In radon testing, why does bias have a larger impact at lower concentrations?

The impact of bias on radon testing is particularly pronounced at lower concentrations because measurement precision decreases as radon levels diminish. At lower concentrations, the statistical variations are more significant, leading to less reliable results. This means that even small biases in the measurement process can lead to larger relative errors compared to measurements taken at higher radon levels.

In essence, when measuring lower concentrations of radon, the instruments may not be as sensitive to those subtle changes, resulting in heightened uncertainty around the true value. Consequently, any inaccuracies or biases in the measurement process can disproportionately affect the interpretation of the data, potentially leading to incorrect assessments of radon exposure risk.

Other aspects, such as background noise being less significant or lower concentrations being easier to detect, do not address the core issue of precision and reliability in measurements of low radon levels. Additionally, while testing devices might vary in effectiveness, it's the precision of the measurement process at lower concentrations that primarily influences the reported results.