> Those household smoke detectors were in the 80s, the ones sold now are optical.

No, ionization detectors are still around. They're better for detecting flame fires than optical. Think of when you've seen a campfire and there's been little smoke. There was definitely a fire, but an optical detector wouldn't have detected it.

In contrast, optical is better for smoking fires. Best practice is to have some of each. In fact, I believe some models have both in the same unit.

http://www.nfpa.org/Public-Education/Staying-safe/Safety-equ...

> But of course there's many still around, sadly

I hope not.

PSA: most smoke detectors have a lifespan of 10 years. Smoke detectors from the 80s would be mostly useless now, 40+ years later.

https://www.allstate.com/resources/home-insurance/how-long-d...

Another PSA: while you're replacing your old smoke detectors, if you have combustion heat, consider replacing some of them with ones that also detect CO. (You'll have to replace them in 5-7years, though.)