Aris Silzars Display Technology Consulting



Fear of the Unknown...December 2001

Yesterday, I met our next door neighbor at the end of our driveway while we were both performing the unglamorous weekly task of putting out the garbage. He told me he was glad to have a short break because he was feeling eyestrain from staring at his computer monitor screen all morning. He next asked me what I thought of the new flat-panel monitors. His reason for asking was that he was concerned that the "radiation" from his CRT monitor was beginning to affect his eyesight. When I asked him what kind of radiation he was concerned about, he really had no idea, but had read somewhere that CRTs create electromagnetic fields that could be harmful.

Next, to probe a little further, I asked him why he thought that flat panels would have less "radiation." Again, he said he really didn't know, but had read or heard that somewhere as well. Would I be able to tell him? Should he buy a flat panel monitor just to be on the safe side? Interesting questions. And a reminder that he was not the first one to pose such concerns to me about the "radiation" and/or "electromagnetic field effects" of displays on the viewer’s health.

A few years ago, I had occasion to explore the levels of electromagnetic fields emanating from display monitors and the standards that most monitor makers meet or exceed. The CRT monitor’s electromagnetic fields are mostly from two sources: the power-supply-related components, and the deflection yoke. At the typical user’s sitting position, the 50 or 60 Hz power-supply-related fields are well under ten milligauss. The higher frequency, 15 to 100 kHz, deflection-yoke-created fields are, for modern monitors, less than 0.25 milligauss when measured at the distance users sit in front of the monitor. This compares to the earth's magnetic field of approximately 500 milligauss. Now, I suppose one could argue that there is a difference between a static field and a varying one, but what about when walking or otherwise moving through the earth's field? Then it is no longer a static field either. If there is a difference, what is it and why? And by the way, flat-panel monitors are not completely free of electromagnetic fields either. A typical LC display produces magnetic fields on the order of 0.10 milligauss -- somewhat less than a CRT but not zero.

This being the case, why does my local computer store offer products that purport to provide shielding again these "electromagnetic fields" that emanate from my computer monitor? Why don't I need to worry about shielding from the "electromagnetic radiation" my shaver and hair dryer put out at much higher levels of well over 1000 milligauss? In any case, these "shields" are only conductive films that reduce the electric fields and have no effect on the magnetic components. I have yet to see one of these products that has an explanation of the difference.

Of course, computer monitors, microwave ovens, and other electrical appliances are not our only sources of concern. What about cellular telephones and power lines? What about homes in the proximity of television transmitters and microwave relay towers? Are the electromagnetic radiation levels safe or should we worry? While I was doing my computer-monitor measurement project, I also did a comparison by making a few spot measurements while standing under some REALLY BIG power lines. To my surprise, the 60 Hz fields were down in the tens-of-milligauss range. How could that be? Apparently, there is sufficient cancellation between the pairs of lines so that even at a 50-foot distance the magnetic fields are really quite small. Until I made the measurements, I had no idea that these impressive structures produced so little effect. No wonder my hair wouldn't stand on end -- even on a dry day!

We live in a world full of radiation, some natural and some created by us. The FM radio spectrum contains perhaps a hundred stations in a typical metropolitan area. Television transmitters and cellular towers dot the countryside. Satellites are continuously beaming down electromagnetic signals of various kinds. Military and commercial aircraft have their own spectrum allocations. The electromagnetic spectrum is becoming a crowded and highly sought-after commodity to be controlled, bartered, and/or sold to the highest bidders.

Should we be worried about any of this? Could there really be detrimental health effects that we don't yet understand? A few hundred years ago, if you had told someone that you could send moving images through empty space, such a statement could have landed you in an asylum at some really remote location. Right this minute, without a radio or television at your disposal, how can you prove to someone that there are hundreds of audio- and image-carrying signals passing right through your bodies? And if you cannot detect those without some instrument to aid you, could there be something else out there that we don't yet know about?

One summer, when I was still in graduate school, I had the job of designing an audio amplifier for a neutrino detector that was being constructed in a mineshaft deep inside a mountain. The objective was to try to detect secondary effects from these tiny particles, which have close to zero mass and that, most of the time, pass through the earth unscathed. How many neutrinos have zapped right through me in my lifetime? Did one or more of them make a collision? If so, what effect did it have?

There is much that we do not yet know and do not understand. On the other hand, creating unnecessary fears for commercial gain should not be considered ethical behavior. Many studies have been done to try to find some detrimental (or perhaps beneficial) health effect from electromagnetic fields. To date, nothing specific has been found, other than such well-understood effects as the increase of tissue temperature at sufficiently high levels of incident microwave radiation, and the destructive effects of x-rays and other high-energy radiation. Studies are sure to continue, but with all that has already been done, it is unlikely that we will find anything new to cause us concern about the low levels of electromagnetic fields found in today's display monitors -- CRT or flat panel. So the next time you meet your neighbor while taking out the trash, let him know that his tired eyes are from too many hours of staring at a computer screen and nothing more.

Now -- in the spirit of the Christmas Season -- should we consider the possibility that there are other dimensions to the electromagnetic spectrum that we have not yet discovered? This would, for example, be like having a conventional television receiver on which you cannot detect the images being transmitted in the new digital formats. Even though the frequency band is the same, those signals have become "invisible" to you. Could there be something like that out there that we don't yet know about? Could any of those stories about Santa Claus and his sleigh with tiny reindeer possibly be true? Just because we cannot yet detect or measure something does not mean that it cannot exist. Is it possible that the worldwide spirit of the Holiday Season may be more than just the wishful thinking of adults and the happy fantasies of innocent children? Well, what if it isn't? What if we are in the beginning stages of discovering yet another communications spectrum that is perhaps dimensionally orthogonal to the one we have explored up to now but grander than anything that we have discovered to date? What if it takes a different kind of receiver and transmitter to explore this new realm?

Could it become possible for us to reduce the background noise of our day-to-day activities, to find the peace and calmness that would allow us to explore the signal that may be emanating from this barely detectable cosmic source. Wouldn't that be one wonderful Christmas present -- one that could change us in ways that we couldn't have imagined. Of the many things we don't yet know, this is one that can be sought without the fear of adverse effects. With that thought, I wish you the very best for this Holiday Season and a coming year filled with discovery, well-being, and the blessing of great friendships.

Since most of the time I am still only capable of the more conventional means of communication, you may reach me by e-mail at or, by telephone at 425-557-8850, by FAX at 425-557-8983, or by mail at 22513 SE 47th Place, Sammamish, WA 98075.