Thread by @DrNick4126

1/9 More reassuring data confirming the safety of Far-UVC with respect to the skin. In this thread I'll summarise the key points from the authors.
onlinelibrary.wiley.com/doi/10.1111/ph…

2/9 The skin’s first line of defence against *all* UV radiation is the outermost layer of the epidermis - the stratum corneum - which acts as a biomechanical barrier.

3/9 Unlike UVB and UVA which penetrate deeper into the skin’s layers, potentially causing damage to dividing cells, UVC is absorbed by the stratum corneum only. Nevertheless, safety thresholds are set by the American Conference of Government Industrial Hygienists (ACGIH)…

4/9...for all UV wavelengths, to minimize any specific biological effects. The current Far-UVC 222 nm limit is set at 480 mJ/cm2 (that’s the amount of energy striking a unit area of the skin).

5/9 This study exposed hairless albino mice (known to be particularly sensitive to UV light and to show skin damage typically seen in humans) to UVC in the 200-270 nm range over a 72 hr period. Photographs of irradiated skin were then compared with non-irradiated sites.

6/9 Skin reddening (erythema), a standard visual feature for evaluating adverse skin effects, was not observed across the UVC spectrum within the threshold doses set by ACGIH. In fact, at 222 nm, the dose had to be increased by ~2.5 times to elicit any skin response - see below.

7/9 The authors concluded that the limits set by ACGIH for Far-UVC 222-230 nm wavelengths are overly conservative. They also noted that the mouse stratum corneum is up to 6 times thinner than in humans, further suggesting significant leeway in the safe exposure limits.

8/9 However, the authors could not completely rule out other stratum corneum skin responses, such as scaling (microscopic dandruff) or some water loss, and recommend further studies. [*All * scientists want to conduct more studies -that’s how we get paid!]

9/9 So... possibly some microscopic dandruff or a *tiny* bit of water loss from the dead outer layer of skin....
OR...
...potentially fatal or life changing H5N1, Sars-CoV-2, anti-bactericidal super-bugs, seasonal flu, RSV, TB etc, etc etc.
Your call.
#FarUVC