It would be useful to mention the issue of aging smoke detectors, particularly the ionization chamber type. These devices rely on a radioactive element: Americium, which decays over time. All ionization type smoke detectors have an expiration date, typically 10 years. Any ionization chamber type smoke detector that is 10 or more years old or has exceeded its expiration date should be replaced.
I already had this:
*Smoke alarms should be replaced when they fail to respond to testing, or every 10 years, whichever is sooner. *
But I’ll add this:
*The radioactive element in ionization smoke alarms will decay beyond usability within 10 years.
I apparently overlooked the “every 10 years, whichever is sooner.” when I read through it.