What is the primary reason why measurement reports must be retained for at least six years?

The primary reason measurement reports must be retained for at least six years is to account for potential long-term health impacts. Retaining radon measurement data allows for a comparison of exposure levels over time, which can be crucial in assessing the health risks associated with radon exposure. Given that radon is a known carcinogen and its effects may manifest years after exposure, having access to historical measurement reports enables public health officials and property owners to make informed decisions regarding remediation efforts and ongoing monitoring. This retention period aligns with health guidelines aimed at minimizing risks associated with radon exposure and ensuring public health safety.