Re: UV & Health

SCHRAMMR@WLSVAX.WVNET.EDU
Tue, 03 Dec 1996 16:05:40 -0500 (EST)

Terry and Louis are quite right. The small band of electromagnetic radiation
to which our eyes are sensitive is called "visable light" or just "light."
The electromagneic spectrum includes a number of different types of radiation.
Visable light is that which lies in the approximate wavelength range of
fromm 8000 Angstroms (red) to 4000 Angstroms (violet). Shorter wavelengths
above 4000 Angstroms are refered to as "ultraviolet radiation." This band
starts at 4000 Angstroms and goes to 10 Angstroms where X-rays begin.
Terry's remark about the inverse square law needs explanation. All radiation
(including light) obeys this law which is: the intensity of light from a
oint source varies inversly as the square of the distance from the source.
(thats point source) This means if I double my distance to the source,
the intensity will be one-fourth as much. e. g. the intensity ten feet from
a source would be 1/100 th the intensity at one foot. This explains why
when your are getting your teeth x-rayed the technician leaves the room. ;-)

Since one should be mostly concerned about one's eyes, one might consider
wearing glasses with UV absorbing plastic in them if one is going to be
looking at the source a lot.

I agree with Terry. The small amount of leakage would not be something to
worrry about. I believe Judy said she uses open FL fixtures but doesn't hang
around them (practical application of the inverse square law). Oh, and
before someone points out that a FL tube is not a point source, let me add
that I know that and we have been through all that and the bottom line
is that the radiation from an FL tube sill falls off with increased distance
according to a complex relationship which reduces to the inverse square law
for large distances.

If you want a good, cheap UV leak detector, get yourself a plastic flourencent
toy (thats flourescent toy) or some other flourescent object like an alarm
clock dial. A white T-shirt or sheet works pretty well also. I have a
plastic lizzard that I got at Spencer Gifts in the US that lights up real
good when around my bank of UV FL bulbs. (Does lizzard have two Z's or
one Z like "Wizard?)

Ordinary eyeglasses absorb some UV especially the short wavelength variety.

Welder's goggles are used to reduce BOTH visable light and UV radiation.

The so-called "skylight" filter is nothing more than a UV filter. I suppose
one could be used as a monocule.

Bob Schramm