If a test result is less than 4 pCi/L, what should be done next?

The EPA recommends that to improve indoor air quality, people should consider installing a mitigation system to reduce radon levels below 2.0. While 4.0 is the number that triggers seller action (usually), the lower the radon, the less cumulative impact on health.

Because radon levels can change over time, the MN Department of Health recommends retesting every 2-5 years, especially if use patterns change or perhaps a lower level of the home becomes occupied or used more frequently. Renovations, changes in ventilation, earthquakes, settling of the ground beneath the home, and other changes may cause indoor radon levels to change over time.