Back in 2008, since the test kit was free from our county’s office of environmental services, we decided to check our very tightly-built and ground-contacted home for radon levels. We used short-term charcoal test kits in both the pantry, with its water pump pit that reached down below the concrete floor slab, and the bedroom. We figured that radon was most likely to accumulate in the pump pit, since radon is a gas that percolates up through rock fissures and soil from very deep, underground uranium deposits. The gas could enter the house from any point either below, or penetrating, the floor slab.
The initial results from a test in the pantry, above the pump pit, done in January when windows were never open, showed a moderately high level (according to the testing agency) of 18,5 pico-Curies per liter of air (18.5 pCi/L). The “actionable level” is supposedly 4 pCi/L and above, although if you read about the way these standards came about, this level is no doubt meaningless. A follow-up test in May showed levels of 14.8 pCi/L in the pump pit and 8.9 pCi/L in the bedroom.
Based on this data, and before we had read either about how meaningless the standard was or about how certain levels of radioactivity could actually promote immune response in humans, we did some work to seal up air leaks in the pump pit and planned for a retest at some point. Another short-term test was done in the bedroom in February of 2012 but the result was higher than the earlier test, at 12.9 pCi/L. Rather confusing, but we read about how inaccurate the short term test results could be and opted for a 7 month, long-term test the following year. The result then was 6.1 pCi/L; still higher than the standard but a significant decrease.
After doing still more reading about Geiger counters, and about how they could possibly be used to do a real-time test of alpha and beta particle counts (the decay emissions of radon and its progeny, the “short-lived radon daughters”), we decided that we needed a unit sensitive enough to detect the easily-blocked alpha particles and accumulate particle count data over a period of time. A friend who does home health work (a “bau-biologist”) lent us his digital meter and we took 3-hour-long samples all over the house. The highest reading, of 30.2 counts per minute (CPM), occurred in the pump pit, as expected. Out of 20 readings taken, the lowest readings were outdoors (17.13 to 17.58 CPM) and in the bedroom (14.98 CPM). So the indoor level of a closed house in all but the pump pit actually tested lower than the outdoors!
Comparing “apples to apples” required additional reading to come up with the equivalence between the radon measurements and the particle counts. The pCi/L figure is hard to compare, but it turns out that our 15 CPM average level was equivalent to a very low reading of .0125 milli-rem. The 1-in-1000 chance of increased cancer risk occurs after roughly 432 days at 100 CPM, nearly 7 times our level. In addition, the dose response of humans to radiation is far from linear, and the standards for radon were based on the 5-year exposure of underground miners at up to 2,720,000 pCi/L-hours. This was mathematically extrapolated for a 70-year, 18 hour/day residential exposure of MUCH lower levels. The bottom line is that we had little to worry about after all, not that we were terribly worried from the beginning.
Just goes to show that a just a little data can be dangerous in the hands of bureaucrats, and even more so as multiple agencies get involved in interpreting it. Numerous scientific studies stubbornly refuse to back the current radon standards, but woe be to any radon mitigation “expert” who alerts the public to this “emperor’s new clothes” situation, lest they lose their EPA accreditation.