[rattray]

Thank you for the thorough feedback!

Ultimately, most of this comes down to your risk tolerance - how much is quality covid protection worth to you? I agree that looks are more likely to be the barrier there than $85, which as you mentioned is high relative to cheap disposable masks but low relative to how bad covid is. Regarding looking weird, I can only point to our product reviews where users consistently find that they are, to their surprise, not treated like aliens: https://narwallmask.com/products/narwall-mask#reviews

Re; filtration, we link to a test data sheet showing that the filter material is tested by Nelson Labs, a major lab testing company. I'm not sure where you get the 0.4um or 1um numbers from - the particle size we test to is 0.1um, and the viruses used in Nelson Labs' VFE testing are much smaller than that (google "Nelson Labs VFE").

Back in the 70s or so, they thought 0.3um was the most difficult size particle to filter, which is why the standards test for that; since then, studies have shown that 0.1um is actually slightly more difficult, but everything in that range is near the bottom of the parabolas and tends to be very close.

I can try to link to some papers on this later but I'm on mobile right now.

Our size guide is next to the size selector on our website; I'll try to make that easier to find.

[MakeUsersWant]

Thanks for your reply. I've elaborated some in the grandparent. I am willing to pay for quality once it is rigorously demonstrated.

The safety issue comes down to this paragraph in your FAQ:

What is the filter material and how is it tested? Our filters are made in the USA with material tested to >99.997% VFE (viral filtration efficiency) by Nelson Labs. Another metric is PFE (particle filtration efficiency). The N95 standard for 0.3-micron PFE is >95.00%, while Narwall's filter material is tested to >99.50% 0.1-micron PFE. You can learn more about these particle sizes here.

The way I read it, you test for 3um (VFE is that according to https://fixthemask.medium.com/the-standards-for-face-masks-i...) and 0.1um, but not 0.3um. I'd be happy if you could point me to papers that those two sizes cover 0.3um and saturation issues.

Is there some kind of independent verification of efficacy and safety of the whole device, not just the mask?

As a minor point - the sticker price is closer to $820 (4 persons times mask and 6 months of filters and international shipping).

I am legally required to wear a medical-grade mask (FFP2 or surgical). Do you have an official-looking document to show to the authorities?

[rattray]

From the article linked:

> Bacteria ~ 3μm while viruses ~0.025μm in diameter

However, SARS-CoV-2 is estimated to be around 0.1um, per https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224694/#:~:tex....

> SARS-CoV-2 is an enveloped virus ≈0.1 μm in diameter

Making the 0.1μm measure more relevant.

Ultimately, it's up to your judgement whether to determine these filters are likely to be at least as useful as alternatives, bearing in mind that a poor seal/fit (which you may get with other masks) reduces effective filtration by quite a bit.

Apart from the aforementioned testing of our filter material, and the third-party fit tests (https://narwallmask.com/#h:testing), the CDC's National Personal Protective Technology Laboratory, under NIOSH, is currently assessing the mask but has yet to release results.

Another option you could pursue is a half-face elastomeric respirator with a surgical mask securely taped over the exhale valve, coupled with tight-fitting goggles. It may be less convenient and may or may not achieve the aesthetic properties you seek, but those masks have been around long enough to be evaluated by government bodies for their ability to protect the wearer (though, not the public).