When should follow-up radon tests be conducted?

Follow-up radon tests should be conducted to confirm that the high levels of radon detected in a previous test warrant mitigation. This is important because determining the need for a mitigation system relies on accurate and up-to-date radon measurements. High radon levels can pose serious health risks, so it is essential to verify that initial findings are correct and that appropriate action is necessary.

Conducting follow-up tests ensures that mitigation systems are deployed based on reliable data. This step is crucial for homeowners and potential buyers to understand the radon levels present in a home before decisions about mitigation or further action are made. Regular validation of elevated radon levels supports public health efforts and promotes safety in residential environments.

The other options suggest testing at intervals or occasions that do not necessarily reflect the current need for mitigation. Annual tests may not be needed if levels were previously verified as safe. Testing only during property sales does not account for the ongoing risk that a home could present at any time. Conducting tests solely after a system repair is also too limited, as regular follow-up is essential to ensure mitigation effectiveness over time.