Post-mitigation radon test in York, PA

When should the post-mitigation test be taken?

The post-mitigation test is taken once the new fan has run for at least 24 hours and within 30 days, the window the EPA gives for a new system. A test earlier than 24 hours measures a house the system has not yet changed, and a test after 30 days leaves a faulty system running longer than necessary.

A short term test of at least 48 hours is the usual method. The result you hold afterwards is the number to keep with the house papers, together with the installer's certification number and the date.

What post-mitigation result counts as a pass?

A post-mitigation result below 4 pCi/L passes the EPA action level, and the EPA also says to consider further action for results between 2 and 4. The York County record shows where installed systems land.

The average post-mitigation reading is 1.70 pCi/L against 21.12 before, a fall of 92.0 percent. The system does what it is built for in nearly every house, and the test exists to find the exceptions.

Do houses that start very high finish clear?

Houses that start very high finish clear less often, though still most of the time. Among jobs starting below 8 pCi/L, 97.4 percent finished below 4. Starting between 8 and 20 the share was 98.3 percent, between 20 and 50 it was 97.0 percent, and from 50 upward it was 90.9 percent.

The few dozen houses that began at 50 or higher are the ones most likely to need a second suction point or a stronger fan. If your pre-mitigation result was very high, ask the installer to explain in advance how they will handle a retest at 4 or more. The shares come from the same 2024 to 2026 cohort, grouped by the reading before the fan.

What happens if the post-mitigation test stays at 4 or higher?

A post-mitigation result at 4 pCi/L or higher means the system needs adjustment before the job is finished. The usual changes are a second suction point, sealing a gap the first suction point does not reach, or a stronger fan.

Ask in writing, before work starts, who pays for that adjustment and how many retests the price includes. A firm that states a written price for the whole job is easier to hold to this than one that quotes only the installation. The profiles under York County radon contractors show which firms say what about their process.

Should the post-mitigation test be independent?

An independent post-mitigation test is recommended by the EPA, because a measurement from someone who did not install the system carries no stake in the answer. Pennsylvania certifies radon testers, and the number of whoever places the device can be checked.

The page on PA DEP radon certification shows how to check a number, and firms that hold both kinds are marked on their profiles. Whoever tests, keep the report.

How often should a mitigated house be retested?

A mitigated house should be retested at least every two years, following EPA advice, and after any change to the house such as a new foundation crack repair or a replaced fan. A fan that has stopped is the most common reason a good result drifts back up, and the signs are on the page about radon fan replacement.

The U-tube manometer on the pipe gives a daily check between tests. Uneven liquid means the fan is pulling, and level liquid means it has stopped.

Common questions about the post-mitigation test