Re: Is light unit after-glow a problem?

Keith Dowsett (kdowsett@rpms.ac.uk)
Tue, 03 Dec 1996 09:29:05 -0100

>Keith says:
>
>
>>Mercury discharge lamps (plate burners) and carbon arcs are a different
>>matter entirely. They emit substantial amounts of short wavelength uv which
>is harmful to both skin and eyes.
>
>This is misleading.

OK. I admit it. I've never used a high pressure mercury light. We use low
pressure mercury discharges in the lab and they emit most of their output
around 254nm. Even the wee ones (6-10W) come with safety stickers all over them.

>What is a ' plate burner' ? How powerful is it ?

They were used in lithographic printing and were a _high_ intensity
discharge light. I was told (I never used one myself) that they would give a
better tan than most sunbeds.

>We should remember that every time we go out into sunshine we are receiving
more
>UV light than will leak from a light box.

Until recently the ozone layer absorbed a lot of short wavelength uv. The
concern over the ozone hole is connected with an increased risk of skin
cancer due to exposure to these wavelengths. Compared to the risks from some
of the chemicals we use it may be small, but it is avoidable.

Keith.
==========================================================
Keith Dowsett "Variables won't; constants aren't."

E-mail: kdowsett@rpms.ac.uk
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