Being a noble gas, radon is chemically not very reactive. However, the 3.8 day half-life of radon-222 makes it useful in physical sciences as a natural tracer. Sony VAIO VPCS12V9E/B Battery
Radon is a member of the zero-valence elements that are called noble gases. It is inert to most common chemical reactions, such as combustion, because the outer valence shellcontains eight electrons. This produces a stable, minimum energy configuration in which the outer electrons are tightly bound. 1037 kJ/mol is required to extract one electron from its shells (also known as the first ionization energy). Sony VAIO VPCW111XX/P Battery
However, in accordance with periodic trends, radon has a lower electronegativity than the element one period before it, xenon, and is therefore more reactive. Radon is sparingly soluble in water, but more soluble than lighter noble gases. Radon is appreciably more soluble in organic liquids than in water. Sony VAIO VPCW111XX/PC Battery
Early studies concluded that the stability of radon hydrateshould be of the same order as that of the hydrates of chlorine (Cl2) or sulfur dioxide (SO2), and significantly higher than the stability of the hydrate of hydrogen sulfide (H2S).
Because of its cost and radioactivity, experimental chemical research is seldom performed with radon, and as a result there are very few reported compounds of radon, Sony VAIO VPCW111XX/T Battery
all eitherfluorides or oxides. Radon can be oxidized by a few powerful oxidizing agents such asfluorine, thus forming radon fluoride. It decomposes back to elements at a temperature of above 250 °C. It has a low volatility and was thought to be RnF2. But 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. Sony VAIO VPCW111XX/W Battery
Theoretical studies on this molecule predict that it should have a Rn-Fbond distance of 2.08 ?, and that the compound is thermodynamically more stable and less volatile than its lighter counterpart XeF2.The octahedral molecule RnF6 was predicted to have an even lower enthalpy of formation than the difluoride. The [RnF]+ ion is believed to form by the reaction: Sony VAIO VPCW111XXP Battery
Rn (g) + 2 [O2]+[SbF6]? (s) ? [RnF]+[Sb2F11]? (s) + 2 O2 (g)
Radon oxides are among the few other reported compounds of radon. Radon carbonyl RnCO has been predicted to be stable and to have a linear molecular geometry. The molecules Rn2 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. Sony VAIO VPCW111XXT Battery
Radon has no stable isotopes. However, 36 radioactive isotopes have been characterized, with their atomic masses ranging from 193 to 228. The most stable isotope is 222Rn, which is a decay product of 226Ra, a decay product of 238U. Among the daughters of 222Rn is also the highly unstable isotope 218Rn. Sony VAIO VPCW111XXW Battery
There are three other radon isotopes that have a half-life of over an hour: 211Rn, 210Rn and 224Rn. The 220Rn isotope is a natural decay product of the most stable thorium isotope (232Th), and is commonly referred to as thoron. It has a half-life of 55.6 seconds and also emits alpha radiation. Sony VAIO VPCW115XG Battery
Similarly, 219Rn is derived from the most stable isotope of actinium (227Ac)—named "actinon"—and is an alpha emitter with a half-life of 3.96 seconds. No radon isotopes significantly occur in the neptunium(237Np) decay series. Sony VAIO VPCW115XGP Battery
222Rn belongs to the radium and uranium-238 decay chain, and has a half-life of 3.8235 days. Its four first products (excluding marginal decay schemes) are very short-lived, meaning that the corresponding disintegrations are indicative of the initial radon distribution. Its decay goes through the following sequence: Sony VAIO VPCW115XW/P Battery
- 222Rn, 3.8 days, alpha decaying to...
- 218Po, 3.10 minutes, alpha decaying to...
- 214Pb, 26.8 minutes, beta decaying to...
- 214Bi, 19.9 minutes, beta decaying to...
- 214Po, 0.1643 ms, alpha decaying to...
At the next step, 214Po decays to 210Pb, which has a much longer half-life of 22.3 years. Its progenies are: Sony VAIO VPCW115XW/T Battery
- 210Bi, 5.013 days, beta decaying to...
- 210Po, 138.376 days, alpha decaying to...
- 206Pb, stable.
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. Sony VAIO VPCW115XW/W Battery
If a closed volume is constantly supplied with radon, the concentration of short-lived isotopes will increase until an equilibrium is reached where the rate of decay of each decay product will equal 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. Sony VAIO VPCW117XC/P Battery
Under these conditions each additional pCi/L of radon will increase exposure, by 0.01 WL (see explanation of WL below). These conditions are not always met: in many homes, the equilibrium fraction is typically 40%; that is, there will be 0.004 WL of progeny for each pCi/L of radon in air. 210Pb takes much longer (decades) to come in equilibrium with radon, but, if the environment permits accumulation of dust over extended periods of time, 210lead and its decay products may contribute to overall radiation levels as well. Sony VAIO VPCW117XC/T Battery
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 one. The equilibrium factor is also lowered by air circulation or air filtration devices, and is increased by airborne dust particles, including cigarette smoke. Sony VAIO VPCW117XC/W Battery
In high concentrations, airborne radon isotopes contribute significantly to human health risk. The equilibrium factor found in epidemiological studies is 0.4.
History and etymology
Radon was the fifth radioactive element to be discovered, in 1900 by Friedrich Ernst Dorn, after uranium, thorium, radium and polonium. Sony VAIO VPCW119XJ Battery
In 1900 Dorn reported some experiments in which he noticed that radium compounds emanate a radioactive gas which he named Radium Emanation (Ra Em). Before that, in 1899, Pierre and Marie Curie observed that the "gas" emitted by radium remained radioactive for a month. Later that year, Robert B. Owens and Ernest Rutherford, Sony VAIO VPCW119XJ/P Battery
at McGill Universityin Montreal, noticed variations when trying to measure radiation from thorium oxide. Rutherford noticed that the compounds of thorium continuously emit a radioactive gas which retain the radioactive powers for several minutes and called this gas "emanation" (from Latin "emanare"—to elapse and "emanatio"—expiration), and later Thorium Emanation (Th Em).Sony VAIO VPCW119XJ/W Battery
In 1901, he 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 names were suggested for these three gases: exradio, exthorio, and exactinio in 1904; radon, thoron, and akton in 1918;[Sony VAIO VPCW11AXJ Battery
37]radeon, thoreon, and actineon in 1919, and eventually radon, thoron, and actinon in 1920. 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. Sony VAIO VPCW11S1E/P Battery
In 1910, Sir William Ramsay and Robert Whytlaw-Gray isolated radon, determined its density, and determined that it was the heaviest known gas. They wrote that "L'expression de l'émanation du radium est fort incommode," (the expression of radium emanation is very awkward) and suggested the new name niton (Nt) Sony VAIO VPCW11S1E/T Battery
(from the Latin "nitens" meaning "shining") in order to emphasize the property of gases that cause the phosphorescence of some substances, 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 among the names radon (Rn), thoron (Tn), and actinon (An). Sony VAIO VPCW11S1E/W Battery
Later, when isotopes were numbered instead of named, the element took the name of the most stable isotope, radon, while Tn was renamed 220Rn and An was renamed 219Rn. As late as the 1960s, the element was also referred to simply as emanation. The first synthesized compound of radon, radon fluoride, was obtained in 1962. Sony VAIO VPCW121AX Battery
The danger of high exposure to radon in mines, where exposures reaching 1,000,000 Bq/m3 can be found, has long been known. In 1530,Paracelsus described 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 Herting and Hesse in their investigation of miners from Schneeberg, Germany. Sony VAIO VPCW126AG Battery
The first major studies with radon and health occurred in the context of uranium mining in theJoachimsthal region of Bohemia.In the US, studies and mitigation only followed decades of health effects on uranium miners of theSouthwestern United States employed during the early Cold War; standards were not implemented until 1971. Sony VAIO VPCW127JC/P Battery
The presence of radon in indoor air was documented as early as 1950. Beginning in the 1970’s research was initiated to address sources of indoor radon, determinants of concentration, health effects, and approaches to mitigation. In the United States, the problem of indoor radon received widespread publicity and intensified investigation after a widely publicized incident in 1984. Sony VAIO VPCW127JC/T Battery
During routine monitoring at a Pennsylvania nuclear power plant, a worker was found to be contaminated with radioactivity. A high contamination of radon in his home was subsequently identified as responsible for the contamination.
All discussions of radon concentrations in the environment refer to 222Rn. Sony VAIO VPCW127JC/W Battery
While the average rate of production of220Rn (from the thorium decay series) is about the same as 222Rn, the amount of 220Rn in the environment is much less than that of 222Rn because of the short half-life of 220Rn (1 minute versus 4 days).
Radon concentration is usually measured in the atmosphere, in becquerel per cubic meter (Bq/m3), the SI derived unit. Sony VAIO VPCW127JC/WZ Battery
Typical domestic exposures are about 100 Bq/m3 indoors, and 10–20 Bq/m3 outdoors.
It is often measured in picocuries per liter (pCi/L) in the USA, with 1 pCi/L=37 Bq/m3.
In the mining industry, the exposition is traditionally measured in working level (WL), and the cumulative exposition in working level month (WLM): Sony VAIO VPCW12AAJ Battery
1 WL equals any combination of short-lived 222Rn progeny (218Po, 214Pb, 214Bi, and 214Po) in 1 liter of air that releases 1.3 × 105MeV of potential alpha energy; one WL is equivalent to 2.08 × 10?5joules per cubic meter of air (J/m3). The SI unit of cumulative exposure is expressed in joule-hours per cubic meter (J·h/m3). One WLM is equivalent to 3.6 × 10?3 J·h/m3. Sony VAIO VPCW12AKJ Battery
An exposure to 1 WL for 1 working month (170 hours) equals 1 WLM cumulative exposure.
A cumulative exposition of 1 WLM is roughly equivalent to living one year in an atmosphere with a radon concentration of 230 Bq/m3.
Radon (222Rn), when released into the air, decays to 210Pb and other radioisotopes, the levels of 210Pb can be measured. The rate of deposition of this radioisotope is weather dependent. Sony VAIO VPCW12AVJ Battery
Radon concentrations found in natural environments are much too low to be detected by chemical means. A 1000 Bq/m3 (relatively high) concentration corresponds to 0.17 picogram per cubic meter. The average concentration of radon in the atmosphere is about 6×10?20 atoms of radon for each molecule in the air, or about 150 atoms in each ml of air. Sony VAIO VPCW12S1E/P Battery
The radon activity of the Earth atmosphere originates from some tens of grams of radon, consistently replaced by decay of larger amounts of radium and uranium.
Radon is produced by the radioactive decay of radium-226, which is found in uranium ores; phosphate rock; shales; metamorphic minerals such as granite, gneiss, and schist; Sony VAIO VPCW12S1E/T Battery
and, to a lesser degree, in common minerals such as limestone. Every square mile of surface soil, to a depth of 6 inches (2.6 km2to a depth of 15 cm), contains approximately 1 gram of radium, which releases radon in small amounts to the atmosphere On a global scale, it is estimated that 2,400 million curies (90 TBq) of radon are released from soil annually. Sony VAIO VPCW12S1E/W Battery
Radon concentration varies widely from place to place. In the open air, it ranges from 1 to 100 Bq/m3, even less (0.1 Bq/m3) above the ocean. In caves or aerated mines, or ill-aerated houses, its concentration climbs to 20–2,000 Bq/m3. Radon concentration can be much higher in mining contexts. Ventilation regulations instruct to maintain radon concentration in uranium mines under the "working level", Sony VAIO VPCW213AG/L Battery
with 95th percentile levels ranging up to nearly 3 WL (546 pCi 222Rn per liter of air; 20.2 kBq/m3, measured from 1976 to 1985).The concentration in the air at the (unventilated) Gastein Healing Gallery averages 43 kBq/m3 (1.2 nCi/L) with maximal value of 160 kBq/m3 (4.3 nCi/L). Sony VAIO VPCW213AG/P Battery
Radon mostly appears with the decay chain of the radium and uranium series (222Rn), and marginally with the thorium series (220Rn). The element emanates naturally from the ground, and some building materials, all over the world, wherever traces of uranium orthorium can be found, and particularly in regions with soils containing granite or shale, which have a higher concentration of uranium. Sony VAIO VPCW213AG/T Battery
However, 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 222Rn), radon concentration decreases very quickly when the distance from the production area increases. Radon concentration varies greatly with season and atmospheric conditions. Sony VAIO VPCW213AG/W Battery
For instance, it has been shown to accumulate in 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 which emit radon. Sony VAIO VPCW215AG/L Battery
To be classified as a radon mineral water, radon concentration must be above a minimum of 2 nCi/L (74 kBq/m3). The activity of radon mineral water reaches 2,000 kBq/m3 in Merano and 4,000 kBq/m3 in Lurisia (Italy).
Natural radon concentrations in Earth's atmosphere are so low that radon-rich water in contact with the atmosphere will continually lose radon by volatilization. Sony VAIO VPCW217JC Battery
Hence, ground water has a higher concentration of 222Rn than surface water, because radon is continuously produced by radioactive decay of 226Ra 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 the atmosphere. Sony VAIO VPCW217JC/L Battery
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 222Rn. The presence of 222Rn has been inferred later from data obtained from the Lunar Prospector alpha particle spectrometer. Sony VAIO VPCW217JC/P Battery
Radon is found in some petroleum. Because radon has a similar pressure and temperature curve to propane, and oil refineriesseparate petrochemicals based on their boiling points, the piping carrying freshly separated propane in oil refineries can become radioactive because of decaying radon and its products. Sony VAIO VPCW217JC/T Battery
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 which form coatings on the inside of pipework.  Sony VAIO VPCW217JC/W Battery
Accumulation in houses
The phenomenon of heightened radon contamination in homes was discovered by chance in 1985 after the stringent radiation testing conducted at a nuclear power plant entrance revealed that Stanley Watras, an engineer entering the plant, was contaminated by radioactive substances. Sony VAIO VPCW218JC Battery
Typical domestic exposures are of approximately 100 Bq/m3indoors. Depending on how houses are built and ventilated, radon may accumulate in basements and dwellings. Radon can also seep into an indoor environment through cracks in solid floors, construction joints, cracks in walls, gaps in suspended floors, gaps around service pipes, cavities inside walls, and the water supply. Sony VAIO VPCW218JC/L Battery
Radon concentrations in the same location may differ by a factor of two over a period of 1 hour. Also, the concentration in one room of a building may be significantly different than the concentration in an adjoining room.
The distribution of radon concentrations tends to be asymmetrical around the average, the larger concentrations have a disproportionately greater weight. Sony VAIO VPCW218JC/P Battery
Indoor radon concentration is usually assumed to follow a lognormal distribution on 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/m3 to over 100 Bq/m3 in some European countries. Sony VAIO VPCW218JC/T Battery
Typical geometric standard deviations found in studies range between 2 and 3, meaning (given the 68-95-99.7 rule) that the radon concentration is expected to be more than a hundred times the mean concentration for 2 to 3% of the cases.
The highest average radon concentrations in the United States are found in Iowa and in the Appalachian Mountain areas in southeastern Pennsylvania. Sony VAIO VPCW218JC/W Battery
Some of the highest readings ever have been recorded in the Irish town of Mallow, County Cork, prompting local fears regarding lung cancer. Iowa has the highest average radon concentrations in the United States due to significant glaciation that ground the granitic rocks from the Canadian Shield and deposited it as soils making up the rich Iowa farmland. Sony VAIO VPCW219AJ/L Battery
Many cities within the state, such as Iowa City, have passed requirements for radon-resistant construction in new homes. In a few locations,uranium tailings have been used for landfills and were subsequently built on, resulting in possible increased exposure to radon.
Radon is obtained as a by-product of uraniferous ores processing after transferring into 1% solutions of hydrochloricor hydrobromic acids. Sony VAIO VPCW219AJ/P Battery
The gas mixture extracted from the solutions contains H2, O2, He, Rn, CO2, H2O and hydrocarbons. The mixture is purified by passing it over copper at 720 °C to remove the H2 and the O2, and then KOH and P2O5 are used to remove the acids and moisture by sorption. Radon is condensed by liquid nitrogen and purified from residue gases by sublimation. Sony VAIO VPCW219AJ/W Battery
Radon commercialization is regulated, but it is available in small quantities for the calibration of 222Rn measurement systems, at a price of almost $6,000 per milliliter of radium solution (which only contains about 15 picograms of actual radon at a given moment). Radon is produced by a solution of radium-226 (half-life of 1600 years). Sony VAIO VPCW21AAJ Battery
Radium-226 decays by alpha-particle emission, producing radon which collects over samples of radium-226 at a rate of about 1 mm3/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 222Rn (half-life of about four days) escapes from the capsule through diffusion. Sony VAIO VPCW21AKJ Battery
An early-20th-century form of quackery was the treatment of maladies in a radiotorium. 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 on. Radon's molecule-damaging radioactivity has been used to kill cancerous cells. Sony VAIO VPCW21AVJ Battery
It does not, however, increase the health of healthy cells. In fact, the ionizing radiation causes the formation of free radicals, which results in genetic and other cell damage, resulting in increased rates of illness, including cancer.
Exposure to radon, a process known as radiation hormesis, has been suggested to mitigate auto-immune diseases such asarthritis. Sony VAIO VPCY115FGS Battery
As a result, in the late 20th century and early 21st century, some "health mines" were established in Basin, Montana which attracted people seeking relief from health problems such as arthritis through limited exposure to radioactive mine water and radon. However, the practice is discouraged because of the well-documented ill effects of high-doses of radiation on the body. Sony VAIO VPCY115FX/BI Battery
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 Prefecture. Drinking therapy is applied in Bad Brambach, Germany. Inhalation therapy is carried out in Gasteiner-Heilstollen, Sony VAIO VPCY115FXBI Battery
Austria, in ?wieradów-Zdrój, Czerniawa-Zdrój, Kowary, L?dek Zdrój, Poland, in Harghita B?i, Romania, and in Boulder, United States. In the United States and Europe there are several "radon spas," where people sit for minutes or hours in a high-radon atmosphere in the belief that low doses of radiation will invigorate or energize them. Sony VAIO VPCY118EC Battery
Radon has been produced commercially for use in radiation therapy, but for the most part has been replaced by radionuclides made in accelerators and nuclear reactors. Radon has been used in implantable seeds, made of gold or glass, primarily used to treat cancers. 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. Sony VAIO VPCY118GX/BI Battery
The gold layer keeps the radon within, and filters out the alpha and beta radiations, while allowing the gamma rays to escape (which kill the diseased tissue). The activities might range from 0.05 to 5 millicuries per seed (2 to 200 MBq). The gamma rays are produced by radon and the first short-lived elements of its decay chain (218Po, 214Pb, 214Bi, 214Po). Sony VAIO VPCY119FJ/S Battery
Radon and its first decay products being very short-lived, the seed is left in place. After 12 half-lives (43 days), radon radioactivity is at 1/2000 of its original level. At this stage, the predominant residual activity originates from the radon decay product 210Pb, whose half-life (22.3 years) is 2000 times that or radon (and whose activity is thus 1/2000 of radon's), and its descendants 210Bi and 210Po, totalizing 0.03% of the initial seed activity. Sony VAIO VPCY11AFJ Battery
In the early part of the 20th century in the USA, gold which was contaminated with 210Pb entered the jewelry industry. This was from gold seeds which had held 222Rn that had been melted down after the radon had decayed. Wearing a contaminated ring could lead to a skin exposition of 10 to 100 rad/day (0.4 to 4 mSv/h) Sony VAIO VPCY11AGJ Battery
Radon emanation from the soil varies with soil type and with surface uranium content, so outdoor radon concentrations can be used to track air masses to a limited degree. This fact has been put to use by some atmospheric scientists. Sony VAIO VPCY11AHJ Battery
Because of radon's rapid loss to air and comparatively rapid decay, radon is used in hydrologic research that studies the interaction between ground water and streams. Any significant concentration of radon in a stream is a good indicator that there are local inputs of ground water. Radon is also used in the dating of oil-containing soils because radon has a high affinity for oil-like substances. Sony VAIO VPCY11AVJ Battery
Radon soil-concentration has been used in an experimental way to map buried close-subsurface geological faults because concentrations are generally higher over the faults. Similarly, it has found some limited use in prospecting for geothermal gradients.
Some researchers have investigated changes in groundwater radon concentrations for earthquake prediction. Sony VAIO VPCY11M1E/S Battery
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 ground water circulation, flushing out radon. Sony VAIO VPCY11S1E Battery
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. Sony VAIO VPCY11V9E/S Battery
However, as of 2009, it is under investigation as a possible precursor by NASA.
Radon is a known pollutant emitted from geothermal power stations, though it disperses rapidly, and no radiological hazard has been demonstrated in various investigations. The trend in geothermal plants is to reinject all emissions by pumping deep underground, and this seems likely to ultimately decrease such radon hazards further. Sony VAIO VPCY218EC/BI Battery
In the 1950s, radon has been used in industrial radiography.
Relative risk of lung cancer mortality by cumulative exposure to radon decay products (in WLM) from the combined data from 11 cohorts of underground hard rock miners. Though high exposures (>50 WLM) cause statistically significant excess cancers, the case of small exposures (10 WLM) is inconclusive and appears slightly beneficial in this study. Sony VAIO VPCY218EC/G Battery
Radon-222 has been classified by International Agency for Research on Cancer as being carcinogenic to humans, and as a gas that can be inhaled, lung cancer is a particular concern for people exposed to high levels of radon for sustained periods of time. During the 1940s and 50s, when safety standards requiring expensive ventilation in mines were not widely implemented, Sony VAIO VPCY218EC/L Battery
radon exposure was linked to lung cancer among non-smoking miners of uranium and other hard rock materials in what is now theCzech Republic, and later among miners from the Southwestern United States.
Since that time, ventilation and other measures have been used to reduce radon levels in most affected mines that continue to operate. Sony VAIO VPCY218EC/P Battery
In recent years, the average annual exposure of uranium miners has fallen to levels similar to the concentrations inhaled in some homes. This has reduced the risk of occupationally induced cancer from radon, although health issues may persist for those who are currently employed in affected mines and for those who have been employed in them in the past. As the relative risk for miners has decreased, so has the ability to detect excess risks among that population. Sony VAIO VPCY21S1E/L Battery
Radon exposure (actually radon progeny) has been linked to lung cancer in numerous case-control studies performed in the United States, Europe and China. There are approximately 21,000 deaths per year in the USA due to radon-induced lung cancers.
One of the most comprehensive radon studies performed in the United States by Dr. R. Sony VAIO VPCY21S1E/P Battery
William Field and colleagues found a 50% increased lung cancer risk even at the protracted exposures at the EPA's action level of 4 pCi/L. North American and European Pooled analyses further support these findings. Many researchers have highlighted a theoretical possible increased risk ofleukemia of radon, but empirical support for this has not emerged. Sony VAIO VPCY21S1E/SI Battery
The effects of radon if ingested are similarly unknown, although studies have found that its biological half-life ranges from 30–70 minutes, with 90 percent removal at 100 minutes. In 1999 National Research Council investigated the issue of radon in drinking water. The risks associated with ingestion was considered almost negligible. Sony VAIO VPCZ110 Battery
As well as being ingested through drinking water, radon is also released from water when temperature is increased, pressure is decreased and when water is aerated. Optimum conditions for radon release and exposure occur during showering. Water with a radon concentration of 10 4 pCi/L can increase the indoor airborne radon concentration by 1 pCi/L under normal conditions of water use. Sony VAIO VPCZ110GB/BI Battery
A controversial epidemiological study showing decreased cancer risk vs. radon domestic exposure (5 pCi/L ? 200 Bq/m3).This study lacks individual level controls for smoking and radon exposure, and therefore lacks statistical power to draw conclusions on what would beradiation hormesis. Sony VAIO VPCZ112GD/S Battery
Because of this the error bars (which simply reflect the raw data variability) are probably too small.
Most models of residential radon exposure are based on studies of miners, and direct estimates of the risks posed to homeowners would be more desirable. Nonetheless, because of the difficulties of measuring the risk of radon relative to other contributors—namely smoking—models of their effect have often made use of them. Sony VAIO VPCZ112GX/S Battery
Radon has been considered the second leading cause of lung cancer and leading environmental cause of cancer mortality by theUnited States Environmental Protection Agency. Others have reached similar conclusions for the United Kingdom  and France. Radon exposure in homes and offices may arise from certain subsurface rock formations and also from certain building materials (e.g. some granites); Sony VAIO VPCZ114GX/S Battery
greatest risk of radon exposure arises from buildings which are tight, insufficiently ventilated and have leaks that let in soil air from the ground into basements and dwelling rooms.
The actionable concentration of radon in a home varies depending on the organization doing the recommendation, for example,Sony VAIO VPCZ115 Battery
the United States Environmental Protection Agency encourages that action be taken at concentrations as low as 74 Bq/m3(2 pCi/L),and the European Union recommends action be taken when concentrations reach 400 Bq/m3 (11 pCi/L) for old houses and 200 Bq/m3(5 pCi/L) for new ones.
On 8 July 2010 the UK's Health Protection Agency issued new advice setting a "Target Level" of 100 Bq/m3 whilst retaining an "Action Level" of 200 Bq/m3. Sony VAIO VPCZ115FC/B Battery
Radon and smoking
Results from epidemiological studies indicate that the risk of lung cancer increases with exposure to residential radon. However, there are always major uncertainties in these studies. A classical and well-known example of source of error is smoking. Sony VAIO VPCZ115FC/S Battery
In addition, smoking is the most important risk factor for lung cancer. In the West, tobacco smoke is estimated to cause about 90% of all lung cancers. There is a tendency for other hypothetical lung cancer risks to drown in the risk of smoking. Results from epidemiological studies must always be interpreted with caution. Sony VAIO VPCZ116 Battery
According to the EPA, the risk of lung cancer for smokers is significant due to synergistic effects of radon and smoking. For this population about 62 people in a total of 1,000 will die of lung cancer compared to 7 people in a total of 1,000 for people who have never smoked.
Radon, like other known or suspected external risk factors for lung cancer, is a threat for smokers and former smokers. Sony VAIO VPCZ116GX/S Battery
This was clearly demonstrated by the European pooling study. A commentary to the pooling study stated: "it is not appropriate to talk simply of a risk from radon in homes. The risk is from smoking, compounded by a synergistic effect of radon for smokers. Without smoking, the effect seems to be so small as to be insignificant." Sony VAIO VPCZ117 Battery
A study of radiation from postmastectomy radiotherapy shows that the simple models previously used to assess the combined and separate risks from radiation and smoking need to be developed. This is also supported by new discussion about the calculation method, LNT, which routinely has been used. Sony VAIO VPCZ117FC/B Battery
Radon and passive smoking
An important question is if also passive smoking can cause a similar synergy effect with residential radon. This has been insufficiently studied. The basic data for the European pooling study makes it impossible to exclude that such synergy effect is an explanation for the (very limited) increase in the risk from radon that was stated for non-smokers. Sony VAIO VPCZ118 Battery
A study from 2001 which included 436 cases (never smokers who had lung cancer), and a control group (1649 never smokers) showed that exposure to radon increased the risk of lung cancer in never smokers. But the group that had been exposed to passive smoking at home appeared to bear the entire risk increase, while those who were not exposed to passive smoking did not show any increased risk with increasing radon level. Sony VAIO VPCZ118GC/B Battery
This result needs confirmation by additional studies. Despite the startling results from 2001, new studies seem not to have been implemented.
Testing and mitigation
There are relatively simple tests for radon gas, but these tests are not commonly done, even in areas of known systematic hazards. Radon test kits are commercially available. Sony VAIO VPCZ118GX/S Battery
The short-term radon test kits used for screening purposes are inexpensive, in many cases free. The kit includes a collector that the user hangs in the lowest livable floor of the house for 2 to 7 days. The user then sends the collector to a laboratory for analysis. Long term kits, taking collections for up to one year, are also available. An open-land test kit can test radon emissions from the land before construction begins. Sony VAIO VPCZ119 Battery
Radon levels fluctuate naturally, due to factors like transient weather conditions, so an initial test might not be an accurate assessment of a home's average radon level. Radon levels are at a maximum during the coolest part of the day when pressure differentials are greatest. Therefore, a high result (over 4 pCi/L) justifies repeating the test before undertaking more expensive abatement projects. Sony VAIO VPCZ119FJ/S Battery
Measurements between 4 and 10 pCi/L warrant a long term radon test. Measurements over 10 pCi/L warrant only another short term test so that abatement measures are not unduly delayed. Purchasers of real estate are advised to delay or decline a purchase if the seller has not successfully abated radon to 4 pCi/L or less. Sony VAIO VPCZ119GC/X Battery
Because the half-life of radon is only 3.8 days, removing or isolating the source will greatly reduce the hazard within a few weeks. Another method of reducing radon levels is to modify the building's ventilation. Generally, the indoor radon concentrations increase as ventilation rates decrease. In a well ventilated place, the radon concentration tends to align with outdoor values (typically 10 Bq/m3, ranging from 1 to 100 Bq/m3). Sony VAIO VPCZ119L Battery
Radon levels in indoor air can be lowered in a number of ways, from sub-slab depressurization to increasing the ventilation rate of the building. The four principal ways of reducing the amount of radon accumulating in a house are:
Sub-slab depressurization (soil suction) by increasing under-floor ventilation; Sony VAIO VPCZ119R/B Battery
- Improving the ventilation of the house and avoiding the transport of radon from the basement into living rooms;
- Installing a radon sump system in the basement;
Installing a positive pressurization or positive supply ventilation system. Sony VAIO VPCZ119R/S Battery
According to the EPA's "A Citizen's Guide to Radon", the method to reduce radon "primarily used is a vent pipe system and fan, which pulls radon from beneath the house and vents it to the outside", which is also called sub-slab depressurization, active soil depressurization, or soil suction. Sony VAIO VPCZ11AFJ Battery
Generally indoor radon can be mitigated by sub-slab depressurization and exhausting such radon-laden air to the outdoors, away from windows and other building openings. "EPA generally recommends methods which prevent the entry of radon. Soil suction, for example, prevents radon from entering your home by drawing the radon from below the home and venting it through a pipe, or pipes, Sony VAIO VPCZ11AGJ Battery
to the air above the home where it is quickly diluted" and "EPA does not recommend the use of sealing alone to reduce radon because, by itself, sealing has not been shown to lower radon levels significantly or consistently" according to the EPA's "Consumer's Guide to Radon Reduction: How to fix your home". Sony VAIO VPCZ11AVJ Battery
Positive-pressure ventilation systems can be combined with a heat exchanger to recover energy in the process of exchanging air with the outside, and simply exhausting basement air to the outside is not necessarily a viable solution as this can actually draw radon gas into a dwelling. Sony VAIO VPCZ11CGX/X Battery
Homes built on a crawl space may benefit from a radon collector installed under a "radon barrier" (a sheet of plastic that covers the crawl space). For crawlspaces, the EPA states "An effective method to reduce radon levels in crawlspace homes involves covering the earth floor with a high-density plastic sheet. Sony VAIO VPCZ11DGX/SJ Battery
A vent pipe and fan are used to draw the radon from under the sheet and vent it to the outdoors. This form of soil suction is called submembrane suction, and when properly applied is the most effective way to reduce radon levels in crawlspace homes." Sony VAIO VPCZ11FHX/XQ Battery,Sony VAIO VPCZ11V9R/B Battery,Sony VAIO VPCZ11X9E/B Battery,Sony VAIO VPCZ11Z9E/B Battery,Sony VAIO VPCZ125GX/S Battery