What is the warning limit RPD for radon measurements with an average of 2 devices above 4 pCi/L?

The correct answer for the warning limit RPD (Relative Percent Difference) for radon measurements when the average of two devices is above 4 pCi/L is indeed 28%. This percentage is important as it reflects the acceptable range of variability between the measurements taken from the two devices used to assess radon levels.

When conducting radon measurements, the RPD provides a means to assess the reliability and consistency of the readings. Specifically, the 28% limit indicates that if the difference between the two measurements is greater than this percentage, it may trigger a warning to the technician that the readings are not consistent enough to be considered reliable. This helps ensure that any remediation efforts or risk assessments conducted based on these measurements are based on accurate and trustworthy data.

In the context of radon measurement practices, adhering to established RPD limits enhances the quality of data and helps maintain safety and health standards for environments where radon exposure is a concern.