Will a vape detector go off if you hold the smoke in?

Yes, a vape detector is very likely to go off even if you hold the smoke (vapor) in. Here's why:

Detection Method: Vape detectors don't detect you exhaling; they detect the chemicals and particles suspended in the air (the aerosol). Holding the vapor in your lungs doesn't make those particles disappear.

Exhalation is Necessary: You must exhale eventually. When you do, the aerosol (even if slightly reduced in volume) is released into the room air.

Residual Vapor: Significant amounts of vapor can still escape your mouth/nose before and during the inhale, and definitely upon exhale, even if you try to minimize the cloud.

Particle Persistence: The fine particles and chemicals in the vapor disperse into the air and linger. Detectors sample this ambient air continuously.

Sensitivity: Modern vape detectors are designed to be highly sensitive to trace amounts of specific chemicals (like propylene glycol, vegetable glycerin, nicotine, flavorings) and particulate matter associated with vaping.

Holding your breath does NOT make you "invisible" to the detector. The vapor still enters the room air when you exhale, and that's what triggers the alarm.

Important Health Note: Holding vapor in your lungs longer also increases the absorption of nicotine and other potentially harmful chemicals into your bloodstream. It doesn't make vaping safer.

In short: Trying to avoid setting off a vape detector by holding in the vapor won't work. The detector senses the aerosol particles and chemicals in the air after you exhale.