Unsafe UV from high-power tungsten halogen in office?

[TKM]

|
| |>I understand that linear tungsten halogen bulbs emit noticeably more
|> UV light than general household incandescent bulbs.
|>
|> Would it be safe to use a 300 Watt tunsten halogen floodlight as a
|> good bright light in my home office?
|>
|> This would be on for approx 8 hours a day. I'm wondering that maybe
|> after that sort of exposure the extra UV could become a significant
|> adverse effect on eyes & skin.
|
| To answer your question -- yes, tungsten halogen lamps do emit
substantial
| amounts of UV and they are perfectly capable of causing skin and eye
damage
| if you are directly exposed to the light of an unshielded lamp. In
Italy
| some years ago, users of small halogen task lamps reported sunburn and
other
| UV-related problems because the lamps were not shielded.
|
| But a piece of glass will filter the UV to minimum levels and the
halogen
| lamps should be enclosed anyway in case of bulb rupture. You definitely
| don't want to experience that in a home office situation.
|
| As others have said, however, there are much better, more efficient and
| safer ways to light your office using fluorescent lamps.

I'm looking for a way that results in a uniform continuous spectrum. I
have
found that fluorescent does not accomplish that. Also, LED does not,
either.
But I think there may be hope in that LEDs are available is lots of
different
wavelengths. A mix of a lot of these could come close to the continuous
spectrum.

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http://ham.org/ |
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NIST has a current project to build an LED lighting system that has sources
which emit at every 5 nm (I think). Each "color" would be individually
controllable in output. What I didn't understand when I heard about it is
how they expect to find or tune LEDs to the various wavelength bands.

Terry McGowan

 

[TKM]

I am newbie when it comes to lighting. I have not come across these
T lamp bulbs.

Is there a web page which show pictures or diagrams of the T lamps
(T5, T8, etc) so I can see how they differ from one another.

Google gives me lots of hits but nothing which illutrates or compares
these lights on a single page.

The information is a bit hard to find, but it's out there. The lamp
manufacturers' catalogs are the best way. For example, go to the
fluorescent section of GE's catalog at :
http://www.gelighting.com/na/busine...ces/literature_library/catalogs/lamp_catalog/
Download the fluorescent section and look on the first few pages. T5, T8,
etc. are all shown with their sockets.

Terry McGowan

 

[Simon Waldman]

I'm looking for a way that results in a uniform continuous spectrum. I have
found that fluorescent does not accomplish that. Also, LED does not, either.
But I think there may be hope in that LEDs are available is lots of different
wavelengths. A mix of a lot of these could come close to the continuous
spectrum.

Well, yes... but good fluorescents come at least that close. Look for
tubes with a colour rendering index of at least 90. They will be
referred to as "colour 9xx", where the second two digits refer to the
colour temperature. These tubes are usually not as bright as standard
ones, but offer a smoother spectrum.

Off the top of my head, one such range is Osram's "Lumilux Deluxe", at
least in Europe.

Osram and Philips have both recently brought out another range of tubes
with *really* good colour rendering (CRI of 98 or so), but they're
pretty dim for the power input. The Philips one goes by the name of
"Graphica" in Europe, I can't remember what Osram call them. ISTR that
they're only available at a 6000K colour temp or thereabouts, and I
*think* that they may only be in T8.

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[TKM]

We had a case here in Oregon a year or two ago. Seems a large group
of teachers was holding an institute day in the school gym under the
metal halide lamps. Unknown to everyone who attended, one of the UV
shields was broken and the teachers were exposed to high levels of UV
exposure all day. Apparently there was a safety feature that was
supposed to estinguish the light if the shield failed, but the safety
feature failed instead.

At the end of the day, there were complaints of retinal burns,
sunburn, severe headachces and a general sickness from just about all
who attended. Lawsuits were threatened and it became a very expensive
medical incident for the school district.

Prior to this, there was a general ignorance about the importance of
mantaining the lamps in good repair. This event prompted a statewide
review for the procedures in maintaining UV producing lamps, mainly
that they need to be inspected periodically and if the shield is
cracked or missing, the lamp should be removed from service.

Beachcomber

Important information. Such cases have occurred since mercury HID lamps
started to be used for indoor industrial and commercial lighting about 1965.
There have not been massive problems; but since people are injured, any
incident gets attention. The safety device inside the lamp has appeared to
work well (when the outer bulb is broken, outside air causes the safety
device to open the arc tube circuit); but anything can fail to work. I've
always promoted the use of enclosed fixtures for such installations, but
users complained about the higher cost and sometimes the enclosure glass was
broken or not replaced when the fixture was serviced. The maintenance
people must also know enough about the risk to install the lamps with safety
devices as standard lamps will also work in the sockets.

The industry/government has not found a 100% solution to the problem -- most
due, I would say, to lack of knowledge/education and concern about costs.
Unfortunately, it takes a large lawsuit sometimes to get proper attention.

There was a similar problem with exploding metal halide lamps some years
back. The problem was understood, fixes were developed; but no foolproof
solution was implemented. Then the problem got massive attention after a
major lawsuit was lost.

Terry McGowan

 

[TKM]

Underwriters Laboratory requires some sort of sheilding, although in
some cases it is wire mesh rather than glass. (In case of "Non-passive
Failure" - my favorite techno term, thanks to GE.) This covers 99% of
North American instalations and equipment.

This UV scare has been going on for well over ten years. There was an
experiment in Italy where they baked some hairless mice with unsheilded
lamps. Gee, they developed skin problems. The press went wild....
***You get more UV walking to your car than from sitting under halogen
lamps.***

Note to JS: As you noticed lighting is not cut and dried, there are
many options and the best solution depends on the details of your
situation. Energy, quality, dimming, start-up, first costs, space,
style, your age!, type of work....

Good Luck

The problem is usually not the amount of UV coming out of the lamp; it's not
knowing that you are being exposed to it and taking proper precautions.
When people switch on a desk lamp, they don't expect to get "sunburned" from
the light.

Terry McGowan

 

[[email protected]]

Important information. Such cases have occurred since mercury HID lamps
started to be used for indoor industrial and commercial lighting about
1965. There have not been massive problems; but since people are injured,
any incident gets attention.

On the other end of the visible spectrum, you can get "IR detector" cards
printed with a special ink or dye. You leave it in normal light for a
little while, then shine infrared light on it (like from a TV remote
control) and it lights up. Is anything like this available for UV? I'm
thinking of a small, inexpensive card that could be taped to the wall in
rooms with mercury HID lights, with simple directions like "if the blue
spot printed above turns red, please check the light fixtures."

I'm sure you could build an active circuit for it, but then you have to
get people to change the batteries. If they won't put batteries in smoke
detectors or maintain light fixtures correctly, they probably won't put
batteries in the UV detector. On the other hand, not mantaining the
fixtures might be explained by having to haul things up and down a
ladder, where changing batteries in a device mounted at eye level on the
wall is easier to do.

Matt Roberds

 

[TKM]

On the other end of the visible spectrum, you can get "IR detector" cards
printed with a special ink or dye. You leave it in normal light for a
little while, then shine infrared light on it (like from a TV remote
control) and it lights up. Is anything like this available for UV? I'm
thinking of a small, inexpensive card that could be taped to the wall in
rooms with mercury HID lights, with simple directions like "if the blue
spot printed above turns red, please check the light fixtures."

I'm sure you could build an active circuit for it, but then you have to
get people to change the batteries. If they won't put batteries in smoke
detectors or maintain light fixtures correctly, they probably won't put
batteries in the UV detector. On the other hand, not mantaining the
fixtures might be explained by having to haul things up and down a
ladder, where changing batteries in a device mounted at eye level on the
wall is easier to do.

Matt Roberds

Good idea. I've heard of such detector "dose" cards; but I haven't tried
any. There's a debate building about UV exposure. Some UV is good for
people -- vitamin D, natural sunshine and all that. Some say people don't
get enough these days to ward off rickets, big diseases and even common
colds. Others say UV=skin cancer. End of story. (I'm overstating , of
course But, maybe there are facilities such as hospitals, retirement
homes or even schools in the far north (or south) where UV from sunlight is
zero for much of the year and where we might want to add some UV to lighting
in "sun spaces" or light therapy rooms. If so, a dose card on a person
might ensure that a person gets their proper amount. Enter "Michael F.
Holick" on Google if you want to read about some the pro-UV research.

Terry McGowan

 

[Victor Roberts]

Good idea. I've heard of such detector "dose" cards; but I haven't tried
any. There's a debate building about UV exposure. Some UV is good for
people -- vitamin D, natural sunshine and all that. Some say people don't
get enough these days to ward off rickets, big diseases and even common
colds. Others say UV=skin cancer. End of story. (I'm overstating , of
course But, maybe there are facilities such as hospitals, retirement
homes or even schools in the far north (or south) where UV from sunlight is
zero for much of the year and where we might want to add some UV to lighting
in "sun spaces" or light therapy rooms. If so, a dose card on a person
might ensure that a person gets their proper amount. Enter "Michael F.
Holick" on Google if you want to read about some the pro-UV research.

I assume There's UV and then there's UV, meaning that energy
at some UV wavelengths may indeed be beneficial while energy
at others other may indeed be harmful so we probably need to
be more specific about the radiation than just "UV." One of
Holick's books is titled just "UV" but in the one Holick
article I read he refers to UV-B, which is a bit more
specific. I wonder if Vitamin D production is even more
specific than UV-B.

--
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[Zak]

On the other end of the visible spectrum, you can get "IR detector" cards
printed with a special ink or dye. You leave it in normal light for a
little while, then shine infrared light on it (like from a TV remote
control) and it lights up. Is anything like this available for UV?

I'm sure you could build an active circuit for it, but then you have to
get people to change the batteries. If they won't put batteries in smoke
detectors or maintain light fixtures correctly, they probably won't put
batteries in the UV detector.

Well, it could be light powered and bleep at you when there's a problem.

Or something that discolors with UV, but that will take time to react.
Fluorescence could work, but I do have no idea how large the UV part is
and how efficiently this can be converted. When glass of
quinine-flavored soft drink turns green, check the lights. Just needs a
filter to keep visible light out except for the viewing hole.


Thomas

 

[Beachcomber]

Well, it could be light powered and bleep at you when there's a problem.

Or something that discolors with UV, but that will take time to react.
Fluorescence could work, but I do have no idea how large the UV part is
and how efficiently this can be converted. When glass of
quinine-flavored soft drink turns green, check the lights. Just needs a
filter to keep visible light out except for the viewing hole.

Materials that Fluoresce under UV light come in different flavors.
Some are sensitive to long wave UV and others will light up only under
short wave UV. There is also a mid-range value.

Rock collectors who collect samples know this well as they frequently
must use a lamp with a combination of UV wavelength outputs (or
multiple lamps).

Beachcomber

 

[[email protected]]

Zak correctly noted something I should have caught... if the point is to
measure UV light from interior lamps, there is also probably enough
visible light to run a solar cell instead of using batteries.

Good idea. I've heard of such detector "dose" cards; but I haven't tried
any.

I Googled and found some; these seem to be sold more for checking
industrial processes that use UV light, but could probably be used as
"dose" cards. One example is at the hideous URL
http://www.uvprocess.com/products/C...UV INTENSITY LABELS.INTS LBL A/INTS LBL A.ASP
..

But, maybe there are facilities such as hospitals, retirement homes or
even schools in the far north (or south) where UV from sunlight is zero
for much of the year and where we might want to add some UV to lighting
in "sun spaces" or light therapy rooms. If so, a dose card on a person
might ensure that a person gets their proper amount.

Sounds reasonable to me. I might add some kind of active detector for
the whole room to help catch any problems with the artifical UV.

Enter "Michael F. Holick" on Google if you want to read about some the
pro-UV research.

I did and it was interesting. I'm inclined to agree with him; laying
out on the beach at the equator for twelve hours every day is probably
not good for you, but neither is getting no unfiltered sunlight
whatsoever.

Matt Roberds

 

[Simon Waldman]

Good idea. I've heard of such detector "dose" cards; but I haven't tried
any. There's a debate building about UV exposure. Some UV is good for
people -- vitamin D, natural sunshine and all that. Some say people don't
get enough these days to ward off rickets, big diseases and even common
colds. Others say UV=skin cancer. End of story.

AFAIUI there isn't anything complicated here. The more UV, the greater
the risk of skin cancer. However too little UV doesn't allow Vitamin D
generation, and probably has other side-effects too. At some point there
will be a sweet spot where the total risk, including that of death from
skin cancer and that of death from lack of UV[1] is at a minimum.

This sweet spot will depend upon the individual's skin colour; this is
not, of course, coincidental, but is the evolutionary reason that races
from different latitudes have differently coloured skin.


-S

[1] Well, of ill health which might well have led to death in a
pre-industrial society