
Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections (2008) - fortran77
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2440799/
======
throwwqy8739
It’s interesting how much commentary there has been in the last week about why
masks supposedly don’t work (for example,
[https://time.com/5794729/coronavirus-face-
masks/](https://time.com/5794729/coronavirus-face-masks/)).

It’s a sort of “sensible contrarianism”, designed to appeal to the vanity of
readers who view themselves as being above the fray.

Another trope is making fun of people who are preparing for possible
quarantines and supply chain disruptions, or comparing the absolute numbers of
people who die from seasonal flu to Covid-19, and pronouncing it overblown
(more common on social media).

Now to find a face mask...

~~~
kencausey
I don't know about the situation worldwide, but it is at least reported that
in the USA currently there is a severe shortage of masks and that shortage is
adversely affecting health professionals. Discouraging the casual mask
purchaser (although not with false information) seems to be of at least
temporary value here.

~~~
TheRealSteel
Surely doctors get their masks from medical suppliers and not off Amazon or
from corner stores?

~~~
owenmarshall
The same companies make both masks, and we have a run on the bank right now.

Most likely 3M and crew are tooling up their production and diverting product
to medical customers, but it’s still going to be tight for a while.

~~~
droithomme
According to early February's reports, 3M's mask making factory - in China -
was nationalized by the Chinese Government. Ships en route to the US with mask
deliveries were supposedly ordered to turn around and bring the masks back to
China.

~~~
yodon
Source? I'm listening to NPR doing an interview with 3M's mask-making division
as I read this and there's zero mention of the supposed nationalization you
report. I strongly suspect you have fallen prey to trolling.

~~~
droithomme
Whitehouse trade advisor Peter Navarro made the claim in an interview on
February 24th:

[https://youtu.be/4nM0gDDKYDQ?t=205](https://youtu.be/4nM0gDDKYDQ?t=205)

 _> "Let's take face masks for example. N95 face masks. Typical problem,
China. China basically makes a bunch of them. Well the first thing they did
was put on export restrictions so that we couldn't get any of them. Next thing
they did was nationalize effectively 3M, our company, in China, to prevent
them from sending us any stuff."_

On February 23rd Navarro discussed it as well:

[https://www.youtube.com/watch?v=ImxuY_yLCBQ](https://www.youtube.com/watch?v=ImxuY_yLCBQ)

 _> "China put export restrictions on those masks and then nationalized an
American factory that produces them there."_

~~~
yodon
Thanks for tracking that down. In any other administration I would have
considered a White House spokesperson to be as good as a primary source but
this administration's messaging does not hold to the same traditions of truth
as previous administrations (of either party).

------
kbos87
I’ve seen the headline that “masks won’t help you so don’t bother buying them”
about a million times over the past month. But when you start to dig into the
justification behind that, it’s loaded with assumptions - that I, the
layperson, won’t have an N-95 mask, I won’t wear it properly, I’ll leave it
somewhere after it’s contaminated and it will make someone else sick.

When you dig past this with the people telling you not to bother wearing a
mask, another line of reasoning bubbles up - that we need to reserve them for
healthcare workers.

It may be true that it’s most important to get N-95 masks into the hands of
healthcare workers first, but lying to the public isn’t the right way to do
it. It turns out that plenty of people are capable of understanding how to
wear a mask properly, and a lot of them - myself included - May already have
access to N-95 masks, like the handful I bought to wear while doing a home
improvement project about six months ago.

I have to agree that more than anything else, this line of commentary that
masks won’t work comes off as holier than though finger wagging. It’s at least
partially a lie, and it strikes me as an ineffective way to deal with the
problem of a shortage of masks for healthcare workers. I also doubt that the
masks on the shelf at Home Depot were ever going to find their way into the
hands of a healthcare worker if they hadn’t already.

------
pella
[https://twitter.com/lwcalex/status/1235091542219448321](https://twitter.com/lwcalex/status/1235091542219448321)

 _" Dr. Pak-Leung Ho, head of Centre for infection at @hkumed, thinks it was
due to the stepped-up vigilance of #HKers that no. of #COVID19 cases in #HK
didn't skyrocket like Iran and Italy. He highlighted universal mask-wearing as
one of the reasons widespread outbreak didn't occur."_

 _" #HKers started wearing masks, universally and regardless of symptoms, even
before the 1st confirmed case emerged in the city. Some say panic, some say
unnecessary, some say cultural difference, but it is really down to our
collective experience of #SARS."_

 _" 17 yrs ago #HKers learnt the impact of a disease outbreak at the cost of
299 lives. We knew if it starts in China, sooner or later it will reach #HK.
Afterall, in the 1st week of Feb alone, 100,000 mainlanders entered HK, not to
mention returning HK citizens."_

~~~
SiempreViernes
So despite being super-prepared they still got it.

This would appear to be line with the statements face masks indeed limit
spread once you're sick, but doesn't do much to protect you when you are
healthy.

~~~
pella
> but doesn't do much to protect you when you are healthy.

[https://twitter.com/yaneerbaryam/status/1233378620690878464](https://twitter.com/yaneerbaryam/status/1233378620690878464)

 _" If everyone wears masks, sick wear them. If nobody wears masks, they don't
If you wear a mask, people will be comfortable wearing a mask with you. If
not, not"_

+"Individual, community and government early outbreak response guidelines "

[https://twitter.com/yaneerbaryam/status/1235354865947365377](https://twitter.com/yaneerbaryam/status/1235354865947365377)

[https://necsi.edu/individual-community-and-government-
early-...](https://necsi.edu/individual-community-and-government-early-
outbreak-response-guidelines-version-3)

------
SiempreViernes
Face masks to prevent transmission of influenza virus: a systematic review
(2014)

> There is some evidence to support the wearing of masks or respirators during
> illness to protect others, and public health emphasis on mask wearing during
> illness may help to reduce influenza virus transmission.

> There are fewer data to support the use of masks or respirators to prevent
> becoming infected.

[https://www.cambridge.org/core/journals/epidemiology-and-
inf...](https://www.cambridge.org/core/journals/epidemiology-and-
infection/article/face-masks-to-prevent-transmission-of-influenza-virus-a-
systematic-review/64D368496EBDE0AFCC6639CCC9D8BC05/core-reader)

~~~
istjohn
Interestingly, the submitted article finds the opposite. According to it,
masks are more useful when worn by healthy people than when worn by sick
people.

~~~
SiempreViernes
Well, the OP just tested how well masks filter particles, and made comments
based on these results. They didn't actually study health outcomes, while the
review I linked did find studies of health outcomes but didn't find any
statistically significant results.

On balance, masks in general usage probably help a tiny bit, but it it's much
more important to wash your hands properly, so you're better of buying soap
and paper towels.

~~~
istjohn
That's a false choice.

------
fortran77
What's fascinating about this is they found masks/respirators made out of "TD
Cerise Multi® teacloth" to be somewhat effective. I looked for this because I
saw some things being tossed around about how to make your own respirators,
and I looked for a "legitimate" site that explained it. Since this is on the
nih.gov site, it is credible.

~~~
jnbiche
> Since this is on the nih.gov site, it is credible.

There's no connection with NIH beyond the fact that they host the PubMed
Central search engine this journal article appears on.

That said, PLoS One is a very reputable peer reviewed journal, so the fact
that this is published here is significant.

------
cwkoss
I saw a picture of someone in china using an inflatable t-rex costume as a
makeshift hazmat suit.

~~~
vinniejames
It wouldn't surprise me if that actually worked to some degree by negative air
pressure alone

~~~
downerending
Even if not, it's still awesome.

------
greenburger
Another study of the efficacy of homemade masks [1]. Seems to find that they
are better than nothing; however, the primary author’s summary of the research
is not effective [2] [1]
[https://www.researchgate.net/publication/258525804_Testing_t...](https://www.researchgate.net/publication/258525804_Testing_t..).
[2]
[https://twitter.com/chaiclate/status/1232972182667612162?s=2...](https://twitter.com/chaiclate/status/1232972182667612162?s=2..).

