This is big topic these days and we have a great deal of expertise on this subject. The EPA recommends that any home be remediated if the radon level is reported as 4.0 pCi/L (pico Curries per liter of air). Well, how do they get reported? Radon detection should follow EPA guidelines which stipulate a procedure for placing the detectors, length of time to detect, number of detectors, and so on.Our company uses Air Chek brand radon detectors, which are a charcoal based detector (you can read about why we use Air Chek radon dectors in our procedure post). The EPA states that if charcoal detectors are used then there must be two detectors and they should be placed close to each other, then the results from each are averaged to a final number. What this is designed to do is reduce error from the individual detector. Now we have a possible problem.
What if one of the detectors is over 4.0, but the average is less than 4.0?
What if the stated error of the average can be added to give 4.0?
I have had several inspections where these two issues have arisen. One detector measured 4.1 and the other measured 3.7 - so the average is 3.9, which is under the EPA recommended action level of 4.0. On another inspection, the error was listed as plus or minus 0.2 pCi/L and the average was 3.8 pCi/L. What do you do in these instances?We hold very highly the importance of our inspections at a CLOSER look, inc, as they are for our customers’ protection. It is our belief that, especially when dealing with known health hazards, it is better to err on the side of safety than technicality. Therefore, we report radon results as shown by Air Chek laboratory with their errors. Then we recommend that properties be remediated for the presence of radon if any of the following three conditions are met:
1) The average radon measurement is 4.0 pCi/L or above2) One of the detectors measures 4.0 pCi/L or above3) The average reading is within the stated error of 4.0 pCi/L or above
- Condition 1 - we round up all averages if there is a hundredth place, so 3.95 would be rounded to 4.
- Condition 2 - We only use these figures if the two detectors are within a statistically acceptable range from each other. The laboratory determines this factor. If they are out of range from each other, the test is invalid and a new test must be performed.
- Condition 3 - The laboratory determines the error of each device and reports this error with the measurement. If the average is 3.8 pCi/L plus or minus 0.2 pCi/L, then measurement plus the error would be 4.0 pCi/L and we would recommend remediation.
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