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?