Which device is the only time-integrating device that requires no lab analysis?

The Electret Ion Chamber is identified as the only time-integrating device that requires no lab analysis because it functions based on the accumulation of ionization events over a specific period. The design of the Electret Ion Chamber allows it to integrate radon levels continuously without the need for collecting samples that must be sent to a laboratory for analysis.

In contrast, other devices listed, such as charcoal liquid scintillation devices and passive collectors, require laboratory analysis to accurately quantify the radon levels collected during the measurement period. These methods involve sample collection techniques, wherein the samples must be processed to provide a readable output, making them less immediate than the direct results from an Electret Ion Chamber.

Therefore, the Electret Ion Chamber is unique in its capacity to measure and report radon levels directly without additional lab intervention, thereby providing a time-integrated measurement that is efficient and straightforward for radon assessment purposes.