Lots of people would like unobtrusive respiratory protection, and nostril filters are an attractive option, or they *could be* if they work, and if you only breathe in through your nose.
🧵
I was given these by Amazon to review. They are from O2 Armor, who provide more filter data than most companies. But check their wording and compare it to their filtration efficiency graph..."up to" is doing a lot of heavy lifting.
You can see in these macro photos how loose the weave of the nostril filter is to make it breathable at such a small size. Compare that to the Drager N95 filter shown at the same magnification.
Electrostatic attraction can make a filter work better than it looks, however...
I got the perhaps lowest filter-only score I've ever tested:
Fit Factor 1.2
17% filtration efficiency
(I made a jig to test the nostril filters directly with a PortaCount at 0.7 liters of airflow per minute. Penetration would be way higher at the 85 lpm NIOSH test airflow.)
The 17% filtration efficiency score is consistent with seller's filtration efficiency chart and the sub-micron counting range of the PortaCount.
Better than nothing, but not much. So avoid risk compensation and don't take on any extra risks if you use these.
Wear a good respirator that fits you well instead of nostril filters when at all possible. The difference in protection is orders of magnitude.
3M Aura and Drager trifold N95s are good respirators to try that fit most, but not all, people well and are very protective.
I didn't test these in my nose because there isn't a way to sample the air above the nostril filters short of a big nose piercing, so I didn't test fit, just filtration. More on that in a later Tweet.
O2 Armor have a pretty detailed write up with test data. They seem to come to opposite conclusions about the utility of their nostril filters based on that data than I do.
If you are thinking, that's just salt, not viruses, not to worry. Scientists have tested N95s using real viruses using an international standard test called Viral Filtration Efficency (VFE). N95s filter viruses extremely well.
Can you make a cheap Amazon Plague Mask into an effective tight fitting PAPR mask?
Yes, yes you can. If you happen to already have a bunch of stuff everyone totally has lying around their home:
I've also done a 4 exercise OSHA fit test in this hacked Plague PAPR mask and passed - well, I got a great fit factor but the hacked mask isn't OSHA compliant, nor is fit testing a PAPR with the blower on, so some might say it didn't pass. 🤔
I may put together a longer video in horizontal format, the one I originally shot, but I'm trying to make my videos less boring and am giving YouTube shorts a try. 😅
More from @NIOSH's Respiratory Protection Week presentation by Susan M. Moore, NPPTL Associate Director for Science:
Respirator fit solutions for people with beards.
The Singh Thattha technique can help, but it is not yet OSHA approved. NIOSH is studying this method.
Currently OSHA fit test regulations require smooth skin at the respirator seal, as shown in this graphic.
But some people have beards for cultural, religious and even health reasons that are incompatible with those regulations. Solutions are needed for equitable safety.
Facial hair has a demonstrable effect on respirator seal and protection, and some masks work better with facial hair than others even without special methods to improve the seal, but it isn't really about whether they are KN95 or N95 or KF94, but individual mask models and design
Thoughts about @NIOSH's Respiratory Protection Week presentation by Susan M. Moore, NPPTL Associate Director for Science:
The presentation showed current and future source control respirators, including a NIOSH exemplar model source control elastomeric mask for HCWs.
I was glad to see elastomeric source control respirators highlighted. Dr. Moore referenced industry creating source control elastomerics for the pandemic. But the 3M mask with the exhalation filter shown is a bit of a mixed bag.
3M created an exhalation filter that fits on a single model of 3M mask, the 6000 series half mask respirator, a good but lower end model with no speech diaphragm. The filter was a good emergency stopgap, but not a good long term solution.
ReadiMask is still selling old stock stick on N95mmasks from ~4 years ago, made before NIOSH approval with no warning about whether the adhesive may have degraded over time.
How old is the other mask stock they are selling? And has the adhesive degraded?
The Readimasks I have don't seem to be adhering as well as when I bought them. I managed to supplement the adhesive with Mastisol liquid adhesive supplied by @findmeabluebird, but I'd like Readimask to be more transparent about the age of their stock.
Is there a way we can monitor how well the adhesive is holding up over time? Can we objectively measure how the adhesion? This standardized method looks good but seems very expensive. And I'm not sure if stainless steel is analogous to skin.
Are valved masks cooler? I tested 3 different 3M N95s to try to learn more about the effect of valves on heat in respirators.
Not much mathematical difference on average, under these specific conditions, with these 3 masks:
V-Flex +7.3°C
Valved Aura +7.3°C
No Valve Aura +7.5°C
I expect that results could vary dramatically under different conditions, including temperature, humidity, airflow rate, mask model and more. Even so, I was surprised that the valve didn't make a more substantial difference in average in-mask temperature.
I also tested valved and unvalved Auras during 15 minute outdoor walks in mixed shade and sun and got a similar lack of difference in average in mask temperatures (using different testing gear with 10 second intervals between samples).