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[2]Historical upper room studies show effectiveness, but variation in how effective as hard to study in practice
[3]Far-UVC promising due to safer for human wavelengths allowing for whole room exposure. Shorter wavelength light absorbed better in proteins(more disinfection). 222nm around 10x more adsorption by proteins than 254nm
[4] 222nm doesn't pass through stratum corneum, dead layer of skin cells. Basically human body has built in sunscreen for this wavelength 
[5] Eyes also protected by the "tear film" a layer of lipids+water+mucus covering our eyes. 222 nm is absorbed in this layer so almost no photons make it to the cornea
[6] Does 222nm work? Lab setups have shown a strong dose response for inactivation by H1N1, HCOV. Still not known why there is two different slopes, but may be due to cell protection
[7]222 nm may likely also more effective for disinfection than 254nm but why?
Energy transfer from protein to RNA? RNA -protein cross linked? More work needed
Energy transfer from protein to RNA? RNA -protein cross linked? More work needed
[8] In room size lab tests, 92% reduction in airborne S. Aurus in under 15min, and at ACGIH limits can reach 98% in 5 minutes. Which is 35 - 180 eACH
[9] In a real life occupied room, in this case an animal cage room, found 99.8% reduction in viable airborne MNV's. Data is pre-print at the moment.
[10] Is it safe?
Older ACCGIh and ICNIRP(agencies that set limits) had 23 mJ/cm^2[8 hour]. New ACGIH has increased it 7 fold to 160 mJ/cm^2 for eye, and 480 mJ/cm^2 for skin. Eye limits likely to be always the limiting factor[<-- my comment]
Older ACCGIh and ICNIRP(agencies that set limits) had 23 mJ/cm^2[8 hour]. New ACGIH has increased it 7 fold to 160 mJ/cm^2 for eye, and 480 mJ/cm^2 for skin. Eye limits likely to be always the limiting factor[<-- my comment]
[11] Animal studies have also not shown any evidence of skin answer or other skin abnormalities
[12] Optical filtration removes wavelengths of light beyond 240nm light as KrCl lamps emit other wavelengths than just 222nm. These filters remove 258nm light which humans should not have a ton of exposure.
[13] Will we kill the good bugs on our skin? Skin biome is very resilient, in large bio films on skin which 222nm may not propagate through[my thought]. Not enough studies yet, but mouse studies don't show any changes on skin microbiome
[14] Will we make a new variant? Needs to be non lethal mutation, inhaled by host, and become more virulent. Very unliely
Has been used in water cleaning for 30+ years with no UV resistant bact/virus formed[my comment]
Has been used in water cleaning for 30+ years with no UV resistant bact/virus formed[my comment]
[15] Ozone is a hot topic. Far-UVC will produce ozone, and can interact with VOC's to form secondary organic aerosol(Ultrafine particles). @jljcolorado had shown increases in a real-world use. Current ozone in auditorium is 14ppm for reference.
[16] VOC also important and how ozone reacts, typically higher in homes than school/outdoors.
May pose a challenge for use in residential space for long term use, but given cost and availability not an issue yet[<---my comment]
May pose a challenge for use in residential space for long term use, but given cost and availability not an issue yet[<---my comment]
[16] Next talk is here
https://twitter.com/masknerd/status/1669005670463733761?s=20
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