Ionising smoke alarms - should I be worried?

CatLady87

Good afternoon all
I have an ionising smoke detector in my attic bedroom that’s been beeping for a while. I stupidly didn’t realise ionising alarms were a thing and now I’ve terrified myself, realising they’ve got a radioactive substance inside them. True unit says “replace by November 2014” and I’ve owned this house since February 2018!

The previous owner had smoke alarms wired into the mains. My ex partner removed two of them and left the one in the attic. I now realise that the attic alarm won’t work even if I replaced the battery. I’ve had two alarms installed by the fire brigade.

My issue is this - how dangerous is the radioactive stuff inside these things? Should I be worried? The casing on the attic alarm is damaged and my dad tried to remove it to replace the battery but since reading about these alarms, I’ve stopped him in his tracks. I’ll post photos below, including ones of the alarms that were removed. I’d appreciate anyone’s advice and whether I should be worried about any potential radiation from these alarms (including the removed ones, as a small unit remains attached to the ceiling).

Many, many thanks!

molerat

As long as you don't eat them you will be fine, the radioactive component is miniscule and protected. A damaged outer plastic casing will not affect that protection.  The biggest danger to you is that they won't work.   You should dispose of your old detectors at your local recycling centre, not in the general waste or general WEEE.

FFHillbilly

those expired 10 years ago, I could tell you that without reading the label they have gone yellow they are so old!
you can buy replacements that will click straight onto the bases without any wiring work,  search for Aico Ei146E thats an optical smoke alarm, so won't have any radioactive materials in it
the Ei141 Ionisation versions aren't sold anymore

GDB2222

It does emit a small amount of gamma radiation, which does escape From the casing. For this reason it would be unwise to take this down from the ceiling and carry it around in your pocket 24/7. 

In normal conditions, the radiation is very small compared to all the background radiation we are all subjected to every day.

To put this in perspective, if you did carry this around in your pocket, you would receive around the same radiation as eating a banana every hour.  With it up on the ceiling, the dose is far lower. 

QrizB

GDB2222 said:

In normal conditions, the radiation is very small compared to all the background radiation we are all subjected to every day.

The ionisation-type smoke detectors that I've seen have all contained 37kBq of Am-241.

From page 330 of IAEA SSG-26, the gamma dose coefficient for Am-241 is 3.3 x10^-15 Sv /Bq /h at a distance of 1 metre.

If you were to sit one metre away from one of these smoke alarms for a complete year, you'd incur a radiation dose of (3.3 x10^-15) x 37000 x 24 x 365 Sv. That's ever so slightly more than 1 microSv (0.001 milliSv, one-millionth of a Sv).

Per this table, that's the same as two dental x-rays or eating 10g of Brazil nuts - about two nuts.

Desmond_Hume

What’s your dad going to use his new super powers for? Good or evil?

Dustyevsky

Desmond_Hume said:

What’s your dad going to use his new super powers for? Good or evil?

I'm sceptical he has them. Did you not read the bit where Cat Lady “stopped him in his tracks? “

GDB2222

QrizB said:

GDB2222 said:

In normal conditions, the radiation is very small compared to all the background radiation we are all subjected to every day.

The ionisation-type smoke detectors that I've seen have all contained 37kBq of Am-241.

From page 330 of IAEA SSG-26, the gamma dose coefficient for Am-241 is 3.3 x10^-15 Sv /Bq /h at a distance of 1 metre.

If you were to sit one metre away from one of these smoke alarms for a complete year, you'd incur a radiation dose of (3.3 x10^-15) x 37000 x 24 x 365 Sv. That's ever so slightly more than 1 microSv (0.001 milliSv, one-millionth of a Sv).

Per this table, that's the same as two dental x-rays or eating 10g of Brazil nuts - about two nuts.

I just took some figures from this source. https://assets.publishing.service.gov.uk/media/5fdca385d3bf7f3a3a963299/JSP_392_Chapter_18_-_SMOKE_DETECTORS__Alt_Text_.pdf

It quoted <.01 micro sieverts per hour at 30 cms, which I took as about .01, ignoring the < sign.