Indoor sunburn??

Status
Not open for further replies.
electricmanscott

electricmanscott

Senior Member
Location
Boston, MA
Text from a letter from my sons school. I've never heard anything like this before.

Last Friday, the 8th grade held its annual Science Olympiad in the Mountview gymnasium. As you are most likely
aware as a result of a series of ConnectEd communications last Saturday and Sunday, a number of students who
participated in the activity began to have severe symptoms of burning eyes and skin irritation at the end of the day
and into Friday night.
A team of us worked through weekend investigating the situation and developing a number of theories. Each one
brought us to a dead end. We had an environmental team in to conduct an air quality test of the gym. Tests
indicated there were no problems with air quality.
Last night, one of our custodians did a complete tour of the gym looking for any possibilities that may have been
missed. He asked about one of our lights which he recalled had been broken during an after school activity.
Upon further inspection, we found that the outer shell of the bulb had broken, but the filament was still operating
when the lights were on. Further information was gathered from the internet providing us with a description
which led us to believe the students were exposed to a short-wave UV radiation which resulted in the irritated,
burning eyes, and the redness of skin.
In other words, our students received an in-door sunburn.
Armed with this information, I visited one of our local optomotrists, who also happens to be the parent of an 8th
grader. In looking over the information we had gathered, he agreed the UV rays from the broken light most likely
caused the symptoms he had seen with a couple of the students he treated. The best news of all was that, in his
opinion, no long-term damage would have been done to the students? eyes. The doctor cautioned parents that if
any symptoms persisted, they should consult a doctor.
 
I am aware that the outer envelope of MV bulbs, as well as that glass shield over halogen bulbs, do block excessive UV.
 
I've heard of an almost identical situation, except that it was teachers who experienced the burns and not the students. They were in the gymnasium all day doing some sort of planning session and a number of them recieved 1st degree burns (i.e. sunburns) from UV exposure due to a broken envelope around the arc tube of a MV fixture. It may have been written up in EC&M.

Off the top of my head, I thought there was some sort of standard or regulation that the arc tube of an HID lamp had to self-extinguish if the outer glass envelope broke?

-John
 
electricmanscott said:
... the outer shell of the bulb had broken, but the filament was still operating
Click to expand...
Doubt this is any sort of lamp to have a filament, but it does tie up with mercury vapour lamps, the majority of the light from which comes from phosphors coated on the inside of the outer bulb which convert UV to visible light.

Edited to add: still pretty freaky though...
 
I beleive they call the sunburn index as A,B,C or just A,B, where the A happens from the worst from 10 AM to 2 PM, B is on either side and C is twilight on either end!

The sickness of exposer is just that, be it an unknown or constant exposure to the EMS - electrical magnetic spectum is what they sat through!

They got a sun burn without sun screen! People will react, respectively! - JMO.
 
peter d said:
This is why MH luminaires must either be "O" rated, or have a containment barrier between the lamp and the reflector.
Click to expand...
That rule has to do with protection from the possible violent end of life failure that can occur with MH lamps. The containment or O lamp does not provide UV protection.
 
As others post, the lamp involved was likely a metal halide or mercury vapour lamp, not a filament type.
Such lamps sold in the UK have a warning that "if the outer bulb is punctured or broken, the lamp must be turned off, and when cool replaced"

Lamps that go out if broken certainly exist, but dont appear to be the norm, they have a small filament in series with the arc, when exposed to air this oxidises and goes open circuit after a minute or two.
 
From the link Iwire posted, it looks like any glass or plastic lens on the bottom of the fixture will eliminate the excessive ultraviolet radiation.

Is that how you guys see it?

Steve
 
don_resqcapt19 said:
That rule has to do with protection from the possible violent end of life failure that can occur with MH lamps. The containment or O lamp does not provide UV protection.
Click to expand...

The containment barrier around the arc tube is thick quartz. How would this not block UV in the same manner that the outer envelope does? :confused:

Likewise, how would a glass or plastic outer containment barrier not block UV?
 
peter d said:
The containment barrier around the arc tube is thick quartz. How would this not block UV in the same manner that the outer envelope does? :confused:

Likewise, how would a glass or plastic outer containment barrier not block UV?
Click to expand...

I know from printing ink jet pictures that regular glass will block UV. Pictures exposed to light without glass or plastic over them will fade in just a few months. I have framed pics that are now 7 years old with no fading, even though ordinary glass only blocks about 30 percent of the UV that passes through it.

Glass can be ordered that filters out UV just for pictures. So far, I haven't felt the need.

Plastic will vary in the amount of UV blockage. Some clear plastic is treated to absorb UV and is made just for that reason.

The quartz envelope used to enclose the arc is designed to operate in a harsh environment while letting the entire spectrum of light pass through. They may not be doped for UV because of the operating parameters needed at elevated temperatures.
 
Last edited:
All materials have their characteristic spectrum.

Ordinary glass passes 'near' UV, but cuts off most UVB and UVC. If you need to cut off all UV, then the glass needs to be treated.

Quartz passes far more UV than ordinary glass, and if specifically selected can pass all of UVB, UVC and beyond.

Quartz halogen filament lamps can produce enough UV to cause sunburn.

-Jon
 
peter d said:
The containment barrier around the arc tube is thick quartz. How would this not block UV in the same manner that the outer envelope does? :confused:

Likewise, how would a glass or plastic outer containment barrier not block UV?
Click to expand...
Peter,
The substantiation for the proposal that led to the code rule was about protection from the violent failure that sometimes occurs at the end of the MH lamp life. If it was related to the UV issue it would have applied to lamps other than MH.
Maybe it does provide the UV protection, but that is not the reason for the code rule. The violent failure and resulting fires were the reason for the containment rule for MH lamps.
 
Status
Not open for further replies.
Top