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Don Klipstein

In ,
wrote:

On Aug 10, 6:10*pm, "HeyBub" wrote:
Don Klipstein wrote:
Right. You can put almost any (relatively clear) water in a clear
plastic bottle, put the bottle in the sun for a few hours, and,
presto, sterilized water.

*Except that the main germicidal wavelngths of UV (UVC of wavelength
around 240-280 nm) are highly blocked by the ozone layer even when the
ozone layer is weakened, and these wavelengths also have a high rate
of being blocked by plastics that are transparent when thick enough
to make bottles from such plastics.

The blockage may be high, but the resulting radiation is sufficient. At
least according to all the studies I've been able to find.

Just buying a UV light and be done with it. I'm lazy.

I just hope you don't rely on germicidal effects from those "blacklights"
whose UV is mainly in the longwave roughly-60% of the UVA range - which
does not even cause much suntanning of human skin. (At higher intensities,
such longwave UV wavelengths still have ill effects on a couple parts of
the human eye and some organic pigments/dyes.)

Killing bacteria with UV depends highly on sufficient exposure to UV
wavelengths that are in or very near the UVC range.
The main germicidal UV wavelength from "germicidal UV lamps" is 253.7
nm, AKA 254 nm, from low pressure mercury vapor combined with an inert
gas, usually argon, sometimes krypton, sometimes neon, sometimes a mixture
of argon with either neon or krypton.

- Don Klipstein )