Which of the following is NOT a type of passive testing device?

The continuous radon monitor is not classified as a passive testing device because it requires an active power source for its operation. Unlike passive devices, which collect radon over time without the need for electricity, a continuous radon monitor continuously measures radon levels and records the data in real-time. This means that it actively processes information and often provides immediate feedback, making it distinct from the other listed options.

In contrast, passive testing devices such as charcoal adsorption devices, alpha track detectors, and electret ion chambers do not require external power and rely on chemical or physical processes to capture radon gas over a specified period. These devices are placed in a location to accumulate radon and must be sent to a laboratory for analysis after the exposure duration, making them passive in nature. Understanding the distinctions between active and passive devices is crucial for effective radon mitigation and testing strategies.