ResourcesGlossary: testing
Post-mitigation test
Short answer
A post-mitigation test is a radon test taken after a mitigation system is installed, to confirm the system has brought the level down.
What post-mitigation test means
EPA sets the window: a post-mitigation radon test should be done within 30 days of system installation, but no sooner than 24 hours after the system is in operation with the fan on, if it has one.
EPA also says who should run it. Having an independent tester perform the test, or conducting the measurement yourself, will eliminate any potential conflict of interest.
The testing window, in hours and days
Each row converts one of EPA's times between hours and days, counting from the moment the system is switched on.
| Point in time | Hours after switch-on | Day |
|---|---|---|
| Earliest start of the test | 24 | 1 |
| A 48-hour test started then ends | 72 | 3 |
| EPA's deadline for the test | 720 | 30 |
| The next routine retest, two years on | 17,520 | 730 |
What it means for your home
Compare the new number with the
One test is not the end of it. EPA says it is a good idea to retest your home at least every two years to be sure radon levels remain low.
Where to go next
- Which radon test to use. Pick the test to run once the system has been on for a day.
- How long after radon mitigation you can retest. The 24-hour wait, the 30-day window and the retest after that.