What type of devices collect a time-weighted average and do not provide hourly readings?

Passive devices are designed to collect radon levels over a specific period, typically serving to gather data that reflects a time-weighted average, rather than providing continuous or hourly readings. These devices typically rely on the natural diffusion of radon gas into the detector material without any mechanical or electronic intervention.

Unlike active devices, which often require power and can provide real-time data and continuous monitoring with hourly readings, passive devices accumulate the radon over a set duration, such as 48 hours to several days, and then require laboratory analysis to determine the average concentration during that time frame.

Digital monitors and electronic sensors also focus on providing immediate results and typically operate continuously, presenting data in real-time, which contrasts sharply with the methodology of passive devices. Thus, when considering the question about devices that specifically compute a time-weighted average without hourly readings, passive devices are the appropriate answer.