What is the Action Level for radon exposures recommended in the United States?

The Action Level for radon exposures recommended in the United States is established at 4 picocuries per liter (pCi/L). This threshold reflects a level at which the U.S. Environmental Protection Agency (EPA) advises that action should be taken to reduce radon levels in homes and other buildings. The 4 pCi/L benchmark is based on evidence linking prolonged exposure to higher radon levels with an increased risk of lung cancer. When testing reveals radon levels at or above this level, it is recommended that homeowners take steps to mitigate radon in order to lower exposure and reduce health risks. Using this Action Level as a guideline helps individuals make informed decisions about radon testing and mitigation strategies in their residences and workplaces.