I just completed my first radon test that came back above the EPA limit of 4.0 pCi/L in someone’s home. So the question becomes, how far above the EPA limit of 4.0 pCi/L do you have to be to decide to mitigate? For your consideration, the EPA says that the average indoor concentration is 1.3 pCi/L. This national average is what the EPA uses to estimate 21,000 cases of lung cancer each year. As there is no “safe” level of radon, the EPA recommends that home owners consider a radon mitigation system for levels between 2 and 4 pCi/L.
To help better understand the results, here is a publication from the EPA called the “A Citizens Guide to Radon”.