Which of the following conditions is NOT a reason for mandatory retesting for radon levels?

The rationale for identifying the condition of a homeowner deciding to retest as not a mandatory reason for retesting stems from the fact that retesting is typically governed by specific environmental and structural changes rather than individual choice.

Mandatory retesting is generally prescribed in situations directly affecting radon levels, such as significant openings to soil that may allow greater radon entry, extensive weatherization that could alter airflow patterns and indoor radon concentration, and specific natural or human-induced activities like earthquakes or nearby construction that might disturb the geological environment or the home itself. These conditions could significantly influence radon levels, necessitating a retest to ensure safety.

Conversely, a homeowner's desire to retest, while prudent and beneficial for monitoring radon levels over time, does not fall under regulatory requirements. It reflects a proactive decision by the homeowner rather than a necessity dictated by changes in the building or environmental conditions. Thus, the correct choice highlights that personal initiative in testing does not equate to mandatory retesting as outlined by radon regulations.