|
|
|
radon
|
radon
Radon is a naturally occuring gas that occurs everywhere, and usually at levels that are harmless. It is invisible and has no smell. In some parts of the country (and the rest of the world!) there are higher levels of radon, and this only becomes a problem when the gas becomes trapped inside an enclosed building, e.g. a house or workplace, and the amounts rise to more dangerous levels.
The geology of the Westcountry results in more radon, and most buildings will have acceptable levels, but it is worth doing a test. The problem with radon is an increased risk of lung cancer - although it is worth remembering that only 9% of lung cancers are attributed to radon, the risk is greatly increased if you are already a smoker, and you still have to balance this statistic against the other health risks of say living in a city/high pollution area etc.
The average household will have a radon reading of 20 becquerels per cubic meter and the health protection agency have set the action level at 200 - ie if your test comes back at or above this level, it is best to take some action to reduce the levels.
We did a test and got a reading just over the 200 level and so decided to do something about it. Most of our neighbours have opted not to test. We got in two 'experts', from a list provided by our council. One was extremely unhelpful and told us, whilst clutching his roll up that he wouldn't bother, smoking would probably kill him anyway!, the other was much more useful, but still the price was prohibative. So, as with most things around here, we decided to do it ourselves, as the mechanics are fairly simple.
Basically, the reason radon levels can be increased in buildings is due the the lower air pressure naturally caused by the structure and the radon effectively gets drawn in, from the ground underneath. A device needs to be installed to draw the gas away. In Buildings with suspended floors, ventilation can be enough, but if, like us, you have solid floors then the solution is a sump.
We got a lot of our information from HPA and vent-axia .
After
a lot of surveying, we established the best place for the sump would
be in the under stairs cupboard. 
This
is because it is one of the lowel level floors ( the whole house is
on a slant!) and fairly central, and a pathway up to the attic could
be established with the minimum inconvenience.
We dug through
the concrete floor, which turned out to be fairly thin, then had to
remove some cobbles, then were down to the packed mud our whole house
appears to be built on. We dug a pit that was about 2.5 ft deep, then
put the pipework, which is standard waste soil pipe, in and loosely
stacked stones leaving as many air gaps as possible. Then the top was
sealed about a 3" layer of concrete. The pipe goes up under the
stairs into the cupboard above, then on into the roof and out under
the eaves. We are hoping that that natural venturi effect will cause
enough vacuum to draw out the radon in the sump, and in turn radon rising
into our home will be sucked into the sump. If the venturi effect is
not enough, then we will install a pump from vent-axia. The levels are
sufficiently close to safe that we hope not to have to use the pump
which will create noise and use electricity, but we are only at stage
one. Next we re-test and see if we have made a change.
links: