What significant air pressure change component may increase indoor radon entry?

The significant air pressure change component that may increase indoor radon entry is leaky return ducts. When a building has leaky return ducts, it can create a negative pressure situation within the home. This negative pressure can cause air to be drawn in from the foundation and soil below, increasing the risk of radon gas entering the indoor environment. Since radon is a naturally occurring radioactive gas that emanates from the decay of uranium in soil and rock, any system that alters the pressure dynamics within a building can impact the level of radon that infiltrates from the ground.

In contrast, sealed windows are designed to keep outdoor air from entering, which may help to decrease indoor radon levels. Evaporative coolers typically introduce moisture to the air without significantly affecting pressure dynamics related to radon entry. Ventilation fans are designed to extract indoor air, which can also potentially reduce radon levels but do not inherently create the negative pressure situation that would cause increased radon ingress. Therefore, leaky return ducts are particularly critical in understanding radon mitigation efforts.