Radon Gas in Caves Is there any Epidemiology within Cavers and Miners?
Bob Mehew
Well-known member
As I am pushed for time I will restrain myself to a few observations.
Radon, as an inert gas, diffuses out of rock into the surrounding atmosphere at a given rate per unit area of rock. Because radon has a short half life before it decays into another radioactive element, the depth of rock from which radon can diffuse out is relatively small. If you grind the rock up, then the surface area per unit mass of rock is much greater and hence the rate of release of radon is much greater. You will find a fair amount of ground up rock in a cave (or indeed a mine). The radon air pressure problem arises because as pressure falls, so air is sucked out of the ground up rock, enhancing the release rate.
The relationship between miners exposure to radon and cancer is well written up in documents produced by the International Commission on Radiological Protection or ICRP as it is usually know. The specific documents are ICRP 32, 50 and 65. There is a recent paper by Darby et al entitled "Radon in homes and risk of lung cancer: collaborative analysis ..." published in the BMJ in December 2004 which indicates that around 2% of all cancers in Europe is caused by radon in homes.
I would strongly recommend you read Radon Underground available from BCA for the implications to cavers. Although the document requires some updating, it provides a reasonable explanation of the problem. (But I have to admit that that is a potentially biased statement since I am a contributor to it.)
Bob
Radon, as an inert gas, diffuses out of rock into the surrounding atmosphere at a given rate per unit area of rock. Because radon has a short half life before it decays into another radioactive element, the depth of rock from which radon can diffuse out is relatively small. If you grind the rock up, then the surface area per unit mass of rock is much greater and hence the rate of release of radon is much greater. You will find a fair amount of ground up rock in a cave (or indeed a mine). The radon air pressure problem arises because as pressure falls, so air is sucked out of the ground up rock, enhancing the release rate.
The relationship between miners exposure to radon and cancer is well written up in documents produced by the International Commission on Radiological Protection or ICRP as it is usually know. The specific documents are ICRP 32, 50 and 65. There is a recent paper by Darby et al entitled "Radon in homes and risk of lung cancer: collaborative analysis ..." published in the BMJ in December 2004 which indicates that around 2% of all cancers in Europe is caused by radon in homes.
I would strongly recommend you read Radon Underground available from BCA for the implications to cavers. Although the document requires some updating, it provides a reasonable explanation of the problem. (But I have to admit that that is a potentially biased statement since I am a contributor to it.)
Bob
nickwilliams
Well-known member
There is an article on Radon in the current issue of Descent, which arrived in my post this morning.
Nick.
Nick.
paul
Moderator
nickwilliams said:
I was just about to say the same thing!
There's and article relating to Estimating the dose from radon to recreational cave users in the Mendips, UK which may be of interest as well.
AndyF
New member
Bob Mehew said:
The synopsis of this paper indicates that they studied lung cancer only.
To draw a conclusion that 2% of ALL cancers in Europe are thus due to radon sounds like a bit of "wild extrapolation", but I can't say without buying the paper and reading it...anyone got a copy I can look at?
Im also puzzled that the control group lived with an average Radon level of 97 Bqm3 whereas the lung cancer group averaged 104 Bqm3. That difference is statistically insignificant in the size of the control group. A valid analysis would have to look at X people living in 97Bqm3 and look at the proportion of lung cancers, and then do the same at some higher level, and see an increased PROPORTION of lung cancers.
That is not what is suggested by the synopsis....but as I say not read the paper yet....
Christian_Chourot
New member
Ouan
Member
paul said:
This paper, "Estimating the dose from radon to recreational cave users in the Mendips, UK" by Malcolm Sperrin, Tony Denman and Paul S. Phillips published in Journal of Environmental Radioactivity 49 (2000) pp235-240 and the nearly identical "Radon Hazards, Geology, and Exposure of Cave Users:A Case Study and Some Theoretical Perspectives" by Gavin K. Gillmore, Malcom Sperrin and Antony Denman published in Ecotoxicology and Environmental Safety 46, pp279-288 (2000) Environmental Research, Section B are two very badly written papers. They made some very unrealistic assumptions about the amount of time cavers spend underground, extrapolate from a limited amount of real data and include some irrelevant information to support their case. As an example in their conclusions they state "This study reported the radiation dose from radon received by recreational, and in particular, occupational caver users in SW England". The study didn't do this! It made a very crude, probably highly over estimated guess for cave users in one cave. Their own personal detector results, which should give the best readings, are conveniently ignored throughout the report.
My impression on reading the papers was that the authors appeared to be radiological protection professionals in whose interest it may have been to stir up trouble and make it compulsory to monitor caves. They seemed to imply that they want access controlled to the caves to protect us from the radon. In short bad science with a possible hidden agenda.
Please PM me if you would like PDFs of the two papers.
C
Colin the Caver
Guest
Some Radon maps for the country.
http://www.hpa.org.uk/web/HPAwebFile/HPAweb_C/1204186227787
Wensleydale and Derbyshire look a bit grim in places.
The full decay path for Radon from Uranium238 to Lead is given in Wikipedia.
http://www.hpa.org.uk/web/HPAwebFile/HPAweb_C/1204186227787
Wensleydale and Derbyshire look a bit grim in places.
The full decay path for Radon from Uranium238 to Lead is given in Wikipedia.
AndyF
New member
Well I've read the BMJ paper and I have to say I'm unimpressed. In my opinion the conclusions drawn are not supported by the data. The data would give at best an "is consistant with" and is definitly not a "shows"...
The reasons are as follows.
Point 1
Essentially radon measuremnts were taken in peoples houses who had lung cancer, and in houses from a control group. These were weighted according to the time spent in each house over a reasonable period. All well and good. However the measurements were all taken recently (during the time of the work), and NOT during the 15-30 year period considered to contribute to the cancers.
Now over 30 years a lot can happen in a house, fitting double glazing, changing ventilation etc. as well as changing patterns of useage. These mean that radon measurements taken recently have been severly extrapolated backwards in time, degrading their usefullness.
The weighted exposure difference between the cancer and the control group was only 7% (104 vs 97), a figure that is easily swamped by the uncertainty due to extrapolation of radon readings. ALL the conclusions are based on this ill conditioned figure, and this point alone so seriously compromises the conclusions as to invalidate them.
Point 2
Where radon readings coud not be obtained, due to demolition for example, the mean of the figure from the control group was used. This is just bad stats. The figure used should have been the mean from control AND cancer groups. This would skew the 7% figure for certain.
Point 3
It is not clear how if weighting was done according to how time was spent in a given dwelling. For instance, a housewife MAY be in a house most of the day,where as a worker may be out of the house for 8-10 hours a day. Also critical is which bedroom they slept in, since a third or so of time in a house is spent asleep. It is likely that radon concentrations are very different in, say,a kitchen than in an upstairs bedroom. It is not suggested that measurements accounted for this, and again it can have a huge effect on exposure.
In short, these factors utterly undermine the key finding on which the conclusions stem i.e. the different weighted exposures. 7% is just not significant enough, when there is such huge uncertainty in the underlying data, and certainly not good enough for a "shows" conclusion.
Good effort, poor maths, invalid conclusions 3 out of 10 - must try harder.
The reasons are as follows.
Point 1
Essentially radon measuremnts were taken in peoples houses who had lung cancer, and in houses from a control group. These were weighted according to the time spent in each house over a reasonable period. All well and good. However the measurements were all taken recently (during the time of the work), and NOT during the 15-30 year period considered to contribute to the cancers.
Now over 30 years a lot can happen in a house, fitting double glazing, changing ventilation etc. as well as changing patterns of useage. These mean that radon measurements taken recently have been severly extrapolated backwards in time, degrading their usefullness.
The weighted exposure difference between the cancer and the control group was only 7% (104 vs 97), a figure that is easily swamped by the uncertainty due to extrapolation of radon readings. ALL the conclusions are based on this ill conditioned figure, and this point alone so seriously compromises the conclusions as to invalidate them.
Point 2
Where radon readings coud not be obtained, due to demolition for example, the mean of the figure from the control group was used. This is just bad stats. The figure used should have been the mean from control AND cancer groups. This would skew the 7% figure for certain.
Point 3
It is not clear how if weighting was done according to how time was spent in a given dwelling. For instance, a housewife MAY be in a house most of the day,where as a worker may be out of the house for 8-10 hours a day. Also critical is which bedroom they slept in, since a third or so of time in a house is spent asleep. It is likely that radon concentrations are very different in, say,a kitchen than in an upstairs bedroom. It is not suggested that measurements accounted for this, and again it can have a huge effect on exposure.
In short, these factors utterly undermine the key finding on which the conclusions stem i.e. the different weighted exposures. 7% is just not significant enough, when there is such huge uncertainty in the underlying data, and certainly not good enough for a "shows" conclusion.
Good effort, poor maths, invalid conclusions 3 out of 10 - must try harder.
Bob Mehew
Well-known member
If you want to read further then http://hosted-www.caves.org/pub/journal/JCKS/PDF/v69/cave-69-01-207.pdf starts with the author claim that "This paper was developed to provide the National Speleological Society reader with an intensive investigation of the potential health effects posed by exposure to elevated levels of radon in caves. To the author?s knowledge, no other publication on radon in caves has delved into the risks to cavers from exposure to radon in caves to the extent that this paper does." From a quick scan, I don't think I am going to take issue with that claim.
mrodoc
Well-known member
As I mentioned in an earlier post actually conducting research on cavers as opposed to speculating about them seemed to me to be a risky thing to do if the results suggested significant exposure. However you could blame me for putting a potential researcher off a project which might have got some hard evidence one way or the other.
P
Prince of Darkness
Guest
graham said:
I think I've got an appropriate avatar for this topic.
I wonder if anyone would be prepared to obtain any radon measurements from the bottom of Nettle Pot, I'm certain they will be very high.
C
Clive G
Guest
Years ago, after periods of heavy rain, people used to find the swollen Turkey Streamway in Agen Allwedd milky white in colour and smelling strongly of diesel fumes. The 'scientific' explanation given was that the shale beds provided the source of the contaminants, which were supposedly being flushed out during the reactivation of little-used fissures and old watercourses, otherwise inactive during 'normal/dry' conditions. Great care was taken to explain how such diesel and white matter could exist in 'the shales'.
It is possible for me to vouch for both effects since I witnessed them in the stream passage, first-hand, during a flood on 2nd January 1984.
However, at the time I didn't believe the 'scientific' explanation given and, quite magically, since the mid-late 1980s, following the closure of new Blaen Onneu Quarry (where limestone was crushed to a fine powder), the milky colourisation of the water has all but vanished. Likewise, the strong smell of diesel in the Turkey Streamway has also not been reported in latter times.
It seems from the above postings that whereas people dispute the theories relating to gasses being issued from solid rock in caves, there is agreement that water can carry radon gas. With everything done in the way of nuclear experimentation during the 20th century, from nuclear blasts visited upon Japan at the end of the 2nd World War, controlled experimental explosions in deserts, on 'remote uninhabited' islands and in the upper atmosphere, through to the (unintended) Chernobyl explosion (26th April 1986), there is no doubt that at some point in time various particles from these 'experiments' are going to rain down on the countryside which we inhabit - depending on how the released particles, and rain clouds to which they have become attached, move around in the atmosphere. All you need is to send some uranium up into the sky and one day (somewhere) radon will drizzle (or pour) back down again.
Stanley Kubrick's film 'Dr Strangelove or: How I learned to Stop Worrying and Love the Bomb' (1964) has as a central plot device the contention that the contamination of the world's water supply, seen as a result of the then popular 'fluoridation' process, was a scheme by the Russians, who escaped the resulting deleterious effects by drinking vodka instead of water! Of course, the pivotal plot device was how misuse of the atomic bomb could lead to the unleashing of a 'domesday device' which could end up enshrouding the planet in a nuclear cloud . . .
Looking at the article on radon levels in Agen Allwedd, the highest levels have been detected near Flood Passage and Ocre Inlet - relatively small subsidiary feeders to the main watercourse. Perhaps the particles responsible for the radon gas emissions enter the cave only at certain times, hence not all the watercourses carry the same level of radon? However, in some places, where the flow rate is sufficiently reduced, instead of being flushed through the system a greater concentration of contaminated particles are deposited at the high water level and remain alongside the watercourses for longer periods at a time? Ultimately, the presence of draughts, induced by faster-flowing water, barometric changes and temperature gradients, between the surface and underground, is going to have a major effect on the reduction of radon levels.
If people are being affected, radioactively-speaking, by where they live, and accumulations of radon which have built up around them, for one reason or another, then carrying out experimentation on cavers isn't necessarily going to help provide 'proof' that any radon contamination present in their system is as a direct result of their caving. Such experimentation backed by an eminent authority could, however, be used to form an argument for closing some caves - perhaps even all?
On the other hand, radon monitoring in caves, such as the work carried out in Agen Allwedd and Eglwys Faen, can only help improve our knowledge of the extent of and variation in radon levels encountered underground. It could be that for caving, as in diving, where decompression was once an unknown quantity, albeit the harmful effect of returning too fast from great depth and suffering 'the bends' was comprehended, one day 'radon tables' will be used alongside lists of pitch lengths and equipment required for underground exploration.
When people find they are getting ill and can't get better, then often a complete change of habit and home location will do the trick in giving a kick start to the immune system and helping the body to sort itself out. So, my advice to anyone who feels that their own personal exposure to radon gas in caves (over time) might have affected them in one way or another, is to do something else for a while, not in caves. I think it is repetitive actions over time - without introducing variety and change, i.e 'everything to excess' as one club proudly exclaims - which can present the greatest potential long-term health issues.
If you're enjoying your caving and mix going underground with climbing and other outdoor activities, then I don't think you're putting yourself any more at risk than everyone else trying to enjoy life in the world which we have inherited from our predecessors . . .
It is possible for me to vouch for both effects since I witnessed them in the stream passage, first-hand, during a flood on 2nd January 1984.
However, at the time I didn't believe the 'scientific' explanation given and, quite magically, since the mid-late 1980s, following the closure of new Blaen Onneu Quarry (where limestone was crushed to a fine powder), the milky colourisation of the water has all but vanished. Likewise, the strong smell of diesel in the Turkey Streamway has also not been reported in latter times.
It seems from the above postings that whereas people dispute the theories relating to gasses being issued from solid rock in caves, there is agreement that water can carry radon gas. With everything done in the way of nuclear experimentation during the 20th century, from nuclear blasts visited upon Japan at the end of the 2nd World War, controlled experimental explosions in deserts, on 'remote uninhabited' islands and in the upper atmosphere, through to the (unintended) Chernobyl explosion (26th April 1986), there is no doubt that at some point in time various particles from these 'experiments' are going to rain down on the countryside which we inhabit - depending on how the released particles, and rain clouds to which they have become attached, move around in the atmosphere. All you need is to send some uranium up into the sky and one day (somewhere) radon will drizzle (or pour) back down again.
Stanley Kubrick's film 'Dr Strangelove or: How I learned to Stop Worrying and Love the Bomb' (1964) has as a central plot device the contention that the contamination of the world's water supply, seen as a result of the then popular 'fluoridation' process, was a scheme by the Russians, who escaped the resulting deleterious effects by drinking vodka instead of water! Of course, the pivotal plot device was how misuse of the atomic bomb could lead to the unleashing of a 'domesday device' which could end up enshrouding the planet in a nuclear cloud . . .
Looking at the article on radon levels in Agen Allwedd, the highest levels have been detected near Flood Passage and Ocre Inlet - relatively small subsidiary feeders to the main watercourse. Perhaps the particles responsible for the radon gas emissions enter the cave only at certain times, hence not all the watercourses carry the same level of radon? However, in some places, where the flow rate is sufficiently reduced, instead of being flushed through the system a greater concentration of contaminated particles are deposited at the high water level and remain alongside the watercourses for longer periods at a time? Ultimately, the presence of draughts, induced by faster-flowing water, barometric changes and temperature gradients, between the surface and underground, is going to have a major effect on the reduction of radon levels.
If people are being affected, radioactively-speaking, by where they live, and accumulations of radon which have built up around them, for one reason or another, then carrying out experimentation on cavers isn't necessarily going to help provide 'proof' that any radon contamination present in their system is as a direct result of their caving. Such experimentation backed by an eminent authority could, however, be used to form an argument for closing some caves - perhaps even all?
On the other hand, radon monitoring in caves, such as the work carried out in Agen Allwedd and Eglwys Faen, can only help improve our knowledge of the extent of and variation in radon levels encountered underground. It could be that for caving, as in diving, where decompression was once an unknown quantity, albeit the harmful effect of returning too fast from great depth and suffering 'the bends' was comprehended, one day 'radon tables' will be used alongside lists of pitch lengths and equipment required for underground exploration.
When people find they are getting ill and can't get better, then often a complete change of habit and home location will do the trick in giving a kick start to the immune system and helping the body to sort itself out. So, my advice to anyone who feels that their own personal exposure to radon gas in caves (over time) might have affected them in one way or another, is to do something else for a while, not in caves. I think it is repetitive actions over time - without introducing variety and change, i.e 'everything to excess' as one club proudly exclaims - which can present the greatest potential long-term health issues.
If you're enjoying your caving and mix going underground with climbing and other outdoor activities, then I don't think you're putting yourself any more at risk than everyone else trying to enjoy life in the world which we have inherited from our predecessors . . .
V
VivB
Guest
Ok, so I have no references to back - up my claims, but I was suprised to learn (last year or year before) that of all the sources of radiation that contribute to a person's annual exposure, radon was responsible about 50% (compared to 10% av. for medical exposure to kV x-rays). But the suprising bit was that bomb testing and nuclear energy production supposedly contributed "too little to meter" , or less than one %. I don't know if I believe it one bit, but that's what I wrote on my exam paper, and I didn't fail!
Isn't the prob with radon that it decay releases alpha particles (helium nuclei) that whilst acting over a short distance rip maximum damage into delicate lung epithilia? That means that when changes occur to tissues, it's widespread and non-resectable (ie you're screwed). Still, stochastic risk and all that...
Isn't the prob with radon that it decay releases alpha particles (helium nuclei) that whilst acting over a short distance rip maximum damage into delicate lung epithilia? That means that when changes occur to tissues, it's widespread and non-resectable (ie you're screwed). Still, stochastic risk and all that...
C
Clive G
Guest
VivB said:
Atmospheric-borne radon seems to be at quite a high level. It is commonly suggested that the 'source' is contaminated rock and soil. However, why is it that just the first few inches of soil is supposed to carry the radon gas-emitting particles? The depth of penetration of rainwater could provide an alternative explanation here.
In studying the radon results from Agen Allwedd and Eglwys Faen, as published in the latest issue of 'Descent' (No. 203) for August/September 2008, what is striking is the difference in levels between the two caves. The plausible-sounding explanation given is: "The theory runs that relatively small caves with many entrances probably have low radon concentrations: radon is heavier than air and can collect in low-flow areas, while the ingress of fresh air will dilute it . . . Eglwys Faen is a relatively small, dry and ungated cave with several large entrances which should allow unrestricted airflow through much of the outer regions, particularly as there are several circular connections."
However, when you understand the make-up of the Llangattock cave system(s) you start to see the flaws in the 'big cave'/'little cave' hypothesis. The entrances to Eglwys Faen are not that large, it is the size of the Main Chamber in close proximity to the surface which gives rise to this misconception. The strong draughts in the system are mirrored by almost equally strong draughts in the Agen Allwedd/Ogof Gam Entrance Series (two separate entrances). So, therefore, according to this hypothesis one would expect readings taken in the nearer sections of the Agen Allwedd Entrance Series, at a similar point in time, to match those of Eglwys Faen, but they do not: the readings are appreciably higher in Agen Allwedd - in the Entrance Series they are, in fact, almost double those of the Main Chamber in Eglwys Faen.
A solution for the Agen Allwedd results appears to be at hand: "The high concentrations recorded in the cave suggest that during the duration of the experiment the airflow was predominantly outwards, bringing air laden with radon towards the entrance." However, the 25 readings carried out for this report are implied to have been taken in both caves simultaneously, between 19 September and 27 October 2007. The draught in Eglwys Faen is not driven by the few relatively small surface entrances being located in close proximity to each other, but by their connection with a large deep-mountain cave system - the Mynydd Llangattwg Cave System - currently inaccessible to cavers and located somewhere beyond the present various end boulder chokes of the cave. So, if a strong outwards cave draught were to be responsible for the high levels of radon detected in the Agen Allwedd Entrance Series, bringing the gas from deeper within the system, then exactly the same effect should also be experienced in Eglwys Faen (eg. in The Warren east passages where the draught has not yet diverged to depart from one of the cave's various entrances), but it is not - the levels throughout the cave are lower than those found in Agen Allwedd. Yet the Llangattock cave draughts act in unison, from one separately-named cave system to another, according to temperature and barometric variations between the surface and underground.
So, the next culprit could be determined to be the limestone strata, except both Agen Allwedd and Eglwys Faen are situated in the same bed of Blaen Onneu Oolite . . .
The only difference of any significance between the two caves is the presence or otherwise of running water. In Agen Allwedd you immediately enter a sizeable stream passage where the water has only had a minimal passage through the overlying strata before entering the cave. Direct rainfall from air to ground to cave has taken place. The small surface stream which enters Eglwys Faen can be seen trickling down the mountainside and falling as a waterfall before it enters the Eastern Series. Tumbling water is one way to cause unwanted gasses and particles to be expelled - look at water treatment plants. There are other very small streams inside Eglwys Faen, but they carry nothing like the quantity of water which is found flowing in the Main Stream Passage of Agen Allwedd - in proximity to which a good number of the radon measurements have been taken and the largest readings obtained. Streams also run from the Ace of Spades Inlet, past the edge of the Music Hall and along the inner end of Trident Passage. Another stream runs beneath the floor of the mouth of Southern Stream Passage - originating from Northern Stream Passage. All carry appreciably more water than that found flowing in Eglwys Faen.
So, for future tests, it would be interesting to see a greater mix of sites ranging between not only the current active stream passages but also inside the old high-level fossil chambers and tunnels, such as in Erse Passage and Midnight Passage.
Having argued the contention that rainwater is bringing a significant quantity of radon into caves, I will accept that high levels of radon in the atmosphere could result from more than a single source. It is certainly naturally present in (man-made) uranium mines. Accepted 'wisdom' appears to discount nuclear experimentation as providing "too little to meter" (but I do not think power stations should be included here, given these perform properly according to design and that waste matter from the reactors is contained and disposed of in a controlled fashion). In addition radon is not listed as emanating from cosmic radiation, but one article I have read suggests that radon is also present on Mars! Does ozone depletion have an effect here? Since there appears to be so much radon around in the atmosphere a re-evaluation of all its potential sources would be useful.
Radon gas appears to be a problem in certain buildings and soils in specific areas. Whilst the means by which people are subjected to its effects are not fully quantified or comprehended, it is impossible to determine what additional effect radon exposure obtained in caves may have over and above already-exisiting exposures to the gas. If things are as dismal as you appear to have been taught, in terms of the effect of radon on the metabolism, then we'll have to stop using whole swathes of the countryside and seal off or demolish many buildings.
I think the human metabolism is more robust than realised and can repair itself. However, those starting caving now need to know more about the risk they may be taking on through entering caves at specific times of the year and under certain conditions. Therefore, I stand by my call for 'radon tables' to be developed through thorough measurement of the variation in radon levels within caves in the various limestones of the UK. Rainfall, barometric and air temperature readings ought to be taken at the same time, to enable a correlation to be made between the quantities of radon gas present and the prevailing water and air flow conditions underground. The exposure to radon for those carrying out the experimentation should be spread as widely and sparingly as possible, using as many different cavers as can be found willing to participate. These will be cavers who are keen to learn more about the mechanism behind the presence of radon gas in caves, rather than bury their heads in the sand.
As I ended my original piece on this subject, my advice for those who have been caving some time, should anyone feel that their own personal exposure to radon gas in caves (over time) might have affected them in one way or another, is to do something else for a while, not in caves. If, on the other hand, you're enjoying your caving and mix going underground with climbing and other outdoor activities, then I don't think you're putting yourself any more at risk than everyone else trying to enjoy life in the world which we have inherited from our predecessors . . .
Bob Mehew
Well-known member
VivB said:
see http://www.hpa.org.uk/webw/HPAweb&HPAwebStandard/HPAweb_C/1195733713848?p=1158945066102 for the authoritative information. (Even though it is for 2005, I see it only got stuck up in 2008.)
VivB said:
You are correct in thinking that a contributing factor is the ejection of an alpha particle (not only from radon, but also from several of its daughter products) which to use the jargon has a high radiological impact. But the impact is still normally confined to one cell, since alpha particles easily give up their energy (being quite large compared to beta particles and gamma & X rays). This and other factors are taken into account in the fairly difficult business of working out just what exposure to so many Becquerels per metre cubed of Radon, plus its daughter products means in terms of Seiverts, the unit of dase and thence into risk factors. See the web site reference in my posting of 4 August for more (much more) details.
Bob
Les W
Active member
One of the reasons why radon is dangerous is its relatively short half life (Radon 222 has a half life of around 4 days and some of its daughters a have half lives that are very short (Polonium 218 has a half life of about 3 minutes so there is a chance it will decay whilst in your lungs, Polonium 214 has a half life of 164 micro seconds or 0.000164 seconds, so it is pretty much guaranteed that if this isotope of polonium is present in your lungs (by the decay of Radon 222) then it will decay whilst still in close contact with lung tissue. It is also very energetic so the decay will cause quite a bit of damage)
C
Clive G
Guest
Les W said:
The information to be found in unexpected places:
Radon [Rn] gaseous radioactive element, discovered by Ernest Rutherford in 1899. A colourless, chemically un-reactive Inert Gas, it is the densest gas known. Highly radioactive (emitting alpha rays), it is used chiefly in the treatment of cancer by radiotherapy. In homes and other buildings in some areas of the U.S. radon produced by the radioactive decay of uranium-238 present in soil and rock can reach levels regarded as dangerous, but the seriousness of the problem is unclear.
from: http://www.bigbangfireworks.co.uk/80260/info.php?p=3
