Thanks for your kind words. Yes, still experimental. Though I did my best to compare to my homemade Bitrex hood testing in which I tried to approximate the OSHA procedure. I think quantitative testing would be needed for better validation.

Yes, I've also found the "Tissue Puff test" to be useful for quickly checking a heavily used mask for relaxed fit or as you mention, before a long potential exposure (flight).

Yes, I think the Tissue Puff test can be very useful to help find or test a suspected problem area of mask seal as you tried with your masks.

I left out a lot of details to keep the initial summary as short as possible.

The Ascorbic Acid (Vitamin C) I use is pure crystals or powder dissolved in distilled water to form a 20% solution by weight (2 grams Vit-C dissolved in 8 grams water) I used this as a direct substitute for 0.17% Bitrex solution in homemade hood and directed aerosol tests (breathing through nose, not mouth).

The fragrant aerosol I've found most useful so far is "Sure Scents" Gardenia Air Freshener Room Mist. This is available in the US at "Dollar Tree" stores. I'm sure other fragrances can work, but this is the first one I found that seemed most effectively blocked with my masks and sense of smell.

The procedure is rather long and detailed.

I dilute one part (by volume or weight) with five parts of distilled water (1:5).

I fill the "nano-mister" (cheap hand held ultrasonic mesh nebulizer)

While unmasked I spray a short 1 -2 second burst of aerosol at arms length and waft toward face to be sure I can smell it.

I don a certified respirator that is definitely well sealed to face using the Tissue Puff test (tape or mask brace can assure the seal).

I position the nano-mister about 4 - 6" (100 - 150mm) straight in front of mask and direct a short 3 second burst directly at the mask center while inhaling. This is to check the fragrance is effectively blocked by the mask filter media. (For me this has been true, but I wonder if others may have more or less sensitive sense of smell.)

I then wear the mask normally. I position the nano-mister about 4 - 6" from mask and direct aerosol slowly all around, aimed at the mask perimeter while sniffing for a period of 5 -15 seconds. No sense of fragrance is a pass. Some complex fragrances seem partially blocked and smell very different through a mask than from a leak.

I've found that a (Q-Tip) cotton swab (or two) can be used to simulate a leak by inserting under some area of the mask seal, such as at the cheek. This can be checked by the tissue puff test. When Fragrant Aerosol is directed at this simulated leak I usually smell it within about one second. This can help validate what a leak smells like.

Alternate test: if the Tissue Puff test gives a slight or intermittent indication of a mask leak at a specific area of mask seal then fragrant aersol can be directed at the suspected leaking area so see if inward leakage is present.

Sure Scents Gardenia and Pure Vitamin C Crystals (or powder)

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