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?
I flew on LOT (Polish Airlines) recently and during the safety demo all flight attendants (I saw 3 or 4 down the aisle) removed their masks and kept them off for several minutes.
Why?
You can't demonstrate the oxygen mask dropping down while you're wearing a mask yourself?
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.
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.
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.
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.
It isn't a "solution" but those stick on aluminum "Nose Bridges" can help a little (they shape the mask around your nose so your breath cannot travel up as well, fogging up your glasses).
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.
Earlier on, I read a suggestion for taking a length-wise folded tissue and placing it under the upper edge of the mask to help seal the gap. Have you tried anything of the sort?
I would guess that if air is escaping from the mask around your nose, it is also entering that way, and so wearing masks of that design is not doing much to help either you or others. The vent merely hides the presence of leaks, by redirecting the leaked outflow, but not the leaking inflow.
The only effective solution is a mask that fits properly.
I had this problem too. Try pulling the bridge of your glasses down a little bit over the top of the mask, that usually helps. Or create a seal at the top as other commenters suggested. Also be mindful if you are breathing out through your nose or mouth, it makes a difference depending on how your mask fits.
I get very little glasses fog with my setup - a 3M 7503 half-face (modified to remove the vent feature), with 2297 filters. With a clean shaven face, I've got a positive seal for both inhale and exhale. I think the little bit of fog I occasionally get is because the 2297 filters direct a little air out of their backside when I exhale deeply. I imagine the problem would completely disappear with 5N71 or 6xxxx (combo) filters. Good luck finding stock though.
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.
I'm not sure that's the safest thing. They still allow all sorts ineffective masks, like ones made of loose fabric. At least a valved N95 mask protects one person. Those loose fitting masks are practically worthless and protects zero people. That said, you can just put fabric over the exhaust port to make it 'legal'.
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
A properly used and fitted N100 or P100 respirator will, by definition, protect the user from infection through inhalation. If we're resorting to making guesses about infection profiles, intuition says these types of users have probably not picked up an infection through other means. Forcing them to downgrade to inferior masks probably puts others at a higher risk...
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.
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.
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!)
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.
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 ...
It was never about science or the virus. We give way too much power too quickly to bunch of people who have the leaway to be as authoritarian as they want.
It is no surprise that the worse hit countries - US, Brazil, India, Russia - are led by populist governments. Virus is a technical issue and immune to the lip service of prayers and declarations.
Define worst hit. Because this statement is blatantly wrong when factoring in population size, death rate, demographics and a bunch of other factors which exist in the real world and not your FUD bubble
Yeah, "authoritarian-ness" or claiming "draconian measures" is just a rhetorical approach. It's not authoritarian to protect your neighbor from your effluent, especially as it barely costs you anything to do so. Save "authoritarian" for people controlling your entire life, thanks.
This is absurd and disregard for the inalienable right to freedom. Your don't dictate what people must do to protect YOU - that's your responsibility. This narcissistic logic is the same that would dictate you lose weight and ride yourself of other comorbidities to protect society as a whole from viruses at all times...
If you're fearful, then get yourself a sophisticated portable air filtration system.
> Your don't dictate what people must do to protect YOU - that's your responsibility.
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.
What an irrational stretch of logic to conflate natural respiration with deliberately intending to harm someone. Breathing freely doesn't harm you, get over yourself or maybe get a therapist because this is an unhealthy degree of neuroticism and little science. And none of the solutions proposed come close to achieving the supremely simplistic view of a radical ideologue.
I don't think this will be remembered "thanks god we gave more power to the police" time. Do we remember anytime we were glad to give more power to the police?
They're solving for the common case, not the exceptional.
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.
every mask has holes, otherwise they'd suffocate you, so taken to its logical conclusion, no masks should be allowed.
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.
no, that's exactly the misunderstanding that leads to such security theater. distance does nearly all the work. a mask adds marginal benefit when distancing.
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.
that example is the only one that ever gets raised, which makes it dubious as more than a fluke incident. though the explanation is nifty, even that has lots of avenues of critique.
I would agree that distance is perhaps the more significant factor but it seems like you are trying to say that Transmission(distance + mask) === Transmission(distance) which I find quite hard to believe. Even ignoring the imperfect distancing that is bound to happen in person. For example, rounding a corner
at the same time as someone else.
marginal means that adding a mask to distance adds little, likely immaterial, benefit, not absolute zero all the time, as such functional formulations imply.
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.
Hey, I appreciate that you have an opinion on this matter, but your opinion is directly opposed with scientific evidence on the matter.
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)
hey, i appreciate that you have an opinion on this matter, but the scientific evidence decidely does not support that opinion.
[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).
>no, that's exactly the misunderstanding that leads to such security theater. distance does nearly all the work. a mask adds marginal benefit when distancing.
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.'
(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.)
that might seem contradictory, but not necessarily. the article doesn't provide enough information to draw a definitive conclusion, but it seems to imply the same order of things later in the article. so distancing as the primary mitigation, masks when you can't, as with trains, concerts, and cinemas (work depends on the office plan).
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.
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.
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
"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 ..."
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.
Airlines don’t care about you, they care about lawsuits and liability. They’ve stripped services and planes back to the bare minimum, and the masks do absolutely zero on an enclosed metal tube with recirculated air. They can’t even keep someone from dying from peanut dust.
> 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.
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.
Can you provide any evidence of this claim? A bandana can be any textile and certainly doesn't filter exhaled air. Being made largely of cotten and rarely washed, they also become virus spreaders if someone infected yet asymptomatic saturates a mask and proceeds to aerosol it around all day like a chum trail of plague.
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 wearing a 3M 7503 that I modded to get rid of the vent (remove all three check valve flaps, cover and seal output port with tape). The modification can't be seen from the outside.
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.
I hope you realize how that looks from anyone else's point of view. So many people lie because they think they personally are the exception, or are extremely mistaken about basic facts, that I don't blame any guard that disbelieves your claims about your mask being really modded to not have a vent. I hope most guards would question something like that.
For sure, that's an integral part of communicating! I'm talking about a hospital, so there are several staff members controlling the entrance. The people who sit behind the desk and actually do the checkin are generally understanding, and the person who questioned me most specifically about the valve now remembers me from day to day - in fact I've since gotten her attention when getting flak from a security guard a few times.
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.
Just throw a surgical mask over the P100's exhaust. You'll get to keep wearing a mask that actually protects you, while appeasing people who don't understand that a P100 wearer probably does not have corona...
At least that's my plan for when exhaust valve restrictions come to my area.
They literally made me do this when going to a doctor apt recently. Took it off and just used their stupid mask even though mine is safer for me when I don't have covid but am forced to go into an place where it's far more likely to be present.
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.
Eh don't lean on em too hard, it's the only term they know in this space and their mode of communication is more like mad libs than actual coherent arguments.
Yes. If I wear an N95 mask with exhalation bypass (The most common type here in Canada, due to our freezing weather) — I’m not protecting anyone else, at all. As for protecting myself, if someone infected sneezes in my proximity, I’m stopping the large particles, but inhaling about 5% of the billions of small water droplets in the air around me. Remember, if you can smell it, you’re breathing it.
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.
Covid primarily spreads through droplets, which are largely stopped by regular surgical masks. There is lots of evidence that shows masks like surgical masks, which don't filter out things like smoke, do slow the spread.
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.
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.
It should be clearly stated that a valve mask is for industrial use only (wood can’t catch Coronavirusis - yet). Non-valued is for use in social settings to correctly contain exhalation droplets and other effluvia.
Valved masks have legitimate uses in construction and hazardous work. They existed well before the pandemic and have a raison d'être.
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?
The number of legitimate uses isn't zero, but it has greatly decreased. How often do people do construction and hazardous work when no one else is nearby?
Actually, no. The number of legitimate uses is still the same. The market share of those uses have simply decreased in relation to the uses causing the new spike in demand.
Actually, yes. Before the pandemic, it was reasonable for construction workers in the same room to use valved masks. Now they are only appropriate for people working in isolation, which is a less common scenario.
"...a less common scenario." But still a scenario.
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.
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.
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.
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.
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.
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.
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.
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.
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?
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.
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?
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.
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[ 3.8 ms ] story [ 204 ms ] threadWhy?
You can't demonstrate the oxygen mask dropping down while you're wearing a mask yourself?
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...
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.
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.
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.
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.
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.
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?
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.
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.
The fact that this needs to be spelled out is just depressing.
(1) https://advances.sciencemag.org/content/advances/early/2020/...