What is a notable feature of the Continuous Radon Measurement Devices?

Continuous Radon Measurement Devices are designed to provide real-time and ongoing measurements of radon levels over extended time frames. The capability to measure radon over a duration that can range from two days to several months allows for a more accurate assessment of radon exposure, which is essential for understanding potential health risks. This extended measurement period is critical, as radon levels can fluctuate due to various factors, including weather conditions and building ventilation.

The other options do not reflect the primary attributes of these devices. For example, while continuous devices may need calibration, there is not an absolute requirement that they require none at all. Operating at high temperatures is not characteristic of radon measurement technologies, which typically function optimally at room temperature. Additionally, these devices are not limited to outdoor environments; they are designed for use indoors, where radon accumulation is a common concern due to building structures. Thus, the strength of Continuous Radon Measurement Devices lies in their ability to continuously track radon levels over extended periods, making option C the most accurate representation of their notable features.