Radon is a chemical element ; it has symbol Rn and atomic number 86. It is a radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon isotopes, only Rn has a sufficiently long half-life (3.825 days) for it to be released from the soil and rock where it is generated. Radon isotopes are the immediate decay products of radium isotopes. The instability of Rn, its most stable isotope, makes radon one of the rarest elements. Radon will be present on Earth for several billion more years despite its short half-life, because it is constantly being produced as a step in the decay chains of U and Th , both of which are abundant radioactive nuclides with half-lives of at least several billion years. The decay of radon produces many other short-lived nuclides , known as "radon daughters", ending at stable isotopes of lead . Rn occurs in significant quantities as a step in the normal radioactive decay chain of U, also known as the uranium series , which slowly decays into a variety of radioactive nuclides and eventually decays into stable Pb . Rn occurs in minute quantities as an intermediate step in the decay chain of Th, also known as the thorium series , which eventually decays into stable Pb .
125-691: Emanation may refer to: Emanation (chemistry) , a dated name for the chemical element radon Emanation From Below , a concept in Slavic religion Emanation in the Eastern Orthodox Church , a belief found in Neoplatonism Emanation of the state , a legal term for a public service body Emanationism , an idea in the cosmology or cosmogony of certain religious or philosophical systems "Emanations" ( Star Trek: Voyager ) ,
250-419: A C atom is in the genetic information of about half the cells, while potassium is not a component of DNA . The decay of a C atom inside DNA in one person happens about 50 times per second, changing a carbon atom to one of nitrogen . The global average internal dose from radionuclides other than radon and its decay products is 0.29 mSv/a, of which 0.17 mSv/a comes from K, 0.12 mSv/a comes from
375-423: A regular octahedral molecule, unlike the distorted octahedral structure of XeF 6 , because of the inert pair effect . Because radon is quite electropositive for a noble gas, it is possible that radon fluorides actually take on highly fluorine-bridged structures and are not volatile. Extrapolation down the noble gas group would suggest also the possible existence of RnO, RnO 2 , and RnOF 4 , as well as
500-443: A 1995 episode of Star Trek: Voyager Emanations (Penderecki) , a 1958 composition by Krzysztof Penderecki "Emanation", a song by Immanuel Wilkins from The 7th Hand "Emanations", a song by Univers Zero from Uzed See also [ edit ] Aeon (Gnosticism) Emanate , a 1999 album by Penumbra Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with
625-403: A Pennsylvania nuclear power plant, a worker was found to be contaminated with radioactivity. A high concentration of radon in his home was subsequently identified as responsible. Discussions of radon concentrations in the environment refer to Rn, the decay product of uranium and radium. While the average rate of production of Rn (from the thorium decay series) is about the same as that of Rn,
750-424: A building directly from the soil through the lowest level in the building that is in contact with the ground. High levels of radon in the water supply can also increase indoor radon air levels. Typical entry points of radon into buildings are cracks in solid foundations and walls, construction joints, gaps in suspended floors and around service pipes, cavities inside walls, and the water supply. Radon concentrations in
875-462: A considerable obstacle to potential future long term human exploration of the Moon or Mars . Cosmic rays also cause elemental transmutation in the atmosphere, in which secondary radiation generated by the cosmic rays combines with atomic nuclei in the atmosphere to generate different nuclides . Many so-called cosmogenic nuclides can be produced, but probably the most notable is carbon-14 , which
1000-424: A depth of 15 cm), contains about 1 gram of radium, which releases radon in small amounts to the atmosphere. It is estimated that 2.4 billion curies (90 EBq) of radon are released from soil annually worldwide. This is equivalent to some 15.3 kilograms (34 lb). Radon concentration can differ widely from place to place. In the open air, it ranges from 1 to 100 Bq/m , even less (0.1 Bq/m ) above
1125-448: A dose of 5 to 10 μSv. A CT scan delivers an effective dose to the whole body ranging from 1 to 20 mSv (100 to 2000 mrem). The average American receives about 3 mSv of diagnostic medical dose per year; countries with the lowest levels of health care receive almost none. Radiation treatment for various diseases also accounts for some dose, both in individuals and in those around them. Cigarettes contain polonium-210 , originating from
1250-436: A few tens of grams of radon, consistently replaced by decay of larger amounts of radium, thorium, and uranium. Radon is produced by the radioactive decay of radium-226, which is found in uranium ores, phosphate rock, shales, igneous and metamorphic rocks such as granite, gneiss, and schist, and to a lesser degree, in common rocks such as limestone. Every square mile of surface soil, to a depth of 6 inches (2.6 km to
1375-594: A given territory. Thus, the geometric mean is generally used for estimating the "average" radon concentration in an area. The mean concentration ranges from less than 10 Bq/m to over 100 Bq/m in some European countries. Some of the highest radon hazard in the US is found in Iowa and in the Appalachian Mountain areas in southeastern Pennsylvania. Iowa has the highest average radon concentrations in
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#17327768744121500-493: A higher concentration of uranium. Not all granitic regions are prone to high emissions of radon. Being a rare gas, it usually migrates freely through faults and fragmented soils, and may accumulate in caves or water. Owing to its very short half-life (four days for Rn), radon concentration decreases very quickly when the distance from the production area increases. Radon concentration varies greatly with season and atmospheric conditions. For instance, it has been shown to accumulate in
1625-494: A low volatility and was thought to be RnF 2 . Because of the short half-life of radon and the radioactivity of its compounds, it has not been possible to study the compound in any detail. Theoretical studies on this molecule predict that it should have a Rn–F bond distance of 2.08 ångströms (Å), and that the compound is thermodynamically more stable and less volatile than its lighter counterpart xenon difluoride ( XeF 2 ). The octahedral molecule RnF 6
1750-507: A measure of radioactivity commonly used in mining). These conditions are not always met; in many homes, the equilibrium factor is typically 40%; that is, there will be 0.004 WL of daughters for each pCi/L of radon in the air. Pb takes much longer to come in equilibrium with radon, dependent on environmental factors, but if the environment permits accumulation of dust over extended periods of time, Pb and its decay products may contribute to overall radiation levels as well. Several studies on
1875-459: A particular location which is not due to deliberate introduction of radiation sources. Background radiation originates from a variety of sources, both natural and artificial. These include both cosmic radiation and environmental radioactivity from naturally occurring radioactive materials (such as radon and radium ), as well as man-made medical X-rays, fallout from nuclear weapons testing and nuclear accidents . Background radiation
2000-445: A population of workers who may have significantly different natural background and medical radiation doses. This is most significant when the occupational doses are very low. At an IAEA conference in 2002, it was recommended that occupational doses below 1–2 mSv per year do not warrant regulatory scrutiny. Under normal circumstances, nuclear reactors release small amounts of radioactive gases, which cause small radiation exposures to
2125-407: A protective and adaptive effect is suggested by at least one study whose authors nonetheless caution that data from Ramsar are not yet sufficiently strong to relax existing regulatory dose limits. However, the recent statistical analyses discussed that there is no correlation between the risk of negative health effects and elevated level of natural background radiation. Background radiation doses in
2250-700: A radioactive gas he named "radium emanation" ("Ra Em"). In 1901, Rutherford and Harriet Brooks demonstrated that the emanations are radioactive, but credited the Curies for the discovery of the element. In 1903, similar emanations were observed from actinium by André-Louis Debierne , and were called "actinium emanation" ("Ac Em"). Several shortened names were soon suggested for the three emanations: exradio , exthorio , and exactinio in 1904; radon (Ro), thoron (To), and akton or acton (Ao) in 1918; radeon , thoreon , and actineon in 1919, and eventually radon , thoron , and actinon in 1920. (The name radon
2375-409: A rate of about 1 mm /day per gram of radium; equilibrium is quickly achieved and radon is produced in a steady flow, with an activity equal to that of the radium (50 Bq). Gaseous Rn (half-life of about four days) escapes from the capsule through diffusion . Background radiation Background radiation is a measure of the level of ionizing radiation present in the environment at
2500-415: A specified radiation source, where the existing background may affect this measurement. An example would be measurement of radioactive contamination in a gamma radiation background, which could increase the total reading above that expected from the contamination alone. However, if no radiation source is specified as being of concern, then the total radiation dose measurement at a location is generally called
2625-455: A tenth of the terrestrial background. Conversely, coastal areas (and areas by the side of fresh water) may have an additional contribution from dispersed sediment. The biggest source of natural background radiation is airborne radon , a radioactive gas that emanates from the ground. Radon and its isotopes , parent radionuclides , and decay products all contribute to an average inhaled dose of 1.26 mSv/a (millisievert per year ). Radon
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#17327768744122750-483: A wasting disease of miners, the mala metallorum , and Georg Agricola recommended ventilation in mines to avoid this mountain sickness ( Bergsucht ). In 1879, this condition was identified as lung cancer by Harting and Hesse in their investigation of miners from Schneeberg, Germany. The first major studies with radon and health occurred in the context of uranium mining in the Joachimsthal region of Bohemia . In
2875-424: Is inert to most common chemical reactions, such as combustion , because the outer valence shell contains eight electrons . This produces a stable, minimum energy configuration in which the outer electrons are tightly bound. Its first ionization energy —the minimum energy required to extract one electron from it—is 1037 kJ/mol. In accordance with periodic trends , radon has a lower electronegativity than
3000-412: Is a scintillation detector used for surface contamination monitoring. In an elevated gamma background the scintillator material will be affected by the background gamma, which will add to the reading obtained from any contamination which is being monitored. In extreme cases it will make the instrument unusable as the background swamps the lower level of radiation from the contamination. In such instruments
3125-496: Is a colorless, odorless gas, the only way to know how much is present in the air or water is to perform tests. In the US, radon test kits are available to the public at retail stores, such as hardware stores, for home use, and testing is available through licensed professionals, who are often home inspectors . Efforts to reduce indoor radon levels are called radon mitigation . In the US, the EPA recommends all houses be tested for radon. In
3250-581: Is a contaminant that affects indoor air quality worldwide. According to the United States Environmental Protection Agency (EPA), radon is the second most frequent cause of lung cancer, after cigarette smoking, causing 21,000 lung cancer deaths per year in the United States. About 2,900 of these deaths occur among people who have never smoked. While radon is the second most frequent cause of lung cancer, it
3375-571: Is a decay product of Ra , the latter being itself a decay product of U . A trace amount of the (highly unstable) isotope Rn (half-life about 35 milliseconds ) is also among the daughters of Rn. The isotope Rn would be produced by the double beta decay of natural Po; while energetically possible, this process has however never been seen. Three other radon isotopes have a half-life of over an hour: Rn (about 15 hours), Rn (2.4 hours) and Rn (about 1.8 hours). However, none of these three occur naturally. Rn, also called thoron,
3500-477: Is a natural decay product of the most stable thorium isotope ( Th). It has a half-life of 55.6 seconds and also emits alpha radiation . Similarly, Rn is derived from the most stable isotope of actinium ( Ac)—named "actinon"—and is an alpha emitter with a half-life of 3.96 seconds. Rn belongs to the radium and uranium-238 decay chain, and has a half-life of 3.8235 days. Its first four products (excluding marginal decay schemes ) are very short-lived, meaning that
3625-433: Is a noble gas and does not adhere to lung tissue (meaning it is often exhaled before decaying), the radon daughters attached to dust are more likely to stick to the lungs. This increases the risk of harm, as the radon daughters can cause damage to lung tissue. Radon and its daughters are, taken together, often the single largest contributor to an individual's background radiation dose, but due to local differences in geology,
3750-522: Is also lowered by air circulation or air filtration devices, and is increased by airborne dust particles, including cigarette smoke. The equilibrium factor found in epidemiological studies is 0.4. Radon was discovered in 1899 by Ernest Rutherford and Robert B. Owens at McGill University in Montreal . It was the fifth radioactive element to be discovered, after uranium, thorium, radium, and polonium. In 1899, Pierre and Marie Curie observed that
3875-513: Is being measured. This is in accordance with the International Atomic Energy Agency definition of background as being "Dose or dose rate (or an observed measure related to the dose or dose rate) attributable to all sources other than the one(s) specified. The same issue occurs with radiation protection instruments, where a reading from an instrument may be affected by the background radiation. An example of this
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4000-624: Is captured, may be incorporated into concrete manufactured with fly ash. The global average human exposure to artificial radiation is 0.6 mSv/a, primarily from medical imaging . This medical component can range much higher, with an average of 3 mSv per year across the USA population. Other human contributors include smoking, air travel, radioactive building materials, historical nuclear weapons testing, nuclear power accidents and nuclear industry operation. A typical chest x-ray delivers 20 μSv (2 mrem) of effective dose. A dental x-ray delivers
4125-449: Is defined by the International Atomic Energy Agency as "Dose or the dose rate (or an observed measure related to the dose or dose rate) attributable to all sources other than the one(s) specified. A distinction is thus made between the dose which is already in a location, which is defined here as being "background", and the dose due to a deliberately introduced and specified source. This is important where radiation measurements are taken of
4250-414: Is detectable via a 239 keV peak from lead-212 , 511, 583 and 2614 keV from thallium-208 , and 911 and 969 keV from actinium-228 . Uranium-238 manifests as 609, 1120, and 1764 keV peaks of bismuth-214 ( cf. the same peak for atmospheric radon). Potassium-40 is detectable directly via its 1461 keV gamma peak. The level over the sea and other large bodies of water tends to be about
4375-704: Is dispersed worldwide. The increase in background radiation due to these tests peaked in 1963 at about 0.15 mSv per year worldwide, or about 7% of average background dose from all sources. The Limited Test Ban Treaty of 1963 prohibited above-ground tests, thus by the year 2000 the worldwide dose from these tests has decreased to only 0.005 mSv per year. This global fallout has caused up to 2.4 million deaths by 2020. The International Commission on Radiological Protection recommends limiting occupational radiation exposure to 50 mSv (5 rem) per year, and 100 mSv (10 rem) in 5 years. However, background radiation for occupational doses includes radiation that
4500-418: Is expected to be more stable than RnF 6 due to spin–orbit splitting of the 6p shell of radon (Rn would have a closed-shell 6s 6p 1/2 configuration). Therefore, while RnF 4 should have a similar stability to xenon tetrafluoride ( XeF 4 ), RnF 6 would likely be much less stable than xenon hexafluoride ( XeF 6 ): radon hexafluoride would also probably be
4625-530: Is expressed in joule-hours per cubic meter (J·h/m ). One WLM is equivalent to 3.6 × 10 J·h/m . An exposure to 1 WL for 1 working-month (170 hours) equals 1 WLM cumulative exposure. The International Commission on Radiological Protection recommends an annual limit of 4.8WLM for miners. Assuming 2000 hours of work per year, this corresponds to a concentration of 1500 Bq/m . Rn decays to Pb and other radioisotopes. The levels of Pb can be measured. The rate of deposition of this radioisotope
4750-399: Is indirect. Radon has a short half-life (4 days) and decays into other solid particulate radium-series radioactive nuclides. These radioactive particles are inhaled and remain lodged in the lungs, causing continued exposure. Radon is thus assumed to be the second leading cause of lung cancer after smoking , and accounts for 15,000 to 22,000 cancer deaths per year in the US alone. However,
4875-430: Is known as "cosmic ray induced neutron signature", or "ship effect" as it was first detected with ships at sea. Frequent above-ground nuclear explosions between the 1940s and 1960s scattered a substantial amount of radioactive contamination . Some of this contamination is local, rendering the immediate surroundings highly radioactive, while some of it is carried longer distances as nuclear fallout ; some of this material
5000-408: Is largely from muons, neutrons, and electrons, and this dose varies in different parts of the world based largely on the geomagnetic field and altitude. For example, the city of Denver in the United States (at 1650 meters elevation) receives a cosmic ray dose roughly twice that of a location at sea level. This radiation is much more intense in the upper troposphere , around 10 km altitude, and
5125-406: Is not measured by radiation dose instruments in potential occupational exposure conditions. This includes both offsite "natural background radiation" and any medical radiation doses. This value is not typically measured or known from surveys, such that variations in the total dose to individual workers is not known. This can be a significant confounding factor in assessing radiation exposure effects in
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5250-533: Is not related to that of the Austrian mathematician Johann Radon .) The likeness of the spectra of these three gases with those of argon, krypton, and xenon, and their observed chemical inertia led Sir William Ramsay to suggest in 1904 that the "emanations" might contain a new element of the noble-gas family. In 1909, Ramsay and Robert Whytlaw-Gray isolated radon and determined its melting temperature and approximate density . In 1910, they determined that it
5375-462: Is over 80 times higher than the world average natural human exposure to radiation. Epidemiological studies are underway to identify health effects associated with the high radiation levels in Ramsar. It is much too early to draw unambiguous statistically significant conclusions. While so far support for beneficial effects of chronic radiation (like longer lifespan) has been observed in few places only,
5500-509: Is produced by interactions with nitrogen atoms. These cosmogenic nuclides eventually reach the Earth's surface and can be incorporated into living organisms. The production of these nuclides varies slightly with short-term variations in solar cosmic ray flux, but is considered practically constant over long scales of thousands to millions of years. The constant production, incorporation into organisms and relatively short half-life of carbon-14 are
5625-485: Is regulated, but it is available in small quantities for the calibration of Rn measurement systems. In 2008 it was priced at almost US$ 6,000 (equivalent to $ 8,491 in 2023) per milliliter of radium solution (which only contains about 15 picograms of actual radon at any given moment). Radon is produced commercially by a solution of radium-226 (half-life of 1,600 years). Radium-226 decays by alpha-particle emission, producing radon that collects over samples of radium-226 at
5750-486: Is seldom performed with radon, and as a result there are very few reported compounds of radon, all either fluorides or oxides . Radon can be oxidized by powerful oxidizing agents such as fluorine , thus forming radon difluoride ( RnF 2 ). It decomposes back to its elements at a temperature of above 523 K (250 °C; 482 °F), and is reduced by water to radon gas and hydrogen fluoride: it may also be reduced back to its elements by hydrogen gas. It has
5875-496: Is the absolute temperature, and A {\displaystyle A} and B {\displaystyle B} are solvent constants. Radon is a member of the zero- valence elements that are called noble gases, and is chemically not very reactive . The 3.8-day half-life of Rn makes it useful in physical sciences as a natural tracer . Because radon is a gas at standard conditions, unlike its decay-chain parents, it can readily be extracted from them for research. It
6000-405: Is the number one cause among non-smokers, according to EPA policy-oriented estimates. Significant uncertainties exist for the health effects of low-dose exposures. Radon is a colorless, odorless, and tasteless gas and therefore is not detectable by human senses alone. At standard temperature and pressure , it forms a monatomic gas with a density of 9.73 kg/m , about 8 times the density of
6125-458: Is thus of particular concern for airline crews and frequent passengers, who spend many hours per year in this environment. During their flights airline crews typically get an additional occupational dose between 2.2 mSv (220 mrem) per year and 2.19 mSv/year, according to various studies. Similarly, cosmic rays cause higher background exposure in astronauts than in humans on the surface of Earth. Astronauts in low orbits , such as in
6250-578: Is unevenly distributed and varies with weather, such that much higher doses apply to many areas of the world, where it represents a significant health hazard . Concentrations over 500 times the world average have been found inside buildings in Scandinavia, the United States, Iran, and the Czech Republic. Radon is a decay product of uranium, which is relatively common in the Earth's crust, but more concentrated in ore-bearing rocks scattered around
6375-445: Is weather-dependent. Radon concentrations found in natural environments are much too low to be detected by chemical means. A 1,000 Bq/m (relatively high) concentration corresponds to 0.17 picogram per cubic meter (pg/m ). The average concentration of radon in the atmosphere is about 6 × 10 molar percent , or about 150 atoms in each milliliter of air. The radon activity of the entire Earth's atmosphere originates from only
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#17327768744126500-493: The Earth's atmosphere are so low that radon-rich water in contact with the atmosphere will continually lose radon by volatilization . Hence, ground water has a higher concentration of Rn than surface water , because radon is continuously produced by radioactive decay of Ra present in rocks. Likewise, the saturated zone of a soil frequently has a higher radon content than the unsaturated zone because of diffusional losses to
6625-436: The Earth's atmosphere at sea level, 1.217 kg/m . It is one of the densest gases at room temperature (a few are denser, e.g. CF 3 (CF 2 ) 2 CF 3 and WF 6 ) and is the densest of the noble gases. Although colorless at standard temperature and pressure, when cooled below its freezing point of 202 K (−71 °C; −96 °F), it emits a brilliant radioluminescence that turns from yellow to orange-red as
6750-449: The ICRP recommended limit for exposure to the public from artificial sources. They additionally receive a substantial internal dose from radon. Record radiation levels were found in a house where the effective dose due to ambient radiation fields was 131 mSv (13.1 rem) per year, and the internal committed dose from radon was 72 mSv (7.2 rem) per year. This unique case
6875-653: The International Space Station or the Space Shuttle , are partially shielded by the magnetic field of the Earth, but also suffer from the Van Allen radiation belt which accumulates cosmic rays and results from the Earth's magnetic field. Outside low Earth orbit, as experienced by the Apollo astronauts who traveled to the Moon , this background radiation is much more intense, and represents
7000-490: The United States Environmental Protection Agency , and other U.S. and international agencies, require that licensees limit radiation exposure to individual members of the public to 1 mSv (100 m rem ) per year. Per UNECE life-cycle assessment, nearly all sources of energy result in some level of occupational and public exposure to radionuclides as result of their manufacturing or operations. The following table uses man· Sievert /GW-annum: Coal plants emit radiation in
7125-622: The Windscale fire , the contamination of the Techa River by the nuclear waste from the Mayak compound, and the Kyshtym disaster at the same compound – released substantial radioactivity into the environment. The Windscale fire resulted in thyroid doses of 5–20 mSv for adults and 10–60 mSv for children. The doses from the accidents at Mayak are unknown. The Nuclear Regulatory Commission ,
7250-530: The background radiation , and this is usually the case where an ambient dose rate is measured for environmental purposes. Background radiation varies with location and time, and the following table gives examples: Radioactive material is found throughout nature. Detectable amounts occur naturally in soil , rocks, water, air, and vegetation, from which it is inhaled and ingested into the body. In addition to this internal exposure , humans also receive external exposure from radioactive materials that remain outside
7375-579: The equilibrium equivalent concentration (EEC) of radon by a factor of 8 to 9 nSv·m / Bq·h and the EEC of thoron by a factor of 40 nSv·m / Bq·h . Most of the atmospheric background is caused by radon and its decay products. The gamma spectrum shows prominent peaks at 609, 1120, and 1764 keV , belonging to bismuth-214 , a radon decay product. The atmospheric background varies greatly with wind direction and meteorological conditions. Radon also can be released from
7500-538: The inert pair effect . Radon reacts with the liquid halogen fluorides ClF, ClF 3 , ClF 5 , BrF 3 , BrF 5 , and IF 7 to form RnF 2 . In halogen fluoride solution, radon is nonvolatile and exists as the RnF and Rn cations; addition of fluoride anions results in the formation of the complexes RnF 3 and RnF 4 , paralleling the chemistry of beryllium (II) and aluminium (III). The standard electrode potential of
7625-595: The International Committee for Chemical Elements and International Union of Pure and Applied Chemistry chose radon as the accepted name for the element's most stable isotope, Rn. Under standard conditions, radon is gaseous and can be easily inhaled, posing a health hazard. However, the primary danger comes not from radon itself, but from its decay products, known as radon daughters. These decay products, often existing as single atoms or ions, can attach themselves to airborne dust particles. Although radon
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#17327768744127750-466: The Rn /Rn couple has been estimated as +2.0 V, although there is no evidence for the formation of stable radon ions or compounds in aqueous solution. Radon has no stable isotopes . Thirty-nine radioactive isotopes have been characterized, with mass numbers ranging from 193 to 231. Six of them, from 217 to 222 inclusive, occur naturally. The most stable isotope is Rn (half-life 3.82 days), which
7875-615: The UK, under the Housing Health & Safety Rating System, property owners have an obligation to evaluate potential risks and hazards to health and safety in a residential property. Alpha-radiation monitoring over the long term is a method of testing for radon that is more common in countries outside the United States. Radon is obtained as a by-product of uraniferous ores processing after transferring into 1% solutions of hydrochloric or hydrobromic acids . The gas mixture extracted from
8000-625: The US due to significant glaciation that ground the granitic rocks from the Canadian Shield and deposited it as soils making up the rich Iowa farmland. Many cities within the state, such as Iowa City , have passed requirements for radon-resistant construction in new homes. The second highest readings in Ireland were found in office buildings in the Irish town of Mallow, County Cork , prompting local fears regarding lung cancer. Since radon
8125-463: The US, studies and mitigation only followed decades of health effects on uranium miners of the Southwestern US employed during the early Cold War ; standards were not implemented until 1971. In the early 20th century in the US, gold contaminated with the radon daughter Pb entered the jewelry industry. This was from gold brachytherapy seeds that had held Rn, which were melted down after
8250-687: The United Kingdom to more than 7 mSv (700 mrem) annually for some groups of people in Finland. The International Atomic Energy Agency states: Terrestrial background radiation , for the purpose of the table above, only includes sources that remain external to the body. The major radionuclides of concern are potassium , uranium and thorium and their decay products, some of which, like radium and radon are intensely radioactive but occur in low concentrations. Most of these sources have been decreasing, due to radioactive decay since
8375-513: The United States and Norway aimed to measure radon indoors and in metropolitan areas. High concentrations of radon in homes were discovered by chance in 1984 after the stringent radiation testing conducted at the new Limerick Generating Station nuclear power plant in Montgomery County, Pennsylvania, United States revealed that Stanley Watras , a construction engineer at the plant, was contaminated by radioactive substances even though
8500-592: The accumulation of radon within the dwelling, exposing its residents to high concentrations. The widespread construction of well insulated and sealed homes in the northern industrialized world has led to radon becoming the primary source of background radiation in some localities in northern North America and Europe. Basement sealing and suction ventilation reduce exposure. Some building materials, for example lightweight concrete with alum shale , phosphogypsum and Italian tuff , may emanate radon if they contain radium and are porous to gas. Radiation exposure from radon
8625-569: The air at the (unventilated) Gastein Healing Gallery averages 43 kBq/m (1.2 nCi/L) with maximal value of 160 kBq/m (4.3 nCi/L). Radon mostly appears with the radium/ uranium series (decay chain) ( Rn), and marginally with the thorium series ( Rn). The element emanates naturally from the ground, and some building materials, all over the world, wherever traces of uranium or thorium are found, and particularly in regions with soils containing granite or shale , which have
8750-644: The air if there is a meteorological inversion and little wind. High concentrations of radon can be found in some spring waters and hot springs. The towns of Boulder, Montana ; Misasa ; Bad Kreuznach , Germany; and the country of Japan have radium-rich springs that emit radon. To be classified as a radon mineral water, radon concentration must be above 2 nCi/L (74 kBq/m ). The activity of radon mineral water reaches 2 MBq/m in Merano and 4 MBq/m in Lurisia (Italy). Natural radon concentrations in
8875-555: The amount of Rn in the environment is much less than that of Rn because of the short half-life of Rn (55 seconds, versus 3.8 days respectively). Radon concentration in the atmosphere is usually measured in becquerel per cubic meter (Bq/m ), the SI derived unit . Another unit of measurement common in the US is picocuries per liter (pCi/L); 1 pCi/L = 37 Bq/m . Typical domestic exposures average about 48 Bq/m indoors, though this varies widely, and 15 Bq/m outdoors. In
9000-410: The atmosphere following seismic events leading to earthquakes , which has led to its investigation in the field of earthquake prediction . It is possible to test for radon in buildings, and to use techniques such as sub-slab depressurization for mitigation . Epidemiological studies have shown a clear association between breathing high concentrations of radon and incidence of lung cancer . Radon
9125-646: The atmosphere. In 1971, Apollo 15 passed 110 km (68 mi) above the Aristarchus plateau on the Moon , and detected a significant rise in alpha particles thought to be caused by the decay of Rn. The presence of Rn has been inferred later from data obtained from the Lunar Prospector alpha particle spectrometer. Radon is found in some petroleum . Because radon has a similar pressure and temperature curve to propane , and oil refineries separate petrochemicals based on their boiling points,
9250-479: The background can be continually monitored in the "Ready" state, and subtracted from any reading obtained when being used in "Measuring" mode. Regular Radiation measurement is carried out at multiple levels. Government agencies compile radiation readings as part of environmental monitoring mandates, often making the readings available to the public and sometimes in near-real-time. Collaborative groups and private individuals may also make real-time readings available to
9375-579: The body and from cosmic radiation from space. The worldwide average natural dose to humans is about 2.4 mSv (240 mrem ) per year. This is four times the worldwide average artificial radiation exposure, which in 2008 amounted to about 0.6 millisieverts (60 mrem ) per year. In some developed countries, like the US and Japan, artificial exposure is, on average, greater than the natural exposure, due to greater access to medical imaging . In Europe, average natural background exposure by country ranges from under 2 mSv (200 mrem) annually in
9500-407: The body. In a radiation metrology laboratory, background radiation refers to the measured value from any incidental sources that affect an instrument when a specific radiation source sample is being measured. This background contribution, which is established as a stable value by multiple measurements, usually before and after sample measurement, is subtracted from the rate measured when the sample
9625-443: The committed dose 1 km away to be 20 μSv/a for older plants or 1 μSv/a for newer plants with improved fly ash capture, but was unable to confirm these numbers by test. When coal is burned, uranium, thorium and all the uranium daughters accumulated by disintegration – radium, radon, polonium – are released. Radioactive materials previously buried underground in coal deposits are released as fly ash or, if fly ash
9750-488: The concentration of short-lived isotopes will increase until an equilibrium is reached where the overall decay rate of the decay products equals that of the radon itself. The equilibrium factor is 1 when both activities are equal, meaning that the decay products have stayed close to the radon parent long enough for the equilibrium to be reached, within a couple of hours. Under these conditions, each additional pCi/L of radon will increase exposure by 0.01 working level (WL,
9875-422: The corresponding disintegrations are indicative of the initial radon distribution. Its decay goes through the following sequence: The radon equilibrium factor is the ratio between the activity of all short-period radon progenies (which are responsible for most of radon's biological effects), and the activity that would be at equilibrium with the radon parent. If a closed volume is constantly supplied with radon,
10000-437: The cosmic rays (or, about 100–300 neutrons per square meter per second). The flux is dependent on geomagnetic latitude, with a maximum near the magnetic poles. At solar minimums, due to lower solar magnetic field shielding, the flux is about twice as high vs the solar maximum. It also dramatically increases during solar flares. In the vicinity of larger heavier objects, e.g. buildings or ships, the neutron flux measures higher; this
10125-403: The decay of radium in radium halides, a reaction that has been used to reduce the amount of radon that escapes from targets during irradiation . Additionally, salts of the [RnF] cation with the anions SbF 6 , TaF 6 , and BiF 6 are known. Radon is also oxidised by dioxygen difluoride to RnF 2 at 173 K (−100 °C; −148 °F). Radon oxides are among
10250-409: The decay products of radon, which stick to tobacco leaves . Heavy smoking results in a radiation dose of 160 mSv/year to localized spots at the bifurcations of segmental bronchi in the lungs from the decay of polonium-210. This dose is not readily comparable to the radiation protection limits, since the latter deal with whole body doses, while the dose from smoking is delivered to a very small portion of
10375-531: The discussion about the opposite experimental results is still going on. About 100,000 Bq/m of radon was found in Stanley Watras's basement in 1984. He and his neighbours in Boyertown, Pennsylvania , United States may hold the record for the most radioactive dwellings in the world. International radiation protection organizations estimate that a committed dose may be calculated by multiplying
10500-426: The element one period before it, xenon , and is therefore more reactive. Early studies concluded that the stability of radon hydrate should be of the same order as that of the hydrates of chlorine ( Cl 2 ) or sulfur dioxide ( SO 2 ), and significantly higher than the stability of the hydrate of hydrogen sulfide ( H 2 S ). Because of its cost and radioactivity, experimental chemical research
10625-493: The essential elements that make up the human body, namely potassium and carbon, have radioactive isotopes that add significantly to our background radiation dose. An average human contains about 17 milligrams of potassium-40 ( K) and about 24 nanograms (10 g) of carbon-14 ( C), (half-life 5,730 years). Excluding internal contamination by external radioactive material, these two are the largest components of internal radiation exposure from biologically functional components of
10750-408: The existence of Xe(VIII), no Rn(VIII) compounds have been claimed to exist; RnF 8 should be highly unstable chemically (XeF 8 is thermodynamically unstable). It is predicted that the most stable Rn(VIII) compound would be barium perradonate (Ba 2 RnO 6 ), analogous to barium perxenate . The instability of Rn(VIII) is due to the relativistic stabilization of the 6s shell, also known as
10875-576: The fact that radon levels in particular dwellings can occasionally be orders of magnitude higher than typical. Since the incident in Pennsylvania, millions of short-term radon measurements have been taken in homes in the United States. Outside the United States, radon measurements are typically performed over the long term. In the United States, typical domestic exposures are of approximately 100 Bq/m (2.7 pCi/L) indoors. Some level of radon will be found in all buildings. Radon mostly enters
11000-563: The few other reported compounds of radon ; only the trioxide ( RnO 3 ) has been confirmed. The higher fluorides RnF 4 and RnF 6 have been claimed and are calculated to be stable, but their identification is unclear. They may have been observed in experiments where unknown radon-containing products distilled together with xenon hexafluoride : these may have been RnF 4 , RnF 6 , or both. Trace-scale heating of radon with xenon, fluorine, bromine pentafluoride , and either sodium fluoride or nickel fluoride
11125-404: The first chemically stable noble gas chlorides RnCl 2 and RnCl 4 , but none of these have yet been found. Radon carbonyl (RnCO) has been predicted to be stable and to have a linear molecular geometry . The molecules Rn 2 and RnXe were found to be significantly stabilized by spin-orbit coupling . Radon caged inside a fullerene has been proposed as a drug for tumors . Despite
11250-478: The form of radioactive fly ash which is inhaled and ingested by neighbours, and incorporated into crops. A 1978 paper from Oak Ridge National Laboratory estimated that coal-fired power plants of that time may contribute a whole-body committed dose of 19 μSv/a to their immediate neighbours in a radius of 500 m. The United Nations Scientific Committee on the Effects of Atomic Radiation 's 1988 report estimated
11375-474: The formation of RnO 3 , but this could not be confirmed. It is likely that the difficulty in identifying higher fluorides of radon stems from radon being kinetically hindered from being oxidised beyond the divalent state because of the strong ionicity of radon difluoride ( RnF 2 ) and the high positive charge on radon in RnF ; spatial separation of RnF 2 molecules may be necessary to clearly identify higher fluorides of radon, of which RnF 4
11500-533: The formation of the Earth, because there is no significant amount currently transported to the Earth. Thus, the present activity on Earth from uranium-238 is only half as much as it originally was because of its 4.5 billion year half-life, and potassium-40 (half-life 1.25 billion years) is only at about 8% of original activity. But during the time that humans have existed the amount of radiation has decreased very little. Many shorter half-life (and thus more intensely radioactive) isotopes have not decayed out of
11625-557: The gas emitted by radium remained radioactive for a month. Later that year, Rutherford and Owens noticed variations when trying to measure radiation from thorium oxide. Rutherford noticed that the compounds of thorium continuously emit a radioactive gas that remains radioactive for several minutes, and called this gas "emanation" (from Latin : emanare , to flow out, and emanatio , expiration), and later "thorium emanation" ("Th Em"). In 1900, Friedrich Ernst Dorn reported some experiments in which he noticed that radium compounds emanate
11750-636: The ground in bursts and then form "radon clouds" capable of traveling tens of kilometers. The Earth and all living things on it are constantly bombarded by radiation from outer space. This radiation primarily consists of positively charged ions from protons to iron and larger nuclei derived from outside the Solar System . This radiation interacts with atoms in the atmosphere to create an air shower of secondary radiation, including X-rays , muons , protons , alpha particles , pions , electrons , and neutrons . The immediate dose from cosmic radiation
11875-412: The human body. About 4,000 nuclei of K decay per second, and a similar number of C. The energy of beta particles produced by K is about 10 times that from the beta particles from C decay. C is present in the human body at a level of about 3700 Bq (0.1 μCi) with a biological half-life of 40 days. This means there are about 3700 beta particles per second produced by the decay of C. However,
12000-640: The hydrolysed solution. That [RnO 3 F] did not form in other experiments may have been due to the high concentration of fluoride used. Electromigration studies also suggest the presence of cationic [HRnO 3 ] and anionic [HRnO 4 ] forms of radon in weakly acidic aqueous solution (pH > 5), the procedure having previously been validated by examination of the homologous xenon trioxide. The decay technique has also been used. Avrorin et al. reported in 1982 that Fr compounds cocrystallised with their caesium analogues appeared to retain chemically bound radon after electron capture; analogies with xenon suggested
12125-440: The immediate vicinity of particles of high atomic number materials, within the human body, have a small enhancement due to the photoelectric effect . Most of the natural neutron background is a product of cosmic rays interacting with the atmosphere. The neutron energy peaks at around 1 MeV and rapidly drops above. At sea level, the production of neutrons is about 20 neutrons per second per kilogram of material interacting with
12250-572: The inhabitants of the affected areas. Thyroid doses for children were below 50 mSv. 167 cleanup workers received doses above 100 mSv, with 6 of them receiving more than 250 mSv (the Japanese exposure limit for emergency response workers). The average dose from the Three Mile Island accident was 0.01 mSv. Non-civilian : In addition to the civilian accidents described above, several accidents at early nuclear weapons facilities – such as
12375-469: The inside of pipework. Measurement of radon levels in the first decades of its discovery was mainly done to determine the presence of radium and uranium in geological surveys. In 1956, most likely the first indoor survey of radon decay products was performed in Sweden, with the intent of estimating the public exposure to radon and its decay products. From 1975 up until 1984, small studies in Sweden, Austria,
12500-440: The level of exposure to radon gas differs by location. A common source of environmental radon is uranium-containing minerals in the ground; it therefore accumulates in subterranean areas such as basements. Radon can also occur in ground water, such as spring waters and hot springs. Radon trapped in permafrost may be released by climate-change -induced thawing of permafrosts , and radon may also be released into groundwater and
12625-439: The mining industry, the exposure is traditionally measured in working level (WL), and the cumulative exposure in working level month (WLM); 1 WL equals any combination of short-lived Rn daughters ( Po, Pb, Bi, and Po) in 1 liter of air that releases 1.3 × 10 MeV of potential alpha energy; 1 WL is equivalent to 2.08 × 10 joules per cubic meter of air (J/m ). The SI unit of cumulative exposure
12750-459: The name of the most stable isotope, radon, as the name of the element. The isotopes thoron and actinon were later renamed Rn and Rn. This has caused some confusion in the literature regarding the element's discovery as while Dorn had discovered radon the isotope, he was not the first to discover radon the element. As late as the 1960s, the element was also referred to simply as emanation . The first synthesized compound of radon, radon fluoride,
12875-453: The ocean. In caves or ventilated mines, or poorly ventilated houses, its concentration climbs to 20–2,000 Bq/m . Radon concentration can be much higher in mining contexts. Ventilation regulations instruct to maintain radon concentration in uranium mines under the "working level", with 95th percentile levels ranging up to nearly 3 WL (546 pCi Rn per liter of air; 20.2 kBq/m , measured from 1976 to 1985). The concentration in
13000-415: The piping carrying freshly separated propane in oil refineries can become contaminated because of decaying radon and its products. Residues from the petroleum and natural gas industry often contain radium and its daughters. The sulfate scale from an oil well can be radium rich, while the water, oil, and gas from a well often contains radon. Radon decays to form solid radioisotopes that form coatings on
13125-405: The principles used in radiocarbon dating of ancient biological materials, such as wooden artifacts or human remains. The cosmic radiation at sea level usually manifests as 511 keV gamma rays from annihilation of positrons created by nuclear reactions of high energy particles and gamma rays. At higher altitudes there is also the contribution of continuous bremsstrahlung spectrum. Two of
13250-638: The public. Events classified on the International Nuclear Event Scale as incidents typically do not release any additional radioactive substances into the environment. Large releases of radioactivity from nuclear reactors are extremely rare. To the present day, there were two major civilian accidents – the Chernobyl accident and the Fukushima I nuclear accidents – which caused substantial contamination. The Chernobyl accident
13375-452: The radioactive equilibrium of elements in the environment find it more useful to use the ratio of other Rn decay products with Pb, such as Po, in measuring overall radiation levels. Because of their electrostatic charge , radon progenies adhere to surfaces or dust particles, whereas gaseous radon does not. Attachment removes them from the air, usually causing the equilibrium factor in the atmosphere to be less than 1. The equilibrium factor
13500-423: The radon had decayed. The presence of radon in indoor air was documented as early as 1950. Beginning in the 1970s, research was initiated to address sources of indoor radon, determinants of concentration, health effects, and mitigation approaches. In the US, the problem of indoor radon received widespread publicity and intensified investigation after a widely publicized incident in 1984. During routine monitoring at
13625-412: The reactor had never been fueled and Watras had been decontaminated each evening. It was determined that radon levels in his home's basement were in excess of 100,000 Bq/m (2.7 nCi/L); he was told that living in the home was the equivalent of smoking 135 packs of cigarettes a day, and he and his family had increased their risk of developing lung cancer by 13 or 14 percent. The incident dramatized
13750-416: The same place may differ by double/half over one hour, and the concentration in one room of a building may be significantly different from the concentration in an adjoining room. The distribution of radon concentrations will generally differ from room to room, and the readings are averaged according to regulatory protocols. Indoor radon concentration is usually assumed to follow a log-normal distribution on
13875-465: The solutions contains H 2 , O 2 , He, Rn, CO 2 , H 2 O and hydrocarbons . The mixture is purified by passing it over copper at 993 K (720 °C; 1,328 °F) to remove the H 2 and the O 2 , and then KOH and P 2 O 5 are used to remove the acids and moisture by sorption . Radon is condensed by liquid nitrogen and purified from residue gases by sublimation . Radon commercialization
14000-423: The temperature lowers. Upon condensation , it glows because of the intense radiation it produces. It is sparingly soluble in water, but more soluble than lighter noble gases. It is appreciably more soluble in organic liquids than in water. Its solubility equation is as follows: where χ {\displaystyle \chi } is the molar fraction of radon, T {\displaystyle T}
14125-436: The terrestrial environment because of their on-going natural production. Examples of these are radium -226 (decay product of thorium-230 in decay chain of uranium-238) and radon-222 (a decay product of radium -226 in said chain). Thorium and uranium (and their daughters) primarily undergo alpha and beta decay , and are not easily detectable. However, many of their daughter products are strong gamma emitters. Thorium-232
14250-464: The title Emanation . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Emanation&oldid=1161761998 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Emanation (chemistry) Radon
14375-682: The uranium and thorium series, and 12 μSv/a comes from C. Some areas have greater dosage than the country-wide averages. In the world in general, exceptionally high natural background locales include Ramsar in Iran, Guarapari in Brazil, Karunagappalli in India, Arkaroola in Australia and Yangjiang in China. The highest level of purely natural radiation ever recorded on the Earth's surface
14500-596: The values quoted here are in Grays . To convert to Sieverts (Sv) a radiation weighting factor is required; these weighting factors vary from 1 (beta & gamma) to 20 (alpha particles). The highest background radiation in an inhabited area is found in Ramsar , primarily due to the use of local naturally radioactive limestone as a building material. The 1000 most exposed residents receive an average external effective radiation dose of 6 mSv (600 mrem) per year, six times
14625-481: The world. Radon seeps out of these ores into the atmosphere or into ground water or infiltrates into buildings. It can be inhaled into the lungs, along with its decay products , where they will reside for a period of time after exposure. Although radon is naturally occurring, exposure can be enhanced or diminished by human activity, notably house construction. A poorly sealed dwelling floor, or poor basement ventilation, in an otherwise well insulated house can result in
14750-579: Was 90 μGy/h on a Brazilian black beach ( areia preta in Portuguese) composed of monazite . This rate would convert to 0.8 Gy/a for year-round continuous exposure, but in fact the levels vary seasonally and are much lower in the nearest residences. The record measurement has not been duplicated and is omitted from UNSCEAR's latest reports. Nearby tourist beaches in Guarapari and Cumuruxatiba were later evaluated at 14 and 15 μGy/h. Note that
14875-422: Was claimed to produce a higher fluoride as well which hydrolysed to form RnO 3 . While it has been suggested that these claims were really due to radon precipitating out as the solid complex [RnF] 2 [NiF 6 ] , the fact that radon coprecipitates from aqueous solution with CsXeO 3 F has been taken as confirmation that RnO 3 was formed, which has been supported by further studies of
15000-487: Was considered to a separate substance: radon, thoron, and actinon. Sir William Ramsay and Robert Whytlaw-Gray considered that the radioactive emanations may contain a new element of the noble gas family, and isolated "radium emanation" in 1909 to determine its properties. In 1911, the element Ramsay and Whytlaw-Gray isolated was accepted by the International Commission for Atomic Weights , and in 1923,
15125-404: Was discovered in 1899 by Ernest Rutherford and Robert B. Owens at McGill University in Montreal , and was the fifth radioactive element to be discovered. First known as "emanation", the radioactive gas was identified during experiments with radium, thorium oxide, and actinium by Friedrich Ernst Dorn , Rutherford and Owens, and André-Louis Debierne , respectively, and each element's emanation
15250-444: Was obtained in 1962. Even today, the word radon may refer to either the element or its isotope Rn, with thoron remaining in use as a short name for Rn to stem this ambiguity. The name actinon for Rn is rarely encountered today, probably due to the short half-life of that isotope. The danger of high exposure to radon in mines, where exposures can reach 1,000,000 Bq /m , has long been known. In 1530, Paracelsus described
15375-422: Was predicted to have an even lower enthalpy of formation than the difluoride. The [RnF] ion is believed to form by the following reaction: For this reason, antimony pentafluoride together with chlorine trifluoride and N 2 F 2 Sb 2 F 11 have been considered for radon gas removal in uranium mines due to the formation of radon–fluorine compounds. Radon compounds can be formed by
15500-490: Was the heaviest known gas. They wrote that " L'expression l'émanation du radium est fort incommode " ("the expression 'radium emanation' is very awkward") and suggested the new name niton (Nt) (from Latin : nitens , shining) to emphasize the radioluminescence property, and in 1912 it was accepted by the International Commission for Atomic Weights . In 1923, the International Committee for Chemical Elements and International Union of Pure and Applied Chemistry (IUPAC) chose
15625-517: Was the only one to cause immediate deaths. Total doses from the Chernobyl accident ranged from 10 to 50 mSv over 20 years for the inhabitants of the affected areas, with most of the dose received in the first years after the disaster, and over 100 mSv for liquidators . There were 28 deaths from acute radiation syndrome . Total doses from the Fukushima I accidents were between 1 and 15 mSv for
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