Irradiation to reuse surgical masks?

Question

High-quality surgical masks require nonwoven fabric that appears to be in short supply at WW level. Reusing masks is typically a big no-no due to obvious reasons. Autoclaving them is not an option either as it would damage the fabric. However, what about reusing the (somewhat) extensive food irradiation facilities to reuse masks faster? Viruses are notoriously resistant to the usual kGy doses used for food, but my (uneducated) guess is that it's a matter of dosage, RNA is a complex fragile molecule. Is there any blocking element that would prevent mask reuse after suitable irradiation?

viggity · Accepted Answer

I bought a few UV-C lamps for this very purpose. I'm sorry I can't find the research I found, but it said that UVC does indeed work, but lowers the efficacy such that it's not worth it more than 5 times (although, I think'd rather re-use a UVC N-95 mask than make one out of paper towels or a home sewn one).
The same research said isopropyl alcohol was a terrible idea as it kills the electrostatic nature of the filter. It said a light bleach solution worked best and could be re-used indefinitely.
A DIFFERENT study showed that soaking in a saltwater solution (NaCl) and letting it dry was extremely effective. As droplets hit the micro salt crystals the a very small solution forms, then recrystalizes as it dries. The crystalization essentially rips the virus apart. https://www.businessinsider.com/mask-coated-in-salt-neutrali...
There are some anti-viral masks that use citric acid, AFAICT for the same reason. bulk Citric acid can be bought in the canning aisle at any grocery store as it is needed to make jams. Although I imagine salt is even easier to find
http://ryanpharmacy.com/curad-antiviral-face-mask/

saurik · Answer

The studies show you can UV-C them (it reduces the physical strength of the mask but not the filtration ability, and can be done many many cycles: I think I saw at least 20); have you actually tried searching for how to sterilize masks yet?

sloaken · Answer

Great idea, I love it. Only reason I can think of is fear of lawsuit. "they reused a mask and I caught xyzzy" - of course there is no proof that was the source, but nuisance lawsuits are common.

anewvillager · Answer

Here's a Nebraskan protocol for reuse of disposable maskshttps://www.nebraskamed.com/sites/default/files/documents/co...

burfog · Answer

Autoclaving is fine. Pick the hottest non-damaging temperature.The plan in some places is to put a mask in a paper bag, write the date on it, and leave it in a warm place for two weeks. This does require that every worker have two weeks worth of masks, plus spares to replace masks that get really splattered.

vermorel · Answer

Hi All, long story short, it is possible, and limited trials have just been started in France with specialized actors. More details (in French) https://blog.vermorel.com/journal/2020/3/23/sterilisation-de...

Gibbon1 · Answer

I don't know what the answer is but it's a materials problem. Almost all medical stuff gets sterilized after manufacturing and packaging. The common ways are gamma radiation, ETO gas, steam. Less common are ebeam and Chlorine Dioxide.There is no golden process. Materials especially polymers have limits to how many times they can be sterilized. Different materials/different processes.

rubidium · Answer

What about just letting it sit out in the sun for a couple days? Sunlight and warmth kills the virus. Would it have a negative material effect?

toomuchtodo · Answer

Are there any gamma emitting devices at hospitals that could repurposed for this? Such as those used for cancer therapy? Or imaging devices (CT scanners)?