If the Action Level is 4.0 pCi/L or greater, what action should be taken?

When radon levels are measured at 4.0 pCi/L or higher, it indicates a significant health risk due to potential long-term exposure to radon gas, which is a known carcinogen linked to lung cancer. The recommended action, in this case, is to fix the home by implementing radon mitigation strategies. These strategies may include installing ventilation systems, sealing cracks in floors and walls, and improving air quality within the property to reduce the radon levels.

Taking action at this level is crucial for the safety and health of the occupants. While monitoring the area or conducting further testing could provide more data, the immediate priority is to ensure the living environment is safe by addressing the elevated radon levels. Notifying authorities may be relevant in certain contexts, but the foremost objective remains the mitigation of radon exposure for those who live in the space.