Researchers find a way to clean N95 masks for reuse - in a common electric cooker

[Demovictory9]

https://www.sfgate.com/news/article/Researchers-find-a-way-to-clean-N95-masks-for-15484513.php

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"It just happened that both Vishal and myself and a number of our students are Asian, and we cook rice every night," Nguyen said. "We said like, 'Oh, maybe some type of electric cooker might work.' "

She swiftly dispatched one of her students to Walmart with specific instructions. "Look for something at Walmart anyone can buy," she said. "Something easy. They just hit the button."

The student came back with a Farberware multifunction pressure cooker that cost about $50.

In a recently published study, Nguyen and Verma detailed how the dry heat produced by such electric cookers (rice cookers or multicookers such as Instant Pots) may be an effective way of decontaminating medical-grade N95 masks. Using the rice preset on the Farberware cooker and N95 respirators from 3M, a major manufacturer of the protective coverings, the researchers found that 50-minute treatments without pressure at a temperature of 212 degrees Fahrenheit left the masks thoroughly cleaned without compromising fit or filtration efficiency.

"The N95 can be reused using a very simple method," said Nguyen, whose research focuses on pathogen transmission and control. "We are not testing exhaustively every device out there, everything, but we want to show that this concept works. Then people can use the idea and apply to other things."

[Blues Heron]

1. This seems inherently hazardous

can't you just let them sit in a sunny spot for a couple of days?

Do they off-gas toxins at 212 degrees? will they catch on fire? Can you run rice cookers empty? Can you switch between cooking rice and then cooking your masks?

[LisaL]

2. And don't these cookers have instructions to not run them without water?

[ProfessorGAC]

6. Doubtful

First question: No. Polypropylene of this molecular weight has a non-measurable vapor pressure.
The vapor pressure listed in the SDS is a mathematically derived value from known pressures at higher temperature.
Second question: No. The autoignition temperature of polypropylene is 388°C. That's around 730°F.
Third Question: Yes. The thermowell for the heat control is touching the same surface being heated. Continued heating when full is due to calories of heat pulling away from the cooking surface, into the food. Once the metal hits temperature X, the current shuts off. The contents don't affect that.
Fourth Question: Yes, as long as you clean between using.
Given the answer to question 1, the residue will be incredibly minute and will wash out with any commercial brand cleaner.
Last Note: ingestion is a remarkably low probability route of infection. The active chlorine in the stomach, and the lipase & protease in the intestinal tract make virus survivability near zero.

[Blues Heron]

8. Thanks! Nicely detailed response professor!

Very much appreciated!

[Chainfire]

3. How do the vinyl/rubber fasteners hold up to that heat and duration?

I am going out so infrequently, that I leave my mask to dry on the dash of my car. A couple of days on the dash in the Florida heat will kill anything.

[tavernier]

7. That's what I've been doing.

I read that this is acceptable. Was that incorrect?

[Awsi Dooger]

4. I defaulted to studies from a long time ago

I didn't want anything rushed together toward this pandemic alone. In March I looked for more detailed evaluations during relaxed time frame. This was the best study:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781738/

[Disaffected]

5. Why not

just use your oven? Set the temp for 210F, wait for it to stabilize (so the masks don't overheat while the oven is warming up), set timer to 50 minutes and go.

Dry heat and no worries about running it w/o water etc.

Personally, I just let it sit for two or three days (I happen to have two of 'em so no prob).

[Hekate]

9. KnR