What type of information do passive devices provide regarding radon levels?

Passive devices for radon measurement typically provide a single time-weighted average concentration of radon over a specific duration, often ranging from days to months. This is important for understanding exposure levels over time, as radon concentration can fluctuate based on various factors such as weather and building occupancy. Unlike active devices, which continuously monitor and provide real-time data, passive devices do not offer immediate feedback; instead, they yield a cumulative measurement that represents an average exposure over the entire sampling period. This type of data is particularly useful for long-term assessments of radon levels in a building and for guiding mitigation efforts when necessary.