Lower-floor apartments and units with concrete-slab construction or basement HVAC can have elevated radon. Multi-story upper floors typically have negligible levels. Test units in question.
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Apartment radon profiles correlate strongly with unit position. Garden-level and first-floor units in Cincinnati buildings frequently test above 4.0 pCi/L because they sit directly on the slab with minimal isolation from soil gas. Second-floor units typically test in the 1.0-2.0 pCi/L range. Third-floor and above almost universally test below 1.0 pCi/L unless the building has a basement HVAC system that recirculates radon-laden air into the supply ducts (uncommon but documented). Multifamily property owners are not required by Ohio law to test or mitigate, though some institutional owners (university housing, senior-living) do test as part of risk-management protocols. Tenants in older Cincinnati apartment stock (Mt. Adams, Clifton Heights, Northside) on lower levels should consider testing, particularly during heating season. Cincinnati apartment-stock context: garden-level units in Mt. Adams, Clifton Heights, Northside, and Walnut Hills walkup buildings frequently test elevated. The Cincinnati Metropolitan Housing Authority does not currently publish radon test results for its units. Tenants in low-income housing concerned about exposure can request the property manager test the unit; cost is low and many managers will accommodate.