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Monitors radiation question.

    Date: Fri, 21 Jun 91 10:47-0000
    From: p2@porter.asl.dialnet.symbolics.com (Peter Paine)

    Does anyone have any feelings (Pan what are your measurement
    techniques?)  whether a monitor which is dimmed (L-machines/Lemo
    brightness turned down, G-machines Function-c-Refresh, MacIvory Radius
    screen saver stars, etc.) should emit less?

All my monitors give the same readings whether dimmed or not (these are
all L and G machine B&W, premium and old style both). I use a Gaussmeter
which is sold for the purpose (reading 50-60Hz emissions). There are a
number of them on the market. My source of information and such
equipment is "Microwave News" published out of New York City. The same
group also publishes "VDT News". If anyone wants contact numbers I can
dig them out.

    Sitting at the focus of 4 screens that get used intermittantlyduring
    the day, I had hoped that dimming the screens would diminish emissions
    to insignificant levels. ie. radiation is caused by the tube beta rays
    striking the phosphore and producing weak X ray? which is absorbed by
    the lead glass?

Don't know where it all comes from, sorry. Note that color screens give
out measurements that are somewhat higher, depending on monitor. All
monitors seem to be worse from the back, so dont sit behind your
colleagues console.

    Or is the only effect a consequence of the 50/60 Hz mains induction
    field - such as is found in homes situated under power line cables?

These locations also give substantial readings, inside homes from
internal wiring as well as from cables strung on the outside.

    If the emissions are not related to the screen illumination intensity,
    ie. dimming completely, viewing as white text on black background, and
    at lowest intensity possibly - then should I be turning the monitor
    power off, except when in active use?

Unfortunately there is no clear answer here. If you want to be extra sure,
given the uncertainties of levels and conditions that are dangerous, the
answer is yes, pain-in-the-neck though it may be.