Eco-Tip: Smoke Detectors and Radiation
by TreeHugger on 12.30.04
You wouldn’t want all your fancy green furniture to go up in flames, so of course you’ve got a smoke detector. But not all detectors are created equal: there’s a choice between photoelectric and ionization detectors, and the latter contains a tiny bit of radiation. Radioactive Americium-241 releases ions that react with smoke in the detector to change an electrical current. It’s not enough radiation to harm you, but it’ll have to go into a landfill eventually—a definite eco no-no. The alternative photoelectric detectors instead works using an internal light source, which reflects light to a photocell when smoke enters the chamber.
In terms of performance, the two types are a bit different. If your house is burning down at the hand of a drapery fire or other flames, ionization would detect and report it slightly quicker. The photoelectric detector would jump in first if you left a cigarette to burn or had a similar smoldering fire. Either way, the detectors will have been UL-certified, which ensures that they’ll detect pretty much anything in a timely fashion.
Smoke detectors that contain radioactive material are labeled, normally indicating Americium-241 or AM-241. Photoelectric detectors are readily available—a battery-powered version from Seattle’s Environmental Home Center costs $26.99, and a wired version is $49.99. Home Depot has tons of choices, too. ::Environmental Home Center ::Newport News Fire Department [by KK]
A little background on Am-241:
http://www.uic.com.au/nip35.htm
Bottom line: Even ingesting the Am-241 oxide in your detector (about 1/5000 of a gram) doesn't represent a toxic or radiologically harmful exposure, since it is chemically inert and would pass right through your (or any other organism's) digestive tract.
The environmental impact of the lead in the solder used in _either_ type of smoke-detector is more significant, since Pb will readily enter the food chain, water table, etc.
Granted, the tiny speck of material in a detector has a half-life of 432 years, which does mean it'll be in the landfill for a while. However, it only produces alpha particles (blocked by anything, even an inch of _air_) and a few gamma rays (blocked by nothing, but at these concentrations, the celery in your fridge is as radioactive) without producing any of the nasty, DNA-smashing neutrons or carcinogenic Beta particles, the Am-241 isn't the main environmental risk.
The real environmental kicker, of course, would be the airborne Dioxins produced by a house-fire that wasn't detected early, so any detector, even a "nasty" ionization-powered one is better than none at all.