I recently had a mitigation system installed.
It's your typical system where a fan sucks the air from under the basement floor.
I did the short term (six day) test.
Results from 'independent tester' are:
Before .... 9.6
After ....... 0.7
I have two digital gages (sitting side-by-side),
for the last three weeks, my readings are below 1.0
After 30 days of getting daily readings, I may turn the fan OFF and see how long it takes for the reading to increase.
The installer told me if I turn the fan OFF, the readings may not go as high as they were originally.
The reason being - there is now a pvc vent-pipe going from under the floor to outside.
Depending on the pressure under the floor, some of the radon may vent itself (with the fan OFF).