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N95 respirators, which are widely worn by health care workers treating patients with COVID-19 and are designed to be used only once, can be decontaminated effectively and used up to three times, according to research by UCLA scientists and colleagues.
An early-release version of their study has been published online, with the full study to appear in September in the journal Emerging Infectious Diseases.
[...] "Although N95 respirators are designed for just one use before disposal, in times of shortage, N95 respirators can be decontaminated and reused up to three times," said James Lloyd-Smith, a co-author of the study and a UCLA professor of ecology and evolutionary biology. "But the integrity of the respirator's fit and seal must be maintained."
[...] The masks treated with vaporized hydrogen peroxide experienced no failures, suggesting they potentially could be reused three times, Lloyd-Smith said. Those treated with ultraviolet light and dry heat began showing fit and seal problems after three decontaminations, suggesting these respirators potentially could be reused twice.
The study authors concluded that vaporized hydrogen peroxide was the most effective method because no traces of the virus could be detected after only a 10-minute treatment. They found that ultraviolet light and dry heat are also acceptable decontamination procedures, as long as the methods are applied for at least 60 minutes.
Journal Reference:
Robert J. Fischer, Dylan H. Morris, Neeltje van Doremalen, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus, (DOI: 10.3201/eid2609.201524)
(Score: 0, Offtopic) by Anonymous Coward on Tuesday September 01 2020, @09:34AM (1 child)
A fool (or several tens of millions) without a mask will still kill you, even if the mask they're not wearing at their mega-assembly is recyclable. Not counting the fact that recycling is for pussies, anyway.
(Score: 0) by Anonymous Coward on Tuesday September 01 2020, @03:35PM
Yep. And my methane emissions will eventually decimate every living thing on Earth.
(Score: 2) by MostCynical on Tuesday September 01 2020, @09:56AM
three uses before they *start* to fail..
Can we assume sneezing into the mask means it gets thrown away, rather than 'sanitized'?
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 1, Insightful) by Anonymous Coward on Tuesday September 01 2020, @10:01AM (1 child)
You could also just put it in Tupperware for a week until all the viruses die. Mine has lasted since the start of the pandemic, for probably 40 total hours of wearing time. (I do a lot of staying home.)
(Score: 1) by nostyle on Tuesday September 01 2020, @04:52PM
My tupperware seems to support the spawning of fuzzy green mold on things left alone for a week.
I'm curious, however, if some sort of ozone treatment might be as effective as UV and H2O2 treatments.
I've been using the same cloth mask for five months now, but treat it with UV after every use.
(Score: 2) by legont on Tuesday September 01 2020, @10:13AM
I am sure scientific thought will change their position on this subject as well once Chinese supply runs out.
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.
(Score: 1) by HammeredGlass on Tuesday September 01 2020, @11:57AM
People were able to drop off used N95s for them to clean and send to the "frontlines" of medical care.
It proved to be helpful, yet unnecessary as the deluge of millions and millions of hospitalizations never occurred.
(Score: 1, Offtopic) by DannyB on Tuesday September 01 2020, @02:19PM
Why should personal respirators be re-used? Wouldn't that be sort of like re-using underwear, clothing, or toothbrushes? If a smartphone is to be discarded because its battery can't be replaced, then shouldn't we be discarding respirators after a single use? And I will point a shameful finger at SpaceX regarding their re-usable rockets. Shame! Follow the lead of Apple! Smart TVs should be discarded if the remote got itself lost -- that could be reinforced by cryptographic keys which tie a single remote to a single Smart TV.
This is America! Why would we accept re-used things?
Young people won't believe you if you say you used to get Netflix by US Postal Mail.
(Score: 3, Interesting) by EETech1 on Tuesday September 01 2020, @04:58PM (9 children)
The fabric used to make masks is only about N40 - N60 for a 3 micron particle (coronavirus is 0.3 micron).
If you make them any more restrictive than that, they become very uncomfortable to wear, and you feel like you're suffocating.
What brings them to N95 are static charges placed on the material that attract and trap the contaminants.
Excessive temperature, or moisture will dissipate the charge and you will only be left with the base filtration properties of the material which at best is N60.
Source: I'm making the machines that make and charge the fabric.
Be safe!
(Score: 0) by Anonymous Coward on Tuesday September 01 2020, @07:38PM (1 child)
and what temp is excessive?
(Score: 2) by EETech1 on Tuesday September 01 2020, @09:06PM
There are specific tests that have to be performed to simulate accelerated aging for determining the shelf life.
There are also other tests that simulate for example being parked in an enclosed semi-trailer for a week in the desert.
I do not have the specifications in front of me, but I don't think it's a high enough temperature for safe sterilization
(Score: 1) by fakefuck39 on Wednesday September 02 2020, @01:11AM (6 children)
So you make hair dryers? That's a "machine" that will charge the fabric.
I usually leave the mask sitting there and just reuse it, since the virus dies on its own. If I need to reuse it in less than 3 days, I spray it with isopropanol, and blow my wife's hair dryer on it (without turning on the static guard button).
I've had the same N95 since March. Left over from when I fixed my drywall.
(Score: 2) by EETech1 on Wednesday September 02 2020, @06:15PM (5 children)
How it's exactly done is the result of much hard work, and considered proprietary information, but I can tell you we use over 4kW @ 30,000 to 60,000 volts to create multiple corona discharges and pass the material through these coronas to trap the charge in the fabric.
It's a fun thing to watch, but dangerous as hell to be around.
You would not want to be touched by 60kV DC at 15mA!
(Score: 1) by fakefuck39 on Wednesday September 02 2020, @06:30PM (4 children)
There's no proprietary information needed on making static electricity. Any air filter with an ionizer does it, and your hair dryer does it. You can run a mask for 5 min with a hair dryer or air filter pointed at it to charge the fabric. Yours is an industrial-size machine that does it fast and at scale. That's completely unnecessary to charge a mask at home.
(Score: 2) by EETech1 on Wednesday September 02 2020, @07:47PM (3 children)
What makes it work is applying different charges to each layer of material.
How do you do that with a hairdryer?
Different nasties are attracted to different charge polarities, and some of them are neutral and have to pick up a charge by passing through one layer, and sticking to the next layer, or layers.
There's industrial hair dryers too, that use static the same way you describe, but they are not effective for this application. They are effective for charge neutralization. We use them to pull the surface charge off of the material that's formed when it's made so that it doesn't get attracted to the rollers in the machine, and end up wound around them. They are also used during conversion, IE taking a big roll, and making smaller ones to meet specific customer requirements. Unwinding the material generates a huge amount of static, but it is not useful in any way towards making the material actually work.
The actual structure of filter material is physically changed when it passes through the corona as well. This has to be done for the media to be effective. These structures do not last forever, and are the nooks and crannies that trap the particles that would normally pass right through. Every time the mask moves, some of these structures fracture, and loose their effectiveness forever, as well as letting go of whatever they have trapped in them.
At best you'd be applying a small surface charge to the outer layers, and they do not do the actual filtering for anything smaller than sawdust.
It's the inner layers that trap the very small particles like viruses and bacteria.
(Score: 1) by fakefuck39 on Thursday September 03 2020, @09:23AM (2 children)
This is false, as my organic chem and physics double minor from 20 years ago states. The virus is huge, on a molecular level. It has parts with positive and sides with negative charges. As long as you have the mask ionized, it will stick to it. Heck, a water molecule H+OH- has two charges. To test, you can line up a bunch of magnets all sticking out with +. Throw a magnet in there. It'll twist and turn, and it's negative part will stick to the + on the magnets you laid out. All you need on the mask is extra electrons, which a hairdryer takes care of. What you're talking about is filtering out tiny molecules, such as individual oil molecules. those are neutral. We're talking about filtering a huge virus.
(Score: 2) by EETech1 on Thursday September 03 2020, @03:36PM (1 child)
Here is a size comparison of the coronavirus to the filler media
https://www.dw.com/image/53480883_7.png [dw.com]
Average pore size is 3 micron, the coronavirus is 10-20 times smaller.
(Score: 1) by fakefuck39 on Thursday September 03 2020, @07:29PM
The mask pore size is 0.3 microns, not 3 microns. You're off by a factor of 10. Still twice as big as the virus though. Which is why we charge the mask - so the charge of the mask attracts the virus and makes it stick to the mask. In reality, most of the virus is surrounded by some other stuff like water and mucous, making the droplet much bigger. But the mask even filters the standalone viruses. Due to the charge. Which you can apply with a hairdryer at home, without damaging the mask.
Your point?
(Score: 2) by krishnoid on Tuesday September 01 2020, @08:19PM (1 child)
Like, from sunlight? I bet they didn't test for that because, you know, they had some Scandinavian dude as one of the non-miscellaneous authors and even though a lot of them list California-institution affiliation, that would have caused them to fail their 1%-er solar access privilege check before publishing.
(Score: 2) by corey on Wednesday September 02 2020, @10:40AM
Yeah, down here in Southern Australia the bureau of meteorology is already recommending Sun protection and it's only the first week of spring. If it's dangerous for your skin then those little microbes can't be doing too well.
I've thought this for ages, the cold virus (and covid) doesn't last more than a few days outside of the body as far as I understand. So even if you don't have UV, just hang up the masks and leave em for a couple of days. I have a bunch on the floor in the car and grab one when I get out of the car. I drive once a week so it should be all good.
I have a bunch of home made ones and they get washed at least once a week.