What must be done with whole house fans during a radon test?

During a radon test, whole house fans must be turned off. This is crucial because these fans can significantly affect the indoor air pressure dynamics, potentially influencing radon levels. Radon is a naturally occurring radioactive gas that can seep into homes from the ground, and its concentration can be particularly affected by changes in airflow.

If the fans are left on, they may create negative pressure that pulls radon gas into the home from the soil or other sources, leading to inaccurate measurement of radon levels. To obtain a true representation of the radon concentration in the home, it is essential to have the environmental conditions as stable and controlled as possible during the testing process. Thus, turning off whole house fans eliminates one variable that could alter radon measurement outcomes, ensuring that the test reflects the home's ambient radon levels accurately.