More on Radon

Grant Feasby | Dec 20, 2017

This was a good discussion of the domestic radon issues but some issues might need some clarification. Radon is all around us, in and outside, resulting in about half of the radiation dose we all receive (medical x-rays excluded). The ambient outside concentration ranges from very little to over 50 becquerels/cubic metre, depending on location and weather. Average is somewhere between 15 and 25. So “no safe level of exposure” may be somewhat misleading; casual exposure to sunlight might be a good analogy. The risk of low level exposure, while very small, is unavoidable.

Radon is a radioactive decay product of radium and is the 7th in the element in the 14 uranium decay “chain”. Take away the uranium from soil and rocks, which nature often does, you still get radon. The health risk is not really from radon itself, but what it decays to – radioactive metallic elements – polonium, bismuth and lead – so-called “radon daughters”.

Smoking multiplies the radon-sourced cancer risk by a significant factor – from 5 to 40 times. This is partly due to the sticking of the daughters to the smoke products.

Radon is quite soluble in cold water. Well water can be a significant carrier. Warm aerated well water releases the radon (lake or river water has less radon).

Some thoughts: Testing for radon at high occupancy indoor locations should be done over extended times, or repeatedly to represent different cold/hot, wet/dry conditions. Ventilation is a good fix for high levels including during showering with well water. Beware of off-the-shelf test devices that may have had exposures in making, transit or storage. Smoking (tobacco and other) should be rigorously avoided. Avoid dust inhalation too.

Some technical jargon: one becquerel is one radioactive disintegration per second. An adult person contains about 7,000 becquerels from several radioactive elements – potassium, uranium, radium, carbon etc. There are about 85 radioactive elements (isotopes) naturally occurring in our environment, e.g. carbon-14 which is made in our atmosphere by cosmic radiation.