http://www.newschannel5.com/content/news/14428.asp
Dangerous UV burns?
From a damaged light bulb?
Care to cast some light on this, Physics/Electrician Dopers?
As pressure and temperature increase, the materials within the arc tube vaporize and emit light and ultraviolet (UV) radiation. A bulb (also called “outer jacket” or “outer envelope”), usually made of borosilicate glass, provides a stable thermal environment for the arc tube, contains an inert atmosphere that keeps the components of the arc tube from oxidizing at high temperatures, and reduces the amount of UV radiation that the lamp emits. Some MH lamps have a coated finish on the inside of the bulb that diffuses the light. Often a phosphor coat is used to both diffuse the light and change the lamp’s color properties.
I did not have this memorised, I found it here.
Basically, the people were exposed to something similar to a welding arc.
We just got done changing out 600+ lights in the factory here from MH to flourescents for many reasons, but none of them were for overexposure to UV rays.
That makes sense, my husband’s welding instructor got “sunburned” on his forearms while pulling a stint as his pipe fitter in class last spring. His teacher grumped at him good naturedly about it the next day.