What does differential pressure in radon mitigation refer to?

Differential pressure in radon mitigation refers specifically to the pressure needed to overcome stack and mechanical effects. In the context of radon mitigation systems, maintaining an appropriate differential pressure is crucial because it helps to ensure that radon-laden air from beneath the structure is efficiently drawn into the mitigation system and expelled outside.

Stack effects are caused by temperature differences between indoor and outdoor air, which create pressure variations; mechanical effects arise from factors like fan systems. Together, these pressures influence the flow of air and the ability of the radon mitigation system to effectively reduce radon levels in the indoor environment.

Achieving the correct differential pressure is essential for optimizing radon removal, ensuring that the system operates effectively without negative impact on the building's overall indoor air quality. The other options do not accurately reflect the specific role of differential pressure in this context, as they either refer to the total pressure of radon gas, pressure exerted by outdoor air, or the force required for general ventilation, rather than the precise balancing act of pressures involved in effective radon mitigation.