All my various postings tracking the COVID-19 pandemic through the end of 2022.
Last 28 days of daily increase in coronavirus cases in Virginia (blue), Fairfax County (orange), and Virginia less Fairfax (yellow).
Shows seven-day moving average (dotted line) and linear trend (solid line).
Left = data through 4/16/2020, right = linear extrapolation to 4/24/2020.
Source: Analysis of Johns Hopkins coronavirus dashboard case counts through 4/16/2020. Continue reading Post #651: Still trending.
Here’s what the last four weeks of new Coronavirus cases look like, for Virginia, when plotted as daily percentage increase. You can’t see it here, because it happened too long ago, but in hindsight, that growth rate started to come down some time after the Governor issued the first set of restrictions on business activity.
Fairfax county does NOT look this good. Fairfax seems stuck at around a 10 percent per day growth rate.
But for Virginia as a whole, as long as this trend continues to be a trend, we’ll get down to negligible daily new cases in about eight days. (And, presumably, if Fairfax County can get it under control).
And at that time, we’d only have about 8500 cases. That’s well within the capacity of our health care system to handle. Based on available beds and respirators, and the average use rate of those by COVID-19 patients, we’d have to have something like 30,000 cases statewide to overtop our hospital capacity.
In effect, we’ve managed to continue the “sub-exponential” growth noted in Post #616, 4/9/2020. So, no train-wreck scenario for Virginia.
Things may yet be difficult for our local hospitals, because we’ve got about a quarter of the cases in the state, and our daily case growth remains high in Fairfax. But for Virginia as a whole, things don’t look too bad, at the moment. As long as current trends continue.
I’m just going to proactively repeat something from Post #616, because if that trend holds, it’s bound to start happening about a week from now. Here’s the text from Post #616:
Here’s my prediction: Give it another two weeks, and if our containment strategies succeed in avoiding ventilator shortages, mass deaths, and so on, those same folks will be back. But this time they’ll be telling us that they were right all along, this was way overblown, it wasn’t that big a deal, we didn’t need to shut down the economy, we wasted a bunch of money, and so on. And, most fundamentally of course, that out response was all just some Deep State plot by Liberals to undermine the President.
So when you start hearing that — and it will be coming out of the woodwork in any number of varieties of argument — just take those arguments out into the light of day, walk them around, and given the a good look-see. Because they all boil down to:
“Our containment strategies worked, and we avoided mass deaths. And so the lack of mass deaths is evidence that our containment strategies were not needed.” (And then thrown in a dash of your favorite conspiracy theory on top of that.)
That’s like saying, e.g., whooping cough doesn’t kill many kids any more, so there’s no point to the DPT vaccine. People rarely get thrown through the windshield in car accidents any more, so seatbelts are clearly unnecessary. Nobody has invaded the US in centuries, so we clearly have no defensive need or a military. And so on.
Those are statements that only make sense to people who are literally too stupid to understand basic cause-and-effect. And you might be saying to yourself, nobody could be that dumb.
Hah. Just wait and see.
I decided I should split this off my mask order page post, because I now direct people to look there if they want more information on those mask liners.
Bottom line, the US CDC is asking citizens to take on additional risk by only wearing cloth masks when in public. That’s because N95 respirators (and possibly, to a smaller degree, hospital surgical masks) are and will be in short supply.
So it seems like it’s our patriotic duty to forego the use of real, proper, medical-grade masks. I don’t see it quite that way. And what I do see, irks me.
The US CDC foresaw the shortage of N95 respirators and made no attempt to get ahead of the game by working up a protocol for their re-use. The most common 3M N95 typically can be re-used until the elastic wears out. But the protocol for safe re-use had to come out of the hospitals. Now everybody knows the drill (drop the mask in a paper bag and let it sit). Much risk to hospital workers could have been avoided if the CDC had been willing to think outside the box.
The US FDA prevented the importation of perfectly functional Chinese-made KN95 respirators for use in US hospitals. That only changed, what, early last week? And only after many important people, including front-line health care workers, more-or-less beat on the FDA to get them to change their mind. Even now, use is on a caveat emptor basis, and (as I understand it) hospitals risk legal liability if they managed to purchase and use knock-offs instead of the real thing.
Hospitals, at present — at least hospitals around here — don’t want your commercial masks unless you can give them full, unopened boxes of them. So it’s not like, if you have a (e.g.) handful that you had for use a dust masks, that you could give them to a hospital anyway. The CDC should have said, wear them if you have them. Instead, they said, wear cloth.
Finally, the CDC apparently is living in some fictional universe where ordinary citizens might divert large numbers of proper medical masks from hospitals by purchasing them through mass-market outlets. That’s why they specified cloth. But that ship sailed, oh, about a month ago. And that universe hasn’t existed since. I’ve gone over that in posts here. You can still roll the dice on Ebay, if you wish, but that’s not going to divert a meaningful number of masks away from the hospital supply chain. And no responsible mass marketers (Amazon, Home Depot, and so on) will let you get your hand on anything that can plausibly be used by hospitals and first responders.
So I don’t see this as some great and logical sacrifice. I see this several stodgy bureaucracies who couldn’t get their acts together. And this is one of the minor results.
If the Feds are going to recommend that we use cloth masks only, as a piece of social engineering in response to their earlier failures to be proactive,the only thing we the people can do is to try our best not to die from it. If you’re going to wear a cloth mask, wear the best one you can. And if you believe these liners will enhance your mask’s performance, please feel free to order some.
And pass the word, as you see fit.
EDIT: See Post #807 for a vastly simpler approach to making a mask liner for a typical cloth mask. Even if you decide to pleat it (as below), the methods in that later post are much easier than what I show below.
EDIT: By contrast, If you want to make a stand-alone Filtrete mask (not a mask liner) See Post #780 for a better way of creating a high-quality aerosol-filtering mask. What you see below is an OK retrofit for existing cloth masks. But if you can find a mask that makes a good seal against your face (e.g., a 3M dust mask), you’d be better off following the instructions in Post #780 and upgrading that tight-fitting mask so that it filters aerosols.
To see all posts on masks, use the drop-down search menu and pick “masks” as the category.
The white object above is what you are going to make. The blue “single-use” disposable mask is there to show the size, and to clue you in that the you’re going to make a piece of Filtrete™ into something resembling the body of a pleated surgical mask.
Continue reading Post #648: Instructions for making a Filtrete™ mask liner
Edit: Rescinded because, apparently, nobody wanted them.
My Filtrete (r) mask liner order form is up on Google Docs, at this location. If you want any of the three products below, order some, I’ll try to accommodate you. And pass the word, as you see fit.
https://forms.gle/x1BfBFaR55h2LhS7A
For now, this is for Town of Vienna addresses only. If nobody wants them, I’ll expand the offer. At present, I don’t have and am not making anything for kids.
I, the offerer, make no guarantees regarding the safety or usefulness of the items offered. If you order them, you use them at your own risk. In fact, I won’t let you order them until you click the box agreeing to that.
Finally, if there are significant orders, I won’t be posting much for a while.
Continue reading Post #647: Filtrete (r) mask liner order form on Google Forms
This white cloth above is my second and final design for a mask liner. (The blue single-use mask is just there to show the size).
This is a piece of Filtrete 2500, encapsulated between two sheets of thin spun-bonded polyester cloth (a.k.a, floating row cover) using fusible interfacing to bind the polyester layers at the edges, then stapled to form a pleated sheet in roughly the same format as a standard surgical mask.
The idea is that you would wear this inside your tight-fitting cloth mask. I am leaving a generous allowance of excess polyester cloth so that you can trim the edges to get the best fit to your own mask. And so that you can find an expedient way to attach this to your own mask, in the correct position, without poking a hole in the Filtrete material.
There is no nosepiece on these. If your cloth mask does not have a nosepiece, you should make one for it. There are instructions for that all over the internet. You will want to position this so that the top edge of the Filtrete material is located under the metal portion of your mask nosepiece.
The pleasant surprise here is that, as constructed, this is incredibly breathable. You pretty much don’t notice that it’s there. (Which is, in fact, what 3M advertises about their filters. They trap 0.3 micron particles without adding materially to the back-pressure in an HVAC system. The MERV-13 material I have obtained, by contrast, seems to have a lot more back pressure. So I’m going with Filtrete until I run out of it, if that ever happens.)
If , upon examination of one of these, you have any fears about inhaling a stray fiber, please attach you own thin cloth backing to the whole assembly. This is just three pieces of non-woven polyester (or possibly polypropylene fiber). But if the idea of breathing though this bothers you, modify it, or don’t ask for one.
If you have a mask with a filter pocket, pick out the staples and you will have a 6.75″ x 6.5″ piece of Filtrete 2500, encapsulated in spun-bonded polyester. As long as a piece that size will do you, I don’t even have to offer something for those of you with filter pockets in your cloth masks. Just undo the staples.
In fact, if I see little enough demand, I’ll use two pieces of Filtrete (r). That should, in theory, capture 95% of 0.3 micron particles. And as I said, it’s amazingly breathable, so that there seems little danger that you will breath around this, rather than through this, if you use it in a filter pocket.
For now, I’m going to advise you not to wash this material. I know that washing N95 masks compromises there filtration ability somewhat. I have no clue what washing does to Filtrete. Do what hospital workers are now doing to re-use N95 masks. Drop this is a paper bag and leave it alone for a few days. Virus particles that you may have picked up with self-destruct over time.
I need to tweak some details. I’ll probably make this a little less wide than my single-use masks (6.75″), because I don’t want my pleats to compromise the fit of your mask. I may also rethink the size of the pleats. But this the general idea.
The construction of these is still slow and fussy, but I’m betting I can get better at this as time moves on. But right now, I have zero stock, and it’s going to be a while before I have a considerable supply of either of these mask liners.
If you have a mask with a tight-fitting nosepiece, this is a better option than my first mask liner. In fact, I’m only going to offer the first one with a nosepiece, and strongly encourage people to use this design instead. It uses less material, and it doesn’t have the cheap commercial mask material impeding the breathability of it, so, plausibly, with this design, more of your breath goes through the cloth, not around it.
In short, it’s a better design. And, if for whatever reason, the way I’ve pleated this does not work for you, you can pick out the staples, redo it, and re-staple it. You could probably even just tape your pleats in place.
I make no guarantees as to the effectiveness of this mask liner, if any. I will only state that I have in fact made this out of the materials that I say I have made this from. Most importantly, if this in any way compromises the fit of your own cloth mask, do not use it. Minimizing air leaks is by far the most important aspect of mask use. Better that your cloth mask filters most of your air, however it does, than that this mask liner gives you filtration that you don’t use, because it disturbs the fit of your mask.
I’m probably going to do one more variant on this that merely shapes the material into a rough conical mask, and does not have the pleats. That would have lower risk of disturbing your cloth mask fit. But that’s another level of difficulty. And, frankly, I hope I am too busy making these first two designs to have the time to come up with a third.
I’m now going going to make the following offers, on some commercial platform (likely Google Forms, maybe SurveyMonkey). I’ll set that up today and post the link here. My offers, to Town of Vienna residents and small businesses, are the following. You may ask for:
If you don’t want to take some for free, please donate some money to some Vienna-oriented charity. My best guess is that (e.g.) the economic situation for local small business is not going to improve any time soon.
I’ll have an order form up as soon as I can figure out how. I’m not going to put it on this website because I realize that lot of people don’t much like what I’ve had to say, and I don’t your dislike of me to stop you from asking for one of these. And if you know any Vienna business that still have public-facing employees (i.e., not delivery people, but anybody who has to talk to customers in person), consider pointing them to this order form. When I figure out how to do it.
Again, I make no claims or warranties as to effectiveness. Use at your own risk.
Christopher Hogan, Ph.D. chogan@directresearch.com
The CDC’s description of how COVID-19 spreads is incomplete. It simply does not fit the facts. That began to bother me more than a month ago, and I summarized the inconsistencies in Post #573, 3/26/2020.
I’m now think I have an understanding of this disease that fits all the facts known at this time. The point of this post is to provide that accurate description, and highlight what you need to do, in addition to what the CDC says, to protect yourself and help contain the spread of coronavirus.
I did not put in citations as to sources here. I’ll revise this later in the day to do that. But I can back up everything I say in this post.
And this is the last I will write, along these lines, because I’ve finally satisfied myself that I have an explanation that fits the facts. I’ll only revisit this if the facts change materially.
The upshot is: Do everything the CDC tells you to do. And more.
Continue reading Post #645: An accurate description of COVID-19/SARS-CoV-2
This is the first model of “mask liner” that I am offering to anyone in the Town of Vienna who would like them. I will go learn Google Forms tonight and set up a form for requesting these, tomorrow.
The base of the mask liner is cheap commercially-made “single-use” mask, not suitable for use by hospital workers. That’s the blue mask pictured above. I then pleat a piece of Filtrete (plus thin cover cloth) and staple that over the outside of the mask. Finally, I add a stiff full-length metal nosepiece in the form of a galvanized wire.
Here, so as not to waste the Filtrete, I used a piece of printed cloth. The actual masks will be plain white on the outside.
My intention with making mask liners is that you would wear this under your regular cloth mask. The small size and weak elastic makes these potentially quite “leaky”, and this really should be used with a tight-fitting cloth mask pressing this against your face.
In an emergency, you could wear this as a mask, by itself, but that’s inadvisable due to the potential for air leaks. If you were forced to do that, you would be well advised to add a couple of pieces of string to the loops on the nosepiece, then tie those behind your head and pull this more tightly against your face.
Surgical-style masks like these are compromised by air leaks, so the nosepiece is important. If your existing mask has a good metal nosepiece and fits snugly against the bride of your nose and cheeks, order the version of the mask liner that does not have a nosepiece. The additional nosepiece will just be in the way. And wear this so that this mask liner is held snugly to your face by your existing mask nosepiece. If you have a mask that lacks a good nosepiece, then order the version of the liner that includes a nosepiece, as pictured above.
I make no warranties as to how well these work. I make no warranties that they work at all. You use these completely at your own risk.
The theory behind this is that it should help filter out smaller particles, of a size that cloth mask is probably unable to filter well, if at all. In particular, Filtrete 2500 claims to catch 77% of particles down to 0.3 microns. Two layers should, in theory capture 95% (but I have not tested that yet for breathability).
Surgical masks do not seal to the face the way respirators do. No matter what you do with a surgical mask, short of literally taping it to your face, you will breath some unfiltered air. And the harder it is to breathe through the mask, the more air will go around the mask. So I have tried to keep this as breathable as possible.
These take longer to make than I had hoped. So I’m not sure how fast I can make them. At some point, if you have a stapler, it might be more expeditious for me to mail these out as kits, rather than assembled. All you need is a stapler, four clothespins, and (if you need the nosepiece) a few pieces of high-quality tape. I would supply the rest.
Do not wash these masks. Washing reduces the filtration ability of most high-quality filtering material. You should treat these masks exactly as hospital workers now treat N95 respirators for re-use. Wash your hands, carefully take it off your face (without touching your face), drop it in an open paper bag, and leave it for a while. The virus self-destructs over time. How long is a while? If you are phobic, leave it for three days. Otherwise, two days. So if you plan to be out every day (which I think is bordering on crazy unless your job requires it), you’d want two of these, to use in rotation.
How long will these last? I suspect that the elastic will break early on, but as long as you are using these under a tight-fitting cloth mask, that’s just a nuisance. The filter material should be good for hundreds of hours of breathing, but I have to do a calculation to determine just how long it should last (based on the rated lifetime of the original filter assembly, and so on).
My intent here is that this would be used when (e.g.) on a weekly shopping trip. Or when going to the doctor. I don’t really see these as suitable for use on an 8-hour shift, day after day. I don’t think they’ll last that long, owing to the generally cheap construction.
I’ll have the form up tomorrow to allow you to order this, or order a kit of materials to make these, or just order up a piece of Filtrete, if you have a cloth mask with a filter pocket in it. Likely, I’ll ask you to pick your up off my front porch. If you’re hesitant to take this as a gift, then donate a few dollars per mask to some worthy Vienna-centric charity.
Whether or not Filtrete will work, as advertised, in this case, is purely an act of faith. For all the world, the stuff looks like a pleated piece of paper with some fibers on one side. But you have to trust something. I trust 3M.
That said, you get no guarantee from me. It should work, but there is absolutely no way to test that, under the circumstances.
Finally, extra points for any old-timers who recognize the brand of tape measure. Ya’ can’t hardly get those any more.
