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From: kludge@grissom.larc.nasa.gov ( Scott Dorsey)
Newsgroups: comp.sys.mac.misc,sci.energy,sci.electronics,sci.environment,ieee.net.tech,ieee.general
Subject: Re: VDT Electric Fields
Message-ID: <1991Feb12.135358.12182@news.larc.nasa.gov>
Date: 12 Feb 91 13:53:58 GMT
References: <12438@pucc.Princeton.EDU>
Sender: news@news.larc.nasa.gov (USENET Network News)
Reply-To: kludge@grissom.larc.nasa.gov ( Scott Dorsey)
Organization: NASA Langley Research Center
Lines: 26

In article <12438@pucc.Princeton.EDU> STENGEL@pucc.Princeton.EDU writes:
>   Recently, while sorting some 35mm slides, I pulled the lamp head closer
>to the desk top, just a few inches above the monitor screen.  When I turned
>the computer on, the lamp tube nearest to the monitor began to fluoresce,
>flickering until the "off" button produced total discharge.  Apparently, the
>electric pulse that occurred when the monitor was turned on was enough to
>initiate fluorescence in the lamp.  The phenomenon has been repeated
>several times since.

   First of all, since the pulse only occurs for a short period of time, the
exposure (which is cumulative anyway) is quite slight.  Secondly, the exposure
from VDTs may be one of the less important elements in the environment.  I
have shared offices with 250 KW transmitters where fluorescent lights would
burn a bright white while unplugged and held in the hand, and caused small 
sparks to jump off the corner of my glasses if the sharp edges were not rounded
with a file.  Currently I am across the street from a radar set which causes 
a noticeable flicker on fluorescent lamps and disconnected CRTs every time the
beam sweeps in my direction.
   VDT exposure is in the sub-microvolt/m2 range, but there are a lot of 
environments where people live and work in the tens of volts/m2 range.  AC
power lines are a contributor to the exposure, and while the actual field
strength produced by AC lines is quite small in most cases, the lower 
frequencies may possibly be more hazardous.
   Personally, I wouldn't worry about it.  But it's a matter that certainly
does deserve more study.
--scott