Re: color of light and color of plant leaves and color of skin cells

["S. Hieber" <shieber at yahoo_com>]

Daniel Larsson said, in part:

" > So my question was: Should we try to get closer to
> sunlight by using UV-A
> and UV-B also?
> 
> (UV-C is the part that cause damage to DNA by the way
> (and used in
> UV-filters). To much exposure of UV-B can be dangerous -
> that's why we
> and the plants develop pigments.)

The notion that some UV is okie doke (tanning salons,
e.g.,) and only some of it is bad for retinal cells, skin
cells, etc. is at best controversial.  Probably the
strongest argument that can be reasonably made is that the
less energetic photons are less harmful.  Since we're
talking about repeated exposures potentiall over courses of
decades, less harmful might not be good enough for some
folks.

Even if it means my plants won't be quite so nice, I'd
rather not risk how long I will be able to view them by
forcing additional UV light onto my tanks.  BTW, virtually
all fluorescent lamps emit some (small amount) ultra violet
that gets past glass tube.  I think that's why photogray
lenses (silver bromide) turn dark inside office buildings. 


Scott H.

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