Let’s talk respirators!

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What’s a respirator?

Short version: it’s like a mask, but better. *Much* better.

Let’s put the headline news up front: if you maintain an airtight seal at all times, a P100 respirator blocks 99.97% of incoming viral particles. [source]

Yeah. 99.97%. That’s a *lot*.

(Specifically, we are going to be talking about what’s called “elastomeric” respirators. These have a base unit made of plastic and silicone, with attachment points on the cheeks for swappable filters.)

99.97%?! What’s the catch?! There’s gotta be a catch, right?

A few catches, but generally nothing dealbreaking.

The filtered air is very dry: take frequent breaks if you can to go outside (or somewhere else with clean air) and drink some water. I work 4 – 5 hour shifts for 2 – 3 straight days a week with a respirator and no water breaks, and that’s *doable* but dehydrating.

They muffle your voice a bit more than masks do. You’ll have to speak louder and probably be more careful with enunciation than usual, and talking on the phone will be very difficult.

The 99.97% figure is for *incoming* air. An elastomeric respirator does not, by default, filter outgoing air at all. This is okay for two reasons: one, since you can’t spread a disease you don’t have, protecting yourself *is* protecting others. Two, for even more protection of others you can tape a layer of cloth over the valve on the bottom of the respirator.

They cost more up-front (about USD$30 for a base unit and USD$11 per pair of filters), but they last for such a long time (more on that later) that in the long run it’s actually very economical.

So why isn’t everyone using them already?

Mostly because people don’t know about them. Cloth masks were supposed to be a stopgap measure until we had a chance to manufacture more respirators, but word never got out when the respirators had caught up. They do *sometimes* go out of stock still, but they’re very often available now.

Also, the kind of respirators we’re going to be talking about here are aimed at construction workers, which means people looking for “medical” masks tend to overlook them. But a particle is a particle, and there’s no reason you can’t use construction respirators against germs. In fact, in some ways they work even *better* against germs than they do against construction fumes.

What do I need to know about how to wear them?

First, check the fit. Take off your glasses if you have them, then put the base unit on and adjust the straps until the seal is airtight without being painful. You won’t be able to get an airtight seal if there’s facial hair in the way: you’ll need to at *least* trim it down very far, and probably shave it.

To confirm that the seal is airtight, there are two methods depending on whether the filters are attached right now.

  • If the filters are *not* attached: cover the attachment points with your palms and try to breathe *in*. If you can’t, the seal is airtight. (Except for the attachment points themselves, of course: *those* are big gaping holes in your seal if they don’t have filters on them. But we’ll be fixing that soon.)
  • If the filters *are* attached: cover the valve at the bottom with your palm and try to breathe *out*. If you can’t, the seal is airtight.

(You’ll want to confirm the seal every time you put the respirator on.)

Next, take a pair of filters and screw them onto the attachment points. (This is much easier to do if you’re not wearing the respirator while you’re doing it.) Be sure to screw them on very tightly, otherwise they might fall off. (I didn’t screw them on tightly enough my first time, and it was pretty scary when one of them fell off in the middle of a crowded restaurant. But now that I’ve gotten them on correctly, they stay put.)

Now you can wear it. If you have glasses, take them off first, then gently rest them on top of the respirator’s nose once you’ve put it on. Check the seal as above to make sure it’s airtight.

Once a week or after every outing, whichever is less frequent, wipe down the silicone (the part that sticks to your face and forms the seal) with some mild cleaning solution to keep the skin oils from building up. You can also wipe down the outside if you are concerned about fomites, but note that of the two styles of filter (more on that later) you can *only* wipe down the plastic cartridges, *not* the pink cloth circles. Here is the official manufacturer’s guide on cleaning these respirators [link]: note that “quat” is janitorial jargon for the type of cleaning solution that Lysol wipes are dipped in.

(Bonus tip: if you’re having trouble sourcing disinfectant wipes, look for bottles of “quaternary ammonium” *next* to the barren disinfectant-wipe section at the grocery store, put it in a spray bottle diluted to the level stated on the bottle instructions, then heavily spritz a paper towel with it. Voila, a disinfectant wipe!)

According to the CDC [link], the filters last somewhere between a month and a year depending on how much you need to conserve resources and how well you can avoid getting them wet or dirty. The main limiting factor on longevity is that the filters get clogged with fumes and dust from the construction work: if you’re not *doing* construction work or similar fume-heavy activities, they can keep going for ages. If you can still breathe through it and the filter hasn’t been wet, you’re good.

Where can I get them?

Depends on where you live.

United States of America:

Base unit (currently USD$27.81): https://www.amazon.com/3M-Facepiece-Respirator-Respiratory-Protection/dp/B008MCUT86


If possible, I recommend getting them from ULine: https://www.uline.com/Product/Detail/S-20007/Reusable-Respirators/3M-7093-Hard-Shell-Particulate-Filter-P100

ULine has the water-resistant plastic-cartridge filters, is a very reputable dealer, and sells for a good per-pair price. The only trouble is that they sell 6 pairs at a time: split a pack with a group of 3 people if you can, so that each of you will have one spare set.

If you really need a smaller pack or if ULine is out of stock, you *can* get the pink-circle kind from Amazon: 3 pairs for USD$28.90 (https://www.amazon.com/3M-2091-Particulate-Filter-Pairs/dp/B00KYX8JBU), 1 pair for USD$12.80 (https://www.amazon.com/3M-50051131070009-Particulate-Filter-2091/dp/B07571LKP4).

The pink-circle filters are *not* water-resistant: try not to stay out in the rain very long or otherwise get them wet, and don’t try to disinfect them (just avoid touching them instead, and wash your hands if you do have to). Also, counterfeits occasionally slip into Amazon’s stocks: try Amazon filters on when you first get them, and if you can still smell anything through them, demand a replacement. You should *not* be able to smell anything through a true P100 filter.


Base unit (CAD$44.19): https://www.amazon.ca/dp/B008MCUT86/


Canada has branches of both ULine and Amazon. Read the tips I gave the Americans on filter selection: the same things apply.

ULine (6 pairs for CAD$89): https://www.uline.ca/Product/Detail/S-20007/Reusable-Respirators/3M-7093-Hard-Shell-Particulate-Filter-P100

Amazon (2 pairs for CAD$24.71): https://www.amazon.ca/Particulate-Nuisance-Organic-Release-2097PA1/dp/B007STCT00/

Amazon (1 pair for CAD$16.95): https://www.amazon.ca/3M-2097-Particulate-Filter/dp/B00328IAO0/

Other countries:

I don’t have links for these on hand. For the base unit, check your hardware and general stores for “3M model 7502 respirators”; for the filters, look for “3M bayonet-style P100 filters” and prefer the plastic cartridges over the pink circles if possible. If you can’t find any of those, try looking into other elastomeric respirators, but I don’t have any experience with other ones so you’d be on your own there. Remember that you should not be able to smell anything through an airtight P100 respirator: if you put the filters on and can still smell stuff, something’s wrong with those filters, go back to the seller and get them to either give you a better set or refund you.

Getting a respirator has been a life-changer for me, and I hope it can help you too. If you found this useful or know someone who would, please let people know.

Important correction: You can actually smell lots of things thru a properly working, plain P100 respirator, because many of the things that we can smell are gasses, which particulate filters do nothing against. This is fine for this purpose: SARS-CoV-2 and droplets that carry it are particles.

As I recall, I was surprised that you’d stopped smelling things when you got yours, but found out that the specific filters you were using were P100 filters with nuisance organic vapor filtering. These contain a relatively small amount of activated carbon which absorbs organic vapors at levels below occupational exposure limits that would require heavier vapor protection, as well as most of the vapors you’d smell in ordinary life, at ordinary concentrations.

Huh. That’s very good to know. I defer to your expertise.

(I’d seen multiple reviews saying that the *two* ways of detecting counterfeits were “suspiciously light” and “scent infiltration”, but since the intended audience doesn’t already have experience with these and wouldn’t know when one feels suspiciously light, I only kept the second one in.)

I would, in that case, recommend nuisance organic vapor filtering for the psychological benefits: respirator-specific anosmia is a great way to subconsciously reassure yourself that you’re not getting exposed to anything *else* in the air. (Admittedly this may be more of a me thing: since I’ve been using anti-pollen masks for years, I’m very accustomed to judging air quality by the amount of scent that gets through. (For pollen, the occasional whiff and a *bit* of background is generally fine, but if my sense of smell seems completely unimpaired I need to replace my mask.))

@nicdevera [link], I have occasionally tried jogging to work when I was running a bit late, and I find I can’t jog for very long in my respirator: I can’t quite get enough airflow. Biking would probably depend on how hard you’re pushing it.

(I get my exercise on a home treadmill, but I recognise that I am incredibly fortunate to have the housing space and stability for one, and also to have gotten it circa 2014 when demand was quite low and you could often pick a used one up for the price of moving it.)

It is becoming increasingly clear that I should have put this post under a read-more: not only is it fairly long, it’s going to need updates. @wingedcatgirl, @moral-autism, @sophia-epistemia, @drethelin: I don’t suppose y’all would be willing to go reblog the read-more version instead?


#reply via reblog #covid19 #the more you know #oh look an update #illness tw

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