Originally Posted by ABN_CBT_ENGR
Yeah and from the article
Conclusions: The study indicates that N95 filtering facepiece respirators may not achieve the expected protection level against bacteria and viruses.
Here's why
It was testing AEROSOL (the carrier) with a model virus. Once the carrier saturates the media even at the particulate level ( like these masks are very thin and 1 pass) then it actually alters the filtering capability ( like a wet napkin) and its compromised.
It also says
When testing at an inhalation flow rate of 85 l min−1, the penetration of MS2 virions (0.01-0.08 μm) through the N95 respirator filter exceeded 5%. For surgical masks, the penetration was much higher and varied from 20.5 to 84.5%. In these studies, the respirators were sealed on a manikin face to account only for particles penetrating through the respirator filter material. However, airborne particles can also enter the respirator cavity through face-seal leaks and be subsequently inhaled into human respiratory systems.
What that means in non techno English is that in a situation like a medical procedure where there is minimal exposure and minimal time and then the filter is changed out- there is an "acceptable" degree of protection from contact from an agent working through the filter from the carrier.
Nobody disputes that under those conditions.
But to believe that this is wear 'all day" and in all circumstances a valid "protection" as is currently being pronounced is not correct. Then to believe a piece of cloth ( forget sub micron filtration with a cut up Tee shirt) is also "acceptable"?
The difference is that those who have actually done these things in real world applications have a little greater depth of understanding that reading an article and not recognizing that it doesn't answer everything and are often conditional in the findings.
See theres a reason there are those big layered filters and complex valves on military grade equipment and we aren't issued nose cups.
I think others have basically been saying it's worthless but it's not. They're also supposed to change masks between patients. The only reason they're wearing them all day is because they don't have enough, not because it was some accepted science. All they're doing is making do with what they have, not going by best practices.
But because it's not completely effective, I don't find that to be grounds for not using them at all. No one every claimed that they were completely effective and we were just talking about N95 mask, the surgical ones aren't as good and mainly the recommendation for that one was basically to stop people who were sick but didn't know it from spreading it around. Only reason for cloth masks is that there isn't enough N95 and surgical masks to go around to everyone. That's just based on the theory that something is better than nothing. I think some are putting filters inside the cloth masks so depending on the material used, it could be close to a surgical one.