EPA recommends "considering" mitigation between 2.0 and 4.0 pCi/L. Many Cincinnati homeowners weigh cost vs. health benefit; mitigation is common in this range when children or chronic-respiratory residents live in the home.
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The decision math at borderline readings depends on household composition and tenure. Risk reduction from mitigating at 3.0 pCi/L (down to about 0.5-1.0 pCi/L post-install) is meaningful but not as dramatic as mitigating at 8.0 pCi/L. Cost is the same ($1,200-$2,400). For a household with young children sleeping on a lower floor, ROI tilts strongly toward mitigation. For a single adult planning to sell within 3-5 years, the cost may not amortize before sale. EPA published risk tables in the Citizen's Guide to Radon showing approximate lifetime lung-cancer risk per pCi/L for smokers and non-smokers; those numbers can inform the decision. Real-estate transactions sometimes require mitigation at borderline levels if the buyer's lender or buyer's agent insists, even though EPA does not technically require it; that is a transaction-specific decision, not a regulatory one. Cincinnati household decision context: at 3.0 pCi/L combined annual reading, mitigation reduces lifetime non-smoker lung-cancer risk by roughly 50% over the EPA risk tables. For a household with children sleeping on a lower floor, that reduction is meaningful enough to justify the $1,200-$2,400 mitigation cost. For an empty-nest household planning to sell within 5 years, the cost may not amortize before sale; the documented post-mitigation report still adds resale value.