(I have carbon monoxide detectors that are not going off)
I have smoke detectors that are incorporated into my home alarm system. The other day, the one by my front door went off for no apparent reason, twice, and when I changed the batteries, it started alarming again immediately.
there was absolutely no reason for it, there were no open windows or doors nearby, it just went off. so, my alarm company replaced it. installed the new smoke detector yesterday and… it just went off again. completely different smoke detector.
there’s absolutely nothing in my house that could produce carbon monoxide, but I have separate CO detectors anyway that aren’t going off. there’s no smell, there’s nothing visible, and these are those electro optical photoelectric style ones.
Depends on what kind of detector it is but alot of them use small amounts of radiation and a detector that triggers when the number of particles detected drops below some level.
How smoke detectors work
That being the case any particulate large enough to interrupt the particles could cause it to go off.
For example high humidity misty water from a shower wafting over a detector placed over the bathroom door, etc.