Yesterday while cooking I set off the smoke detector, no I did not burn anything. They go off when I cook over a high heat. And yesterday once they started going off they would not stop. I ended up having to disconnect them all (they are hard wired with an interconnect) and I replaced them this morning. Aaaaaaaand let me tell you, I had a sleepless night last night knowing there were no detectors installed.
https://www.southernliving.com/how-often-should-you-replace-smoke-detectors-8774122
The half life for americium 241 is like 450 years. The 10 year replacement has nothing to do with decay. It’s just a non specific safety in case any of the electronics or board etc start to fail. Photoelectric detectors have the same 10 year recommendation as a max.
It’s actually recommend by many organizations (like the NFPA) to replace photoelectric detectors more often than ionization detectors, if anything.
It’s tuned to a specific output and isn’t exactly field adjustable. Certainly it will continue to be radioactive long after you’re dead, but that doesn’t mean it will still be working properly.