True or False: Circulating fans should be operating in the area during testing.

The correct answer is that circulating fans should not be operating in the area during testing. The rationale behind this lies in the need to obtain accurate radon measurements that reflect the true levels of radon gas present in a space. When fans are in operation, they can alter the air flow and disturb the natural conditions of the environment, potentially leading to a decrease in the concentration of radon detected. This disruption can create an environment that does not accurately represent typical conditions, thus skewing the results. Ensuring that all ventilation equipment, including fans, is turned off during the testing process helps to achieve reliable and valid radon levels, which is crucial for assessing health risks and determining necessary mitigation measures.