on cleaning / reusing N95 masks

[orleans]

i thought i heard recently that they can be boiled or steamed to be sterilized but now i'm finding that they could could lose their effectiveness.

" Because N95 masks have that special static charge that helps filter out viruses, you shouldn’t wash the masks, as water will dissipate the charge, Marr said."
https://www.mercurynews.com/2022/01/14/how-long-you-can-wear-an-n95-mask-and-how-to-sanitize-it/

wapo has an article titled "How often can you safely reuse your KN95 or N95 mask?"

(with no paywall btw; "this article is free to access; The Washington Post is providing this news free to all readers as a public service." )

How many times can I reuse my mask?

“In the ideal world — or pre-pandemic — many masks were really viewed as single-use,” said Michael G. Knight, an assistant professor of medicine at George Washington University. “The reality is they do have a little bit more length in the amount of time we can use them.”

What’s crucial, Knight said, is making sure the mask has “maintained its integrity.” Think about how many times you’ve used it and for how long, he said.

“If I’m just putting a mask on to go to the grocery store for 45 minutes and I’m taking it off, that mask very well should be able to last me a couple of days,” he said.

But if you’re wearing a mask all day, such as during a long work shift where you may be sweating and talking all day to the point the mask becomes soiled, “then that may not be a mask that I can reuse.”

https://www.washingtonpost.com/health/2022/01/13/kn95-n95-mask-reuse-omicron/


(i was hoping i could steam it or boil it when it needs to get cleaned ... but i guess not)

[SYFROYH]

1. Probably better than nothing.

But my son gets a new individually wrapped KN95 each day for school.

And I use one each week.

[captain queeg]

2. I read you can put in the microwave. It was a video by a doctor but don't remember where

He said get a small microwave safe bowl or cup, put a mesh over it (like the stuff you see on bags of potatoes or oranges) and stretch out the mask over it. Use about 2oz of distilled water and have a low boil for 2 minutes. The husks I have are fairly rigid I don’t think I would need the mesh. But he also said just put a mask in a paper bag for 3 days and it can be reused. Since I don’t go out much that works for me. He said you could reuse 20 times if nothing serious happens during use.

Also, that little metal strip for your nose isn’t a problem for microwaving purposes.

[SheltieLover]

3. I've been reusing my N95s several times, regularly for 2 yrs

Put in paper bag for 2-3 days.

[JCMach1]

4. That tends to be car side pocket at my house, but whatever works

I assume the extreme Texas heat in vehicles actually doesn't hurt the bacterial situation (similar to microwave)

[SheltieLover]

5. Not sure

What docs told me is it's important to dry it out.

Pfffft - nothing is dry here. Humidity is near 100% when it's below freezing. 😓

[tavernier]

8. Yup same here in Florida

I dangle it in full sunlight as I walk from my job to my car and then set it up on the dash till next day. It cooks in the car for about 4 hours.

[we can do it]

12. That's pretty much what I do. Rotate a couple.

Most of us are not in health care situations. You put a mask on to run in store and back out. Even when I have one on for a couple hours. The virus does not live long on surfaces. It’s over kill with the disinfecting and other nonsense.

[Liberal In Texas]

6. Don't clean them.

When they get too bad or the straps start to loosen up, throw them out and replace them with a new one.

I use them once and was putting them in a paper bag for at least a week "to rest." I figure by that time any virus particles would be long dead. I was using one bag for every day of the week.

[ProfessorGAC]

7. While The Electret Aspect Is Crucial...

...the fibers are very tightly loomed, so the simple filtration absent any standing static charge, is still fairly effective.
You can wash them.
Are they going to meet KN95 standard after that? No. But, it's still a pretty efficient particle filter.

[Ms. Toad]

11. Absent the electrostatic filtration, I'd wear cloth.

My cloth masks are about a factor of 10x harder to breathe through - which tells me they are better at particle fitration. (I've also never had an issue with moist air coming through the mask fogging my glasses - and it happens on a daily basis with my KF94 (equivalent to an N95)

[ProfessorGAC]

14. I Wear Cloth

But, the porosity of cloth is still higher than the PP based 95s.
That said, most cloths (whether polyester or cotton) have a more relaxed spin of the fibers. So, there's more microscopic stragglers & frays. This effect actually substantially increases the overall surface area and decreases the % of free flow path.
That's why cloth masks are significantly more effective than some experts would have us believe. We've had posts here in GD quoting experts in virology or epidemiology overstating things, calling cloth masks essentially useless.
That's simply untrue.
They may be experts in their field, but those statements suggest they aren't experts in surface chemistry or separation science.
I'm with you, though. Doubling up a cloth mask provides substantial filtration, just not as good as 94s or 95s. But, still quite good.
I still occasional get some fogging, but more from the change in temperature. Happens now when I put the mask on going into a store. Cold here, of course.
I noticed the opposite in hot weather. Mask would fog when I went into the air conditioned store.
But, when I sub I don't have issues with it once everything equilibrates.
Back when working in a manufacturing site, if I was doing something potentially dangerous, I'd wear a full respirator. I couldn't wear half face, because of fogging. I had a full face with a special set of lenses that fit right onto the inside of the face glass. Worked great. Never had a fogging issue, but admittedly I didn't use it all that often.
In the lab, I rarely had to use anything because of the high efficiency laminar flow hoods.

[Ms. Toad]

16. The filtration of 2-layer 600 tpi cotton is as good as N95.

(Same with 2-layer quilter's cotton + another layer of a different to add the electrostatic filtration.) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7185834/ I've been fed up with people insisting they are worthless, especially quoting "experts" without research to back them up.

Since the filtration of 600 tpi cotton is as good as an N95 relying on two types of filtration, the N95 will be worse if you simply rely on the physical filtration having washed out the electrostatic filtration.

The relaxed spin of the fibers with microscopic stragglers & frays increases the efficiency of the pysical filtration - think adding more layers of swiss cheese (and, yes, the tight weave plus the meandering path air takes to pass through the mask is what makes it harder to breathe) .

The fogging I'm experiencing is from moist air coming through the face of the KN94 (which never happens with my cloth mask). I've checked for air flow around the nose - there is none (with either). But I can feel the air flow through the KF94 mask surface.

[FakeNoose]

9. Please stop tossing used facemasks onto sidewalks and city streets

It upsets me to see these things while I'm walking my dog in the neighborhood. It's ignorant behavior, but it's also forcing someone else to carefully pick them up off the street and discard them.

Sorry for the rant! I know it's not any DUers doing it.

[orleans]

10. i live among condo/apartment land with two strip malls

i've picked up numerous discarded masks to throw them away

pisses me off every time i have to clean up after someone else's shit -- especially those surgical masks!

(you certainly aren't the only one who doesn't want their dog going up to some asshole's mask)

[Demovictory9]

13. I saw a few on the ground near store today. Never sure if dropped accidently or just tossed