Why must the first 4 hours of continuous monitoring data be disregarded?

The first four hours of continuous monitoring data must be disregarded primarily to ensure stable readings. During initial monitoring, the radon measurement equipment can experience fluctuations and the readings may not accurately reflect the true radon levels in the environment. This period often includes stabilization time during which the equipment adjusts to the conditions of the environment it is measuring, ensuring that the data collected later is consistent and reliable. Once the equipment has had time to acclimate and provide stable readings, the data collected afterward can give a more accurate representation of the radon levels, which is crucial for effective assessment and mitigation strategies.

The other choices, while related to the monitoring process, do not accurately reflect the primary reason for this practice. Calibration may occur but is not typically the reason for omitting the initial data. Compliance with regulatory requirements is important, but the specific focus here is on achieving stable readings as a key factor in obtaining valid results.