The EPA recommends home owners mitigate with radon levels of 4 pCi/L and above, and the EPA recommends home owners mitigate ”consider” mitigation at levels 2-4. Often you will see people post radon results in the 10+ or even 50+ range, which may lead you to think 4 pCi/L is not too bad, but in fact exposure to that level is the equivalent of 8 cigarettes a day or 200 chest X-rays/year.