What is the criterion for averaging test results to determine if mitigation is necessary?

The criterion for averaging test results to determine if mitigation is necessary is based on the relationship between the higher and lower radon test results. When the higher result is less than twice the lower result, it indicates that there is not a significant disparity between the two measurements. This allows for the possibility of averaging the results to provide a more reliable estimate of the indoor radon levels.

In radon measurement, significant differences in test results may suggest variability in radon concentration due to factors such as time of day, weather changes, or other factors affecting indoor air quality. By having the higher result be less than twice the lower result, it implies that the radon concentration is relatively stable, thus making averaging a valid approach to determine the overall risk and whether mitigation is warranted.

Using this criterion helps to ensure that the assessment of radon levels is accurate, and subsequently, the decision regarding mitigation reflects a true representation of the indoor radon exposure risk.