Previous 1 2 Next 17 Replies Latest reply: Feb 28, 2008 10:59 AM by fragmore
plavalle Level 1 Level 1 (0 points)
I had two 30". My face felt burned after working two weeks full time plus weekends before a dead line. I went to a dermatologyst and he told me Uv radiation could be quite harmfull.

Anyone have any idea how to lower emissions? (filter or something) I could not find what is the specification for these emissions. Anyone have any idea or experience with this?

Thanks

Dell, Windows XP Pro, Nvidia Quadro FX 4600 2x
  • Niel Level 10 Level 10 (268,535 points)
    If you are using an Apple Cinema Display, it is an LCD and does not emit radiation.

    (26851)
  • BSteely Level 5 Level 5 (7,635 points)
    LCDs are backlit by flourescent lamps. The way flourescent lamps work is that they produce UV light inside the tube which is coated with a phosphor. The phoshor absorbs the UV and re-emits light in the visible spectrum.

    There is some stray UV that comes from the lamps. But there are other UV filtering layers in the LCD "sandwich" of layers. The amout of UV that would actually reach a user is very low. I don't have specific figures for this but would guess that two 30" LCDs cranked up to full brightness for eight hours would be at most like 5 minutes of direct sunlight exposure. It's not very much.

    If you really are concerned about this limited exposure, one way to lower the emission is to dim the monitor. Generally you will find it more ergonomic to work with the monitor at reduced brightness anyway.
  • Network 23 Level 6 Level 6 (11,865 points)
    I would seriously doubt that the monitors are a significant source of radiation. First of all, it's well established that LCDs emit far less than the old CRTs that we all grew up with. The early Mac and PC screens emitted rather high levels compared to the CRTs that came out after new standards in the 1990s, and LCDs are even below those. The dermatologist might have carried over experience from CRT levels of radiation that do not apply to today's LCD monitors.

    Also, the light isn't even pointing directly at you like a CRT. The backlight is at the end of the display, and the light is directed across the screen, not out at you. A large diffuser evens out the light, and it filters out the front. Obviously, by that time, the light's been reflected and diffused quite a bit.

    OK, so then where might this UV have come from? I have a guess. What is your workspace like? Are there large banks of fluorescent bulbs above you in your office? If so, I think there is a higher chance that you may be receiving a UV dosage from those lights. It's much more direct, and at a much higher level than any monitor. I have seen photo prints fade under normal fluorescent lighting as if they were exposed to direct sunlight. If there are one or more defective bulbs, maybe that could cause a problem.

    Even more likely: If you happen to work in a facility where there are high-intensity metal halide bulbs, and any are broken or defective, it is possible to suffer serious UV-related effects. Read this article as an example.

    "In February, a broken bulb was discovered in a middle school gymnasium in Haywood County, Tenn., after 40 children complained of burning eyes and skin rashes, said Timothy Jones, a state epidemiologist."
  • OvBacon Level 1 Level 1 (15 points)
    Although I'm trusting what everyone is saying..... wverything that emits light has radiation.
    I had a 17"iMac and now since like as month a, working on a 23" HD display..... My face feels like its lightly burned too.... so how would that be?

    I know for a fact that what ever a producer says, What ever emits light therefore emits a form of radiation.... I have no doubt its the screen, but I have the feeling I have to ajust to the size difference.
  • BSteely Level 5 Level 5 (7,635 points)
    Yes, of course, anything that emits light is emitting radiation because light itself is radiation! But the discussion was centered on harmful UV radiation, of which an LCD emits essentially zero. Otherwise a lot of office workers would have really great face tans.

    LCDs also emit infra-red radiation, but not much. Infra-red is not harmful to tissue at all but you will sense it as heat. Perhaps that is what you feel.
  • OvBacon Level 1 Level 1 (15 points)
    Let me make clear that I was not saying that it is radiating UV or is harmful.
    I was just saying that like me it could just be that your body has to adapt to the new environment.
    The human body is a pretty neat tool... and is very advanced in its ability and its ways of dealing with change, So I just wanted to say... your not crazy or making it up.. You could definitely feel something but chances are it is completely harmless.

    sorry for the confusion.
  • David DeCristoforo Level 5 Level 5 (6,175 points)
    Well these things might not emit much in the way of radiation, UV or otherwise. But heat? Now that's another matter altogether. I have not worked with a 30" display but if it gives off the same proportion of heat per sq inch as my 23 does at the "default" brightness setting of maximum, I can understand why your face is getting burned off. I have found that lowering the brightness to around 80% does not adversely affect the quality if the image and you don't need shades and/or sunscreen to work. After I calibrated my display (with the Spyder2 Pro) the brightness level was much lower than the "stock" level also. If I switch the display between the default and calibrated profiles, there is a huge difference in the brightness level.

  • Network 23 Level 6 Level 6 (11,865 points)
    I still don't think it can be the monitor. It's just a weak light bulb that is not even pointed at the viewer. In comparison, every CRT was literally a cathode ray gun aiming radiation straight into your eyes. An LCD isn't even close.
  • OvBacon Level 1 Level 1 (15 points)
    for a weak lightbulb, my screen lights up pretty much the whole room.
  • Network 23 Level 6 Level 6 (11,865 points)
    Well, I googled "lcd radiation emission" and found this article.

    Which says:
    We have attempted to measure any UV that might be radiated from LCD screens (we have not yet measured plasma screens) and were unable to detect any UVA or UVB using meters capable of measuring as low as 1 microwatt per square centimeter in the UVA and UVB spectrum.


    Basically, the only kind of radiation coming out of an LCD is the same kind of electromagnetic radiation that also comes out of the computer itself and everything else in the house. If there is a sensitivity to that, there is going to be a sensitivity to other electronic devices as well.

    If there is an actual UV problem at the original poster's workplace, it is coming from a source other than the monitor. The same article I linked to contains cautions about UV emissions from halogen, mercury vapor, and metal-halide lamps. In particular, halogen desk lamps because they are so close to the worker.

    Quartz, because of its purity, allows a greater portion of the UV to pass. For this reason most quartz halogen lamps are housed within a larger (regular) glass bulb or are protected by another glass covering of some sort in the fixture. This reduces the UV significantly. However, if the outer glass is broken or not in place, the risk of exposure to damaging UV is real. Also, there are some desk lamps and under counter fixtures that do not shield the quartz bulb.


    On the other types:
    ...both metal halide and mercury lamp arc tubes emit enough ultraviolet radiation to cause adverse biological effects. Skin repening and eye damage are both potential problems if someone is exposed to an operating arc tube which is not surrounded by an outer jacket. The extent of injury to the general population depends upon a number of factors: lamp wattage, exposure time and individual sensitivity. This warning is meant to alert users to the possibility of injury if the outer jacket of the lamps were to be broken. When this occurs, a lamp may continue to operate for an extended period of time (usually not more than 100 hours). During this time, however, injuries to individuals could occur.


    So the potential risks of UV from workplace lighting are much higher than the level of UV from the monitor. As it says, UV from an LCD is difficult to detect even with sensitive lab equipment!
  • David DeCristoforo Level 5 Level 5 (6,175 points)
    All true. Radiation is not a significant issue. But heat is. Anyone who does not think so should sit with his face a foot and a half from a 23" ACD running at full brightness. Trust me...these things get hot....

    Furthermore, the design exacerbates the "problem" because these displays have no vents. Instead of heat being allowed to disperse by convection as it would if the displays had vents top and bottom, the entire unit acts as a big heat radiator.

  • Network 23 Level 6 Level 6 (11,865 points)
    I have a 20" and feel little heat. Anyway, to burn a face at that distance in a lateral direction using heat alone would require wattage far in excess of what these displays actually produce.
  • David DeCristoforo Level 5 Level 5 (6,175 points)
    The 20s run a lot cooler. The 23s get very hot, the 30s even more so and the OP has two of them. I don't want to argue but I can tell you that if I set the brightness on my 23 to max, I can feel the heat on my face at a distance of about 18 inches from the screen. Maybe it's not enough to burn my face but it's enough to feel "too hot". Maybe the OP has sensitive skin.

  • Network 23 Level 6 Level 6 (11,865 points)
    David DeCristoforo wrote:
    The 20s run a lot cooler. The 23s get very hot, the 30s even more so and the OP has two of them. I don't want to argue but I can tell you that if I set the brightness on my 23 to max, I can feel the heat on my face at a distance of about 18 inches from the screen.


    Interesting, I'm going to have to check that out next time I'm at the Apple store since I want to upgrade my monitor size next year.
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