According to the EPA, at what level does radon become a health concern requiring mitigation?

Radon becomes a significant health concern requiring mitigation at a level of 4.0 picocuries per liter of air as established by the Environmental Protection Agency (EPA). This threshold is based on extensive research demonstrating that continuous exposure to radon at or above this level increases the risk of lung cancer, particularly for smokers and people with prolonged exposure.

The EPA suggests that if radon concentrations are at or above this level, homeowners should take steps to reduce the radon levels in their homes. While lower levels of radon may also pose some risk, 4.0 picocuries per liter is the level at which action is strongly advised to protect health. Addressing radon levels at or above this guideline can help mitigate potential health risks associated with long-term exposure.