True or False: Exterior doors should be kept closed on all levels of the building during closed-building conditions.

Keeping exterior doors closed on all levels of the building during closed-building conditions is essential for ensuring accurate radon measurement. Closed-building conditions refer to the practice of maintaining the building in a consistent state, minimizing any influence from outside air. When exterior doors are closed, it helps stabilize the indoor environment, preventing drafts and fluctuations in temperature or air pressure that could affect radon levels.

Open doors can allow outside air, which may have different radon concentrations, to enter the building, leading to misleading test results. Maintaining closed conditions helps ensure that the radon measurement reflects the levels present in the building itself, rather than being influenced by external factors. This practice is crucial for obtaining reliable data for radon testing, which can ultimately inform decisions about mitigation and health risks associated with radon exposure.