EPA recommends: If you are buying or selling a home, have it tested for radon; for a new home, ask if radon-resistant construction features were used and if the home has been tested; fix the home if the radon level is 4 picocuries per liter (pCi/L) or higher; radon levels less than 4 pCi/L still pose a risk and, in many cases, may be reduced; and take steps to prevent device interference when conducting a radon test. This Guide answers important questions about radon and lung cancer risk. It also answers questions about testing and fixing for anyone buying or selling a home.