Why is it important to leave an active depressurization system fan on?

The importance of leaving an active depressurization system fan on is primarily related to ensuring the effective mitigation of radon gas within a building. An active depressurization system works by creating a negative pressure beneath the foundation, which prevents radon from entering the living space.

Keeping the fan running is crucial for maintaining this negative pressure and ensuring that radon levels are reduced consistently over time. If the fan were to be turned off, the pressure could equalize, allowing radon to seep back into the building, thus compromising the safety and health of the occupants.

While factors such as preventing rusting, air circulation, and energy efficiency are considerations in the maintenance of the fan and the overall system, they do not directly address the critical function of radon mitigation that the fan serves when it is operational.