Thread by @enn_nafnlaus

Thread: Mask Fit Testing

This evening, I decided to put all of my masks to a proper qualitative fit test using a nebulizer, bitrex solution, and improvised hood. From the upper left, counterclockwise:

1. HygoStar MP9017 surgical mask
2. Demetech DT-N95-FH N95 mask (Amazon)

3. Wisent BAU 4837 FFP2 mask (hardware store)
4. 3M Aura 9330+ FFP3 mask (Amazon; used for ~20h)
5. 3M Aura 9320+ FFP2 mask (Amazon; new)
6. 3M Aura 9330+ FFP3 mask (Amazon; new)
7. GVS Elipse SPR 644 P100 unvalved elastomeric respirator (Amazon)

8. 3M 6800 elastomeric full face respirator (valved) with 3M 2135 P3 R particle filters.

Test setup:

A cheap portable nebulizer was purchased on Amazon:

amazon.com/dp/B08FF3TW59?…

While you can test with stevia or saccharin, bitrex is generally considered to be the easiest...

to detect, so I also purchased a bottle of Ft-30 bitrex solution:

amazon.com/dp/B000TBN93K?…

(Bitrex (denatonium) is the most bitter compound known and is not hazardous to health)

While you can fit test without a hood just by nebulizing near the mask, a hood can increase the...

... concentration and make detection of aerosols easier. This need not be complex - I used a loose transparent garbage bag, placed over my torso and left open enough at the waste so as to not pose a suffocation risk.

Masks were tested individually, each going through initial...

basic breathing tests, speaking tests, tests with angling the head in each direction, and deep/rapid breathing tests. The airstream was directed across my tongue to aid in tasting. At the conclusion of each test I removed the mask while still in the hood to make sure that I...

could taste the aerosols easily. Between tests, I ate a small piece of banana to cleanse my palate to avoid getting used to the Bitrex.

Results:

1) Surgical mask: you already know how this is going to go. I actually tasted the bitrex before I even started up the nebulizer,...

just from putting on the hood that had been used in the last attempt. Barely better than no mask. Rating: 1/10.

2) Demetech: the masks feel like they have a reasonable fit - certainly better than the Wisent cup mask - though the material feels light. But the bitrex taste came..

... disappointingly quickly, with no difficulty tasting at all. Rating: 3/10.

3) Wisent: a hardware store FFP2 mask clearly intended for industrial rather than medical uses, its fit felt poor and expectations weren't high. But it still outperformed the Demetech. Rating: 4/10.

4) 3M Aura 9330+ FFP3, used: the Aura series is the gold standard in disposable medical FFP2/FFP3 masks, although there are some doubts whether the ones you find on Amazon are legit. This mask had been used by me for maybe 20 hours. I was quickly disappointed - while better...

than the aforementioned masks, I was still very clearly getting Bitrex through it. Rating: 5/10.

5) 3M Aura 9320+ FFP2, new and...
6) 3M Aura 9330+ FFP3, new: I group these together because, honestly, I couldn't tell a difference between them. New, they performed much better...

... than the used Aura. I could still taste a little bit of Bitrex through them at high concentrations in normal positions, and a moderate amount of Bitrex when looking foward while directing Bitrex around the nosepiece. Rating: 8/10.

7) GVS Elipse SPR 644: What can I say? It aced the test. I might have imagined tasting Bitrex, but I think it was just my imagination. That said, it's certainly not the most comfortable of mask, though you do get used to it - and under prolongued wearing I find I sweat in it,

... and then who knows how well the seal works. Rating: 10/10

8) 3M 6800: I'd put this in the same "may have imagined tasting something, but probably didn't" category as the GVS Elipse. This is a IMHO much more comfortable mask, but is vented. Rating: 10/10.

Yet to test: I have a 3M half-facepiece with official vent filter attachment for source control on order; will try it when it gets here, but I expect it to also ace the test.

These are qualitative tests, and are not as good as quantitative ones (particle count measurements),...

... but were still good enough to make some points quite clear:

1) Don't trust "N95" / "FFP2" / "KN94" masks without testing them.

2) A new FFP2 is better than a used FFP3.

3) Elastomerics rock.

@threadreaderapp unroll

*** waist

Followup: I was in the Elipse for nearly two hours today, enough time to start sweating along the seals and really "shake it loose" if it were to get loose, so I decided to leave it on and do a new fit test at home, to see whether sweat and wear affected the fit.

Answer: no. And I really tried, but I couldn't get a single taste of bitrex no matter what I did. Its fit appears to hold up well to wear.

(As usual, for confirnation I took the mask off in the hood and immediately got a strong bitrex taste)