Radon Mitigation

[Ted Bear]

I had to sell a house in part of the country where Radon levels are generally higher. The first 'test' came in high (predictable) and when I went to the hardware store for a replacement test, the guy said to me "oh, you're not falling for that old scam are you? Radon is a naturally occurring substance, especially in this part of the country. Open the windows, run the test for 24 hours and you will be fine."

Truth, that.

[Barking Spider]

To answer the original question without resorting to cheating or subverting the test....
we usually wait 48 hours to re-test after a mitigation system is installed.