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

No, holding vape smoke (or aerosol) in your lungs will not prevent a vape detector from going off.

Here's why:

They Detect Particles, Not Breath: Vape detectors don't detect "smoke" or "breath." They are laser-based sensors that detect the suspended aerosol particles (tiny liquid droplets) released by vaping and e-cigarettes. When you exhale-even a small amount after holding it in-you still release these particles into the air.

"Ghosting" Doesn't Work: The technique of holding vapor in until it disappears (sometimes called "ghosting") is ineffective against these detectors. While less visible to the human eye, a significant amount of ultrafine particles and chemical residues (like propylene glycol and glycerin) are still exhaled and can be detected.

Secondary Emission: Particles can also escape from the device itself and from your mouth/nose before you inhale. The detectors are sensitive enough to pick this up.

What Vape Detectors Actually Sense:

The aerosol particulate matter (PM2.5).

Specific chemical signatures like nicotine, THC, or the base liquids (PG/VG).

A sudden, sharp increase in particle concentration in a room.

Important Health Note:

Holding vapor in your lungs for longer periods is also more harmful, as it increases the absorption of nicotine and other chemicals into your bloodstream and allows more time for potential tissue damage.

In short: There is no reliable way to vape in an area monitored by a quality vape detector without significant risk of setting it off. The technology is designed specifically to counter such avoidance attempts.