I asked this very same question here a couple of months ago. Some people thought it was impossible to set off a smoke detector with an e-cig because "it's not smoke".
There are different types of detectors. Some
sense the particulates in the air and not necessarily just smoke.
Most didn't want to try it by blowing vapor directly into a smoke detector because it would scare their pets or neighbors if it did set it off.
But one poster did say that his home smoke detector did sound off when he vaped heavily in an enclosed room long enough that you could see the vapor in the air.
So, yes it is possible to activate one with an E-cig. But I think it would have to be a very heavy concentration of vapor. I used to smoke cigs in a small bedroom (actually a computer room) with a smoke detector on the ceiling. Never set it off tho.
But the smoke alarms did go off the other morning when the electric central heat came on for the first time this season. You know the smell it makes, kinda like burnt dust. No visible smoke in the house but still set it off. Does that every year.
I guess the next time I have the ladder in the house to change a light bulb or the smoke alarm
batteries, I will try it. If the wife is not home and the cat is outside, LOL.
I am curious too if anyone has ever vaped in an airplane rest room.