
American Airlines bans masks with exhaust valves and vents - simpleflyong
https://kokpitherald.com/american-airlines-new-masks-policy/
======
rsync
This prohibition on masks with valves has been in effect in many places in the
bay area for months with the accompanying signage, verbal directions and
public admonishments, etc.

Ironically, what this means is that instead of wearing a tight, form fitting,
purpose built mask with, perhaps 0.5-1.0 square inches of exhaust, we have
loose, floppy fabric masks - many without any below chin attachment - with 4
or 8 or 10 square inches of "exhaust".

A local organic, progressive grocery chain in Marin County will stop you at
the door with a vented P100 mask but a flowy, loose fitting bandana, totally
open across the bottom goes right in.

Setting aside the safety or epidemiological ramifications of this, it is
_fascinating and stupefying_ to witness these social evolution play out in
front of us ...

~~~
zerocrates
So, I have a construction N95-type mask: its vent/valve/whatever is dead
center right on the front. If we're talking about droplets/aerosols mostly, it
seems directionality would be a pretty big factor, so it's actually somewhat
plausible that the bandana could be relatively effective despite nonexistent
fit.

It seems like we could/should have had pretty reasonably authoritative
information about this kind of thing from public health services by now,
though.

~~~
lowmagnet
They both point down (actually look at the valve on the N95) is the main
point, BUT the n95 is 95% filtering everywhere the valve ISN'T. The bandana is
certainly not.

~~~
jbdigriz
Many of the vented masks come with N95 inserts as they are intended to filter
inhaled air of particles - originally for mountain biking in dusty climates

------
DeRock
This study was posted earlier this week to HN:
[https://advances.sciencemag.org/content/early/2020/08/07/sci...](https://advances.sciencemag.org/content/early/2020/08/07/sciadv.abd3083)

If you look at the figures, you see that valved N95 masks still outperform
many other non-valved options for filtering expelled droplets. I wonder if
there is any study backing AAs decision, or is it based solely on public
perception?

In general, I'm surprised about the lack of information and evangelization
about effectiveness of different types of masks. Non-valved N95 are vastly
superior to all other low cost / disposable masks, yet they are difficult to
find. I've heard reports that the supply chains are being directed
predominately towards medical use, but I'm curious what's limiting the
production side to making these viable for everyone.

~~~
arcturus17
> Non-valved N95 are vastly superior to all other low cost / disposable masks,
> yet they are difficult to find

In the study you link, surgical masks come in second, extremely close to non-
valved N95, at nearly 0 relative droplet count.

Are surgical masks not considered disposable and low cost, or are they hard to
find in the US?

Where I live, they are price-capped by the government and available everywhere
from pharmacies to grocery stores.

~~~
DeRock
If you look at the supplemental figure S1 here:
[https://advances.sciencemag.org/content/suppl/2020/08/07/sci...](https://advances.sciencemag.org/content/suppl/2020/08/07/sciadv.abd3083.DC1/abd3083_SM.pdf)

You'll see that the N95 exhibit an order of magnitude greater reduction than
surgical (99.9% vs 99% reduction against no mask baseline). Whether this
practically matters, I don't know. If surgical masks are much cheaper/easier
to manufacture, then I concede that those should be the focus.

However, my point still half stands. Most cotton masks perform poorly. If AA
was basing this policy on empirical effectiveness, they would ban those before
valved N95.

------
ransom1538
If you own a valuable n95 with a vent — put a cheap mask over it. Done. No one
will complain and you wont be pushed into wearing a mask that doesnt work!
(It’s what the nurses in my family do!)

~~~
arielweisberg
This is exactly what I do. I use
[https://www.amazon.com/gp/product/B07SC1MWYL/ref=ppx_yo_dt_b...](https://www.amazon.com/gp/product/B07SC1MWYL/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
which is the least amount of mask I could find to wear over the N95.

I do seal the valve on my N95 masks with a sticker. The ones I have breath
quite well with the valve sealed and I don't wear them for long enough for it
to matter.

I also use the less effective mask for situations that are mask required, but
not actually necessary such as Autocross.

I use Cambridge masks. They will still order and deliver in a reasonable (if
long) amount of time. Claim to be lab tested N95, and have above average fit
for my face.

------
vorpalhex
As someone who wears glasses, the masks without vents constantly fog up my
glasses and make it a real pain to function. Not to mention the last thing I
want is to be fussing with something on my face without washing my hands
first, but I also need to be able to see to accomplish anything.

~~~
davmar
sounds rough. on the other hand, healthcare workers perform surgeries with
them on, so.......you should just deal with it.

~~~
vorpalhex
Yes, it's also important to note that they typically use surgery masks, not
homemade masks or N95. A surgery mask fits very differently and having worn
one for hours, I can attest that they are much more comfortable and at least
for me don't present the glass fogging issue. They also are not sufficiently
protective against coronavirus.

I encourage you to remember that this is a place of meaningful discussion, not
brow beating or one-upping.

------
moomin
This makes sense. Valve masks protect you, but don’t protect others. Regular
paper masks don’t protrct you well, but protect others. Now, I have no idea
what the infection profile of everyone wearing a valved N95 mask is, but I do
know it’s never gonna happen unless the airline supplies them. With that ruled
out, the safest thing to do is ban them.

~~~
vorticalbox
If a paper mask doesn't protect you very well, as in they let the virus in
then why would it project others? If the virus can get it you can bet it can
get out too

~~~
shuntress
This is the part that is not true: _" If the virus can get it you can bet it
can get out too"_ and also does not hold up to basic reasoning.

"If a firefighter can get down the firepole, you can bet they can get up too"

Virus ingress is slightly impeded but virus egress is _significantly_ impeded.

------
techer
I flew short haul on BA last week and the flight attendant pulled his mask
down under his nose regularly and the passenger next to me was barely using a
scarf. I was using an mask with a vent. Should the airlines supply them? Can’t
rely on 300 random people to be “aware” can we?

~~~
giantg2
If I have to fly, I'm using my P100 paint respirator. I never thought it would
be useful in this way after painting my car.

~~~
ohazi
Don't fly AA then, respirators have a vent.

~~~
giantg2
It's fine, you just need to put cloth over the vent to meet their
requirements.

~~~
mindslight
If it's like my 3M mask, you should be able to take the face piece apart, pull
off the check valve flaps, and seal the vent port. Cleaner job, no worries
about the vent retaining moisture, and P100 output filtration. It does retain
a bit more warmth, but after a few months of wearing it modded I've stopped
noticing.

------
ohazi
This is really stupid. An airplane where everyone wears P100 respirators is
clearly preferrable to one where everyone wears unvented N95 masks, yet this
wouldn't be allowed because all P100 respirators are vented.

The only masks that don't have vents are lower quality paper masks that don't
seal along the edges. They _can 't_ seal along the edges because masks without
a vent don't magically force all of your exhaled air through the filter --
your exhaled air goes out the sides.

The point of a vent is not to bypass the filter (Unless you have a backpack
sized filter, that's going to happen regardless). The point of the vent is to
control how and where exhaled air leaves the mask.

Controlled exhaust is arguably more important in an airplane where you're
sitting side to side with other people, because uncontrolled exhaust from an
N95 mask goes straight into the face of the person sitting next to you. P100
respirator exhaust can at least be directed into your lap.

------
mnm1
I assume this is based on the CDC recommendation which doesn't seem to be
based on any scientific research. On the other hand, this study finds that
valved masks are as effective as cloth masks as far as leakage is concerned.
(1) Also, I would assume a valved mask covered by a surgical would be ok
(doctors and nurses do this sometimes) but that's not clear. Otherwise, they
are asking people to wear less protection based on nothing but conjecture.

(1)
[https://advances.sciencemag.org/content/advances/early/2020/...](https://advances.sciencemag.org/content/advances/early/2020/08/07/sciadv.abd3083.full.pdf)

------
hyko
What’s the likelihood that someone who goes to the trouble to source and wear
an n95/n99 mask is infected with SARS-CoV-2, vs someone who decides to wear a
glorified handkerchief?

------
e40
Don't many N95 masks have valves?

~~~
moomin
All of them do, yes.

EDIT: I stand corrected.

~~~
rsync
That is incorrect.

N95 and P100 masks are available with and without valves.

One of the purposes of the exhaust valve in a respirator like this is so that
moisture from exhalations does not build up in the mask, forming droplets,
which then drip onto the finish surface that you are
staining/sealing/painting.

This is a problem when performing fine finishing as a drop of water can wreak
havoc in the finish you are applying.

------
erokar
Usually such masks are N95 masks. It's possible to get a variant where the air
out is also filtered. I wasn't aware of this problem with many N95 masks until
very recently.

~~~
computator
That's a very good point that the article didn't make clear. I had assumed
that the exhaust is filtered. Since the airline agents don't have an easy way
to visually identify which masks do or don't filter the exhaust, it seems that
the airline decided to ban all of the vented masks.

------
computator
Do doctors and nurses ever wear vented masks during surgeries and other
invasive procedures? In those cases, I assume that the mask is primarily meant
to protect the patient from the doctors' and nurses' germs, so why wasn't this
a concern in the pre-Covid days?

~~~
azalemeth
Unless the patient presents a truly astounding infectious risk, almost
certainly not. Surgical masks are not valved. However, the fact that theatres
have a truly _huge_ and _mind boggling_ amount of air handling equipment on
the floor above them, directing highly sterile and laminar air flow directly
down to the floor from all angles, definitely _does_ help this not matter as
much...in an operating theatre, at least, not an aircraft.

------
Havoc
>materials such as mesh or lace fabrics.

The fact that this needs to be spelled out is just depressing.

------
t0mbstone
Just wear a cloth mask or bandana over your vented N95 or N100 mask. Now you
have protection for yourself, and also others. Boom. Problem solved.

------
aleister_777
I was part of mask and respirator testing in the Air Force to support a new
method of repairing runways after an attack. The main issue we were battling
was the amount of respirable crystalline silica in our new repair material ...
and OSHA recently added it to their standards list. Therefore, we need to find
a solution. Our main contenders were: 1) surgical mask, 2) N95 respirator, and
3) USAF gas mask.

After lots of laboratory testing and field testing, we determined the N95
respirator was the least intrusive method to meet the OSHA requirements. Yes,
the USAF gas mask would work but placed considerable undue stress on the
Airmen performing the repair work on the runway.

DETAILS: Respirators (ex. N95) are designed and engineered for distinctly
different functions than surgical masks (and homemade cloth masks). And
filters (respirators or surgical) do NOT act as sieves. Finally, the filter’s
collection efficiency is a function of the size of the particles and is not
dependent on whether they are bioaerosols or inert particles.

There is a particle size at which none of the “mechanical” collection
mechanisms (interception, impaction, or diffusion) is most effective. This
“most penetrating particle size” (MPPS) marks the best point at which to
measure filter performance. Therefore, N95 respirators filter at least 95% of
airborne particles and is not resistant to oil. (R is somewhat resistant to
oil and P is strongly resistant to oil).

It is important to note that respirators must meet stringent certification
tests established by NIOSH, whereas manufacturers of surgical masks get to
choose from a variety of protocols (including ones that charge the particles)
and only have to demonstrate their product is at least as good as a mask
already on the market. We looked at numerous studies comparing the performance
of surgical masks using a standardized airflow, filter performance showed to
be highly variable. Collection efficiency of surgical mask filters can range
from less than 10% to nearly 90% for different manufacturers’ masks when
measured using the test parameters respirators need for NIOSH certification.
Therefore, surgical masks were out of the running.

N95 respirators were then compared to USAF gas masks. Both worked at filtering
the silica, however, the USAF gas mask was bulkier, heavier, and more costly.
Unfortunately, the most important aspect of a respirator’s performance is how
well it fits the face and minimizes the degree of leakage around the
facepiece. Therefore, we had to institute a fit test program for all
engineers.

OSHA's action level for silica is 50 μg/m3 (micrograms of silica per cubic
meter of air), averaged over an 8-hour day. While the size of silica varies
significantly from .01 μm (micrometre or micron) to 100 μm in diameter, our
median silica particle size was ~3 μm. SARS-CoV-2 is significantly smaller
than our median silicon particle size (0.1 μm in size), SARS-CoV-2 always
bonds to something larger. It could be respiratory droplets (>5 μm) or
aerosols (<5 μm).

Therefore, if you want to be effective in stopping particles, you need a N95
respirator and it needs to be fit tested to the individual and is only good
for one time use.

~~~
mindslight
Why are you saying one time use? The guidance I have been able to find from 3M
about their P100 filters says you can use them indefinitely until it becomes
too hard to breathe. The situation is a bit different if you're counting on
blocking larger droplets/aerosols, as the smaller virii could separate and
leach through. But I would think rotating filters should be sufficient for
that.

~~~
aleister_777
Those would be two different things. The only thing that matters is the size
of covid, the fact that it still kills much few people than the flu (with a
vaccine), and that no normal person will ever wear a mask correctly to the end
state that they prevent themselves from being infected by a virus.

If a mask was the cure for a virus we would be living in an extremely
different world. Fortunately, this portion of public madness ends on Nov 4.

~~~
mindslight
Oh, sorry. I had thought we were sharing tips about constructively working to
protect ourselves and our families. Not trying to rationalize defeatism to
cope with living in a disintegrating country that cannot even equip its
citizens with basic medical supplies.

------
p1mrx
About time. Anyone manufacturing valved masks in 2020 should probably stop and
think about the harm they're causing.

~~~
83457
I'm not familiar with this topic. Please explain.

~~~
p1mrx
Valves are designed to bypass the air filter when breathing out. This makes
sense if you're working alone in a dusty environment, but not if you're trying
to prevent stuff in your lungs (virus particles) from reaching people around
you.

~~~
83457
Ah. That makes perfect sense now. Thank you

------
pjkundert
Thus exposing the astonishing idiocy of "mask" requirements.

All masks have wildly varying protective capability, for the wearer, or
others. Laws requiring "wear a mask" are therefore simply virtue signalling,
not actually useful.

If you are at risk -- you would be protected only by wearing a personal
powered HEPA filtration unit, and eye goggles.

If you're not at risk, you don't protect other at-risk people by wearing most
masks. If the mask you're wearing would allow you to smell someones smoke --
you're not being protected; small vapor particles carrying active viral loads
are similar in size to smoke particles.

The whole thing is so astonishingly stupid, it's breathtaking.

~~~
roywiggins
Wait, why do surgical masks (not N95s) exist then? Have doctors been virtue
signalling for decades?

~~~
jaywalk
As it happens, kind of:

"A recent review concluded that it is not clear whether face masks prevent
surgical wound infections, and the scientific evidence for this practice is
weak and insufficient."
[https://anesthesiology.pubs.asahq.org/article.aspx?articleid...](https://anesthesiology.pubs.asahq.org/article.aspx?articleid=2085803)

