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Black lights

  1. Dec 21, 2004 #1


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    In another post, someone was asking about black lights..

    Are they really emitting UV? Is it enough to be dangerous? In theory I mean. Obviously (scratch that, I mean: 'one would assume') they wouldn't market them if they were actually dangerous when used properly.

    My son lights his room with them. Is he exposing himself to an excess of UV?

    Also, do they put out more heat than normal bulbs? They seem to get very VERY hot. It occurs to me that using more than one in a fixture might be dangerous.
    Last edited: Dec 21, 2004
  2. jcsd
  3. Dec 21, 2004 #2


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    They do emit UV. There is a low level of risk, probably less than sunlight at the beach that can cause skin cancer after years of exposure. Depends on how many and how bright the UV sources are. You’re not able to determine the brightness of the source by looking at it, as your eye does not respond to UV light. What distinguishes UV from visible light is that UV light is ionizing radiation and can cause DNA damage. I suggest the UV light source(s) be placed where they cannot be viewed directly, but only the objects being illuminated are visible. The light emanating (fluorescing) from the object is of lower energy than UV and not hazardous. Babies are sometimes exposed to UV radiation to help lower biliruben concentrations in their blood. Moderation is the guideline.
    UV radiation is more energetic than visible radiation and requires more energy to create it. Most means of generating visible light are inefficient, even the common incandescent lamp gets very hot because most of the emitted light is in the infrared, and only sensed as heat, not seen. The fixture should be labeled with it’s wattage rating and intended use.

    For your info, UV radiation comes in three flavors and among many uses: UVA is used in sun tanning parlors. UVB is used to treat certain skin conditions such as Psoriasis. UVC (highly dangerous) is used for sterilization. Your son’s UV sources likely emit mostly in the UVA range.

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