In addition to air quality, another neglected front is ultraviolet light,
Huh. I was going to say that “warning, UVC is dangerous. It’s not ‘neglected’, it’s evaluated and discarded for very good reasons”.
And then I started digging.
The main issues with UV are: 1) eye damage, 2) skin damage, and 3) ozone production.
Turns out that there’s apparently surprisingly recent research showing filtering out wavelengths longer than 230nm helps significantly with 1[1] and 2[2], which is weird. I would normally expect shorter wavelengths to be more destructive. (Hypothesis is that the shorter wavelengths have a lower penetration distance, and so ‘just’ kill cells that are on the surface and going to be shed shortly anyway?)
And there’s apparently a window around ~220nm that’s short-wavelength enough that it avoids 1⁄2, but long-wavelength enough that it doesn’t have significant ozone production[3]. And KrCl lamps peak at 222nm.
Yet another small update in favor of tuned physics, I suppose. (Small update. There are many possible combinations of a few elements + power to produce EM radiation.)
That being said, I’d be much more relaxed if the paper had explicitly monitored/measured room O3 concentration, and/or if they had also filtered out short wavelengths.
Huh. I was going to say that “warning, UVC is dangerous. It’s not ‘neglected’, it’s evaluated and discarded for very good reasons”.
And then I started digging.
The main issues with UV are: 1) eye damage, 2) skin damage, and 3) ozone production.
Turns out that there’s apparently surprisingly recent research showing filtering out wavelengths longer than 230nm helps significantly with 1[1] and 2[2], which is weird. I would normally expect shorter wavelengths to be more destructive. (Hypothesis is that the shorter wavelengths have a lower penetration distance, and so ‘just’ kill cells that are on the surface and going to be shed shortly anyway?)
And there’s apparently a window around ~220nm that’s short-wavelength enough that it avoids 1⁄2, but long-wavelength enough that it doesn’t have significant ozone production[3]. And KrCl lamps peak at 222nm.
Yet another small update in favor of tuned physics, I suppose. (Small update. There are many possible combinations of a few elements + power to produce EM radiation.)
That being said, I’d be much more relaxed if the paper had explicitly monitored/measured room O3 concentration, and/or if they had also filtered out short wavelengths.
https://pubmed.ncbi.nlm.nih.gov/33749837/ (...in rats)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8638665/ (in human, singular)
Although that being said, many common UV lamps also produce ozone due to arcing[4]. This component can largely be mitigated by proper design.
https://onlinelibrary.wiley.com/doi/pdf/10.1111/php.13391 - though take it with a grain of salt, as it’s by someone that produces UVC lamps.