What is the radon action level set by the EPA?

The radon action level set by the Environmental Protection Agency (EPA) is established at 4 picocuries per liter of air (pCi/L). This level is significant because it serves as the threshold at which the EPA recommends taking remedial actions to reduce radon exposure in homes and buildings.

Radon is a colorless, odorless gas that can accumulate indoors and poses health risks, particularly lung cancer, due to prolonged exposure to elevated levels. The decision to set the action level at 4 pCi/L is based on extensive scientific research linking radon levels to health risks, and the understanding that at this level and above, mitigation measures, such as ventilation improvements or radon removal systems, are warranted to protect occupants.

The other radon levels listed in the options are not designated by the EPA as action levels for radon mitigation, thus reinforcing the significance of the 4 pCi/L threshold for public health interventions.