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Comment by rattray | Hacker News Reader

Speaking as the creator of a high-quality mask (eye protection, good seal, >99.99% viral filtration efficiency filters), the lack of guidelines on what makes for a good mask have been flabbergasting. And what is there is incredibly lackluster - usually nothing very good on how to check your seal, or about eye protection, or about ensuring your filters are still any good on a disposable mask.

I honestly can't believe that at this point in the pandemic, full-face respirators haven't been adapted to have exhale filters and widely distributed. I think our product (https://narwallmask.com) is still the only such device, and I'm just some software engineer who thought to do something.

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Probably because hospital staff are the ones who would afford it and truly benefit. Maybe some patients there. It's probably too late for most of them.

Single use masks are much easier, but indeed there's a lot of mask-like products that have enough leakage to let a tank through, or have an unfiltered vent which is unacceptable.

I found you while researching how to verify a mask is good as an end-user, because I cannot get a good seal out of any of the six types of FFP2-masks I have tried. On the one hand, I've always been on the lookout for something similar. On the other hand, there are a few showstoppers that keep me from buying.

* Looks. Even if I can decide to look like the Reddit alien in a motorcycle helmet while everybody else is wearing an FFP2 mask, there is no way I can persuade my wife or kids. Would it be possible to make the exhaust pipe a bit more inconspicuous? E.g. inhale from the left cheek, exhale to the right cheek?

* Filtration efficiency and trust. There is a reason the FFP2/FFP3 standards test with 0.3um sized particles - those are the most difficult to filter out. Your marketing copy talks about 0.4um and 0.1um, and the headline screems about 3um large virus particles, which are even less relevant. Even though the 0.4um numbers look close to FFP3, any official certification is missing. Is it safe to say that your product does not meet the FFP2 standards?

Additionally, I'd love a mask that does not saturate out within minutes if I am panting (from chasing after kids).

https://fixthemask.medium.com/the-standards-for-face-masks-i...

* Sizing. How do I know which size I need? Maybe you could publish a guide like the CPAP mask manufacturers do. https://www.resmedshop.de/media/pdf/b1/e4/06/ResMed-AirFit-F... https://www.resmedshop.de/media/pdf/03/b0/57/ResMed-AirFit-F...

* Facial expressions. If you could make the mouth covering transparent, it would show my mimics in a conversation. That could be a killer feature, especially for socializing (or salesy jobs).

* Glasses and field of vision.

* Sticker price shock. Most FFP2/KN95 masks are counterfeit and none have a good seal, so I might as well grab the ones for $0.17 a piece from aliexpress. But, I am already spending much more on other Covid safety measures.

EDIT: Can you give me an accessible way to experience the mask's safety? So far, the best criterion I have come up with is if I can smell the smoke when I'm standing next to a smoker. In defense of that metric: There are absolutely no credible alternatives proposed on the internet. Mask fit used to be tested officially with noxious smoke. Cigarette smoke particles are pretty close in size to the virus-laden droplets. But in practise, an FFP2 mask passes this test only if I tape over all of its edges with a band-aid, and my skin won't tolerate that day-in day-out.

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.

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?

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).

Responding to your edit, yes, we do provide a simple way to evaluate the mask's safety on your person; a negative pressure test: https://narwallmask.com/pages/usage-guide#h:negative-pressur...

This makes it easy to tell that you have a complete seal.

The fact that your existing masks do not pass without tape indicates that you do not have a seal, and the filtration numbers you're seeing are reduced by many percentage points (eg; from 95% to 90% or lower) as air enters the mask unfiltered through the sides.

I have not performed the cigarette test myself, and haven't seen information indicating it is a reliable covid test, but you are certainly welcome to try it with a Narwall! I'd be keen for your results, and could provide a discount in exchange for the information.

For me, the Narwall's main value proposition beyond a standard FFP2 respirator is a super tight seal. Smoke is probably the best proxy I can test that with.

Would you be open to a full refund if I order it and can still smell cigarette smoke?

Would a negative pressure test suffice? (See our website). Smoke may have a false negative, as odorants are many times smaller than the target challenge particles.

Unfortunately not. There is a huge safety difference between a negative pressure test ("fit check" below) and a test with an actual aerosol ("qualitative fit test"). All of the FFP2 respirators I have checked pass one and fail the other. I am hoping the Narwallmask can fill this gap.

From https://associationofanaesthetists-publications.onlinelibrar...

Due to the associated time and costs, some health officials propose the elimination of fit testing and advocate that a fit check is sufficient in determining respirator fit [39]. The NIOSH conducted a study that demonstrated protection of N95/FFP2 masks improved from 67% without fit testing to 96% with fit testing [40]. Subsequently, NIOSH determined fit check alone to be insufficient and fit testing should be mandatory when selecting filtering facepiece respirators or elastomer half mask respirators.

Three studies that included 1111 Asians assessed the ability of fit check to detect leak determined by a quantitative fit test [36, 41, 42]. Average (range) sensitivity and specificity of the fit check to correctly detect leak were 26 (14–40)% and 79 (58–92)%, respectively, and consequent average (range) fit test pass rate following ‘successful’ fit check was 56 (34–73)%. Another study found the protection factor of filtering facepiece respirators increased from 3.3 to 20.5 when comparing the results of the entire test panel with those who had passed the fit test [32]. However, non‐fitted filtering facepiece respirators are still likely to provide greater protection than surgical masks, with a measured protection factor of 1.2 (Table 1) [32].

In summary, while fit check remains recommended before each use of any respirator to ensure fit on a day‐to‐day basis (Grade 1C evidence), we recommend not to use fit check as a substitute for fit testing to identify the size and shape of respirator that fits best (Grade 1B evidence).

Thank you, I hadn't seen this!

For what it's worth, I think we provide tools to perform more accurate fit checks than are possible with other masks, but of course I don't have data to back that up, and this is a situation that warrants caution.

You can perform a standard fit test (eg; with Bitrex) with a Narwall, by the way, or a home-jury-rigged one, like this customer did: https://cdn.shopify.com/s/files/1/0264/5311/4970/files/Tim-s...

The smoke check sounds like a great idea too, I just can't confirm that it will produce a true result for Narwall since we haven't specifically evaluated that methodology.

Even if we can't accept a full return because the mask has been tried on, we always offer partial refunds at least when a customer isn't satisfied for any reason, if that's any help.

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