Are the radioactive element in ionization units a hazard?
No. The bit of Americium 241 that is used will not cause harm. It has less power than the radium that is used in watch dials. To give you an idea of its safety, a person flying coast to coast gets more radiation in the sky than you do with a long-term exposure to an ionization smoke alarm. In fact, you can discard the smoke alarms in normal household waste without any special precautions.
