How much intensity do I need to kill virus

[kambo]

i have been searching to this info, with some graphics, but no result!
lets say i have 254 nm UVC with 10mW/cm2 output at 10cm distance...

how long would it take to kill this corona virus...  has anyone seen any data/graphic!

all i could find is, some X amount Watt of UVc lighs desenfects Y sqm meter room in Z time... not really helping me out...
not all same watt lights are outputting the same amount of radiation reading!

 

[JohnRoberts]

I found a note in a CDC report about mask decontamination that suggests 0.5–950 J/cm2. The report has multiple footnotes that may give more detail.

https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html

JR

PS: I have multiple UVc lamps around the casa, they even make UVc CFL lamps that are easier to use and more powerful than small fluorescent tubes. Be careful, I heard an anecdote about a school teacher in Russia who forgot to turn off the UVc lamps used to decontaminate the class room over night, students suffered eye damage.

PPS: The far/deep UVc (short wavelength 207-222nm) is still not widely available while reportedly there is a potential LED technology that makes 210nm light. There is a factor relating effective coupling of UV light wavelength and the size of the virus, but I do not know any details, common UVc is typically around 250nm.

 

[cyrano]

I don't think you can practically disinfect masks with UV. Maybe microwave them?

The only experience I have with UV disinfection is for water. It's not completely effective, but there aren't that much possibilities. You need high power UV lamps and those aren't cheap, or easy to get.

UV is used for room disinfection, as is ozone, usually from a high voltage needle. These were and still are used in hospitals. Obviously, UV can only be used when no people are present in the room. Ozone tends to affect people with asthmatic problems.

Fluorescent UV tubes, like the ones used to get a tan, are not suitable for disinfection. That's why bronzing sets still need to be disinfected.

There's a new material developed that should make reusable masks possible. I'll see if I can find the link to the article...

 

[cyrano]

Can't find it...

Some info about the effectiveness of masks against influenza virus:

https://moscow.sci-hub.tw/2357/1ce69f8b60e1c2ac12c0a52412db56a8/makisonbooth2013.pdf

 

[Scodiddly]

I would think that one of the tricky things about using UVc for killing viruses is whether those viruses (which are really incredibly small things) can lodge themselves in cracks out of the light, and then shake loose when you start using the objects again.  BigClive is doing UVc light testing on youtube with a piece of glass to block the UVc component and it's very effective.

 

[JohnRoberts]

The Battelle mask cleaning technology (recently in the news when FDA approval was fast tracked)  uses vapor phase hydrogen peroxide. Not sure how easy that would be to incorporate into a paper path.

I already shared a link about using UV for mask disinfection.
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For today's does of TMI, I have wrestled with black mold inside my house for years, that was fueled by leaky plumbing in my bathroom and poor sanitation. Over the last decade my remediation has it pretty well under control with lots of elbow grease (cleaning) and by managing indoor humidity, mold cannot thrive in low humidity.

That said one persistent black mold colony that I was unsuccessful at squashing was under the lip of my toilet bowl. This area was dosed with life sustaining water with every flush and shaded from UV sunlight by the lip overhang.  Since I like to tinker, I cobbled a spare UVc tube I had laying around from inside a broken water sterilizer, and mounted this to bottom of the toilet seat lid.  I even rigged up a shield for the lamp when not in use so it doesn't get peed on.

Previously lightly scrubbing under the lip with my toilet brush would release a cloud of black mold... out of sight but never gone.  Now after a few weeks of twice daily dosing with UVc, the the under lip brush scrub returns clean...  8)

JR