Thread by @masknerd

[1]Inactivation of SARS-CoV-2 on surfaces in the built environment by irradiation from a far-UVC light source
Lukas Oudejans, United States Environmental Protection Agency
#ICFUS2023

[2]Can we Far UV for surface disinfection of SARS-COV-2? Questions include what surrogate to use, dose, material, wet or dry conditions, what can you dose with. Looked at 222nm KrCl, 275nm UV-C led and Pulsed Xenon lamp[

[3] Goal is to test in applied setting(e.g real world). Used wild type SARS-COV-2, materials wer3 bus seat fabric, abs plastic and stainless steel. Used 10 x 10ul droplets to represent sneeze type droplets. Looked at fresh wet and dried

[4] Strong point that your 0mJ control needs to also match the same time that the other samples sit out, as virus dies naturally and if not done then will show artificially larger deactivation rate.

[5]222nm and Stainless showed largest disinfection by almost 4 orders of magnitude of bus seat using tissue culture. Saliva droplets not much with 222nm.
275nm LED shower saliva disinfectantion so may highlight wavelength issue. Again bus seat fabric saw little impact.

[6] Absorption of dry droplets have strong absorption of UV of the left over stuff when it dries. Coffee ring effect during drying is interesting, where does virus end up?

[6] While COVID is not spread by surfaces, still in testing to see what happens if you try and use 222nm for surface disinfection for viruses. Fabric or carpets will be very difficult to disinfect.

[7]Question: Normally 222nm is left in all the time. Answer: This experiment looked at just short term application at high dosages, could be used for continues use and different results.