Ionization Smoke Detectors

The ionization smoke detector is more complicated than a photoelectric smoke detector. Inside an ionization smoke detector there is a small amount of americium-241. This chemical isotope is radioactive, emits alpha particles and has a half-life of 432 years. The alpha particles ionize the air molecules in between the two plates of the ionization chamber.

When smoke enters the ionization chamber, it disrupts this current and triggers the alarm.

The ionization detector responds faster to small smoke particles and to the smoke produced by flaming fires. It is also cheaper than the photoelectric smoke detectors.

The americium in the smoke detector can be dangerous only if you inhale it.