Post #1516, COVID-19 trend, now 31/100K/day, rising 23%/week


At this point, I could probably just copy a post from any random day in the past month or so, and I doubt anyone would notice.  New cases continue to grow roughly 25 percent per week.  Today’s case count of 31/100K/day is there just a matter of arithmetic, plus or minus some random variation. Continue reading Post #1516, COVID-19 trend, now 31/100K/day, rising 23%/week

Post #1432: COVID-19 trend to 2/11/2022: Great news, the case counts are wrong.


The official count of U.S. new COVID-19 cases per 100K population per day now stands at 57, down 42% over the past seven days.  The U.S., unlike any other country, is seeing an extended, uniform, smooth decline in new case counts, with no slowdown in sight.

See caveat section below before you get too excited about that.

Continue reading Post #1432: COVID-19 trend to 2/11/2022: Great news, the case counts are wrong.

Post #1404: Apparently, the Governor didn’t read the law, or didn’t care.


In Post #1403, I noted how badly-written the Governor of Virginia’s Executive Order 2 is.  This is the order that guts all mask mandates in K-12 schools in Virginia, starting 1/24/2022.

Along with various grammatical errors, some truly awkward writing, and bizarre rationales (e.g., children’s masks collect parasites), the Governor managed to get the name of the U.S. CDC wrong.  Got it wrong, in the process of  mis-characterizing the CDC’s research on effectiveness of masks in schools.

It looked like somebody threw it together, and never bothered to check anything.  Not the grammar, not the facts, and not the logic.

Turns out, another thing they didn’t bother to check was the law of the Commonwealth of Virginia.

I’m just going to given you a reference to the reporting on this issue, because that explains it clearly.  Read it at this web page, from WJLA.

The gist of it is that the Virginia legislature passed a law last year that required schools to remain open for in-person instruction, and required them to follow the CDC’s advice on mitigating COVID-19 risks.  This was passed with bipartisan support.

On the face of it, that’s typical sound Virginia legislation.  Keep the schools open, but do it as intelligently as you can.  Burden every school district to adhere to national safety standards in this area, as promulgated by CDC.

For my last post on this topic, I looked up the current CDC guidance.  Yep, they still call for universal indoor mask use in schools.

Source:  US CDC (that’s Centers for Disease Control).

Either the Governor was unaware of the law, or chose to ignore the law, or maybe will now claim that the law doesn’t say what it plainly appears to say.

Let me lift a quote from the WJLA reporting, so you can see exactly how clearly this is stated in the law:

The bill also says school districts should "provide such in-person instruction in a manner in which it adheres, to the maximum extent practicable, to any currently applicable mitigation strategies for early childhood care and education programs and elementary and secondary schools to reduce the transmission of COVID-19 that have been provided by the federal Centers for Disease Control and Prevention."

And now, Republicans in Virginia government are claiming that the law doesn’t actually say what it appears to say.  School districts are either setting themselves up to follow the law as written, or to follow Executive Order 2, as they choose. And the net result of the Governor’s Executive Order 2 will be to sow discord and confusion, and force the issue to be settled in the courts.

Post #1403, Why can’t Virginia be more like Florida?


I knew it was too good to last.  Republican mask nuttiness has come to Virginia

Our new Governor has not only rescinded a state-wide mask mandate for K-12 schools, he has barred any school district or school or school teacher from enforcing any sort of mask requirement.  Executive Order 2 (.pdf) takes effect on 1/24/2022.  At that point, there is no longer any state mandate, and any parent can demand that his or her child be allowed to attend any K-12 school without wearing a mask. Continue reading Post #1403, Why can’t Virginia be more like Florida?

Post #1394: The U.S. CDC: Argh.

I saw this headline in today’s Washington Post.  It appears that the U.S. CDC is almost ready to maybe sort of recommend that you wear a good mask, not just any mask.

I guess, as pictured above, they’re looking back on the entire history of the pandemic, assessing where we now sit, and asking whether or not they might, possibly, at this stage, as a last resort, recommend an easy, cheap, and effective method for radically reducing the population’s exposure to COVID-19.


If you read this blog, you know I’ve been strongly in favor of use of high-filtration masks for a long time.  Since before the CDC even recommended wearing masks.  Just search the “mask” category and you’ll see what I mean

With this latest near-pronouncement from the U.S. CDC, I hardly even know where to start.  In the interest of saving time, I’ll skip the rant, and remind you of a few useful things.

1:  An N95 isn’t just better than a standard blue procedure mask, it’s vastly better.

2:  If you insist on wearing a cheap blue procedure mask, at least learn the “tucked and tied” technique.

3:  Leave the KN95s on the shelf.

1:  An N95 isn’t just better than a standard blue procedure mask, it’s vastly better.

Here, I’m just repeating a part of Post #938, from almost exactly one year ago.

Here’s a simple question.  Even if you think you really, truly understand masks, take 15 seconds to see if you can get the correct answer.

Question:  An N95 respirator (mask) filters out 95% of airborne particles.  A procedure mask with ear loops filters out about 30% of airborne particles.  (That’s based on an actual test of those masks as published more than a year ago in JAMA).   Let me loosely call that an “N30” mask.  Roughly speaking, how much better is an N95 mask, compared to an N30 ear-loop procedure mask?

  1. Obviously, it’s about three times better, because 30 x 3 = 90, which is close to 95.
  2. Obviously, it’s about 14 times better, because (100 -30)/(100 – 95) = 70 / 5 = 14.
  3. Obviously, this must be a trick question.

The answer is B, it’s 14 times better.  Why?  The mask rating (N30, N95) shows you what the mask keeps out.  But the viral load you inhale isn’t about what the mask keeps out.  It’s about what the mask lets through.  It’s about 1-minus-the-mask-rating.  And in any given situation, the ear-loop surgical mask will let through and expose you to 70% of what’s floating around.  While the N95 exposes you to 5%.  And 70/5 = 14.

In case you still don’t quite get it, let me do the math the other way.  How much better is that N30 ear-loop surgical mask, compared to wearing no mask at all?

Question 2:  Assume that you need to inhale 100 copies of COVID-19, at a sitting, in order to get infected.  Assume that you are going to inhale one cubic meter of air, at a sitting.  How dense can the COVID-19 particles in the air be, before you inhale enough to get infected, based on wearing:

  • No mask.
  • N30 mask (ear-loop surgical mask, worn loosely)
  • N95 respirator.


Question 2, same math, but rephrased.  Suppose there’s a room filled with COVID-19 aerosol.  Suppose that, without a mask, you can sit in that room for no more than 10 minutes before you get infected.  How much more time does your cheap, blue ear-loop surgical mask buy you?  That is, how long could you sit in that room and remain uninfected, wearing an ear-loop procedure mask? And then, how long wearing an N95 respirator?


  • No mask — 10 minutes.
  • N30 mask (ear-loop surgical mask, worn loosely) – 14 minutes (10/.70)
  • N95 respirator — 200 minutes (10/.05).

That cheap blue mask buys you a whopping four additional minutes of time, before you get infected.  Which not only makes my point, but which shows you why you want to stay away from close, crowded situations, mask or no mask.

Sure, a loosely-fitting ear-loop surgical mask is better than no mask at all.  But not by a whole lot, in the overall scheme of things.

I hope you now get why I’m so persnickety about masks.  The difference between a good mask and a poor mask isn’t a little bit.  It’s a lot. It’s an order-of-magnitude difference in performance.


Still wearing those 20-cent blue procedure masks that you bought a year ago?  Can’t bring yourself to pay a whopping 89 cents each for genuine 3M N95 respirators, even though the 3Ms are good for hundreds of hours of normal use before the filter material clogs? Or maybe just just plain don’t like N95s of any sort, despite the wide variety available?

Then you should at least learn the tucked-and-tied technique.  By itself, this improves the filtration ability of the typical surgical style mask from roughly an N30 to roughly an N60.

Takes a few seconds to do.  Costs you nothing.  Doubles the effectiveness of the mask.  What’s not to like?

Or watch that directly in YouTube.

In the U.S., KN95 is a style of mask, not a legally-enforceable filtration standard.

The CDC will be doing nobody any favors if they recommend using an N95 or KN95 mask.  I’ll go so far as to say that adding KN95 to the recommendation is simply an incompetent mistake.

In the U.S., N95 is a U.S. standard maintained by the U.S. National Institute for Occupational Safety and Health (NIOSH).  A NIOSH-certified N95 respirator must fit tightly to the face, using straps that pass behind the head (never ear loops), and, when properly fitted, filter out at least 95% of of the hardest-to-filter particles (0.3 micron).

Masks may then be further certified for medical use by the FDA.  Masks certified for medical use must meet additional standards, including resistance to splashes.  It is completely possible to have a NIOSH-certified N95 that is not suited for medical use.  Most or all NIOSH-certified N95s sold for industrial use — such as the ones you can easily purchase at your local Home Depot or other hardware store — filter to the N95 standard, but are not certified for medical use.

In the U.S., KN95 means nothing.  It’s a Chinese standard, and has no legal meaning in the U.S.  Anybody can make a mask and sell it as a “KN95” mask.

Practically speaking, in the U.S., KN95 refers to a style of mask, not to a guaranteed level of filtration.  A mask that will fold flat, unfold into some sort of cone shape, and use ear loops rather than behind-the-head straps.

I have tried several KN95 masks over the course of the pandemic, and none of them worked well enough to use.  They all fit too loosely, allowed too much air to leak around the face seal, allowed my glasses to fog, and were generally insecure due to loose-fitting ear loops.

My point is, the things you can buy in the drug store labeled “KN95” are in no way a substitute for a NIOSH-certified N95 respirator. Not even close.  I sincerely hope that some CDC bureaucrats will get out from behind their desks, walk into a few hardware and drug stores, buy a few packs of what are routinely sold as “KN95” masks in the U.S., and assess them for air-tightness and likely filtration ability.  And come to the realization that, as I just said, the typical KN95 in America is not even in the same league as a NIOSH-certified N95.

In theory, the FDA had, at one time, a list of certified Chinese manufacturers whose masks could be used in U.S. hospitals under an emergency use authorization.  The FDA has long-since cancelled that EUA, and so, technically speaking, there are no KN95 masks certified for medical use in the U.S.

The bottom line is that, for the average consumer, you have no idea what you are buying when you purchase a KN95 mask. For myself, at least, every one I tried failed due to obvious air leaks.  And that doesn’t even begin to address the actual filtration ability of the cloth itself, which you have no way of testing, and which was never tested or certified by an U.S. agency.

Maybe if you’ve never worn a properly-fitted N95, you wouldn’t know the difference.  But once you’ve worn an N95, and realize that absolutely no air is supposed to leak around the mask, you will instantly reject any hardware-store KN95s on the basis of lack of air-tight fit.

If you must use an ear-loop mask, I’d recommend a made-in-Korea KF94, such as the LG Airwasher.  (KF94 is a filtration standard more-or-less equivalent to N95 in terms of particulate filtration.)  If it’s genuinely made in Korea, that provides a known filtration ability, and the ear loops are adjustable for tight fit.  Of all the masks that I asked my daughter to try, that was by far the most preferred (Post #1246, What mask should I wear?  We have a winner).

And at the end of the day, it’s all about wearing the best mask that you are willing to wear.

Post #1357: Final William and Mary COVID-19 update for 2021


For the week ending last Friday, there were six new COVID-19 cases found at William and Mary.   So the rate is back under one new case per day on average.

Source:  Calculated from William and Mary COVID-19 dashboard.

In hindsight, that little blip of 11 new cases in the prior week might plausibly be attributed to infections acquired over Thanksgiving.  If you think of W&M as a bubble of sorts (98%-vaccinated, mask-mandated, rule-enforced, low infection rate), Thanksgiving forced students to step outside the bubble in large numbers.  It wouldn’t be a surprise if they brought a few cases back to campus.

The timing is about right.  My best guess, for the U.S. as a whole, is that it takes an average of about 4 to 5 days for symptoms to appear following infection, and then about another 5 or 6 days for the typical individual to seek care, be tested, and have the test results tabulated.  Call it 10 days on average.  Which would mean that the bulk of infections incurred around Thanksgiving would show up in the data for the week ending 12/10/2021.

We’ll never know for sure one way or the other.  But the timing is right.


I guess it seems a bit compulsive to have continued to track this, given the low infection rate.  But not all colleges have been as lucky as W&M.  In particular, Cornell shut down just four days ago due to an outbreak of COVID.  Apparently, what they have is an outbreak of Omicron.  Which tore through the student body despite a mask mandate and a 97% vaccination rate.

And if you’re of a mind to indulge in some gloom and doom, note that Cornell was not the only instance.  Most of these new campus outbreaks are being attributed to likely Omicron infections, as they are all occurring in places with vaccination rates similar to those of William and Mary.

So, lucky.  I think that’s the correct term.  That’s an odd word, given all the precautions taken by W&M administration and students.  But if you look at Cornell, and other cases like Cornell, that appears to be the right word for it.

Our kids appear to have brought back just good old Delta, after Thanksgiving.  So we got a little bump in cases, but that’s the end of it.  If a few of them had stumbled across Omicron, my guess is that we’d be singing a different tune.

Omicron, my fringe opinion.

Let me preface this with a few old saws.

Free advice is usually worth what you paid for it.  Opinions are like belly buttons, everybody has one.  YMMV.  So take this FWIW.

I’ve been tracking the data on Omicron just about as carefully as a person outside of the official U.S. public health bureaucracy can.  And I’m a Ph.D. health economist, so I’ve had a lot of experience dealing with the ins and outs of health care data.

My opinion on Omicron now falls far, far outside of the mainstream.  In a nutshell, I’m betting that the U.S. Omicron wave will be short and sharp, that it might lead to more peak cases than the just-prior Delta waves (but not vastly so), and that despite that, we’ll see far fewer hospitalizations and deaths than we’re seeing under Delta.

If you want to see how I arrived at that opinion, just start reading back through my last dozen or so posts.  Starting with what I posted earlier today (Post #1356),  on the peak of the Omicron wave in South Africa now occurring just three-and-a-half weeks after the first cases of it were detected.

So what’s my best guess for W&M, next year?

For sure, when W&M students return to campus near the end of January 2022, they will do so under Omicron, not Delta.  That’s a given at this point.  The U.S. will likely pass the point where Omicron is the dominant strain some time next week (Post #1353).

In addition, I’ll bet that the U.S. Omicron wave will have already peaked in mid-January.  Weeks before the late-January general return to campus.  How fast new Omicron cases will fall, after the peak, is yet to be determined.  It’s well worth continuing to watch South Africa in that regard.  I’m not even going to hazard a guess absent hard data.

By that time, if the severity of the typical Omicron infection is as low as I believe it to be, that fact should be apparent from South African data, as well as data from Great Britain.  In other words, if the typical Omicron case really is as mild as I think the preliminary data show (see prior posts), it should be hard to ignore that.

But that’s not going to stop people from trying.  As of mid-January 2022, our official public health infrastructure might still be telling us that it’s just too soon to tell about the overall severity of Omicron relative to Delta.  As I noted in my just-prior post, they more-or-less have an ethical duty to do that for as long as possible.

At that point, colleges will face some interesting choices about return to campus.  And we can all be glad that we aren’t college administrators.

Best available evidence shows that two shots of vaccine doesn’t produce much of an antibody response to Omicron.  In other words, Omicron blows past the standard two-dose vaccination regimen.   That’s how you can have a huge outbreak on a campus that’s 97% vaccinated.  But three vaccine shots, by contrast, produces some reasonable antibody response (though only about half as much for Omicron as occurs for Delta).

Given that, I would be completely unsurprised if W&M requires everyone to have a booster shot before returning to campus.  If I were running the show, that’s the first thing I’d do.  And, given that it takes time to build immunity, they’re going to have to announce that no later than in early January.  Which will be good timing, because the U.S. should be squarely in the grip of a large wintertime wave of Omicron just about then.

At which point, my sincere hope is that folks will just roll up their sleeves and get it done.  In the hopes of having something approaching a normal semester.   Because, after that, the tools consist of things that are a lot more disruptive, both of quality of life and quality of education.

If it were up to me, the obvious next step would be to mandate not just use of masks, but use of high-filtration masks. I’d require use of NIOSH-certified N95 masks (respirators).  Those are no longer in short supply (you can pick them up at Home Depot, e.g.).  Given that they are cheap and plentiful now, it’s not like recommending N95 masks for all is a novel idea (see Post #977).  And that can easily be enforced because every NIOSH-certified N95 mask has to have that literally printed on the mask.

That said, when I supplied my daughter with a “mask sampler” of masks that I judged to be adequate, the hands-down winner was an ear-loop-style KF94 mask.  It was the LG Airwasher, to be precise: See Post #1236 and Post #1246.  So at some level, it’s not entirely about the best possible mask.  It’s about getting people to wear the best mask that they are willing to wear.  Possibly, the school administration would merely encourage people to wear only good masks, and provide a list of masks that meet some standards of adequate filtration, if the list needs to be broader than NIOSH-certified N95.

That said, my emphasis on quality masks reflects my own take on the data (see, e.g., Post #935, If you have 10-cent lungs, by all means, wear a 10-cent mask.)  You might also check out Post #942, where I do the math to show why an N95 results in exposure to vastly less viral load than a typical cloth or procedure mask.

Once you get past a) better vaccines and b) better masks, things get fairly intrusive in terms of the educational and social experience on campus.  We’re back to remote learning, hybrid classes, restrictions on social gatherings, no indoor dining.  And all the rest of that stuff.

So if you don’t like vaccines or masks, well, guess what?  Nobody does (see All the masks I’ve ever loved, Post #987).  It’s just a question of the lesser of evils.  I’d rather see on-campus learning, masked, than remote learning in any form.

Finally, what’s going to make this all the more interesting is that W&M administrators will have to make all these choices in advance.  Which, given how fast Omicron appears to be moving, means they’ll probably be making them around the time Omicron is peaking in the U.S.  And that will almost certainly be before any official U.S. pronouncement regarding the severity of Omicron relative to Delta.

In other words, those decisions are going to have to be made when things are looking pretty bleak.  I’m sure glad that’s not my job.

Post #1236: What mask should I wear?


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.


Post #1204: All the things that were to blame for the 2020 COVID-19 surge in Florida

If it weren’t for the fact that this involves illness and death, keeping tabs on Florida and COVID-19 could be entertaining.

That said, I’m having a hard time facing the current news this afternoon.

Instead, I’m going to look back to the 2020 summer surge in Florida, and list off  off all the people and things that the governor of Florida tried to blame for that surge.

If nothing else, it give current headlines a sense of deja vu. Continue reading Post #1204: All the things that were to blame for the 2020 COVID-19 surge in Florida

Post #1148: COVID trend to 5/17/2021, unfinished business

The number of new COVID-19 cases per day is now down 56% from the peak of the U.S. fourth wave.  As a whole, the U.S. is now well below 10 new cases / 100,000 / day.

Source for this and other graphs of new case counts:  Calculated from The New York Times. (2021). Coronavirus (Covid-19) Data in the United States. Retrieved 5/18/2021, from”  The NY Times U.S. tracking page may be found at Continue reading Post #1148: COVID trend to 5/17/2021, unfinished business