xiao1985 said:
benefit of AM241: it's an alpha emitter... so even a trace of smoke particulate will block the radiation and trigger the alarm
problem: all radiation has the potential to hurt.
If you chucked a smoke alarm in space it'll go off regardless.
There's an ionization chamber in a smoke alarm.
Incoming gas molecules in the air are ionized at a constant rate by the alpha emitter Americium-241, and since those ionized molecules now contain a charge they can conduct electricity within the electric field of the ionizing chamber.
If this rate of ionization falls, noted by less charge carriers within the electric field then an alarm will be trigggered.
And yes radiation has the potential to hurt
... even at low energies ...