Post #1236: What mask should I wear?

Posted on September 8, 2021


This post is my briefest answer to the question “what mask should I wear?”.  My wife was asked this question yesterday in the context of the high levels of COVID-19 currently circulating at the College of William and Mary.

If you don’t feel like reading this, then my shortest possible answer is “3M Aura masks, available in the paint department at Home Depot”.  Read on for other options.

This is a timely question for me, because I just sent a “mask sampler” to my daughter.  I sent boxes of seven different high-quality masks.  She will try one of each, find what suits her best, and pass the remaining unused masks to friends, who may then do the same.  Faces vary, people vary, and what works best for one person may not work well for another.

To be clear, everything I recommend in this post, I’ve bought for myself or my family.  And I’m answering this question under the assumption that you are as serious about avoiding COVID-19 as I am.

I’m going to make some specific recommendations, first, including options for people with small faces.  Then I’ll get this posted.  And later today I may add information on (e.g.) N95, National Institute for Occupational Safety and Health (NIOSH)-certified, when to throw a mask away, and so on.  Undoubtedly more than you ever wanted to know about masks.

In general, you want a NIOSH-certified N95 respirator (mask).  If you won’t wear one of those, I think your next best bet is a name-brand, made-in-Korea KF94 mask.  In either case, you want something with a snug fit, ideally an air-tight fit, against your face.

If you don’t like how they look, wear a cheap thin loose cloth mask over them.  You can get quality KF94s in black, if that fits your style better.

If you won’t wear either an N95 or name-brand, made-in-Korea KF94, I have no advice for you, other than to suggest that you read the final sections of this post, once they are written.

Surgical masks, even proper ones with both a BFE and a PFE rating, do not work as well as N95 respirators.  And if you buy “procedure masks” — cheap surgical-style masks — you have no idea what you’re getting.

If you insist on wearing those cheap blue procedure masks, at least learn the “tied-and-tucked” method for wearing them.  Read the article in the Journal of the American Medical Association (JAMA), or see one of the authors of that article explain it in this YouTube video.

Otherwise?  “KN95” has no legal meaning in the U.S.  Anything can be sold as a “KN95” mask.  Cloth masks are a total gamble.  Some work almost as well as a surgical mask.  Others don’t.  Double-masking is a gamble, because it increases back-pressure and so increases the likelihood that you breathe around the mask, rather than through it.

During the U.S. N95 shortage, when citizens couldn’t buy an N95 through legitimate retail channels, people had to make do.  Any mask was better than no mask.  But now?  When name-brand N95s are on the shelf at every hardware and drug store in the U.S.?  When you have your pick of sizes and types of fit?  Now you have no excuse not to wear a proper N95.

1: An expedient and low-risk N95 option

Go to the paint department at your local Home Depot and buy a box of 3M 8210 masks or 3M Aura masksClick the links to see pictures of them on the Home Depot website.  (You can also get curbside pickup, or (for a fee, in most places) have them delivered to your house, from your local store.  You could also get either if these from other vendors, via Amazon).

The 3M 8210 is a traditional “cup style” mask.  It’s a soft cup, with a foam-padded flexible metal nosepiece (for fit), and two thick elastic straps to hold it tightly against your face.

The Aura is a “flat fold” mask.  The Aura is probably a little easier on your face, and, in general, it’s just a lighter-weight mask.  It’s more flexible than an 8210, useful if you plan to do a lot of talking.  As with the 8210, it has a bendable metal nosepiece (for fit), and straps that go behind the head to hold it tightly against the face.

Beyond that, it’s all about how well it fits your face.  Note that, formally, these products are respirators, not masks.  A respirator is designed to seal tightly against your face.  Masks are not.  That’s a big advantage for these products over (say) surgical masks.  But if you don’t fit them right — if they leak around the edges — you don’t get the full N95 level of filtration.

Whatever you buy, try it on after you’ve read the NIOSH instructions on how to put one of these on.  While you’re at it, you might want to read what 3M says about wearing one of these properly (.pdf).  E.g., you are not supposed to pinch the metal nosepiece with one hand, to shape it to your face.  Use both hands, press it into shape, and you will get a better fit with less chance of a leak.

There’s a little trick to putting one of these on easily.  You hold it in your palm, let the straps dangle underneath your hand, put your palm to your face, then pull the straps over your head.

I use the 8210 and similar 3M “cup-style” products.  But I’ve been using them for decades (as dust masks), so I’m used to them.  They seal against my face well, and I find that semi-rigid style easier to put on than the flat-fold style.  So I’ve stuck with the product that I know.  The elastic straps start off quite tight, but stretch with use.

That said, 3M advertises the ease-of-fit of the Aura mask, and its ability to fit a wider range of faces.  For this reason, if you’re unsure of which to buy, you’re probably better off with the Aura.  I don’t think it gives quite as good a seal as the 8210 in an ideal case.  But it will work across a broader range of face shapes.  It’s the choice with  a lower risk of failure.

Buying them at Home Depot eliminates your risk of buying counterfeit masks.  Presumably, those masks were shipped from 3M to Home Depot, and that’s a reasonably secure supply chain.  When N95 masks were in short supply, that was a real problem.  (Check out the numbers on the 3M respirator fraud page.)   I’m not sure how much of a risk remains.  But I’m pretty sure that risk is minimal if I buy from a major retailer such as Home Depot.

The only hard thing about any of this is remembering that they are in the paint department, not the tool section.   Home Depot has a separate display of protective equipment, including masks, with the tools.  But the ones that you want are with paint.  Hence the picture.

2:  Other NIOSH-certified N95 masks I have recently bought.

NIOSH-certified respirators come in a variety of types and sizes.  If the first ones you buy don’t work out well for you, there are other options.  Here are four that I have bought — two for my daughter’s mask sampler, one that turns out to be my wife’s preferred mask, and one that fits over a small beard.

If you have a small face, #1:  3M 8110S.  This is a smaller version of the 8210 “cup-style” mask described above.  This is a specialty item, and you’re going to have to buy it over the internet and pay a modest premium for it.  The listings on Amazon keep changing, which is a little unsettling.  That said, it’s such an oddball item that I think risk of counterfeit is low.  I bought these via Amazon, from OZ Medical, which is an actual bricks-and-mortar full-service supplier of medical goods.  That particular listing is no longer up, and I’m not sure how long the current Amazon listing will remain.

If you have a small face, #2:  Patriot cup mask in size small.  This is another NIOSH-certified N95 cup-style mask.  This is made by a U.S. startup, which then has the advantage of being so obscure that nobody could make money counterfeiting their masks.  These are expensive, and with shipping, worked out to be $5 per mask.  I thought it was worth a try because a) it comes in size small, and b) the shape of the mask and seal differs from the 3M product.

A lightweight, breathable N95 option:  Kimberly-Clark duckbill.  This is a lightweight mask with weak straps and a thin metal nosepiece.  Oddly, that combination works well for me and gives an excellent seal around my face.  These masks are also spacious and flexible, which makes them comfortable for wearing for long periods of time.  This is my wife’s preferred mask.  These are also available in size small through specialty medical suppliers on-line.  The only real drawbacks I can see are that they look a bit odd, and because they are thin, they don’t last as many hours as the 3M cup mask above.

If you wear a goatee, you might want to try a Magid mask.  In general, beards prevent N95 masks from sealing.   They are a bad idea during a pandemic.  This was the only N95 I found that seemed to work well with a goatee.  It’s an odd mask with a thin, flexible silicone seal all the way around the circumference of the mask.  And it is quite large.  That combination means I can put it on over my goatee and still have it seal properly.  But be warned:  I find that about one-in-three of these masks will not seal.  You just have to accept the waste as part of it.  This will not fit a person with a small face.

3:  Ear loop masks, the caveats.

Ultimately, the question isn’t “what’s the best mask”.  The question is, “what’s the best mask that a person is willing to wear“.  That’s why I added three packages of ear-loop style masks to my daughter’s mask sampler.  They don’t filter as well as N95s, but they are more convenient and more stylish.

First, there’s a reason that all NIOSH-certified N95 respirators have behind-the-head straps, not ear loops.  You cannot get enough pressure from over-the-ear elastic loops to hold the respirator against the face with sufficient force to make an air-tight seal.  If you go with an ear-loop mask, you should understand that it’s not going to filter as well as a NIOSH-certified N95.

A second pitfall is that there are no U.S. standards for how well U.S. ear-loop masks actually function.  There are standards for the filtration efficiency of the cloth they are made from (typically expressed as BFE and PFE), but there’s nothing equivalent to actual on-the-face test that NIOSH-certified N95s must pass.  And that’s because, unlike an N95 respirator, you can’t get a compete seal from an ear-loop-style mask.  Unless you tape it to your face, it will leak to some degree.

Third, there are many masks sold as in the U.S. as “KN95” masks, but that has no legal meaning in the U.S.  (It does in China, but not the U.S.)  You can sell anything as a KN95 mask, and in the U.S., “KN95” really boils down to the flat-fold style typically found on actual, for-medical-use, Chinese-made KN95 masks.

KF94 is a Korean standard, and so, like the Chinese KN95 standard, it has no legal standing in the U.S.  You can and will see just about anything sold as a “KF94” mask. That said, because KF94 is less-well-know, and Korean supply channels are less polluted by fakes, that may not be as much of a problem as it is with “KN95” masks.

Fourth, you can buy and use a standard 20 cent blue ear-loop procedure mask.  But why?  I see those hanging off people’s faces all the time.  I always wonder why they think that does much good, when you can (e.g.) see their mouth through the gaps at the edge of the mask.  Even if worn correctly, in the standard fashion (not tucked-and-tied), these offer minimal protection.  (Don’t take my word for it. Read this mask-testing article in the Journal of the American Medical Association (JAMA).

Finally, if you really want to understand why N95s are better than cheap blue ear-loop procedure masks, read Post #938.  It’s not what the mask stops that counts.  It’s what the mask lets through.  And those masks let through a lot more virus than a properly-fitted respirator.  Again, see the JAMA article.  My graph (below) is an illustration of the difference between letting 70% of airborne particles through (typical ear-loop procedure mask) and letting 5% through (properly-fitting N95 respirator).

4:  Ear loop masks, my choices.

After working through all of that, I decided that my best choice for the ear-loop portion of my daughter’s mask sampler was to buy top-dollar, brand-name, Korean-made KF94 masks.  With adjustable ear loops.  I thought that provided the least chance for knock-offs, and the best level of filtration for an ear-loop-style mask.

I bought the following, all via Amazon.  Based on my research, these are three different well-known (in Korea) brands of Korean-made KF94 masks.  The cloth in these should filter almost exactly as well as the cloth in an N95 mask.  So, as with N95 respirators, it’s all about the fit.

An added bonus is that some come in black, and some come in small sizes.

Blauna, black, adult-sized mask.

BOTN, white, medium (small adult-sized mask)

LG, black, adult-sized mask.

These were relatively expensive, up to $2.50 per mask.

There were plenty of offers on Amazon for cheaper “KF94” masks.  Uniformly, of the ones I looked at, those much-cheaper offers tended tended to be a) made in China, and b) poorly made, based on user comments.

In the end, I took my own advice:  Post #935, If you have ten-cent lungs, by all means wear a ten-cent mask. I bought the expensive ones for my daughter.

5:  Placeholder for everything you never wanted to know about masks.

In theory, I’m going to come back to this and fill in all the details I have learned in the past half-year, regarding masks.  For now, let me just offer a few practical bits, all of which I have documented, at some time, in prior posts here.

How long does an N95 respirator last?  This depends on a lot of things, including how dusty your environment is.  In a clean environment, a mask such as a 3M 8210 will filter at an N95 level for hundreds of hours.

Typically, for the 3M N95s, the elastic is what limits the life of the mask, not the filter medium.  It gets stretched, and the mask gets too loose to seal properly.

That said, the filter medium will eventually clog.  As the filter medium gets near the end of its life, it gets harder to breathe through.  I experienced this first hand, early in the pandemic, when I couldn’t buy an N95 and so replaced the elastic on my 3M mask and kept wearing it.  Eventually, it will get so hard to breathe through that you will notice it.  Particularly if you have both a new and a used copy of the mask, to compare the back pressure.

How do you sterilize a mask after you’ve used it?.  The simple answer is, don’t.  If you are worried about the mask being contaminated, wear three masks in a three-day rotation.  Just letting the mask sit out in the air for a couple of days between uses is sufficient to reduce an viral contaminant on the mask surface to a negligible amount.

(And, in fact, last time I checked, there had not been even a documented case of spread of COVID-19 via fomites.  That is, via contaminated inanimate objects.  And that’s the main reason that you don’t get nagged about washing your hands much, any more.  Early on, CDC was worried about the potential for fomite transmission.  But I think experience has shown that if it occurs, it is vanishingly rare.

I’m a pretty cautious guy, as you might guess from this post.  But I don’t flinch at (e.g.) touching the cash register at the supermarket any more.  In fact, I’ve forgotten to wash my hands after my last N supermarket trips.  The whole “contaminated surfaces” thing was just another aspect of this that the CDC got wrong early on and never issued any type of clear statement correcting their initial position.)

What’s the difference between NIOSH-certified N95 respirator and FDA-certified-for-medical-use N95 respirator?  As far as the non-medical user is concerned, nothing.  Both filter out airborne particles to the exact same extent.  But medically-certified masks and respirators also have to stop a splash of liquid (e.g., spurting blood).  So the medically-certified ones have a waterproof factor that’s not required for (e.g.) food service or industrial use.

What are N95, BFE and PFE, HEPA, MERV, PM2.5, and so on?  These are filtration standards for masks, air filters, and the like.  I summarized that in the “Filtration Standards” section of Post #593.