Wouldn't Nitrogen be just as effective, and far cheaper? Halon is the mandated standard for airliners and is perfect for the application. If people are really concerned about greenhouse gas/ozone layer depletion they should train cows to stop farting.
Actually, I think I read about an injection that claims to cut this in sheep by a significant percentage. I wouldn't mind volunteering some humans of my aquaintance for these tests.....
Ripline
Ah, yes, it's here:
http://www.newscientist.com/news/news.jsp?id=ns99996431