Editing Smoke detector (section)

==== Radiation ====
[[File:Americium button hd.jpg|thumb|A 141 [[nanogram|ng]] speck of [[Americium dioxide|americium-241 dioxide]] on a coin-sized aluminum button<ref>{{cite magazine |last1=Bettenhausen |first1=Craig |title=Chemistry in Pictures: Americium the beautiful |magazine=[[Chemical & Engineering News]] |date=July 7, 2021 |url=https://cen.acs.org/materials/Chemistry-Pictures-Americium-beautiful/99/web/2021/07 |access-date=11 June 2023 |publisher=[[American Chemical Society]] |issn=0009-2347}}</ref>]]
[[Americium-241]] is an [[Alpha decay|alpha emitter]] with a [[half-life]] of 432.6 years.<ref>{{Cite web |title=NuDat 3.0 database |url=https://www.nndc.bnl.gov/nudat3/ |website=NNDC.BNL.gov |publisher=[[Brookhaven National Laboratory]] |access-date=24 September 2022 }}</ref> Alpha particle radiation, as opposed to [[Beta decay|beta]] (electron) and [[Gamma ray|gamma]] (electromagnetic) radiation, is used for two reasons: the alpha particles can ionize enough air to make a detectable current; and they have low penetrative power, meaning they will be stopped, safely, by the air or the plastic shell of the smoke detector. During the alpha decay, {{SimpleNuclide|Americium|241}} emits [[gamma radiation]], but it is low-energy and therefore not considered a significant contributor to human exposure.<ref group=Note name=Note01/><ref group=Note name=Note02/><ref group=Note name=Note03/>

The amount of elemental americium-241 in ionization smoke detectors is small enough to be exempt from the regulations applied to larger deployments. A smoke detector contains about {{convert|37|kBq|abbr=on|lk=on}} of radioactive element americium-241 ({{SimpleNuclide|Americium|241}}), corresponding to about 0.3&nbsp;μg of the isotope.<ref>{{cite web | url = http://media.cns-snc.ca/pdf_doc/ecc/smoke_am241.pdf | title = Smoke detectors and americium-241 fact sheet | publisher = Canadian Nuclear Society | access-date = 2009-08-31 | url-status = live | archive-url = https://web.archive.org/web/20110706173242/http://media.cns-snc.ca/pdf_doc/ecc/smoke_am241.pdf | archive-date = 2011-07-06 }}</ref><ref>{{cite web|url=http://www.atsdr.cdc.gov/toxprofiles/tp156.pdf|format=PDF; 2.1MiB|title=Toxicological Profile for Americium|first=Julie Louise|last=Gerberding|publisher=[[United States Department of Health and Human Services]]/[[Agency for Toxic Substances and Disease Registry]]|access-date=2009-08-29|date=April 2004|url-status=live|archive-url=https://web.archive.org/web/20090906112953/http://www.atsdr.cdc.gov/toxprofiles/tp156.pdf|archive-date=2009-09-06}}</ref> This provides sufficient ion current to detect smoke while producing a very low level of radiation outside the device. Some Russian-made smoke detectors, most notably the RID-6m and IDF-1m models, contain a small amount of plutonium (18&nbsp;MBq), rather than the typical {{SimpleNuclide|Americium|241}} source, in the form of reactor-grade {{SimpleNuclide|Plutonium|239}} mixed with titanium dioxide onto a cylindrical alumina surface.<ref>{{Cite web |date=2017-02-07|title=Analysis of Soviet smoke detector plutonium|url=https://carlwillis.wordpress.com/2017/02/07/analysis-of-soviet-smoke-detector-plutonium/|access-date=2021-12-23|website=Special Nuclear Material|language=en}}</ref>

The amount of americium-241 contained in ionizing smoke detectors does not represent a significant radiological hazard.<ref>{{cite web |title=Backgrounder on Smoke Detectors |url=https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/smoke-detectors.html |website=NRC Library |publisher=U.S. [[Nuclear Regulatory Commission]] |access-date=24 September 2022}}</ref> If the americium is left in the ionization chamber of the alarm, the radiological risk is insignificant because the chamber acts as a shield to the alpha radiation. A person would have to open the sealed chamber and ingest or inhale the americium for the dose to be comparable to [[Background radiation#Natural background radiation|natural background radiation]]. The radiation risk of exposure to an ionizing smoke detector operating normally is much smaller than natural background radiation.