How should the ventilation with outdoor air be set during a radon test?

During a radon test, it is important to set the ventilation with outdoor air to the lowest possible conditions. This approach helps ensure that the radon levels in the indoor environment are not artificially reduced due to increased air exchange. High ventilation can dilute the concentration of radon, leading to potentially misleading results about the radon levels present in a building. By minimizing outdoor air ventilation, the test can more accurately reflect the actual radon levels, allowing for a comprehensive assessment of whether radon mitigation actions are necessary.

Normal operational levels of ventilation might not provide reliable readings either, as they could also impact the radon concentration. Likewise, setting ventilation to the highest possible setting would further dilute the radon levels, creating an inaccurate representation of the indoor radon exposure. While the option stating that no ventilation is needed might seem appealing, it does not allow for any assessment of typical environmental conditions that could occur in an occupied building. Therefore, minimizing ventilation is critical for accurate radon measurement during testing.