evidence’ neglect this key finding?

This statement in the article is completely disingenuous. The study in
question[1] was looking at whether wearing a mask protects the wearer from
getting infected. The primary purpose of wearing the mask is to prevent the
wearer from infecting others. These are unrelated!

[1] Text of the study:
[https://bmjopen.bmj.com/content/5/4/e006577.full](https://bmjopen.bmj.com/content/5/4/e006577.full)

------
haltingproblem
This is pure clickbait and here is why. In the debate over masks, the anti-
mask side always forgets that this epidemic is multiplicative i.e. it each
person spreads it to multiple people (R0 > 1).

Even a marginally effective mask that cuts infection by 30% will greatly bend
the curve. How? A 30% effective mask (where 100% is full hazmat outfit) does
not mean 30% fewer cases. It could mean greater than 30% or even 90% fewer
cases. The same non-linearities (read: exponential) that work for virus spread
also help in the other direction. [1]

Social distancing is expensive and we need it. Social distancing requires the
shutdown of large parts of our economy and changing the way we live. Masks are
a relatively minor inconvenience and one whose effectiveness, no matter how
marginal, we can _not_ afford to ignore.

Do science all you want, and that blog post is hardly science, but do it with
an ethical and moral responsibility to not turn people away from masks.
Turning people away from masks is akin to telling them the virus is not
contagious or fatal.

References:

[1]
[https://twitter.com/nntaleb/status/1249296844712218624](https://twitter.com/nntaleb/status/1249296844712218624)

~~~
jatone
the point of the article wasn't to say don't wear a mask. the point was that
it is dangerous to tell people a mask is 90% effective when its not. lying
about the effectiveness WILL cause people will take risks they shouldn't
making the situation worse. being honest about the masks effectiveness and
explain why it still helps is the best thing we can do.

------
generalpass
I wonder if the author of this article is aware that evolutionary biologist
Bret Weinstein uses and promotes using a bandana as being far more effective
than nothing for those who are unable to get an N95 mask.

