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Comment by pmorici | Hacker News Reader

Whats even more nuts is that N95's have taken this level of importance in healthcare at all instead of reusable P100 masks. I read a post on medium the other day about a hospital in Texas that does that and it was being treated as some kind of amazing discovery as if this was some unknown miracle device.

[0] https://elemental.medium.com/a-tiny-hospital-in-texas-might-...

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> Whats even more nuts is that N95's have taken this level of importance in healthcare at all instead of reusable P100 masks.

The obvious drawback to using reusable respirators to manage a pandemic disease is that they're another item to become contaminated and spread infection.

Sure, but disinfecting a mask like that is a known protocol. I mean I'd rather wipe down a mask daily than worry about baking my disposable N95 in an oven because there aren't enough. P100's are also more effective at filtering 100% vs 95% filtration.

Those are great but you still have to replace the filters quite often, right? Doesn’t solve the problem as the P100 filters are also sold out, and were in shortages back in January from what I saw.

No, Unless you are using it in a very dirty environment the filters should last 30 days or more. I've had one I use occasionally for wood working for several years and am still using the original filters.

I've found that the P100s tend to make me feel lightheaded pretty quickly. I tried to wear one on a very smoky drive from LA to SF during the fire season last year, but had to take it off after ~45 minutes because I felt my ability to concentrate on the road was being weakened too much. That would definitely be an issue for healthcare workers. I haven't experienced anything similar with an N95.

You might not have been wearing it right. You might also want to get your lungs checked with a spirometry machine a standard test that is done to make sure peoples lungs are healthy before letting the wear a respirator.

https://www.healthline.com/health/spirometry

I run 3-5 miles most days, so I don’t think it was a lungs issue. I was wearing it very tightly—maybe I made a mistake, but I’m pretty sure it was on right.

The elastomeric masks allow any filter to be used in them. I have N95 pads in mine. Once a week I swap in "OV" (Organic Vapor) cartridges before I go change the cat litter, the activated carbon in the OV cartridges filter out harmful gases like H2S or even Chlorine gas.

Part of the point, is that the flat, simple, small, replaceable pads for the elastomeric masks use less "melt-blown fabric" than the curved, complex, large N95 face masks. Right now lack of the melt-blown-fabric is preventing us from making enough masks. So being able to make more masks from the same fabric would help a lot.

Most doctors felt the elastomeric masks were inappropriate for healthcare workers. Articles like this are important for helping to challenge that perception. https://elemental.medium.com/a-tiny-hospital-in-texas-might-...

However, the filters do need to be swapped out from time to time. I don't think there's clear guidance on that yet, but there needs to be science backing up any kind of replacement cycle. Once per year would be atrocious, I feel. And of course the rubber itself should be constantly/consistently disinfected as you move between environments or take it off/put it back on.

Industry has been using these masks for years. The masks and filters come with documentation from the manufacture on filter replacement intervals depending on the use case and exact filter medium.

I do largely agree with this, but this is slightly outside of the typical use case for these masks. I'm not an industrial hygienist or other true PPE specialist, but I am a chemical engineer who has decent experience with a wide variety of PPE and it's been difficult for me to determine when I should replace my 6006 cartridges or 5P716 filter pads for home use (cleaning cat litter, preventing coronavirus).

Here they say to replace when "It becomes difficult to breathe comfortably (this will vary from individual to individual)." https://multimedia.3m.com/mws/media/565214O/3m-cartridge-fil...

This other brochure essentially implies the OV cartridges last up to 6 months, but those don't filter particulates. It does say however, that N95 masks become more effective as they get "dirtier", at the expense of being able to breathe easily. In this case, a tight seal would be extremely paramount, because eventually it would clog enough that you'd be breathing "around" the mask instead of through it. http://multimedia.3m.com/mws/media/447121O/filter-change-out...

They do have a web tool for calculating service life but it assumes you have at least one chemical contaminant, so the tool simply fails to calculate anything at all for hospital or home use.

The "documentation that come with the masks and filters from the manufacturer" are of no help to me: N95 pads - https://multimedia.3m.com/mws/media/528213O/userinstruction-... https://multimedia.3m.com/mws/media/994802O/userinstruction-...

These are verbatim PDF's of the documentation in the boxes that I have.

The filters meant for chemical contaminants usually have some kind of active absorber ingredient that get used up which is why the replacement intervals are more defined. With particulate (which includes viruses) the only thing you have to worry about is the filter getting clogged or the filter breaking down due to old age but that isn't going to happen with indoor use unless you are talking years. That's why the filter replacement guidelines seems less specific.

Were you using a fresh filter cartridge?

And even if you were, was the smoke so severe that the cartridge may have quickly collected so much particulate matter that it was rendered less capable of allowing a high flow of air at a low pressure difference?

For most healthcare workers, it is unknown to them. N95 is the standard.

And P100s were sold out early into this adventure.

I wonder, could the plastic part of P100s be 3D printed? (Or otherwise manufactured in fablabs)?

Not unless you have a material that conforms nicely to a face. But you can still buy face pieces. The filters are what are hard to get.

Yes, search on Montana Mask. The 3D files are available and you could print them at home. Part of the mask is the filter holder which you can stuff with N1900 or greater furnace filters, vacuum cleaner HEPA bags or whatever. Edit- sorry, it's not quite like the P100, the filter holder is a rectangle in the center of the mask as opposed to the mask in the article that has two filter holders.

Yep, one by Czech Technical University:

https://www.ciirc.cvut.cz/covid-2/

https://www.rp95.cz/en/

And most rencently, after the 3D printed protoypes turned ot to work very well, an automated assembly line was put togehter in record time:

https://www.ciirc.cvut.cz/seriova-vyroba-ceske-masky-s-nejvy...

The other major technical university - Brno Uiversity of Technology - also developped a 3D printable face mask design:

https://www.vutbr.cz/en/mask

https://www.vutbr.cz/en/but/news-f19528/covid-19-protection-...

In comparion to the mask above, this is a 100% DIY design that one can assemble with common hashold items and a 3D printer.

N95s are also reusable. Put them in an oven at 60°-100° for 20 minutes and all the virus will belong to death.

For people accustomed to Fahrenheit, that's 140 to 212.

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