Re: Anyone moved to LED Lighting?

[don@xxxxxxxxxxxxxx (Don Klipstein)]

In article <hhm3pq$s41$1@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Robert Green wrote:
>"Don Klipstein" <don@xxxxxxxxxxxxxx> wrote in message
>news:slrnhj2nr6.gq4.don@xxxxxxxxxxxxxxxxx
>
>> >You may be interested in this (spurred by your supplied links elsewhere)
>> >LEDs may be just as bad as CFLs for health damage due to spectral
>content.
>> >
>> >http://www.international-light-association.eu/PDF/
>> >Artificial%20Light%20and%20Health%20PLDC07.pdf
>>
>>   Except this stuff on blaming health problems by melanopsin peaking at
>> 460 nm being stimulated by CFL's blue peak (436 nm) is BS.  An equivalent
>> amount of daylight has more stimulation of the blue color sensors in the
>> eye (peaking at 445 nm), as indicated by daylight appearing more blue.
>
>Some people are doomed to stay inside for most of their lives because of
>their sensitivity to UV.  So saying CFL's aren't any more harmful than the
>sun is actually confirming they are indeed harmful to those people.

  But typical home lighting is at a couple hundred to a few hundred lux
ballpark, give-or-take, while direct sunlight is upper 10,000's to around
100,000 lux.  The typical home CFL lighting has intensity a couple orders
of magnitude less than that of direct sunlight, along with a less harmful
spectrum in this area.

>There are any number of biological systems that depend on light.  The
>full-spectrum light boxes you wrote about are thought to work via the eye
>and brain, simulating summer light in the winter months and (hopefully)
>reducing depression that's well known to be more of a problem in the winter
>months than in the summer.

  Please keep in mind the known and suspected photoreceptors!

>  Some people believe SAD (Seasonal Affective
>Disorder) is due to the overall reduction in daylight hours, others believe
>it's the absence of the very bright, white light of summer that does the
>trick.  The people I know that use them, swear by them.  A case could be
>easily made the benefits are purely placebo effects, but I doubt it.  Since
>we share so many genes with so many other animals, it's not hard to believe,
>that we, like them, are sensitive to daily and seasonal changes in light.
>
>A brief search through the Merck manual at:
>
>http://www.merck.com/mmhe/sec18/ch214/ch214c.html
>
>lists the following drugs as having potential photosensitive effects:
>
<SNIP a list of drugs where direct sunlight is a couple orders of
magnitudes worse than fluorescent indoor lighting>
>
>Most of us have taken at least one of them;  others, many more. For a long
>time, nearly everyone poo-pooed the idea that CRT's were harmful to some
>people and caused serious skin ailments.  But anyone who has owned a CRT has
>likely noticed that they are often the dustiest item in the room.

  Probably removing dust from elsewhere!

> It turned out that once the Swedes, notorious for their stringent
>consumer protection laws, actually did the research, they found the
>claims credible.  They discovered that sitting in front of a CRT with its
>high voltage components acting as a attractant, caused people's hands,
>arms and faces to be showered with microscope dust particles and those,
>in turn, clogged skin pores with all sorts of airborne irritants,
>resulting in sometimes serious skin ailments.

  In my heavy Usenet experience with a CRT monitor, this is news to me!
Can you post a cite?

>I mention this only to point out that there are many things that seem highly
>unlikely until someone bothers to design
>the proper experiments to prove or disprove a contention.  Another thing to
>consider is the manufacturing process.  It's pretty obvious to me, at least,
>that Chinese manufacturers vary greatly in their adherence to quality
>control principles.  Bearing that in mind, what happens to the UV output of
>a fluorescent bulb with a thin, defective or non-existent phosphor coating?

  The UVC that is the main UV emission by low pressure mercury vapor arc
- is reliably mostly absorbed by the coating - that is necessary
for the phosphor to produce visible light with good efficiency.

  UVC is also very highly blocked by the glass tubing unless the
glass tubing is made of an expensive specialty glass to pass it.

  UVB is also mostly blocked by glass not specifically designed to pass it
at extra cost, and low pressure mercury vapor only weakly produces UVB and
UVA.

  That little bit of UVA gets through glass well - but it is
"blacklight-range" rather than "tanning range" UVA.  It is mainly 365-366
nm wavelength.

  CFLs with color rendering index around 82 and color temperature at least
3500 K even have a phosphor component absorbing and making use of some of
this UVA.

>It spikes tremendously.  Why?  Because fluorescent bulbs are designed to
>emit short wave UV radiation that strikes the phosphor coating, causing it
>fluoresce and converting the UV to visible light waves.  With bad or thin
>phosphor, there's less material to impede the UV emissions.  So I'm not at
>all surprised that the research varies tremendously.  The items under
>investigation do, too.
>
>--
>Bobby G.

 - Don Klipstein (don@xxxxxxxxx)