If the annual average level of radon in a home is above 4.0 pCi/L, the EPA and MDH recommend that steps be taken to lower it. While it isn't possible to reduce radon to zero, the best approach is to lower the radon level as much as possible.he Environmental Protection Agency and MDH set the recommended action level for radon at 4.0 picocuries/liter(pCi/L). To apply the recommended action level correctly, the results should be based on the annual average level of radon measured in a home.