What is the recommended maximum radon exposure in a home?

• A. 4.0 pCi/L
• B. 2.0 pCi/L
• C. 8.0 pCi/L
• D. 10 pCi/L

Answer: (A)

Radon exposure in a home is about how much radon gas is present in the indoor air, measured in picocuries per liter (pCi/L). Because long-term exposure increases the risk of lung cancer, public health guidance sets a practical action level to decide when to mitigate. The widely accepted maximum to aim for is four picocuries per liter. If testing shows four pCi/L or higher, steps to reduce radon should be taken, such as installing a radon mitigation system, sealing entry points, or improving ventilation, to bring levels down toward or below that threshold. Values around two pCi/L are lower than the action level and are not the standard maximum used for decision-making, while much higher levels like eight or ten pCi/L indicate substantially greater risk and are well above the recommended target.