4 ms·

If Your Mask Has a Valve, It's Half Useless

10 points by miked85 7y ago

projektfu 7y ago
Data or GTFO. I’m not sure if there are studies showing this to be true, but the existence of authorities saying it is is really not enough. I’d be happy with mechanical data, but actual droplet data would be better.
- _bxg1 7y ago
  It's an intentional feature of the product, though? It sounds like they're specifically designed not to obstruct exhalation. Why would you be skeptical of that?
  - projektfu 7y ago
    Because that fact doesn’t mean it doesn’t protect against spreading.
    - _bxg1 7y ago
      "The fact that this hammer is heavy and shaped for hammering things doesn't mean it will drive nails. Data or GTFO."
      - projektfu 7y ago
        Almost everything in medicine ends up being surprising. So much "knowledge" is just someone's assumption being passed as gospel only to be discovered false years later. Medicine isn't an engineering problem. There is an analogy in software engineering where people argue about the most "efficient" way to do something and don't bother profiling it with real world data. There are consequences to advising people that their masks are half worthless, if it is not true. People might not be willing to wear valveless N95 masks. Or they take those masks off more and expose themselves more. Asking for a little data behind a recommendation is more than reasonable.
tenken 7y ago
But there's a pm2.5 filter insert that covers the Whole mouth portion between cloths. Yes there is an airhole, but there's a filter snug up against the whole airhole ....
beerandt 7y ago
This author has no business writing on this subject if she can't even get the basic terminology correct. There's a difference between a mask and a respirator. To over simplify, one deflects and one filters. Masks don't have valves, respirators (sometimes) do. A valved n95 respirator is essentially acting as a respirator (filter) while inhaling, and as a mask (deflector) while exhaling. Calling valved respirators half useless implies that masks are wholly useless. Neither surgical masks or cotton/other homemade masks (or valved respirators) are designed to filter exhaled breath; in fact, most of the air goes around surgical masks, but droplets hit and stick to the mask based on the same principles of bugs hitting a windshield. And that's all they're designed to do- retain/deflect droplets/particles expelled by the wearer. Valved respirators still do this. Even the tiny gap in the open valve usually is filtered, just not to n95 levels. Of course all of this presumes the user is using the PPE correctly in the first place. If you don't know the difference between a mask and a respirator, I can almost guarantee you're using yours wrong.

10 points by miked85 7y ago

Data or GTFO. I’m not sure if there are studies showing this to be true, but the existence of authorities saying it is is really not enough. I’d be happy with mechanical data, but actual droplet data would be better.

_bxg1 7y ago
It's an intentional feature of the product, though? It sounds like they're specifically designed not to obstruct exhalation. Why would you be skeptical of that?
- projektfu 7y ago
  Because that fact doesn’t mean it doesn’t protect against spreading.
  - _bxg1 7y ago
    "The fact that this hammer is heavy and shaped for hammering things doesn't mean it will drive nails. Data or GTFO."
    - projektfu 7y ago
      Almost everything in medicine ends up being surprising. So much "knowledge" is just someone's assumption being passed as gospel only to be discovered false years later. Medicine isn't an engineering problem. There is an analogy in software engineering where people argue about the most "efficient" way to do something and don't bother profiling it with real world data. There are consequences to advising people that their masks are half worthless, if it is not true. People might not be willing to wear valveless N95 masks. Or they take those masks off more and expose themselves more. Asking for a little data behind a recommendation is more than reasonable.

tenken 7y ago

But there's a pm2.5 filter insert that covers the Whole mouth portion between cloths. Yes there is an airhole, but there's a filter snug up against the whole airhole ....

beerandt 7y ago

This author has no business writing on this subject if she can't even get the basic terminology correct. There's a difference between a mask and a respirator. To over simplify, one deflects and one filters. Masks don't have valves, respirators (sometimes) do. A valved n95 respirator is essentially acting as a respirator (filter) while inhaling, and as a mask (deflector) while exhaling. Calling valved respirators half useless implies that masks are wholly useless. Neither surgical masks or cotton/other homemade masks (or valved respirators) are designed to filter exhaled breath; in fact, most of the air goes around surgical masks, but droplets hit and stick to the mask based on the same principles of bugs hitting a windshield. And that's all they're designed to do- retain/deflect droplets/particles expelled by the wearer. Valved respirators still do this. Even the tiny gap in the open valve usually is filtered, just not to n95 levels. Of course all of this presumes the user is using the PPE correctly in the first place. If you don't know the difference between a mask and a respirator, I can almost guarantee you're using yours wrong.