Final answer:
For a home with an initial radon test result of 12 pCi/L, it is recommended to confirm the results with a follow-up test and mitigate the high radon levels by hiring a professional to install a radon reduction system.
Step-by-step explanation:
Recommended Action for High Radon Levels
If an initial radon test in a home not involved in a real estate transaction reveals a radon level of 12 pCi/L, it is well above the EPA's action level of 4 pCi/L. Therefore, it is highly advisable to take action to reduce radon levels. Since radon is the number one cause of lung cancer in nonsmokers and very hazardous for smokers as well, mitigating radon exposure is crucial. The recommended steps include confirming the test results with a follow-up test and hiring a qualified radon mitigation professional to install a radon reduction system.