Why does welding produce UV light? Looking directly at a welder is dangerous because large amounts of UV light is produced. What makes this light? Is it electrons from the current that excites metal atoms, and these atoms sends out UV light? Or does the extreme heat have anything to do with this?
Is it dangerous to look directly at a nail being melted (glowing brightly) by hundreds of amperes?
Is it dangerous looking at an oxyhydrogen explosion in itself, or could it be dangerous if the explosion touches other substances exerting UV light because of the extreme heat of the explosion?
 A: All materials emit thermal radiation (such as light).  The hotter the material, the more the radiation is shifted to high frequencies (shorter wavelengths).  The radiation comes from oscillating electrons (regardless of whether there is an electric current). Welding reaches temperatures high enough to cause significant emission of UV light.  Oxyacetylene and oxyhydrogen flames can both be over 3000 C degrees and therefore can produce hazardous amounts of UV light.  Arc welding is even hotter and produces more UV light.  Running hundreds of amps of current through a nail would be similar to arc welding.  
http://www.mapfre.com/fundacion/html/revistas/seguridad/n124/articulo1En.html
A: in welding a plasma is created, it's a mix of ions, electrons and atoms. alltogether they are a neutral mix. once you get plasma you get a ton of UV coming out of it, very dangerous to eyes not only on the direct contact, but also via reflection from other objects.
in your case, I still don't know what exactly is the device you are creating. It sounds like there's a similar condition to welding with a lot of current going through air. that's what creates plasma in welding. can you point to a description of a similar device on web?
don't go to the court with this :) but I doubt that there's significant UV during what appears like explosion. I don't think it's plasma, there's probably some ionization, some UV, but not much at all. now, i'm going to run and hide from your lawyers :)
