I've been given a humidifier as the air in my room is very dry and I'm having health issues which might (or not) be related.
However, I've a smoke detector in my room (it's a klaxon so I'd rather not try it and see as it'll disturb everyone in building and next door!). It's actually much bigger than I expected it to be. I know the alarm goes off if I put heating on too high and if I burn oils. Would this be the same sort of thing? Ironically when tested it didn't go off for ages 
I've never had one before.