Common Technical Questions
1. Could tanning beds be used for sterilization of cloth masks?
Yes, UV radiation can be. A few hospitals are using UVA1, UVB, and UVC, including Stanford, UT Southwestern.
It was also mentioned in COCA extending PPE, and also in the JAMA discussions.
Whatever sanitization or sterilization method, it’s been stated that it’s more ideal to also cycle 3 days. So if you’re thinking of cloth masks or N95s, you’re rotating through every 3 days to reduce chances of contamination.
2. Does leaving a "slot" or pocket in the 2 layered cotton mask allow for a portal of entry for germs? Can a single layer of a HEPA vacuum bag be sandwiched in the cotton masks and go through a HOT HEAT dryer for sterilization as long as no body fluids on mask requiring washing?
There are many different types of HEPA filtering, from your domestic use to true H13.
The inner pocket as long as it is tightly designed much like the foldover/crimping technique seen in traditional surgical masks wouldn't introduce more ”germs” or pathogenic particulate transfer. The entire mask would have to be able to tightly form a seal to prevent as much face leakage as possible.
The ideal situation here is to source the dedicated face mask filters that Vogmask, Cambridge Mask are alluding to. They have a 5-ply layer that filters up to 2.5ppm (like N95) and one could reasonably obtain Chinese ministry of health, CE, and FDA approval under the category of respirators/face masks.
The off-the-rack HEPA solutions will often filter dust up to 99.97 (just throwing a number) and up to .6 microns. But remember coronaviruses are small particulate viruses that are as small as .06 microns (1/10 that size) and around .125 microns.
You'll reasonably filter dust, pollen -- and have some protective effect but if you're plan is to source these HEPA vacuum bags, I wouldn't necessarily bother. You're in the same unknown territory as if you were using Deaconess’ no filter hospital-approved template. And it's 2 steps fewer. Remember that these cloth masks are anyway supposed to be last resort under CDC guidelines so the idea is to try to push out as many as feasibly possible and so these kinds of theoretical blockades will only get in the way of sending aid.
3. So, do you know why the pocket in the Deaconess Hospital video that CDC is approved?
As you probably know by now, CDC is approving the use of fabric masks due to the humanitarian crisis. They are not officially recommending them as PPE since their level of protection is quantitatively unknown. Like you mentioned, doctors are commonly putting the cotton masks over the N95 mask. There's so much confusion about the designs being posted/published right now, if you do whatever is feasible for you and get that out (based on either providence's or deaconess' design) -- it will be put to use. The pocket is just a theoretical design/used in Belgium (also "acknowledged"). The bottom line is that we can theorize about the protective qualities but that says nothing without medical/humanitarian device testing. At 11am I'll make an inquiry to the CDC though about your question.
To reiterate, in practice 2 or 3 layer cotton masks -- with elastics if you can get them/ties if you cannot -- would be extremely helpful as is to have on hand as last resort. That's why hospitals are asking for them.