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Current thoughts on reusing KN95s and the like?


kokotg
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DH has been wearing KN95s to school because apparently I'm never going to be able to get Happy Masks again (I'm on the restock list, and I've tried twice through that and gotten shut out within 2 minutes of it opening). What's the latest on whether/how they can be reused? He's been letting them sit in a bag for a week and then reusing once...is that okay? too conservative? not conservative enough? I've tried googling, but I'm mostly finding stuff aimed at health care workers and N95s from very early on when there were supply issues. There are no supply issues now, just "damn, I'm spending a lot on masks!" issues. 

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For HCWs who theoretically wear properly fitted N95s, we’re told we can wear them as long as they’re easy to breathe through. Which seem an odd standard to this HCW. Before I got my respirator I rotated my two N95s every shift (3 days).

I imagine he can reuse them more than once. HCWs certainly are. 

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We reuse them unless dirty or hard to breath through per the listing on the KN95 site we buy from.  But for things like a sweaty dance class or something we might not.  Depends on what the kid said. 

Powecom KN95 - Headband Style - FDA Authorized (bonafidemasks.com)

  • Make sure to discard the face mask when it becomes visibily ditry or breathing resistance increases remarkably.

 

Here are the same ones we buy cheap

A 10 pack for $5

Powecom Non Medical Disposable KN95 Respirator Face Masks Adult Size Pack Of 10 - Office Depot

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We reuse. We let them properly dry and age. As long as they are easy to breathe through, not visibly soiled, and the fit is still good (the straps tend to stretch out after a few wears), we consider them ok to use.  Some of us are averaging 5+ wears, others are wearing much longer.  

And, yeah, I hear you on the $$$ of keeping multiple family members in higher quality masks.

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I do.

Officially, n95s are single use.  But as Brehon said, many of us were required to re-use them professionally in healthcare.

The issues with re-use are 1) self-contamination when doffing and donning, 2) mask degradation (mostly straps stretching out) and 3) soil (with your own sneeze in the mask, etc)

I put mine in mask quarantine A.K.A. a paper bag for a few days between uses to decrease self-contamination risk.  I throw out when straps are stretched out or the mask is soiled.  I get maybe 5 uses per mask?  Maybe more if uses are short.  Strap-stretching and sneezing are my issues.

 

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I decontaminate our N95's in the instant pot, but then I had an instant pot I was using to "sterilize" trach tubes and similar things before the pandemic. I don't know that I'd want to do this in an instant pot that was also used to cook food, because food smell would make it's way into the mask.

https://www.verywellhealth.com/instant-pot-to-clean-your-mask-5074455

My FIL runs a construction business that used a huge number of N95's before the pandemic.  We donated a lot, but we also have had a supply throughout the pandemic. 

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52 minutes ago, Bootsie said:

In Italy, masks are required on trains and you are supposed to change masks every four hours.  What happens at the 4-hour mark?  Just a build up of moisture?

WHO recommends changing after four hours based on a study conducted on mask tolerance. The report was published in March(?) 2020z Self contamination from touching the mask jumped at that point.

France has a similar recommendation. 

 

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Aaron Collins’s test data on KF94s showed only small drops in efficiency with used KF94s, with ones that had gotten wet affected the most (this included treating with alcohol). We’re talking from 99+ % filtration to 90-98+% filtration, depending on the conditions. I would throw away one that got wet and I do the paper bag rotation thing and reuse after they have sat for awhile. 
 

I can dig up his test data spreadsheet link, if it’s helpful. 

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We are wearing (and rotating) KF94s daily right now. Is it advisable to throw out masks that have been in potentially higher exposure areas like airports, or given several days is it ok to reuse those? I had planned to toss them but I guess if HCWs are reusing theirs, maybe I don’t need to throw them out? 

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I just received Be Healthy masks and had Dd use it instead of the Happy Mask or Enro mask. I find it more comfortable bc it's stiffer creating a pocket of space. She used the one that looks just like the AoPS design on the book and wants to reuse it after using it for about 7 hours indoors. I'm planning to air it out for a week, and it doesn't look dirty, so I'm fine if she uses it one more time. 

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When I was reusing KN95s I had a system to keep track of them. 

For one week, each day I would wear a new mask. At the end of the day, I would spray it 3 times on the inside and outside with 70% rubbing alcohol and set it in a bin. When the last one was dry, I would put all of them in a plastic bag and label them. "sprayed with alcohol 1x use"
The next week, I would reuse these masks that had all been used once prior. The alcohol kept them fresher. I would repeat the process (labeling this bag 2x use) and eventually used them all 3 times at work. I am sure I could have used them more, but after 3 uses of 8-10 hour days, they aren't fresh anymore and I work in pharmacy where we have a lot of exposure so it was important to me to be most protected there.

After using them at work 3x, I would then toss these masks in the car to be used as needed until they were hard to breath through or dirty. I used a sharpie on the inside by the ear loop to put an initial on them so we knew whose was whose.  When I had too many for the car, I would put the bags in a bin and save them for reuse later if I needed them. I also have used them around the house for things like sanding or working in the yard (when kicking up lots of dirt). 

The other day, I grabbed one that was in a bag that hadn't been sprayed with alcohol yet. It was amazing to me, how much different the alcohol spray really did keep some odors down. It wore it for the time I needed to, and then tossed it.

Edited by Tap
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I don't know what the verdict on alcohol overall is, if people do just a spray. Aaron Collins tested a mask that had been "soaked in alcohol" and it dropped to 86.7% efficiency, which is a bigger drop than with the mask that was soaked just in water (dropped to 96.3%). I just let mine sit, since the virus doesn't seem to persist on surfaces for a very long time, particularly outside lab conditions.

Test data:

Mask Data Set

eta: Oh! I see he just added Enro test data. They didn't do nearly as well as the KF94s, unfortunately (much better than surgical, though. 69.2% as worn normally, increasing to 75.2% when sealed to the face (I haven't found his video yet to know what that test condition entailed).

Edited by KSera
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1 minute ago, KSera said:

I don't know what the verdict on alcohol overall is, if people do just a spray. Aaron Collins tested a mask that had been "soaked in alcohol" and it dropped to 86.7% efficiency, which is a bigger drop than with the mask that was soaked just in water (dropped to 96.3%). I just let mine sit, since the virus doesn't seem to persist on surfaces for a very long time, particularly outside lab conditions.

Test data:

Mask Data Set

That is interesting. I haven't heard of anyone soaking them in alcohol (odd choice since they are essentially paper). I guess that makes sense in extreme cases of reusing them. 

For me, the alcohol helped with odors and with keeping them fresh after use. I don't soak mine, but just spray them. When you are eating and drinking, cleaning/stirring up dust, and wearing the mask for 8-10 hours....they aren't so fresh the next day if you don't spray them. They may lose a bit of efficacy, but they stay fresher and I am more likely to reuse them.  I am sure front line workers a year ago who are actively caring for patients and only have the one mask were grateful for anything, but now we can buy them easily, so I don' reuse to the same extent. 

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24 minutes ago, KSera said:

I don't know what the verdict on alcohol overall is, if people do just a spray. Aaron Collins tested a mask that had been "soaked in alcohol" and it dropped to 86.7% efficiency, which is a bigger drop than with the mask that was soaked just in water (dropped to 96.3%). I just let mine sit, since the virus doesn't seem to persist on surfaces for a very long time, particularly outside lab conditions.

Test data:

Mask Data Set

eta: Oh! I see he just added Enro test data. They didn't do nearly as well as the KF94s, unfortunately (much better than surgical, though. 69.2% as worn normally, increasing to 75.2% when sealed to the face (I haven't found his video yet to know what that test condition entailed).

Here's the Enro video if anyone is interested. I haven't actually finished watching it (running it in the background because it's a live testing video showing the whole process, so it's long). I didn't realize the Enro filter isn't edge to edge. I wonder how they thought they would get 99% efficiency with a filter that wasn't edge to edge? 🤔 Enro Mask testing video

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And Enro invites customers batch by batch and if you don't buy after the second invite, you are dropped to the back of the line. I had DH wear theirs on a 5 hour flight thinking it was safer than other masks. Happy Masks doesn't fit from top of the nose to the button of the chin for him, but Enro does.

ETA: And there's no air pocket with Enro, it just lays on my face, which I can't stand. But I use it when I need to go in and out of a store. 

Edited by crazyforlatin
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10 minutes ago, crazyforlatin said:

And Enro invites customers batch by batch and if you don't buy after the second invite, you are dropped to the back of the line. I had DH wear theirs on a 5 hour flight thinking it was safer than other masks. Happy Masks doesn't fit from top of the nose to the button of the chin for him, but Enro does.

ETA: And there's no air pocket with Enro, it just lays on my face, which I can't stand. But I use it when I need to go in and out of a store. 

Well, it would still be safer than a lot of things, and performs like the better performing surgical masks. But it's a lot to spend for something that doesn't work nearly as well as KF94s (or KN95s, but those you have to be more careful on sourcing). I hadn't seen how the Enro is built until watching the video, and the results aren't surprising in light of seeing that the filter is only in the middle section and it has a wimpy nose wire. I have a Happy Mask that I find has a very wimpy nose wire as well, so I rarely use it except occasionally if I need to just put on a mask quick for something like getting a curbside pickup outside. He hasn't tested the Happy Mask yet, though. I've been mostly using only KF94s since I switched in January, though. Much more comfortable than my cloth masks I made at the beginning.

I've watched through the Enro test part now. It starts at ~29:20 on the above video link two posts before this. If you're not familiar with his test procedure, the first part of the video explains more about his test setup. He uses a test aerosol and measures concentration as worn inside the mask, and repeats controls every time. He has no stake in any of this except wanting transparent data. It made me lol in this video when he said they need more people testing masks, because it shouldn't just be him in his bathroom. Truth.

Edited by KSera
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1 hour ago, crazyforlatin said:

And Enro invites customers batch by batch and if you don't buy after the second invite, you are dropped to the back of the line. I had DH wear theirs on a 5 hour flight thinking it was safer than other masks. Happy Masks doesn't fit from top of the nose to the button of the chin for him, but Enro does.

ETA: And there's no air pocket with Enro, it just lays on my face, which I can't stand. But I use it when I need to go in and out of a store. 

We’ve been wearing KF94s sometimes all day recently (including flying overnight). Yesterday DS and DH wore their Enro masks instead and both declared them much less comfortable after a short while. Both found them to fit well for something like quick trip to a shop, but not for walking and trying to hold a conversation. We all find the Posh/Be Healthy KF94s so comfortable we literally forget we are wearing them. 

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1 hour ago, MEmama said:

We’ve been wearing KF94s sometimes all day recently (including flying overnight). Yesterday DS and DH wore their Enro masks instead and both declared them much less comfortable after a short while. Both found them to fit well for something like quick trip to a shop, but not for walking and trying to hold a conversation. We all find the Posh/Be Healthy KF94s so comfortable we literally forget we are wearing them. 

I wear the BeHealthy masks for teaching all day and they're great. 

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My kids and I have noticed that there is a lot more humidity buildup inside our 3M N95s than the KF94s we have (Bluna, Dr. Puri). It’s especially noticeable hours 4-8…not a big deal before then. On school days my kids are in masks for 8 hours. One wears a N95 for better fit, one wears a KF94. (All of us trialed all styles for full days before school started.) Both are eating outside for lunch—taking a 15 min mask break then to rehydrate and breathe freely while they eat before they head back in to school. Because the masks are getting such heavy wear, we give them a good week off between wears; we have day color tags made of washi tape to keep track of them in their holders.

Edited by prairiewindmomma
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