How dangerous are the fumes of a faulty battery charger?

Ralph asked:


I could not find the original charger for my air mattress pump, so I used another charger that fit into it. I left it charging through the night. When I woke up, there were fumes being emitted (sulfide?) and what appeared to be water leaking from it. I disposed of it and started airing my room out immediately. Is there more I should do (any extra precautions)? What caused this to happen? And was that water leaking from the battery pump? Any help or insight would be great. Thanks.