Radon gas in buildings

We get a lot of people asking about Radon - there is an industry out there based on providing 'radon risk reports' and then offering to protect your home from radon. So how risky is radon? Is there really a problem? And what do you do, if your solicitor or someone associated with a house purchase suddenly starts to get upset about radon.

Radon is produced as a result of the breakdown of various rocks - usually granitic - and in particular from zircon.  Things get a bit more complex because zircon is often found in shales - we have it in our mine, but only really in the upper levels where there is a lot of shale - in the limestones it is not a problem. We monitor it using a Canary meter - which measure in Becs - (Bequerels/m3) and its almost impossible to get an instant reading - you need long term averages, although when I do surveys, I take it with me and bung it in the house - by end of day, I'll get an indicative reading as to whether its higher or lower than my all in average reading. The canary meters arent expensive - you can get them here: I always have one but never bother reporting unless the readings are higher than about 50, which they never have been, except cornwall - where all the rules go out of the door.

When we first entered the mine, we got readings off the scale - ie, more than 10,000.  We consulted the mines dept, and HM Chief Mines Inspector is a whizz on this stuff. Radon is basically a cloud of radon 'daughters' - ions that are released from the surrounding rock - and will be released more in times of low atmospheric pressure than at high pressure. The important thing here is ventilation. We installed a vent system, and the mines inspector showed me that running the vent system for only 1/2 hour a day cleared the radon below detectable limits. We test regularly but have never seen the stuff since we put the vents in - we only run about 2 hours a month, and there is no radon to speak of. This is in an area of very high potential - in shales over decomposing granite.

So.. from mines to houses..

A dangerously high level of Radon is variously defined as being in excess of 100, 150 or 300 depending on whether its UK government nimbies, WHO, or the EU - who are quite happy with 300. The thing is, that at these levels, you would need to be continuously exposed for 24 hours a day - and even then, there is only a very tenuous link with the main danger - lung cancer. If you go outside or work out of the home for 12 hours, that reduces the average to 50, and you're fine.

My house is sitting at about 21 Bq - the country average - this week its 27, and today its 13. 

How do you reduce it - simple - ventilation.  Which is what we tell everyone to do to old houses anyway.  With adequate ventilation, you will not, and cannot get, a build up of radon.

The entire radon scam is just that - its another excuse to build an industry based on hype and commercialism. I took the meter down to Cornwall last time I went, and as I came over Dartmoor the meter went up over the 100 range - that was in the car, driving over Dartmoor granite. In Camborne, it was around 120 just in the car park and higher in my motel room. So does that mean that anyone living in Cornwall will get lung cancer ?? No - and from what I can tell, it's no more prevalent in those areas than anywhere else. 

BRE are pretty useless for most things, but these 'solution sheets' underscore what I say - ie better ventilation is the key. https://www.bre.co.uk/page.jsp?id=3134

Their website states:

Radon solutions

There are essentially three generic solutions that can be applied to a building, either independently or in tandem, to reduce indoor radon levels.

  • Sump system Effective for all radon levels
  • Improved under floor ventilation  Natural under floor ventilation generally effective for radon levels up to 500 Bq m-3, mechanical ventilation effective for all radon levels.
  • Positive house ventilation  generally effective for radon levels up to 500 Bq m-3.

These can be supplemented with:

  • Improved house ventilation
  • Simple sealing

So - my advice would be to ignore the Radon hype, and stick to our normal recommendations anyway, of having good humidity controlled ventilation, which will cover both moisture AND radon. 

As the Meerkat says - Simples !


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