6 ms·

CDC now says valved N95 has better source control than cloth/surgical masks [pdf]

36 points by simpleguitar 6y ago

simpleguitar 6y ago
From the study: "FFRs with an exhalation valve provide respiratory protection to the wearer and—according to the findings from this study—can also reduce particle emissions to levels similar to or better than those provided by surgical masks and unregulated barrier face coverings. This study shows that modifications to these respirators can further reduce particle emissions. The use of an ECG pad or surgical tape secured over the valve from the inside of the FFR can provide source control similar to that of an FFR with no exhalation valve." And valved N95s are now around $2-3 each from established (not pandemic profiteering) online sources.
- sbinthree 6y ago
  Science: "wearing a thing in front of the air makes the air move slower and spread less, different things work to the extent the thing reduces the flow of air."
- kbelder 6y ago
  "surgical tape secured over the valve from the inside of the FFR can provide source control similar to that of an FFR with no exhalation valve." Well... yeah?
  - pauljurczak 6y ago
    A piece of duct tape works even better for source control...
  - SkyPuncher 6y ago
    I think you're under estimating how hard it is to actually get a proper seal with a piece of tape. The valved n95s I've seen are a bit fuzzy. You can certainly block most airflow, but there's still a small path at the intersection of the tape and mask that can't be properly sealed. For the layperson, that's fine. For a scientific study, that's a problem.
- Evil_Saint 6y ago
  Really? Who is selling n95's at that price point?
  - maxerickson 6y ago
    Costco has 100 packs for ~$3 per: https://www.costco.com/face-masks-coverings.html https://www.costco.com/face-masks-coverings.html Maybe a bit much for a household (100 masks I mean).
  - simpleguitar 6y ago
    search for N95 at zoro, costco online, digikey.
  - throwaway81523 6y ago
    https://www.safetyemporium.com/11156 https://www.safetyemporium.com/11156 I have some of these on order, not yet received. 20-pack of N95 for $30 plus $9 shipping to California. Shipping said UPS ground but they actually shipped by USPS priority mail which is faster, so I guess that's a good thing. They also have valved N99, at 12 for $25. wellbefore.com also has various brands of N95.
oalae5niMiel7qu 6y ago
Does this mean we'll be allowed to wear valved N95 masks on flights?
- rudolph9 6y ago
  I would just put a cloth mask over my valved N95 mask if I wanted to wear one on a flight. Someone probably won’t have got the memo, then you can avoid the whole conversation.
  - WheelsAtLarge 6y ago
    Agree 100%. You see this all over TV news. It makes total sense to wear 2 masks one with a valve and another over it. It protects both the wear and the people around. My one issue is that long term it's hard to wear both. Air restriction can be bad for the wearer. It's important to know this.
    - deleted 6y ago
      [deleted]
  - deleted 6y ago
    [deleted]
- FuckButtons 6y ago
  Last time I flew I put a surgical mask over my valved N95 that I had sealed with tape - no one asked any questions or asked me to wear anything different.
postalrat 6y ago
Cloth masks suck. Most people I see when surgical masks don't realize you should adjust it for your nose and have huge gaps all over.
- Daho0n 6y ago
  >and have huge gaps all over They are not supposed to be a tight fit. It is to stop virus/spit going directly into another persons face (or, originally, a wound). They aren't made to actually filter the air. If you want filtered air you need a N95 mask.
  - tguvot 6y ago
    check ASTM level 3 mask. Material for it has filtration similar to N95 but fit is not good. Hence was born this project https://www.fixthemask.com/ https://www.fixthemask.com/
- anonuser123456 6y ago
  At least they have it over their nose? 1 in 5 people I see can’t seem to manage that.
andred14 6y ago
Time for you to stop lying there is no emergency. Here we can see there was no large increase in deaths in Sweden or BC after 2020 compared to other years: https://www.statista.com/statistics/525353/sweden-number-of-deaths/ https://www.statista.com/statistics/525353/sweden-number-of-... https://www2.gov.bc.ca/gov/content/life-events/statistics-reports/deaths https://www2.gov.bc.ca/gov/content/life-events/statistics-re... https://drive.google.com/file/d/1DGHKhuyAKEKyaWGKIIWTcye_zUJ-Q4c4/view https://drive.google.com/file/d/1DGHKhuyAKEKyaWGKIIWTcye_zUJ...
ricardobeat 6y ago
I think this post's title is heavily editorialized, and is not reflected in the study's conclusion, which is quite confusing: With mitigation measures such as surgical tape or an ECG pad secured inside, the FFRs can perform nearly as well as an FFR with no exhalation valve Note "nearly as well". This will be contradicted by the conclusion. Also it's quite logical that if you tape over the exhaust valve, it will behave like a non-valved mask? When compared to models without valves: the maximum particle penetration through the unmitigated FFRs evaluated in this study was 55%, which occurred at 55 lpm, while the maximum penetration for surgical masks was 17% for the filter media and 76% when considering fit 17% seems quite a bit better than 55%. And then they conclude with FFRs with exhalation valves can reduce 0.35-μm MMAD particle emissions more consistently than surgical masks, procedure masks... followed immediately by: With mitigations that cover the exhalation valve, 0.35- μm MMAD particle emissions can be limited to 5% if the filter media does not interfere with providing a good seal to the exhalation valve 5% is where the number in N95 comes from, that's not any better? the exhalation valves could be improved by establishing criteria for valve performance Why would it matter to improve the valve design, if it's being covered? The conclusion is that taping with micropore performs just as well as a non-valved mask, but blocking the valve completely with an ECG pad performs better than not having a valve at all. How? Are there other design differences in valved masks that account for the difference? If I attach an ECG pad to the center of a non-valved mask would it improve performance?
- maxerickson 6y ago
  Why would it matter to improve the valve design, if it's being covered? The best valves filtered particles very well without any mitigation. If there was a standard there might not be anything to talk about (they could all be better than other masks). I think the statement about improving them is sort of misplaced in the flow (it's related to the containing paragraph and previous 2 paragraphs).
  - ricardobeat 6y ago
    > The best valves filtered particles very well without any mitigation That's not supported by the study: 17% max penetration for surgical masks vs 55% for valved masks without any 'mitigation'. They only perform similarly for inwards flow, which is expected when both have an N95 rating.
beerandt 6y ago
Study aside, this whole thing is absurd. A cloth (medical) mask is not what people are wearing. Nitpicking on differences in real, tested, filtered and/or non-woven and/or paper medical PPE... Might be useful. But not while 90% of the public are wearing woven-material marketed on any other product as being breathable. It's like debating head safety of NFL vs MLB, and then complaining about someone wearing a football helmet without a chinstrap, while you stand there in a baseball hat.
- thatguy0900 6y ago
  I remember etsy shutting down a few stores that were selling masks made out of a mesh that merely looked solid for getting into stores. I assumed a decent percentage of people were never wearing things significantly better than those anyway

36 points by simpleguitar 6y ago

From the study: "FFRs with an exhalation valve provide respiratory protection to the wearer and—according to the findings from this study—can also reduce particle emissions to levels similar to or better than those provided by surgical masks and unregulated barrier face coverings. This study shows that modifications to these respirators can further reduce particle emissions. The use of an ECG pad or surgical tape secured over the valve from the inside of the FFR can provide source control similar to that of an FFR with no exhalation valve." And valved N95s are now around $2-3 each from established (not pandemic profiteering) online sources.

sbinthree 6y ago
Science: "wearing a thing in front of the air makes the air move slower and spread less, different things work to the extent the thing reduces the flow of air."
kbelder 6y ago
"surgical tape secured over the valve from the inside of the FFR can provide source control similar to that of an FFR with no exhalation valve." Well... yeah?
- pauljurczak 6y ago
  A piece of duct tape works even better for source control...
- SkyPuncher 6y ago
  I think you're under estimating how hard it is to actually get a proper seal with a piece of tape. The valved n95s I've seen are a bit fuzzy. You can certainly block most airflow, but there's still a small path at the intersection of the tape and mask that can't be properly sealed. For the layperson, that's fine. For a scientific study, that's a problem.
Evil_Saint 6y ago
Really? Who is selling n95's at that price point?
- maxerickson 6y ago
  Costco has 100 packs for ~$3 per: https://www.costco.com/face-masks-coverings.html https://www.costco.com/face-masks-coverings.html Maybe a bit much for a household (100 masks I mean).
- simpleguitar 6y ago
  search for N95 at zoro, costco online, digikey.
- throwaway81523 6y ago
  https://www.safetyemporium.com/11156 https://www.safetyemporium.com/11156 I have some of these on order, not yet received. 20-pack of N95 for $30 plus $9 shipping to California. Shipping said UPS ground but they actually shipped by USPS priority mail which is faster, so I guess that's a good thing. They also have valved N99, at 12 for $25. wellbefore.com also has various brands of N95.

oalae5niMiel7qu 6y ago

Does this mean we'll be allowed to wear valved N95 masks on flights?

rudolph9 6y ago
I would just put a cloth mask over my valved N95 mask if I wanted to wear one on a flight. Someone probably won’t have got the memo, then you can avoid the whole conversation.
- WheelsAtLarge 6y ago
  Agree 100%. You see this all over TV news. It makes total sense to wear 2 masks one with a valve and another over it. It protects both the wear and the people around. My one issue is that long term it's hard to wear both. Air restriction can be bad for the wearer. It's important to know this.
  - deleted 6y ago
    [deleted]
- deleted 6y ago
  [deleted]
FuckButtons 6y ago
Last time I flew I put a surgical mask over my valved N95 that I had sealed with tape - no one asked any questions or asked me to wear anything different.

postalrat 6y ago

Cloth masks suck. Most people I see when surgical masks don't realize you should adjust it for your nose and have huge gaps all over.

Daho0n 6y ago
>and have huge gaps all over They are not supposed to be a tight fit. It is to stop virus/spit going directly into another persons face (or, originally, a wound). They aren't made to actually filter the air. If you want filtered air you need a N95 mask.
- tguvot 6y ago
  check ASTM level 3 mask. Material for it has filtration similar to N95 but fit is not good. Hence was born this project https://www.fixthemask.com/ https://www.fixthemask.com/
anonuser123456 6y ago
At least they have it over their nose? 1 in 5 people I see can’t seem to manage that.

andred14 6y ago

Time for you to stop lying there is no emergency. Here we can see there was no large increase in deaths in Sweden or BC after 2020 compared to other years: https://www.statista.com/statistics/525353/sweden-number-of-deaths/ https://www.statista.com/statistics/525353/sweden-number-of-... https://www2.gov.bc.ca/gov/content/life-events/statistics-reports/deaths https://www2.gov.bc.ca/gov/content/life-events/statistics-re... https://drive.google.com/file/d/1DGHKhuyAKEKyaWGKIIWTcye_zUJ-Q4c4/view https://drive.google.com/file/d/1DGHKhuyAKEKyaWGKIIWTcye_zUJ...

ricardobeat 6y ago

I think this post's title is heavily editorialized, and is not reflected in the study's conclusion, which is quite confusing: With mitigation measures such as surgical tape or an ECG pad secured inside, the FFRs can perform nearly as well as an FFR with no exhalation valve Note "nearly as well". This will be contradicted by the conclusion. Also it's quite logical that if you tape over the exhaust valve, it will behave like a non-valved mask? When compared to models without valves: the maximum particle penetration through the unmitigated FFRs evaluated in this study was 55%, which occurred at 55 lpm, while the maximum penetration for surgical masks was 17% for the filter media and 76% when considering fit 17% seems quite a bit better than 55%. And then they conclude with FFRs with exhalation valves can reduce 0.35-μm MMAD particle emissions more consistently than surgical masks, procedure masks... followed immediately by: With mitigations that cover the exhalation valve, 0.35- μm MMAD particle emissions can be limited to 5% if the filter media does not interfere with providing a good seal to the exhalation valve 5% is where the number in N95 comes from, that's not any better? the exhalation valves could be improved by establishing criteria for valve performance Why would it matter to improve the valve design, if it's being covered? The conclusion is that taping with micropore performs just as well as a non-valved mask, but blocking the valve completely with an ECG pad performs better than not having a valve at all. How? Are there other design differences in valved masks that account for the difference? If I attach an ECG pad to the center of a non-valved mask would it improve performance?

maxerickson 6y ago
Why would it matter to improve the valve design, if it's being covered? The best valves filtered particles very well without any mitigation. If there was a standard there might not be anything to talk about (they could all be better than other masks). I think the statement about improving them is sort of misplaced in the flow (it's related to the containing paragraph and previous 2 paragraphs).
- ricardobeat 6y ago
  > The best valves filtered particles very well without any mitigation That's not supported by the study: 17% max penetration for surgical masks vs 55% for valved masks without any 'mitigation'. They only perform similarly for inwards flow, which is expected when both have an N95 rating.

beerandt 6y ago

Study aside, this whole thing is absurd. A cloth (medical) mask is not what people are wearing. Nitpicking on differences in real, tested, filtered and/or non-woven and/or paper medical PPE... Might be useful. But not while 90% of the public are wearing woven-material marketed on any other product as being breathable. It's like debating head safety of NFL vs MLB, and then complaining about someone wearing a football helmet without a chinstrap, while you stand there in a baseball hat.

thatguy0900 6y ago
I remember etsy shutting down a few stores that were selling masks made out of a mesh that merely looked solid for getting into stores. I assumed a decent percentage of people were never wearing things significantly better than those anyway