I would almost say the challgenge is acceptable, especially with ten sachets I was overdoing it, 1 or 2 sachets I would still like to believe.

Anyway, an irrelevant comment anyway, because you said it yourself: gas; This is of course very different from a virus. Just via googled, H2S (the typical moldy odor) are particles around 0.5 nm in size, coronavirus is around 100 nm in size. In addition, H2S can actually be smelled at a concentration of 0.67-4.75ppm, which is one thousandth of the 5% allowed by the N95 mask – were it not for the design/testing of those masks for particles larger than 100nm.

Masks should fit snugly against the face and be universally airtight. This means that they have, by definition, a limited shelf life for this.

‘Particularly fitting’, that goes for every mask… and have you seen the movie? The connection looks much better than the typical disposable N95 mask. The only problem is good use: how easy it is to sanitize in between. Where do you get the idea that this mask is disposable, by the way?

“My world is tight”, what does “my world” mean? And why airtight, want to breathe
It doesn’t have to be completely airtight anyway, as long as the filter has less resistance than the rest of the mask, you’re breathing through it.