If a post-mitigation test shows levels below 4, when should a retest occur?

In mitigation practices, after successfully reducing radon levels to below the action level of 4 pCi/L, it is critical to ensure that the mitigation system remains effective over time. The recommended approach for retesting in this scenario is to conduct a follow-up test after 2 years. This interval allows homeowners and professionals to confirm that radon levels remain low and the mitigation system continues to function properly. Testing at this point serves as a verification measure to ensure that future fluctuations or potential issues in the mitigation system do not lead to elevated exposure levels.

Waiting too long, such as 5 years, may delay the detection of a significant issue, and retesting immediately may not provide enough time to assess the system's ongoing effectiveness in maintaining low radon levels. Regular retesting every 2 years is a proactive strategy in radon management to ensure that health risks associated with radon exposure remain minimized over time.