Saturday, April 2, 2011

Radon Mitigation System Testing

About a month ago I posted about installing a radon mitigation system in our home. Our active sub-slab depressurization system started running February 5, but we didn't start measuring the radon level in the house until about March 9 when we left on vacation. At that time we set our new SafetySiren Pro Series 3 Radon Gas Detector on a table in the basement, where it monitored and averaged the radon level over the ten days we were gone. Because the unit requires about 48 hours of sampling before it displays the radon concentration, we don't know what the level was when the testing began. When we returned home, we were pleased to discover the radon concentration in the basement averaged 1.3 pCi/L while we were gone.

I next moved the tester to the other side of the basement, and recorded the 1.1 pCi/L average (shown above) over a three-day test. Those two tests were enough to convince me that the mitigation system was adequate to keep our home below our 4 pCi/L goal. Armed with this handy device, gathering data was so easy I felt compelled to measure more areas of the house. Upstairs, in our living room, the tester surprised me by reporting a concentration of 1.8 pCi/L after two days, which was higher than any of our readings in the basement. I let the tester continue to run for several more days, over which time the tester found the radon concentration continually dropping such that the average dropped to 1.3 pCi/L before I reset the tester and moved it into our bedroom. A reading of 1.1 pCi/L after two days satisfied my curiosity for that room.

Why was the radon concentration higher upstairs than in the basement? Since the house was closed up quite a bit between the time the system started operating, and the upstairs testing commenced, the sub-slab system may have removed more radon from the basement than was removed by the natural ventilation of the house upstairs. We had never tested the upstairs prior to installing the mitigation system, but one would expect the radon concentration there to be lower than the level in the basement without active mitigation.

We purchased our tester from Radon at Tahoe through, as they were one of many stores on the internet selling the item for $129.95, including free shipping. Now that I'm confident we've got our radon problem licked, I'm willing to let my local readers borrow this tool to check the radon levels in their homes. Let me know in the comments section or by email if you're interested.

Thanks for visiting!

Related posts:
Radon Mitigation System Installation
Radon Mitigation System Cost Breakdown


  1. Thank you for your post. We are currently deciding on purchasing a home with a radon mitigation.

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