EPA radon action level 4

https://myradonbasementnews.unionquill.com/posts/understanding-radon-in-basement-a-st.-louis-homeowner-s-guide

The EPA radon action level is set at 4 picocuries per liter of air, prompting homeowners to take steps to reduce radon if tests show levels at or above this threshold. Radon is a radioactive gas from soil, and long-term exposure is a leading cause of lung cancer, second only to smoking. This guideline helps identify when mitigation, like installing a vent system, is advisable. It's a practical benchmark based on health risk data, not a perfect safety line. Lower levels still carry some risk, bu…