It looks like 222 nm UV has been used disinfect things going back to 2008 or earlier.
But note:
1) The wavelength range is rather small (only a 15 nm wavelength window). Outside it, one risks burns and ozone generation and all the bad aspects of ozone and UV.
2) 2 mJ/cm^2 - how much is that? Standard AM1.5 sunlight is about 1000W/m^2 or 100 mW/cm^2 total. A J is 1 W*s.
The peak AM1.5 spectrum is about 2 W/m^2/nm^-1 x 15 nm or about 30 W/m^2 peak over a 15 nm passband. Or 3 mW/cm^2. Or for 1 second, 3 mJ/cm^2. So, the far-UVC light necessary is about 1.5x the peak solar intensity. So, it's quite a bit of light (in a small wavelength band), but not a huge amount. But, given the amount of viruses going into and out of a real room, the light would have to be on quite frequently.
3) The testing setup was a chamber that was 6.3 cm (2.5") deep and had an aluminum back wall to reflect more of the incident light. Real rooms aren't quite so ideal, of course. More light will be required in real situations.
No silver bullet. But interesting.
Thanks.
Cheers,
Scott.
But note:
1) The wavelength range is rather small (only a 15 nm wavelength window). Outside it, one risks burns and ozone generation and all the bad aspects of ozone and UV.
2) 2 mJ/cm^2 - how much is that? Standard AM1.5 sunlight is about 1000W/m^2 or 100 mW/cm^2 total. A J is 1 W*s.
The peak AM1.5 spectrum is about 2 W/m^2/nm^-1 x 15 nm or about 30 W/m^2 peak over a 15 nm passband. Or 3 mW/cm^2. Or for 1 second, 3 mJ/cm^2. So, the far-UVC light necessary is about 1.5x the peak solar intensity. So, it's quite a bit of light (in a small wavelength band), but not a huge amount. But, given the amount of viruses going into and out of a real room, the light would have to be on quite frequently.
3) The testing setup was a chamber that was 6.3 cm (2.5") deep and had an aluminum back wall to reflect more of the incident light. Real rooms aren't quite so ideal, of course. More light will be required in real situations.
No silver bullet. But interesting.
Thanks.
Cheers,
Scott.