It can happen, but it is fairly unlikely. Vapor would certainly not set off any actual fire or carbon monoxide detection systems, but some smoke alarms use an electronic "eye" to detect "particulates"--the vapor from an e-cig generally does not contain any solid particulates like actual smoke, but if the vapor is thick enough, water droplets from e-cig vapor or theatrical fog machines can conceivably set off an alarm, but unless you're blowing vapor directly at the detector, it would probably need to be pretty thick or a very small room to detect a the very tiny amounts of liquid vaporized in an e-cig....
Think of it this way, a fog machine can use up to a gallon of
e-liquid for one concert, haunted house, dance club, or theatrical performance and generally does not set off fire alarms....how much do you think that
vaping less than a teaspoon (5ml) is going to effect??
