Editing Radon (section)

== Applications ==

=== Medical ===

==== Hormesis ====
{{Main|Radioactive quackery}}
An early-20th-century form of [[quackery]] was the treatment of maladies in a [[radiotorium]].<ref>{{cite book |title=The Clinique, Volume 34 |publisher=Illinois Homeopathic Medical Association |date=1913 |url=https://books.google.com/books?id=KM5XAAAAMAAJ&q=%2Bradiotorium&pg=PA243 |access-date=2011-06-30}}</ref> It was a small, sealed room for patients to be exposed to radon for its "medicinal effects". The carcinogenic nature of radon due to its ionizing radiation became apparent later. Radon's molecule-damaging radioactivity has been used to kill cancerous cells,<ref name="Radon seeds">{{cite web |title=Radon seeds |url=https://www.orau.org/health-physics-museum/collection/brachytherapy/seeds.html |access-date=2009-05-05 |website=ORAU Museum of Radiation and Radioactivity}}</ref> but it does not increase the health of healthy cells.{{cn|date=October 2022}} The ionizing radiation causes the formation of [[free radicals]], which results in [[cell damage]], causing increased rates of illness, including [[cancer]].

Exposure to radon has been suggested to mitigate [[autoimmune disease]]s such as [[arthritis]] in a process known as [[radiation hormesis]].<ref>{{cite web |url=http://www.roadsideamerica.com/story/2143 |title=Radon Health Mines: Boulder and Basin, Montana |publisher= Roadside America |access-date=2007-12-04}}</ref><ref name="Hg">{{cite journal |author=Neda, T. |title=Radon concentration levels in dry CO<sub>2</sub> emanations from Harghita Băi, Romania, used for curative purposes |volume=277 |issue=3 |date=2008 |doi=10.1007/s10967-007-7169-0 |journal=[[Journal of Radioanalytical and Nuclear Chemistry]] |page=685 |last2=Szakács |first2=A. |last3=Mócsy |first3=I. |last4=Cosma |first4=C.|bibcode=2008JRNC..277..685N |s2cid=97610571 }}</ref> As a result, in the late 20th century and early 21st century, "health mines" established in [[Basin, Montana]], attracted people seeking relief from health problems such as arthritis through limited exposure to radioactive mine water and radon. The practice is discouraged because of the well-documented ill effects of high doses of radiation on the body.<ref>{{cite journal |last1=Salak |first1=Kara |last2=Nordeman |first2=Landon |title=59631: Mining for Miracles |journal=[[National Geographic (magazine)|National Geographic]] |date=2004 |url=http://ngm.nationalgeographic.com/ngm/0401/feature7/index.html |archive-url=https://web.archive.org/web/20080124233142/http://ngm.nationalgeographic.com/ngm/0401/feature7/index.html |url-status=dead |archive-date=January 24, 2008 |access-date=2008-06-26}}</ref>

Radioactive water baths have been applied since 1906 in [[Jáchymov]], Czech Republic, but even before radon discovery they were used in [[Bad Gastein]], Austria. Radium-rich springs are also used in traditional Japanese [[onsen]] in [[Misasa, Tottori|Misasa]], [[Tottori Prefecture]]. Drinking therapy is applied in [[Bad Brambach]], Germany, and during the early 20th century, water from springs with radon in them was bottled and sold (this water had little to no radon in it by the time it got to consumers due to radon's short half-life).<ref>{{Cite web |date=2004-08-18 |title=For that Healthy Glow, Drink Radiation! |url=https://www.popsci.com/scitech/article/2004-08/healthy-glow-drink-radiation/ |access-date=2022-09-17 |website=Popular Science |language=en-US}}</ref> Inhalation therapy is carried out in [[Gasteiner-Heilstollen]], Austria; [[Świeradów-Zdrój]], [[Czerniawa-Zdrój]], [[Kowary]], [[Lądek-Zdrój]], Poland; [[Harghita Băi]], Romania; and [[Boulder, Montana]]. In the US and Europe, there are several "radon spas", where people sit for minutes or hours in a high-radon atmosphere, such as at [[Bad Schmiedeberg]], Germany.<ref name="Hg" /><ref>{{cite web |access-date=2008-06-26 |url=http://www.petros.cz/spa/spa_ja.asp |title=Jáchymov |publisher=Petros |url-status=dead |archive-url=https://web.archive.org/web/20020107060646/http://www.petros.cz/spa/spa_ja.asp |archive-date=January 7, 2002 }}</ref>

==== Nuclear medicine ====
[[File:Radioactive Seeds (7845754328).jpg|thumb|{{sup|222}}Rn- and [[Iodine-125|{{sup|125}}I]]-containing seeds used in [[brachytherapy]]]]
Radon has been produced commercially for use in radiation therapy, but for the most part has been replaced by radionuclides made in [[particle accelerator]]s and [[nuclear reactor]]s. Radon has been used in implantable seeds, made of gold or glass, primarily used to treat cancers, known as [[brachytherapy]]. The gold seeds were produced by filling a long tube with radon pumped from a radium source, the tube being then divided into short sections by crimping and cutting. The gold layer keeps the radon within, and filters out the alpha and beta radiations, while allowing the [[gamma ray]]s to escape (which kill the diseased tissue). The activities might range from 0.05 to 5 millicuries per seed (2 to 200&nbsp;MBq).<ref name="Radon seeds" /> The gamma rays are produced by radon and the first short-lived elements of its decay chain (<sup>218</sup>Po, <sup>214</sup>Pb, <sup>214</sup>Bi, <sup>214</sup>Po).

After 11 half-lives (42 days), radon radioactivity is at 1/2,048 of its original level. At this stage, the predominant residual activity of the seed originates from the radon decay product <sup>210</sup>Pb, whose half-life (22.3 years) is 2,000 times that of radon and its descendants <sup>210</sup>Bi and <sup>210</sup>Po.{{cn|date=October 2022}}

<sup>211</sup>Rn can be used to generate <sup>211</sup>At, which has uses in [[targeted alpha therapy]].<ref>{{cite journal | last1=Crawford | first1=Jason R | last2=Kunz | first2=Peter | last3=Yang | first3=Hua | last4=Schaffer | first4=Paul | last5=Ruth | first5=Thomas J | title=<sup>211</sup>Rn/<sup>211</sup>At and <sup>209</sup>At production with intense mass separated Fr ion beams for preclinical <sup>211</sup>At-based α-therapy research | journal=Applied Radiation and Isotopes | publisher=Elsevier BV | volume=122 | year=2017 | issn=0969-8043 | doi=10.1016/j.apradiso.2017.01.035 | pages=222–228| pmid=28189025 | bibcode=2017AppRI.122..222C }}</ref>

=== Scientific ===
Radon emanation from the soil varies with soil type and with surface uranium content, so outdoor radon concentrations can be used to track [[air mass]]es to a limited degree.<ref>{{Cite journal |last1=Lambert |first1=Gérard |last2=Polian |first2=Georges |last3=Taupin |first3=D. |date=1970-04-20 |title=Existence of periodicity in radon concentrations and in the large-scale circulation at lower altitudes between 40° and 70° south |url=http://doi.wiley.com/10.1029/JC075i012p02341 |journal=Journal of Geophysical Research |language=en |volume=75 |issue=12 |pages=2341–2345 |doi=10.1029/JC075i012p02341|bibcode=1970JGR....75.2341L }}</ref>{{efn|See [[radon storm]].}} Because of radon's rapid loss to air and comparatively rapid decay, radon is used in [[hydrology|hydrologic]] research that studies the interaction between groundwater and [[stream]]s. Any significant concentration of radon in a river may be an indicator that there are local inputs of groundwater.<ref>{{Citation |last1=S. |first1=Sukanya |title=Radon Distribution in Groundwater and River Water |date=2023 |work=Environmental Radon: A Tracer for Hydrological Studies |pages=53–87 |editor-last=S. |editor-first=Sukanya |url=https://link.springer.com/chapter/10.1007/978-981-99-2672-5_3 |access-date=2024-10-15 |place=Singapore |publisher=Springer Nature |language=en |doi=10.1007/978-981-99-2672-5_3 |isbn=978-981-99-2672-5 |last2=Joseph |first2=Sabu |editor2-last=Joseph |editor2-first=Sabu}}</ref>

Radon soil concentration has been used to map buried close-subsurface geological [[fault (geology)|faults]] because concentrations are generally higher over the faults.<ref>{{cite journal |author=Richon, P. |author2=Y. Klinger |author3=P. Tapponnier |author4=C.-X. Li |author5=J. Van Der Woerd |author6=F. Perrier |name-list-style=amp |date=2010 |title=Measuring radon flux across active faults: Relevance of excavating and possibility of satellite discharges |url=http://www.ipgp.fr/~klinger/page_web/biblio/publication/Richon_RadMeas2010%20.pdf |journal=[[Radiat. Meas.]] |volume=45 |pages=211–218 |doi=10.1016/j.radmeas.2010.01.019 |issue=2 |bibcode=2010RadM...45..211R |hdl=10356/101845 |access-date=2011-08-20 |archive-date=2013-06-26 |archive-url=https://web.archive.org/web/20130626115736/http://www.ipgp.fr/~klinger/page_web/biblio/publication/Richon_RadMeas2010%20.pdf |url-status=dead }}</ref> Similarly, it has found some limited use in prospecting for [[geothermal gradient]]s.<ref>{{cite conference |last1=Semprini |first1=Lewis |last2=Kruger |first2=Paul |date=April 1980 |title=Radon Transect Analysis In Geothermal Reservoirs |conference=SPE California Regional Meeting, 9–11 April, Los Angeles, California |doi=10.2118/8890-MS |isbn=978-1-55563-700-2}}</ref>

Some researchers have investigated changes in groundwater radon concentrations for [[earthquake prediction]].<ref>{{Unbulleted list citebundle|{{cite journal |author=Igarashi, G. |author2=Wakita, H. |date=1995 |title=Geochemical and hydrological observations for earthquake prediction in Japan |journal=[[Journal of Physics of the Earth]] |volume=43 |pages=585–598 |url=http://www.jstage.jst.go.jp/article/jpe1952/43/5/43_5_585/_pdf |doi=10.4294/jpe1952.43.585 |issue=5|doi-access=free }}|{{Cite journal |first1=Masayasu |last1=Noguchi |last2=Wakita |first2=Hiroshi |date=10 March 1977 |journal=[[Journal of Geophysical Research]] |doi=10.1029/JB082i008p01353 |title=A method for continuous measurement of radon in groundwater for earthquake prediction |pages= 1353–1357 |volume=82 |issue=8|bibcode=1977JGR....82.1353N }}}}</ref><ref name="Mindoro">{{cite journal |author=Richon, P. |author2=Sabroux, J.-C.|author3=Halbwachs, M.|author4=Vandemeulebrouck, J.|author5=Poussielgue, N.|author6=Tabbagh, J. |author7=Punongbayan, R. |date=2003 |title=Radon anomaly in the soil of Taal volcano, the Philippines: A likely precursor of the M 7.1 Mindoro earthquake (1994) |journal=[[Geophysical Research Letters]] |volume=30 |issue=9 |page=34 |doi=10.1029/2003GL016902|bibcode=2003GeoRL..30.1481R|s2cid=140597510 }}</ref> Increases in radon were noted before the [[1966 Tashkent earthquake|1966 Tashkent]]<ref>{{Cite book |editor-last=Cothern |editor-first=C.Richard | editor-last2=Smith | editor-first2=James E. |date=1987 |title=Environmental Radon |url=https://books.google.com/books?id=K7WvwZlc72MC&pg=PA53|series=Environmental Science Research |volume=35 | publisher=Springer Science & Business Media | publication-place=New York |isbn=978-0-306-42707-7|page=53}}</ref> and [[1994 Mindoro earthquake|1994 Mindoro]]<ref name="Mindoro" /> earthquakes. Radon has a half-life of approximately 3.8 days, which means that it can be found only shortly after it has been produced in the radioactive decay chain. For this reason, it has been hypothesized that increases in radon concentration is due to the generation of new cracks underground, which would allow increased groundwater circulation, flushing out radon. The generation of new cracks might not unreasonably be assumed to precede major earthquakes. In the 1970s and 1980s, scientific measurements of radon emissions near faults found that earthquakes often occurred with no radon signal, and radon was often detected with no earthquake to follow. It was then dismissed by many as an unreliable indicator.<ref>{{cite news |url=https://www.npr.org/templates/story/story.php?storyId=102804333 |title=Expert: Earthquakes Hard To Predict |newspaper=NPR.org |access-date=2009-05-05}}</ref> As of 2009, it was under investigation as a possible earthquake precursor by [[NASA]];<ref name="EARTHq">{{cite web |url=https://www.earthmagazine.org/article/earthquake-prediction-gone-and-back-again/ |title=EARTH Magazine: Earthquake prediction: Gone and back again |date=2012-01-05}}</ref> further research into the subject has suggested that abnormalities in atmospheric radon concentrations can be an indicator of seismic movement.<ref>{{Cite journal|doi=10.1038/s41598-024-61887-6 |last1=Tsuchiya |first1=Mayu |last2=Nagahama |first2=Hiroyuki |last3=Muto |first3=Jun |first4=Mitsuhiro |last4=Hirano |first5=Yumi |last5=Yasuoka |title=Detection of atmospheric radon concentration anomalies and their potential for earthquake prediction using Random Forest analysis |journal=[[Sci Rep]] |volume=14 |issue=11626 |date=2024|page=11626 |pmid=38821969 |bibcode=2024NatSR..1411626T |pmc=11143197 }}</ref>

Radon is a known pollutant emitted from [[Geothermal power|geothermal power stations]] because it is present in the material pumped from deep underground. It disperses rapidly, and no radiological hazard has been demonstrated in various investigations. In addition, typical systems re-inject the material deep underground rather than releasing it at the surface, so its environmental impact is minimal.<ref>{{cite web |title= Radon and Naturally Occurring Radioactive Materials (NORM) associated with Hot Rock Geothermal Systems |publisher= Government of South Australia—Primary Industries and Resources SA |access-date= 2013-07-16 |url= http://www.pir.sa.gov.au/__data/assets/pdf_file/0013/113341/090107_web.pdf |archive-url= https://web.archive.org/web/20120402134109/http://www.pir.sa.gov.au/__data/assets/pdf_file/0013/113341/090107_web.pdf |archive-date= 2012-04-02 |url-status= dead }}</ref> In 1989, a survey of the [[collective dose]] received due to radon in geothermal fluids was measured at 2 man-[[sievert]]s per [[Kilowatt-hour#Multiples|gigawatt-year]] of electricity produced, in comparison to the 2.5 man-sieverts per gigawatt-year produced from [[carbon-14|{{sup|14}}C]] emissions in [[nuclear power plants]].<ref>{{Cite journal|url=https://www.iaea.org/sites/default/files/publications/magazines/bulletin/bull31-2/31205642131.pdf |title=Radiation versus radiation: Nuclear energy in perspective |journal=IAEA Bulletin |issue=2 |date=1989 |first1=Abel J. |last1=Gonzalez |first2=Jeanne |last2=Anderer}}</ref>

In the 1940s and 1950s, radon produced from a radium source was used for [[industrial radiography]].<ref>{{Unbulleted list citebundle|{{cite journal |doi=10.1088/0950-7671/23/7/301 |title=Radon. Its Properties and Preparation for Industrial Radiography |date=1946 |author=Dawson, J. A. T. |journal=[[Journal of Scientific Instruments]] |volume=23 |page=138 |issue=7 |bibcode = 1946JScI...23..138D }}|{{cite journal |title= Use of radon for industrial radiography |first= A. |last= Morrison |journal= [[Canadian Journal of Research]] |date= 1945 |volume= 23f |issue= 6 |pages= 413–419 |doi= 10.1139/cjr45f-044 |pmid= 21010538 }}}}</ref> Other X-ray sources such as [[Cobalt-60|{{sup|60}}Co]] and [[Iridium-192|{{sup|192}}Ir]] became available after World War II and quickly replaced radium and thus radon for this purpose, being of lower cost and hazard.<ref>{{Unbulleted list citebundle|{{Cite web|url=https://www.orau.org/health-physics-museum/collection/radioactive-sources/radium-industrial-radiography-source.html |website=ORAU Museum of Radiation and Radioactivity |title=Radium Industrial Radiography Source (ca. 1940s) |access-date=22 August 2024}}|{{Cite web|url=https://www.nde-ed.org/NDETechniques/Radiography/Introduction/history.xhtml |website=[[Iowa State University]] Center for Nondestructive Evaluation |title=History of Radiography |access-date=22 August 2024}}}}</ref><!--{{Unbulleted list citebundle|{{Cite journal|doi=10.1002/maco.19550060317 |title=Memorandum on gamma-ray sources for radiography. Prepared by a committee of the industrial radiology group, London, 1952 |date=1955 |last=Scheichl |first=L. |journal=Materials and Corrosion |issue=6 |pages=163-163}}|{{Cite journal|url=https://www.nature.com/articles/174726a0.pdf |journal=Nature |date=October 16, 1954 |volume=174 |title=Gamma-Ray Sources for Radiography}} Sources for continued availability of radon, radium in the 1950s as a gamma ray source - along with others-->