Given the results of our last blog. This casts an interesting phenomenon related to radon which is the effect of when you carry out the test. The laboratory analysis gave a whole house property average and called it “seasonally corrected”. Whilst no doubt there is a complex formula behind this calculation, we wanted to see the differences and when it would be best to test.
Clearly in our previous blogs ventilation of a property seems to be key. Especially relating to subfloor ventilation and the use of positive input ventilation. The lifestyle of the occupant also appears to be important. Would you leave windows and doors open during the test period. If the weather is warm then windows would be open overnight for example.
The seasonable factor will also have a major impact on results. When we tested during the summer. The results were much lower than when we tested in the winter. So if you are commissioning a test, then you may wish to consider this. Our results showed a much larger change than the “seasonally adjusted” figures showed. So if you are purchasing during the summer the readings will naturally be lower than the benchmark 200bq/m3.
Then there are the much more complex factors related to the geology. Radon gas has a half life of 3.8 days and is water soluble. Given that half of UK radiation exposure is due to radon then the groundwater issue we mentioned in our first blog, have a bearing although a limited one. During the winter when the groundwater tables are higher they also have an effect on the levels of radon being released by the ground. The readings will be higher in winter.
Given this it would be sensible to test for a full 12 month. Rather than the usual three month or 6 month tests that are carried out. This is where electronic monitoring becomes a much cheaper and more accurate alternative. As a full 12 month sample of results would clearly give the correct reading rather than attempting to seasonally correct an average from a specific part of the year.