https://www.bostonglobe.com/2020/04/02/metro/boston-hospitals-getting-game-changer-machine-that-sterilizes-80000-protective-masks-day/

The Battelle Critical Care Decontamination SystemTM is a self-contained, mobile decontamination system that uses vapor phase hydrogen peroxide (VPHP) to decontaminate N95 filtering facepiece respirators (FFRs). Our system is based on published research that Battelle performed for the FDA in 2015, and we are working closely with the FDA in anticipation of receiving Emergency Authorization Use for decontamination of compatible FFRs. Battelle CCDSTM renders SARS-CoV-2 non-infectious on FFRs and enables up to 20 reuses without degrading filter performance to help address the current U.S. FFR shortage.

https://www.battelle.org/docs/default-source/commercial-offerings/industry-solutions/730_battelle-ccds-critical-care-decontamination-system-1.pdf

I thought UV was really bad for N95 masks

UV light is pretty hard on a lot of materials so durability will be a question. Not sure how that compares to the Hydrogen Peroxide treatment, but I'm sure it's better than nothing. Good to see innovative ideas being used.

I would think they could be misted with alcohol, peroxide or some other cleaning agent, but again the material may not react well.

My hospital is starting to have us return our N95 masks to eventually use the hydrogen peroxide vapor whenever it looks like it is needed. My concern is not that the mask becomes sterilized, but more so that the masks effectiveness is reliant on having a good seal. How patent will the seal on these masks be when it's been used 5-6+ times by different individuals with different face shapes 8+ hours each? How likely are the borders to warp after such extended use since the masks aren't exactly the most durable nor were they designed to be used multiple times

Bake them at 158F for 30 min.

https://m.box.com/shared_item/https%3A%2F%2Fstanfordmedicine.box.com%2Fv%2Fcovid19-PPE-1-1

I don't know why the authors kept saying, "Not your home oven." It's probably a CYA thing. They might worry about food contaminating the masks or vapors from masks contaminating food.

In regards to the elastic, they seem to hold up fine according to one person:

Quote:

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"I wanted to test the elastics survivability using the oven method. I used a mask that was being sterilized decontaminated improperly and was destined for the trash.

It took me a crazy amount of time to get the temp at or near (above 158F) because I have a sh**** apartment grade oven. I set the dial to a unmarked place and waited 10 mins then checked a baking sheet surface for the temp using a infrared thermometer. I got about 165 stabilized for a half hour. I then put the mask in, sitting naked on the rack. Let it cook for 35 minutes. Temp when I took it out was still around 165. Checked elastic and seem to be fine and no additional stretching or cracking. So it worked. Not sure how long the elastic will hold up doing this but it's probably longer than the number of times you can use a mask and run thru this process when ultimately you really should be disposing them after each use.

Now these are my results and I was only testing to see if the bands would hold up and they seem to have. Is it sterile decontaminated? According to the temp and time data provided on that table it should be. At least I can breathe (get it?) a tiny bit more life into my remaining two. I only use them to go procure something for dad and I basically got all that out of the way and I'm not going out again unless he needs something.

Edit. Used proper word: decontaminated. I am so illiterate sometimes."

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Snap E Tom said:

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Bake them at 158F for 30 min.

https://m.box.com/shared_item/https%3A%2F%2Fstanfordmedicine.box.com%2Fv%2Fcovid19-PPE-1-1

I don't know why the authors kept saying, "Not your home oven." It's probably a CYA thing. They might worry about food contaminating the masks or vapors from masks contaminating food.

In regards to the elastic, they seem to hold up fine according to one person:

Quote:

---

"I wanted to test the elastics survivability using the oven method. I used a mask that was being sterilized decontaminated improperly and was destined for the trash.

It took me a crazy amount of time to get the temp at or near (above 158F) because I have a sh**** apartment grade oven. I set the dial to a unmarked place and waited 10 mins then checked a baking sheet surface for the temp using a infrared thermometer. I got about 165 stabilized for a half hour. I then put the mask in, sitting naked on the rack. Let it cook for 35 minutes. Temp when I took it out was still around 165. Checked elastic and seem to be fine and no additional stretching or cracking. So it worked. Not sure how long the elastic will hold up doing this but it's probably longer than the number of times you can use a mask and run thru this process when ultimately you really should be disposing them after each use.

Now these are my results and I was only testing to see if the bands would hold up and they seem to have. Is it sterile decontaminated? According to the temp and time data provided on that table it should be. At least I can breathe (get it?) a tiny bit more life into my remaining two. I only use them to go procure something for dad and I basically got all that out of the way and I'm not going out again unless he needs something.

Edit. Used proper word: decontaminated. I am so illiterate sometimes."

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[TLDR - Does anybody have any materials research connections or contacts at 3M? I have a proposed decontamination method that could work for areas with less access to resources and also could be adapted to mitigate the "Fit" concern for disposable PPE]

I've been doing as much reading on this topic that I can find (Even called a microbiology PhD Ag friend and emailed the authors of the paper you reference).

First, Its important to state that Dr. Price and Dr. Chu's paper's specifically mentions that they have not tested the efficacy of these methods against decontaminating against COVID-19. They have simply been testing the integrity of the meltdown material in the N95 masks.

Secondly, they leveraged a vacuum oven to run their tests which is quite different than a home oven.

I emailed them both, proposing an alternative method and asked them to weigh in. I'd also love any feedback from those knowledgeable here....

As their paper states, "To be useful a decontamination method must eliminate the viral threat, be harmless to end users, and retain respirator integrity." The paper summarizes, "70C/158F heating in an oven for 30 min... is an effective decontamination method". In an updated paper they increased the temperature to 75C. I thought of a possible "low tech" solution that could be leveraged in situations where specialized equipment is unavailable (ex. vacuum ovens or Vaporous Hydrogen Peroxide (VHP) autoclaves as were posted in the article posted by OP).

My proposed solution is placing an N95 mask in a vessel (ex. ziploc bag) and immersing in a water bath set to 75C(or higher) for 30 min (or longer)? Home chefs use this method often for cooking sous vide (under vacuum) and holding food at a set temperature for extended periods of time. The lower the temperature, the longer you have to hold to kill bacteria and viruses)

I think this method should also be tested to measure the impact to the meltblown fibers? Perhaps a water bath method would cause less damage to respirator integrity due to the nature of the gentle thermal load. additionally, perhaps you could hold at a lower temperature for longer, decreasing the impact to the elastic and nose padding.

The Vacuum oven method also requires that masks be placed on a rack or flat surface. One of the additional concerns the CDC and The National Institute for Occupational Safety and Health (NIOSH) mention is the fit of the masks after multiple decontamination cycles. https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html

Additional considerations the water bath method: Molds could be developed to place masks over before sealing in "the vessel" and immersed, essentially maintaining (or resetting) the masks shape and therefore its fit.

Vaporous Hydrogen peroxide (VHP) enclaves are probably a better solution but they are going to take some time to be available in other areas in the nation let alone globally. In poorer countries, they wont even have that as an option.

I'm asking for anybody's thoughts here on Texags. If you know someone who is in materials research and can weigh in or possibly know someone who is connected to 3M engineers, let me know. I'd be happy to jump on a call with anyone who wants to discuss further.

-Bryan

Anything is better than what my girlfriend's hospital is making them do - they get an N95 to wear for the day, then they place it in a brown paper bag and put it on a shelf; and after 72 hours, poof, it's magically "clean" and they wear it again. They won't be issued another one unless their first one breaks...

According to the linked article by Aggie Bryan it seems to me that suspending the masks over boiling water for 10 minutes might be the best alternative assuming no UV light device.

rally-cap said:

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Anything is better than what my girlfriend's hospital is making them do - they get an N95 to wear for the day, then they place it in a brown paper bag and put it on a shelf; and after 72 hours, poof, it's magically "clean" and they wear it again. They won't be issued another one unless their first one breaks...

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That hospital administrator needs fired ASAP. Huge lawsuit potential.

AgResearch said:

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rally-cap said:

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Anything is better than what my girlfriend's hospital is making them do - they get an N95 to wear for the day, then they place it in a brown paper bag and put it on a shelf; and after 72 hours, poof, it's magically "clean" and they wear it again. They won't be issued another one unless their first one breaks...

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That hospital administrator needs fired ASAP. Huge lawsuit potential.

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Yeah, not a fan. I'm not sure how they are getting away with it

FrioAg 00 said:

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We're using Virtual Reality headset sanitizers at my hospital. They use UV light to kill germs and each can sanitize 3 N95 masks in 55 seconds.

So during an 8 hour shift we can sanitize around about 4,000 of these. Durability will be a question for the mask and the machines, but for now it's making a big difference.

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Any idea which VR sanitizer your hospital is using?

Surprised we haven't seen people recommend vacuum bagging the masks and popping them in a sous vide for a bit. Seems that would work and potentially lessen the wear on the masks lime an oven or UV light would.

In the end, an abundant supply of new masks is all that will help the situation.

I'll check

2 of them were donated by our auditors, whose form has some cool VR training

Update: Dr. price at Stanford got back to me and said they are testing the "sous vide" method with promising results. She cautioned and reiterated that they do not have access to test against the COVID-19 virus which requires a level III laboratory.

A someone posted elsewhere, the vaporous hydrogen peroxide Method will probably be the preference due to hospitals having access to the necessary equipment for sterilization off surgical equipment.

Anyone out there have a way for EMS to sanitize their PPE?

Would appreciate it. Wife's clinic has limited masks so an ability to sanitize what they have obviously would be beneficial in many ways.

Also can drink a pint of vodka and just wear it for an hour. JK.

OK. We dry porous material in a vacuum oven at 140 F. If you can get vacuum, I would think the required temp would be lower, since the medium is being completely dehydrated. This would of course be less damaging to the material. Home use wouldn't likely have access to a vacuum pump.

Chlorine dioxide would have been an option for institutional use. You can make it by mixing sodium chlorite and phosphoric acid. I have sodium chlorite in my lab, but it's not readily available as far as I know.

I've made my own face masks out of MERV 13 AC filters that are reinforced with wire. I wonder if I could spray them with quaternary amines and then wash in the sink to remove the amines.

It's made by a company called CleanBox.

We've got a national leader over our Infectious Disease department, I'll keep you posted as to what she says we observe in terms of the masks holding up.