Radon Gas in Caves Is there any Epidemiology within Cavers and Miners?

[Ship-badger]

The first is that "low air pressure" results in radon being "drawn out" of the rock at a greater rate. This seems to me to be unlikely. Air Pressure is ALWAYS positive and ALWAYS around 14psi. It only varies slightly except at high altitude. At see level up to 1000m (the area of most caves) the variation is negligable, only around 10%.

Rock, on the other hand, does not have gas pressure (!) to any appreciable degree, and any radon gas atoms contained in it's crystaline structure formed by uranium decay will be independent of any external gas pressure. It's my assertion that this statement is utter tosh 

I think you are wrong. One of the jobs of a pit deputy, according to my friend who has a coal mine, is to record atmospheric pressure each day. Apparently it does have an effect on gas levels within a mine.

 

[Prince of Darkness]

The first is that "low air pressure" results in radon being "drawn out" of the rock at a greater rate. This seems to me to be unlikely. Air Pressure is ALWAYS positive and ALWAYS around 14psi. It only varies slightly except at high altitude. At see level up to 1000m (the area of most caves) the variation is negligable, only around 10%.

Rock, on the other hand, does not have gas pressure (!) to any appreciable degree, and any radon gas atoms contained in it's crystaline structure formed by uranium decay will be independent of any external gas pressure. It's my assertion that this statement is utter tosh 

I think you are wrong. One of the jobs of a pit deputy, according to my friend who has a coal mine, is to record atmospheric pressure each day. Apparently it does have an effect on gas levels within a mine.

I also reckon that that statement to be wrong. Yes, atmospheric pressure doesn't change much absolutely but at any given atmospheric pressure there will be an equilibrium between air pressure and any gases trapped in rocks or other strata. If atmospheric pressure is reduced then the flow from the ground must increase albeit temporarily before equilibrium is reached again. This assumes a steady rate of radon generation which is a reasonable assumption. Any radon not trapped in rock or shale will no doubt decay within that strata according to whatever half life it has (I think there is more than one radon isotope)

 

[AndyF]

but at any given atmospheric pressure there will be an equilibrium between air pressure and any gases trapped in rocks or other strata. If atmospheric pressure is reduced then the flow from the ground must increase albeit temporarily before equilibrium is reached again.

Nah....  You can't consider such an equilibrium, because a solid (or specifically gas dissolved in a solid) does not have a "pressure". Gas can only escape from the immediate surface of a solid. Gas molecules migrates through a solid at a finite rate, irrespective of the external gas pressure on the solid,and limited by the crystalline structure of that solid.

Try blowing into, or sucking air out of a housebrick.... you can get a much bigger differential in pressure than the atmosphere provides in the stated altitude range, but you wont get much gas in or out of it.... 

 

[Peter Burgess]

I have been in an ironstone mine at Coalbrookdale where it is only safe to enter during periods of high pressure. During low pressure events, something caused oxygen depleted air (I think) to exude from the rock into the mine. High pressure reintroduces a certain amount of fresh air into the mine again, and displaces the bad air into hte rock to a certain extent. I expect something in the rock (which may or may not be porous but which does contain fissures, cracks and joints) is oxidising and removing the oxygen. Either that or something is generating carbon dioxide, in which case it is a CO2 problem and not an oxygen depletion problem. It's too long ago now to remember! Anyway, the conditions in the mine (which is a single entrance system so no great air current) do vary with the weather. Trips were only carried out during fine weather.

 

[Speleokitty]

Sorry to say this Andy but you are wrong on this one. Atmospheric pressure has a well proven effect on Radon levels in mines.

All solids have some degree of permeability including house  bricks.  In fact  this is often done with house bricks is as part of routine quality control testing where it is replaced by water to determine open porosity and density. Reduced air pressure also influences the amount of dissolved gasses that are released from water just like the gas that escapes when you reduce the pressure in a bottle of champagne when the cork is removed.

Generally I would say that Radon poses little risk to weekend cavers although the risk to miners and caving instructors who spend much larger amounts of time underground is more significant and is considered a recognised workplace hazard. Some caves such as Giants are known to have high levels of radon daughters (offspring) and it may be prudent to avoid frequent visits.

Personally I avoid the well known risks of radiation in sunshine and the polonium in tobacco but do put up with the risk of high altitude flights and caving.

kitty

 

[Peter Burgess]

Thus proving that using words such as "utter tosh" and "bo11ox" does not increase the credibility of one's argument...  :tease:

 

[graham]

Im with andyF (despite my scare mongering)

I consider it on a par with not exposing ourselves to sunlight incase we get skin cancer.

Which is not much of a problem in Manchester but is a serious issue in Sydney.

 

[AndyF]

Sorry to say this Andy but you are wrong on this one. Atmospheric pressure has a well proven effect on Radon levels in mines.

I didn't dispute that - I disputed that changes in atmospheric pressure affects the emmision of radon from stone. That is not the same thing....   Other mechanisms can be at play.

The article also says

One unexplained anomaly is that Radon levels in mines seem to be lower in winter.

. In other words Winter (low air pressure!?) = low radon......er......ummmm.......

Thus proving that when a boffin is faced with there own OBSERVED data that contradicts their own assertion then it is an "anomaly" and not "just plain wrong"  

Think I'm sticking to my own personal theory of "utter tosh"..... supported by the observed data....  The article is bad science.

 

[AndyF]

Reduced air pressure also influences the amount of dissolved gasses that are released from water just like the gas that escapes when you reduce the pressure in a bottle of champagne when the cork is removed.

...champagne is a liquid and behaves very differenty. To use the example though, now consider FREEZING the said bottle of champagne turning it into a solid. Now what happens when you remove the cork....?  Lots of Gas? No Gas? Some change in pressure....

I think you'll find it's "no gas", since the gas is unable to escape from the solid ice/wine inresponse to the huge pressure change.

 

[Peter Burgess]

The article also says

One unexplained anomaly is that Radon levels in mines seem to be lower in winter.

. In other words Winter (low air pressure!?) = low radon......er......ummmm.......

Thus proving that when a boffin is faced with there own OBSERVED data that contradicts their own assertion then it is an "anomaly" and not "just plain wrong"  

Maybe in winter the fluctuations in atmospheric pressure are wider - more severe storms etc, and consequently the gas normally stagnating in the joints and fissures gets flushed into the mineworkings more? Rocks are rarely homogenous and to consider the composition of air in a mine one has to consider quite a complicated mechanism. Maybe on average, mine temperatures are closer to ambient in the winter than in the summer, and consequently, on average, natural circulation of fresh air is reduced? I don't pretend to know what is going on, but I am prepared to consider a wide range of mechanisms that might be at work, affecting gas concentrations.

 

[andymorgan]

Who produced the article?


I found this magazine-type article produced by the National Radiological Protection Board (see page 2) http://www.hpa.org.uk/web/HPAwebFile/HPAweb_C/1194947362874 In the intro on page 1, it also says that 'health studies of miners consistently show that increased exposure to radon is associated with increased risk of lung cancer', athlough I would like to see the studies myself before drawing my own conclusions.


By the way it seems radon can be good for you... http://www.radonmine.com/why.html

 

[fuzzy-hair-man]

I have been in an ironstone mine at Coalbrookdale where it is only safe to enter during periods of high pressure. During low pressure events, something caused oxygen depleted air (I think) to exude from the rock into the mine. High pressure reintroduces a certain amount of fresh air into the mine again, and displaces the bad air into the rock to a certain extent. I expect something in the rock (which may or may not be porous but which does contain fissures, cracks and joints) is oxidising and removing the oxygen. Either that or something is generating carbon dioxide, in which case it is a CO2 problem and not an oxygen depletion problem. It's too long ago now to remember! Anyway, the conditions in the mine (which is a single entrance system so no great air current) do vary with the weather. Trips were only carried out during fine weather.

http://wasg.iinet.net.au/CO2ASFpaper.html
The above link has a good explanation of the causes of high CO2 in caves, the effect on human's, etc and the fact that in general it is increased levels of CO2 that are encountered in caves and not lowered oxygen levels.
Bungonia which is mentioned in the website and papers and where we cave often commonly has high CO2 levels in many of the caves, however some other caves in the area and we have never experienced CO2 build ups, the depths are the same or similar, CO2 caves seem to either have water in them or bats/guano, but some won't have either but perhaps we just can't go deep enough to find them. When caving in this area we always carry a lighter or matches or both, these will not burn before the CO2 levels become dangerous, once you know it's effect on you you can often pick up high levels without matches etc (but we still carry them).

The site also confirms and gives an explanation for why high and low pressure make a difference to CO2 levels in a cave, at a guess the same or similar probably happens with Radon gas.

I don't know much about Radon (hopefully we don't have it.)..., CO2 is scary enough thanks.

 

[mrodoc]

I failed to mention in my last posting that I, indirectly, might have saved Mendip Caving from a fate worse than death once. Somerset's Public Health consultant who knew I was a caver (patient of mine then) thought as radon was then fashionable that it would be interesting to get some cavers to stand around in various cavers and then take blood from them afterwards for analysis re daughter products of radon. I was to say the least lukewarm in my response! God knows what would have happened if the study had gone ahead and thrown up any data suggesting a potential problem. I suspect landowners would have closed some caves to avoid liability.

 

[Peter Burgess]

I have been in an ironstone mine at Coalbrookdale where it is only safe to enter during periods of high pressure. During low pressure events, something caused oxygen depleted air (I think) to exude from the rock into the mine. High pressure reintroduces a certain amount of fresh air into the mine again, and displaces the bad air into the rock to a certain extent. I expect something in the rock (which may or may not be porous but which does contain fissures, cracks and joints) is oxidising and removing the oxygen. Either that or something is generating carbon dioxide, in which case it is a CO2 problem and not an oxygen depletion problem. It's too long ago now to remember! Anyway, the conditions in the mine (which is a single entrance system so no great air current) do vary with the weather. Trips were only carried out during fine weather.

http://wasg.iinet.net.au/CO2ASFpaper.html
The above link has a good explanation of the causes of high CO2 in caves, the effect on human's, etc and the fact that in general it is increased levels of CO2 that are encountered in caves and not lowered oxygen levels.
Bungonia which is mentioned in the website and papers and where we cave often commonly has high CO2 levels in many of the caves, however some other caves in the area and we have never experienced CO2 build ups, the depths are the same or similar, CO2 caves seem to either have water in them or bats/guano, but some won't have either but perhaps we just can't go deep enough to find them. When caving in this area we always carry a lighter or matches or both, these will not burn before the CO2 levels become dangerous, once you know it's effect on you you can often pick up high levels without matches etc (but we still carry them).

The site also confirms and gives an explanation for why high and low pressure make a difference to CO2 levels in a cave, at a guess the same or similar probably happens with Radon gas.

I don't know much about Radon (hopefully we don't have it.)..., CO2 is scary enough thanks.

Now I think about it, it probably was CO2 in the ironstone mine as it was only in the bottom of the workings that the problem was found. It was sometimes the case that a candle would burn happily at roof level, but go out if placed on the floor. Sitting down for a rest was not a good idea, and we were in there during a spell of good weather.

 

[Peter Burgess]

we are (I am) getting off topic now, but this is the mine. Confirmed as a CO2 problem.

http://www.aditnow.co.uk/mines/Crawstone-Level-Coal-Mine/

The good news is that I understand radon is not a problem in the Surrey mines.

 

[Speleokitty]

[

...champagne is a liquid and behaves very differently. To use the example though, now consider FREEZING the said bottle of champagne turning it into a solid. Now what happens when you remove the cork....?  Lots of Gas? No Gas? Some change in pressure....

I think you'll find it's "no gas", since the gas is unable to escape from the solid ice/wine in response to the huge pressure change.

The champagne analogy was liquid water not ice or rock so what has freezing got to do with anything. Radon is soluble in water and hence water acts as a transport mechanism. The rate at which radon is transported to the (cave/mine) atmosphere is dependent on pressure, temperature and surface area. OK its carbon dioxide in champagne but the principle is the same.


Kitty

 

[AndyF]

[

...champagne is a liquid and behaves very differently. To use the example though, now consider FREEZING the said bottle of champagne turning it into a solid. Now what happens when you remove the cork....? Lots of Gas? No Gas? Some change in pressure....

I think you'll find it's "no gas", since the gas is unable to escape from the solid ice/wine in response to the huge pressure change.

The champagne analogy was liquid water not ice or rock so what has freezing got to do with anything. Radon is soluble in water and hence water acts as a transport mechanism. The rate at which radon is transported to the (cave/mine) atmosphere is dependent on pressure, temperature and surface area. OK its carbon dioxide in champagne but the principle is the same.


Kitty

...because myassertion wasthat Radon emmisionfrom rock is not dependent on air pressure. Thus the analogy with champagne de-corking is onlyvalid if the champagne is in the same state as rock, i.e. frozen. In this state it does not emit gas when decorked, thus suggesting that gas release from a SOLID is not a function of surface air pressure.

I don't see what a liquid analogy demonstrates or suggests. 

You say that

The rate at which radon is transported to the (cave/mine) atmosphere is dependent on pressure, temperature and surface area. OK its carbon dioxide in champagne but the principle is the same.

but the principle is NOT the same because one is a liquid/air scenario and the other is a solid/air scenarioand there is no analogybetween them.

You also say that the rate is dependent on pressure, temperature and surface area. While I'd agree on the "area" point, I can't find any support for the influence of the other two factors at a solid/air boundary,so I'm sticking to my assertion that this is an unsupported assertion and bad science.

The only law that seems to come close is Grahams Law ( http://en.wikipedia.org/wiki/Graham's_law ) which descibes emission of gas through a small crack ( and that is not dependent on either temperature or pressure.)

 

[LarryFatcat]

I do not know of any researched links between Radon and the death of cavers.

Its a subject that I have often pondered as I have known two cavers both of whome spent long periods underground, died of lung cancer and didn't smoke.

Peak Cavern seem worried enough to have installed ventilation into the cave.

There was a fan in Ingleborough Cave some twenty years ago when I worked there. 

There was a large study in the eighties published in Cave Science.  I've got a copy somewhere.  Giants came out as being the worst offender.  Commercial cavers were aware and limited their visits to Giants.    The levels were not considered a danger to recreational cavers. 
Those living in granite areas like Aberdeen were more at risk in their own homes.

 

[Speleokitty]

Hi Andy

I'm quite familiar with Grahams Law. Thank you for reminding me of my school days.

It deals with the relative diffusion of gasses of differing molecular mass or in this case atomic mass under identical conditions. We  are considering the diffusion rate of one gas of known mass under differing conditions where speed of diffusion is driven by differences in absolute and/or partial pressure. In this case the rate of diffusion is driven by differences in absolute and partial pressure in the (mine/cave) atmosphere.

The solubility of radon in water is also important in the transport of radon. The solubility of radon is higher at higher absolute/partial pressure and reduces as absolute and/or partial pressure reduces or the temperature increases. The rate of diffusion also increases as surface area increases. This  is where the champagne analogy is so relevant.

Kitty

 

[Ouan]

AndyF
sedimentary rocks are not 'solid' they are all have a certain amount of porosity and thus contain gas, water or oil. These fluids are sometimes at very high pressure.  If the rocks also have permeability the fluids will move through the rocks.  Thus radon from a deep source can make its way to the surface. The atmospheric pressure will have an effect on the rate at which the radon diffuses to the surface.