American Airlines bans masks with exhaust valves and vents
kokpitherald.com
kokpitherald.com
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 ...
If you're fearful, then get yourself a sophisticated portable air filtration system.
In the real world, it's pretty well established principle that you can't deliberately or recklessly toss harmful items onto other people’s person's or property without being liable for the harms thus incurred, and that restrictions reasonable in proportion to the risk can be adopted to prevent you from doing so as well as you being held responsible if you nevertheless do so.
This idea that there is an entitlement to recklessly endager the public health without constraint or penalty is novel and bizarre.
Namely, people were encouraging others via social media to add holes in their masks to help them "breath easier," "reduce CO2," etc. This results in them "wearing a mask" but that mask had poor/no effectiveness.
This is a blanket rule that is easier to enforce. It isn't reasonable to ask minimum wage, sometimes temp, untrained employees manning the entrance to retailers be able to identify different styles, qualities, and risks of masks and manage that. It is reasonable to ask them "If it has a hole, they need a mask without a hole."
Unfortunately, "we cannot have nice things," because bad people continue to abuse them.
and please don't condescend and generalize:
> "It isn't reasonable to ask minimum wage, sometimes temp, untrained employees..."
it's impossible for anyone to see or know what size hole is the "right" one, especially when there isn't a right answer. stores just shouldn't sweat these details. masks have only marginal benefit over distance anyway, and such security theater in stressful times is unhelpful at best.
Either alone is significantly less effective than both together.
when not distancing, like on a cramped airplane, a mask is better than nothing and is doing the work. in that scenario, any mask is better than no mask.
there is no multiplying going on.
transmission is primarily a function of time and distance, which is why imperfect is probabalistically ok. we've already covered distance. passing someone around a corner is a miniscule additional risk because of the time factor. just don't stop to shoot the shit and you'll be fine.
It turns out that wearing a simple surgical face mask dramatically reduces the detection of coronavirus in a closed laboratory setting over a period of 30 minutes (1). It also turns out that social distancing alone works too (2). Both reduce the R0 (reproduction number) of a disease. Masks reduce the "contagiousness" because fewer infectious droplets make it out into the open. Social distancing and quarantine measures reduce the likelihood of infectious transmission between infected and healthy individuals.
This is multiplicative.
For the sake of easy numbers, let's assume that wearing a mask captures 90% of infectious droplets and that every meter of distance results in 60% of the droplets in the air to fall to the ground. If a sick individual wearing a mask coughs out 100 starting droplets and is 2 meters away from a healthy individual, the healthy individual will be breathing in 2.5 infectious droplets (100 * 0.10 * 0.50^2).
This is multiplicative.
For what it's worth, in real-world studies, when the use of face masks and/or social distancing became enforced, the rate at which infectious transmission occurred saw a measurable drop. The introduction of mandates requiring face masks (with social distancing already in effect) saw a 2% decline in the daily growth rate of COVID (3). If you'd like to read more, there is a recent meta-paper that surveys 172 different studies and concludes that:
"The findings of this systematic review of 172 studies (44 comparative studies; n=25 697 patients) on COVID-19, SARS, and MERS provide the best available evidence that current policies of at least 1 m physical distancing are associated with a large reduction in infection, and distances of 2 m might be more effective. These data also suggest that wearing face masks protects people (both health-care workers and the general public) against infection by these coronaviruses, and that eye protection could confer additional benefit. However, none of these interventions afforded complete protection from infection, and their optimum role might need risk assessment and several contextual considerations. No randomised trials were identified for these interventions in COVID-19, SARS, or MERS." (4)
1: https://www.nature.com/articles/s41591-020-0843-2
2: https://www.thelancet.com/journals/laninf/article/PIIS1473-3...
3: https://www.healthaffairs.org/doi/10.1377/hlthaff.2020.00818
4: https://www.thelancet.com/journals/lancet/article/PIIS0140-6...
[1] limited, controlled experiment =/= real-world effect. every researcher knows this (even if they sometimes don't want to admit it). at best, you have a line of inquiry to follow, not a conclusive policy measure to enact and enforce.
> "For the sake of easy numbers..."
frictionless point-masses are pretty amazing too. an idealized 2d planar diffusion model ignores the very important 3rd dimension, not to mention a large part of the time dimension too (as well as many other significant variances in the real world).
> "...will be breathing in..."
potential exposure =/= ingestion =/= infection
> "...in real-world studies, when the use of face masks and/or social distancing... 2% decline..."
confounding explanatory variables. it's the distancing, yo.
that study summary [3] even says "estimates suggest..." up to 2% (at a population level), not we found undeniable and replicable effects across a variety of conditions that control for confounding measures.
[4] "...could confer..." == we don't know yet. it's the distancing, money!
even your selectively chosen citations show that research has yet to reach conclusive positions on the role of masks on real-world effects (and they don't contradict the idea that masks may be additive but marginal), and certainly not lockdowns. they do show decent evidence that distancing works as the primary mitigation (at the very least, not contradicting that position).
FWIW...
'Yuen Kwok-yung, a professor of infectious disease at the University of Hong Kong, has advised his government that all social distancing can be relaxed – but only if people wear masks in enclosed spaces such as on trains and at work, and that no food or drink are consumed at concerts and cinemas.'
https://www.theguardian.com/world/2020/may/22/why-we-might-n...
(Yuen Kwok-yung is one of, if not the leading infectious disease specialist in Asia among other things, and has his name on many peer reviewed scientific papers.)
It seems like we could/should have had pretty reasonably authoritative information about this kind of thing from public health services by now, though.
This is correct, but look closely - there is a flap valve inside the little valve housing that hinges at the top, and the direction of the exhaust is downward.
What people don't seem to be considering here is that the loose bandana is still directing exhalation down at the ground instead of out at other people's faces like the vented masks.
Bandana is the worst option, especially compared to many vented masks actually use N95 filters preventing the inhalation of covid to begin with - and much more securely than your earloop equivalent
I've been visiting a hospital, and have to explain and sometimes insist that it does not have a vent. The worst is the security guard type people, enforcing what they think are the rules without really understanding them. So far I've been lucky and have been able to ignore/put off the security guard and talk to the friendlier person doing the actual gatekeeping. Human judgment is key to these policies and I can only hope that they're implemented with low-level discretion. It would be terrible if well meaning policies ended up pushing people back towards wearing ersatz cloths.
The security guards are meanwhile more on alert, presumably because they are primed to be tough with any covidiots (although thankfully I haven't seen any incidents!). They have that cop mindset of seeking trouble with people who stand out, and don't know specifically about the valve requirement. One time after I was approved by the checkin person, I heard them talking among themselves with one saying "those masks are actually better", but it's tough to directly pierce the fog of their authorituh.
I haven't had a larger problem here precisely there are people in multiple roles, some empowered to exercise actual judgement. But I can just imagine that when you try to scale this down to a single overworked security guard, the better equipped people are likely to experience unreasonable pushback.
Thinking about it, my own next step might be to put a piece of visible tape over where vent would exhaust, so I can at least point to something physical. But the problem hasn't been the security guards not believing me about the valve specifically, but rather just seeing that my mask is not their standard surgical mask.
At least that's my plan for when exhaust valve restrictions come to my area.
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.
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.
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.
Given how close to N95s the next options are, in terms of droplet transmission, will anyone realistically choose full N95s?
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.
I encourage you to remember that this is a place of meaningful discussion, not brow beating or one-upping.
You'll still get some fogging even with a Nose Bridge, but it is less severe. They're available from many online retailers for quite cheap.
The only effective solution is a mask that fits properly.
"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.
Why?
You can't demonstrate the oxygen mask dropping down while you're wearing a mask yourself?
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.
(1) https://advances.sciencemag.org/content/advances/early/2020/...
EDIT: I stand corrected.
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.
"Some disposable N95 masks come with an optional exhalation valve." https://www.honeywell.com/en-us/newsroom/news/2020/03/n95-ma...
The fact that this needs to be spelled out is just depressing.
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.
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.
You really think suppliers should cap or completely halt entire lines of (legitimate) business because governments are not properly regulating mask use or people are not heeding public health advice?
You have three buckets and six balls evenly distributed among them. Now you move the balls so they have a distribution of 4, 1, and 1. You still have three buckets, even though two of them are used less.
Please reread my prior comment with this in mind as you are misinterpreting what I wrote.
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.
What "virtue" is being signalled?
Care for others in your community?
So, virtue signaling. And, deluding the elderly and those w/ comorbidities that you are caring for them and that they are “safer”, neither of which is true.
As I said - if you are at risk, you should be wearing a HEPA filter and sealed eyewear.
"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...
Those kind of masks certainly won't protect you from others, at least not entirely, since you can breath in droplets through gaps in the mask, but they protect others from your breathing or coughing.
Interestingly I don’t think that’s quite true.
Droplets don’t explain almost any of the super spreader events.
And it is the super spreader events that are so concerning.
Note: I have no idea if masks help with the clearly airborne super spreader events.