Radon Question

I have a question that I didn’t see addressed in the epa protocol (unless I overlooked it) & am having trouble finding an answer to it. When testing on a house that has been vacant for sometime, 6 months to a year or so, do you need to open the windows & air the place out prior to starting the test (& if so how long?) I closed them for min 12 hours prior to aired out test. I ran two tests, I tested with it w/out airing out & it was 18.8 Pcl . I aired it out & it still showed 9.8 Pcl . . This is the first time I 've ran across this of a house being vacant for a year. Please helpful replies only. We are here to help each other.
Thanx in advance,

No, you do NOT “air out” a home prior to the test.

You do however, run the HVAC in normal operating mode during the 12 hours prior to and during the test, along with the closed house conditions.

Since it’s summertime, I would probably set the AC on 76 or 78 for the period of the test. It doesn’t have to be “cold” (or “hot” in the winter), just in a “normal” level.

The half life of radon is approximately 4 days. It doesn’t matter if the house was closed up for a week or a year, or even 10 years. Test under closed house conditions that have been maintained for 12 hours before the start of the test which is following the EPA guidelines. Don’t get creative and try to alter testing methodology because you got back higher than expected results. Radon levels can and will change drasticlly on an hourly basis. Weather conditions will effect the results. Test under optimum conditions as outlined by the EPA. If test levels are high, either recommend mitigation or a long term test be performed which is often not feasible in real estate transactions.

thanx for the replies, much appreciated