What types of skin conditions may result from exposure to nitric fumes?

[joe]

My dad was exposed to nitric fumes while working about one year ago. When he came home his skin turned red and started to burn up (around his face and neck area). He washed with cool water for quite some time and the symptoms faded away. Ever since then, his skin was fragile to hot temperature or sunlight. His skin would irritate him (from the inside of the skin; not the surface) almost everyday. Dermatologists are giving him little analysis and information on what his condition is and they keep giving him different creams that seem to prove useless for his condition. It doesn't seem like a temporary condition considering that he's been like this for almost a year. For anyone out there who has knowledge of nitric fumes, what do you think his condition might be? Do you think its permanant? Any advise?