Question:
For an ionization type of smoke detector, is it only small particles of combustion that will trigger it, or most any type of particle in the appropriate size range ? (if combustion oarticles only, what would be some examples, please ?)

Same question for a photoelectric type ?

Answer: IIUC: Photoelectric sensors just use the particles as reflectors - so will respond to any particle size. The sensor senses the *increase* in reflected light - hence need a baseline to establish a reference point.

Ionisation types both sense the change in current caused by particles removing ions and by air temperature changing rapidly. Carbon particles are particularly effective..hence also the need to establish a baseline reference point.