Yes, only a N95 or better mask would protect you from incoming, as opposed to outgoing, viruses, and these masks are both impractical for everyday wear and need to be conserved for public health users.
I think that different sources are using different definitions of "effective" here. If a simple surgical mask cuts down transmission rates by 50% that isn't anywhere near good enough for health workers working with sick patients every day. But it might still make a significant improvement in your chances of getting infected and, combined with social distancing, might drop the R0 below 1. Hence why Chinese and Korean authorities are encouraging everyone to wear surgical masks but the CDC saying they're ineffective.
I completely agree. Even having a mask that only results in a 20% reduction of transmission could be the difference between a growth factor that is less than 1, vs a growth factor of greater than one. It could be the difference between taking off or halting.
I suspect that even a spare cotton t-shirt material affixed over the face would stop a significant amount of droplets from transmitting.
It would be worth researching the effectiveness improvised masks, at the very least.
The problem is that a mask that isn't regularly replaced and handled very carefully actually increases your chances of catching the virus, via a mask->hand->face transmission.
Is there data or a study that says that risks increase from using masks poorly? I’ve looked into the literature and everything I’ve seen says they are significantly protective in real-world use.
The masks encourage a warm moist environment surrounding your nose and mouth.
If the mask becomes contaminated, it becomes an ideal vector for encouraging infection -- so if you touch the inside of the mask with your contaminated hands (say you move the mask to touch your face or adjust it or whatever), for example, the mask becomes the opposite of protective.
Masks are somewhat effective at reducing spread if the already-infected person is wearing the mask.
Which part of this is being made up? That improperly fitted mask isn't protective? That unless you very carefully handle a mask when taking it off, you'll transfer the contaminants from it onto your hands and/or face? That people compensate for risk[0]? That those masks are disposable and lose their protective power over short time (hours)?
Yes. Do you have a study that shows that a mask that has not been fit tested either provides no protection or actually increases the overall risk to the wearer?
I have looked at a fair bit of research on masks lately, and everything I've seen is that they are significantly protective, and, for example, reduce your risk of catching SARS by about 70%.
Yes, if a mask doesn't fit properly, some air will come through the sides. Even in that case though, the mask is still filtering some air, and it's protecting you from touching your mouth or nose, and it's protecting you from droplets hitting your mouth or nose from being coughed or sneezed on.
TL:DR:
The most effective use of disposable masks for blocking germ transmission is by the people with the germs who might pass them to this without but at risk.
Surgical masks are meant to protect surgery patients from the medical staff and the droplet-encased germs they emanate. N95 masks are meant to protect the wearer from particulate matter (harmful dust) in the air, specifically those particles over 30 microns. SARS-CoV02 is roughly half the size, so as an aerosolized virion, as opposed to droplet-suspended virions, they may have limited effect. N95 masks also often come with exhalation valve releases to improve inhalation fit - so exhalation pressure does not break the seal around the sides. A sick person wearing a mask with a valve that releases right in front of their mouth may be better than no mask, but it is a potential bypass for droplet suspended virions.
The US just doesn't have the culture where everyone puts on masks during flu season, like some places (HK for one), and that level of herd usage is really what might be likely to slow transmission to a breakable rate.
What I've read about Coronaviruses is that most transmission is either through hand to face contact or droplet-suspended virions so a mask that doesn't protect against aerosolized droplets would still be fairly effective. I understand that surgical masks aren't intended to prevent inhalation of droplets but the substantial symmetry between air passing through one way or the other would suggest at least broadly similar effects either way. Given the empirical results from elsewhere in the thread it seems like that may be the case.
Are surgical masks sealed around the edges? I've only worn N95 before and if you don't have a proper seal you're not even filtering the air. That's what I've always assumed was the problem with surgical masks. It's not that they're not a good enough filter, it's that they aren't even filtering the air when you breath in. But I might be wrong.
> N95 masks are meant to protect the wearer from particulate matter (harmful dust) in the air, specifically those particles over 30 microns. SARS-CoV02 is roughly half the size, so as an aerosolized virion, as opposed to droplet-suspended virions, they may have limited effect.
The N95 filters are tested with particles at 30 microns, but that doesn't say anything about their effectiveness against other particles.
3M, naturally, has released some information on this exact topic [1] which goes into a fair bit of detail on the various methods by which masks effect filtration. The tl;dr version is that there are several ways by which filtration is achieved that generally overlap and work towards providing effective protection well above and below 30um. There is generally a small dip in the transition between two primary methods which creates a specific size range where filtration is less effective.
Whether that's an issue depends on your definition of "limited effect". For the masks they tested, that dip generally occurred around 0.04-0.1um. Even in the worst case scenario, however, the worst masks tested were still filtering ~94% of the particles (in a mask that only claims 95% effectiveness to begin with). The linked document has coronaviruses listed as being about 0.125um in size, which has them falling toward the end of the dip where the mask is trending back towards 100% efficacy.
(For what it's worth, they also have the distribution of droplet sizes in a sneeze and they are all smaller than 30um as well. However they're still in a range where the mask will be about 100% effective.)
Which is all to say I certainly wouldn't describe an N95 mask as being of "limited effect".
And as to that not our culture comment, I mean it's the American of course who got told to isolate himself on suspicion of infection but decided to go to a group political event across state lines regardless, only to infect at least one other person and lead to further isolation calls for everyone else he came into contact with.
I'm not sure I would call them impractical for everyday wear. I wear N95 masks when commuting during active wildfires. The news always says not to wear them because you won't put them on properly, but it's really not that hard to ensure the fitment is correct. It's not like the construction workers that wear them occupationally are rocket scientists.
My partner is more vulnerable to respiratory problems and has always worn N95 masks when in public during flu season. What's changed now is she gets all kinds of shit from people because they think she somehow hoarded masks away from healthcare workers. We've had boxes N95 masks for years, but now we're assholes for hoarding...
Telling people they should wear masks because they don't put them on properly is like telling people they shouldn't drive cars because some people drive them into trees.
I think what OP means is N95 masks must be properly fitted to the individual. When my wife started working at a hospital she had to undergo such a fitting. So unless you get the proper size, you could still be exposed. I think that’s what he meant.
> N95 masks must be properly fitted to the individual.... So unless you get the proper size, you could still be exposed.
I'd really like to know how often those fit tests actually result in someone needing to select a different respirator size or style.
I wonder if they're only needed if you're required to be 100% sure all your people can use their respirators with near-100% effectiveness. That's probably necessary if you're working in a contagious disease isolation unit or removing asbestos all day every day, but maybe not for less dangerous environments.
Looking at the current infrastructure and the current investment in said infrastructure. I think it’s a safe bet to go out 30 years or more before self driving cars are the norm.
In cities sure. Rural areas not happening. Add the fact people like to drive to Mexico Canada and Alaska I’d call it a non starter.
Example. I have a place where the road on google maps and the place people drive vary because rural Arizona uses washes as roads. Cars driven by humans get stuck.
A lot hinges on whether one considers level 4 or level 5 to be "self-driving".
I wouldn't want to own a car without a steering wheel, sometimes you have to do weird stuff like park on a specific patch of grass at a rural wedding and it's going to be easier to do that myself than try and convince a robot.
But a car that can a) handle 'most' driving for some value of 'most' and can b) safely hand over or come to a stop under basically all circumstances including a sleeping driver? That's actually a much simpler task and it's a very useful vehicle. I would want one of those even if I lived somewhere where road conditions were such that I had to steer it myself on a daily basis.
Like in Arizona, once you got to paved road you could enter an address in Phoenix and kick back in actual safety, without having to worry about taking over at a moment's notice. I think that's achievable in 10-20 years, and it could be less.
I wouldn't say it's a certain type of people ("some people" vs. "sometimes people"). You could argue for it, though seems like a hard argument to push.
Cars are inherently dangerous, because there isn't a reasonable guarantee that something will not go critically wrong (as opposed to, say, a train). Also, when driving a car, you're not only betting that you won't make a mistake, but also that someone else won't make a mistake (that would affect you).
Occupationally I'm a diesel mechanic,so I suppose I could be lumped into the non occupational rocket scientist category. Im learning python.
Yes, we wear n95, but we also get OSHA/niosh specific training on fitment, changing, PPE exposure limit, and appropriate environments. You do not. What people are hoping is that an industrial particulate mask is going to somehow prevent the flu or corona, which honestly I have never understood. Wearing a mask while pressure cleaning a paccar12 engine? Yes, you don't want fine grease mist in your lungs. Powder coating something? Better mask up. Wearing it for a fire? Yes, but change it out once or twice a day and check it often. The flu? How?
I used to be a residential painter. AIUI (and I could be wrong here) biological and water-based molecules are larger than other chemical molecules so can be stopped by the particulate mask. This is why you can wear a dust-cup when spraying with acrylic (water-based), but need a respirator for oil or lacquer-based paint.
TBH I'd expect the n95 to work better for infection than a surgical mask because you can get a better seal to your face
> I'm not sure I would call them impractical for everyday wear. I wear N95 masks when commuting during active wildfires.
Right on. For the past couple of years, because the Seattle summers have been hazy due to the wildfire smoke, I still have quite a large batch of N95 masks. I too used to wear them during my commute and the only problem I see is that if you're at risk (underlying respiratory/heart problems) you'll not be able to tolerate the mask... With a good fitment, it makes it harder to breathe.
I think it's unfair to label people hoarders for having these masks... After a couple of consecutive years of wildfire smoke, I think this is the new normal and everyone should have them. It's not my problem that the healthcare industry has a supply issue with these masks, they should have a different, hopefully more efficient and preferential supply chain. I hope they don't buy them from Home Depot (where I got them from).
I was under the impression that there isn't (yet? But not even close to) a supply issue for the healthcare sector, but rather only at retail, due to a combination of increased demand and supply switching over to for-healthcare-only mode.
This will be something that's routine, just following the plan, that exists to serve some combination of regulation, duty, and risk (burning important healthcare customer or government relationship) mitigation.
Regular surgical masks won't protect your from inhaling the virus, but they will protect you from rubbing your face and nose 100 times a day with contaminated hands, without even noticing it. I wouldn't dismiss their efficacy.
Bank customers in bandanas would probably be a good way to get shot by a security guard in a bandana. The days of Butch and Sundance aren't that far behind us!
Many places small and large put a large value on butts in seats.
For a less cynical take, there's a lot of conversations that do happen more efficiently in-person, particularly at a lot of places that aren't set up for "full remote".
It's sometimes seen as a security issue, especially if you are not provided with a company-issued laptop. Or your work may require specialized equipment like beefy machines for 3D rendering or local access to a server.
I think there's a legitimate question here. Intuitively, if a non-N95 mask only stops 25% or 50% of incoming viruses, that still seems helpful? It's worth noting that in countries where wearing masks is normalized, making sure the general public can get some is a top priority.
On top of providing some limited protection of the wearer, it also works like herd immunity in that if everyone wears them, then those that don’t yet know they’re sick are reducing their spread.
At the moment because of the misinformation people wearing masks are being mocked and chided in public and its really unhelpful. Especially since there are immune compromised individuals and individuals with other conditions that really need to take every precaution they can, including that 10% reduction a surgical mask may give them.
My layman's understanding is that any barrier will stop some percent of most things. In the case of small, airborne particles, this stopped percentage of already-dry, floating material is very small. That means inhaling through them is relatively ineffective at stopping you from inhaling the particles.
When you exhale it is more wet and the moisture causes the barrier to catch more of the airborne particles. The barrier also catches any more-solid material that would otherwise land elsewhere, providing a mechanism for the particle to spread.
This means the net gain for wearing them to keep from catching the disease is relatively small compared to the gain by wearing them to prevent the spread if you may have been exposed.
I would agree if everyone exposed wore masks the spread of this contagion would be reduced considerably.
Logically, I might extend it to everyone wearing masks would considerably reduce the spread of exhaled contagions. This might first be encouraged in high population density areas, like parts of Asia, and first need to be integrated with fashion[0] to have any chance of broad success. I suspect it will never be a preference everywhere barring some sort of serious consequence (like death) for not wearing the mask.
In this situation, I think the most important thing is to know that normally available or homemade masks are helpful for presenting the spread of the disease. The more expensive masks are better but in this instance, not better in a meaningful way for the average person. The current supplies should be saved for those at-higher-risk populations like medical staff.
I will argue this is wrong: Only N95 or better masks have studies proving their effectiveness. I don't think we have good data on weaker masks or even "home made" masks- It's totally possible they are also effective, with proper technique.
Please somebody show me data that proves otherwise, I'm totally open to it. (Note: I'm not saying I want you to post opinions from people in authority, I'm saying I want to see data)
No, there is a 2009 study which compares N95 mask efficiency with surgical masks, because they predict that during a pandemic N95 masks will be in shorter supply. (1)
They don't find significantly more efficiency for N95 masks, but other studies do find N95 masks slightly better. (2)
Even a simple homemade mask has some efficacy [1] though it significantly less. The primary author’s summary of wether they would be protective is “no” [2]
> Quality commercial masks are not always accessible, but anecdotal evidence has showed that handmade masks of cotton gauze were protective in military barracks and in healthcare workers during the Manchurian epidemic.
> The prototype mask achieved a fit factor of 67 for 1 author with a Los Alamos National Laboratory (LANL) panel face size of 4, a common size. Although insufficient for the workplace, this mask offered substantial protection from the challenge aerosol and showed good fit with minimal leakage.
One of my coworkers, who is a staunch supporter for wearing face masks to protect against coronavirus, wears an N95 the entire time he's in the office. Yesterday he claimed he's having chest discomfort (which is what some people will feel when they wear N95 24x7 awake) and went to a hospital to demand a test for coronavirus infection. Needless to say his request got declined and he's doing just fine but I am simply speechless at the irony.
Meanwhile in South Korea everyone has masks. In WWII we built one bomber an hour at one plant, and now we can't figure out how to build millions or billions of masks.
Multiple companies in the US, China, and Europe have announced that they will be producing millions or more masks a month with availability beginning as soon as next week, just 2 months after the virus went global...
It took most of the war for that plant to get to the point of building a bomber an hour.
Even N95 masks are not fully sufficient. They typically block particles at 0.3 microns or larger, but coronaviruses tend to be smaller, around 0.1 - 0.3 microns.
You need an ASTM Level 2 or higher surgical mask to block coronavirus from completely penetrating the mask.
That said, any mask is better than no mask, first because it prevents you touching your mouth and nose with potentially infected hands, and second because coronavirus travels in water droplets which can be stopped by the mask from going straight into your mouth or nose.
Yes, the virus itself is small enough to get through, but typically the virus comes in a water droplet (as in being coughed or sneezed out) and those will be mostly stopped by an N95 mask.
Hmm. Based on what I read, particles smaller than 0.3 microns have a widely "wandering" path of travel through the mask fibers on account of Brownian motion. My understanding was that 0.3 micron particles are the size that the N95 mask is least effective at blocking. Smaller particles are blocked more effectively, not less, until you get down to a scale so small that you pretty well exclude live biological material.
I think we should all ask ourselves why we take it for granted that we should simply have to ration masks. Why aren't there enough masks available for everyone for inevitable outbreaks like this? Why don't we have the industrial capacity to manufacture masks in the US, leaving us reliant on foreign imports?
We spend ~$80 billion dollars a month on our endless war, military and spy agencies in the name of "national security", but I'd argue that having ample medical supplies (and the ability to manufacture them) are just as, if not more important, to our "national security" as the vast majority of our military activities. Hopefully this crisis will not become to severe and will serve as a wakeup call for us to rethink our national priorities before the next inevitable crisis.
There was an article recently about an US mask manufacturer (small one, not 3M), which for years warned that this will happen: a pandemic will hit and there will be a severe lack of masks anywhere.
He also recounted how after the 2009 flu scare everyone was telling him how after it ends they will now stockpile masks to be ready for the next one, he increased production, but then was stuck with it because people stopped taking his calls the moment the flu faded.
> Why aren't there enough masks available for everyone for inevitable outbreaks like this?
I don't know anyone who has conclusively demonstrated there are not. What we have right now are runs on Home Depot and the like buying out respirators and dust masks faster than the stores can restock them.
> Why don't we have the industrial capacity to manufacture masks in the US, leaving us reliant on foreign imports?
We haven't and aren't. 3M manufactures their masks in the US.
It comes down a question of priorities - the money is being spent right now. Is the average American better off if we spend $25 billion dollars next week arming Turkish Jihadists and sending missiles to Ukraine, or spending that money to build up our own country and respond properly to this outbreak before it gets out of control?
> The study reported 'no significant difference in the effectiveness' of medical masks vs. N95 respirators for prevention of influenza or other viral respiratory illness.
I have a small box of N95 masks in my shop - bought last summer for dust protection. When is the right time for me to put them on my family. Part of this is how long will they last before I must replace them. Or should I put them on eBay for a million dollars and hope I life to enjoy my new found wealth?
Surely you have elderly friends and relatives, give each one one of your masks (once things are dire enough that people will actually learn to use masks properly and not waste it.)
There isn't a shortage if you're a hospital. There's a run on the retail supply, and retail restocking will be very limited, if at all. But your local hospital is fine.
And it would have to be apocalyptic for them to accept a box of medical equipment from some guy wandering in.
I've used them a fair bit at work, you get used to them. Proper fit is important though, and many people with facial hair will need to remove it before the mask will be effective.
It's almost a moot point right now though because they're sold out pretty much everywhere.
This is NOT true. N95 is needed for health professionals in an active care environment. THIS DOES NOT IMPLY MASKS in general ARE NOT EFFECTIVE for individuals in public spaces who may run into someone who’s infected.
