Case Study · Real Estate Transactions·Pittsburgh, PA · 2024

Pre-1980 Pittsburgh home with 12.4 pCi/L initial radon. Mitigation outcome

Squirrel Hill home, pre-1980 construction, initial 48-hour continuous radon monitor result of 12.4 pCi/L. Three times the EPA action threshold. Documents the mitigation system design, install, and post-mitigation clearance test result.

Initial12.4 pCi/L

Post-mitigation1.9 pCi/L

EPA action4.0 pCi/L

ZoneEPA Zone 1

Context

A buyer under contract to purchase a 1968-construction Squirrel Hill home with a partially-finished basement retained us for pre-closing radon testing. Allegheny County is EPA Radon Zone 1. Average indoor radon levels are higher than the national average, and pre-1980 construction typically lacks sub-slab depressurization or vapor barriers. The seller had provided a free Allegheny County Health Department charcoal-canister kit result of 4.8 pCi/L; the FHA lender required a continuous radon monitor (CRM) report for the closing file.

Methodology

EPA short-term protocol: closed-house conditions established 12 hours prior to monitor placement; continuous radon monitor (Sun Nuclear 1028) deployed in the basement living area at 36 inches off the floor and 8 feet from interior walls; 48-hour measurement period with hourly readings recorded. Instrument was calibrated by the manufacturer within the prior 90 days per PA DEP requirements.

Initial reading

Final 48-hour average: 12.4 pCi/L. Hourly readings ranged from 8.2 to 18.6 pCi/L, with elevated readings during overnight hours consistent with reduced ventilation. This significantly exceeded the EPA action threshold of 4.0 pCi/L and required mitigation before closing under the FHA lender's environmental requirements.

Mitigation design referral

Because we do not perform radon mitigation, we referred the buyer to two independent PA-DEP-certified mitigators for competitive bids. The selected contractor installed an active sub-slab depressurization (ASD) system: PVC pipe through the basement slab to outside-discharge above roof line, in-line radon fan (Radon-Away RP-265) sized for the home's footprint, manometer pressure gauge for visual monitoring. Install cost: $1,485.

Post-mitigation verification

We returned 4 weeks post-install for follow-up CRM testing under closed-house conditions. Final 48-hour average: 1.9 pCi/L. Below the EPA action threshold and below the 2.0 pCi/L EPA-recommended consideration threshold. The FHA lender accepted the post-mitigation report and the closing proceeded.

Outcome

Closing proceeded with $1,485 mitigation expense (allocated 50/50 buyer/seller per the contract amendment) + $185 post-mitigation re-test. Total environmental-testing-related closing delay: 18 business days from initial test to FHA approval of post-mitigation report.

— — Takeaway

Allegheny County radon levels can be significantly higher than the typical free-kit result suggests. Kits are passive carbon canisters subject to operator handling variance + multi-day-averaging variance. A 48-hour CRM with hourly readings reveals the actual exposure profile. Buyers should not skip CRM testing on Allegheny County pre-1980 properties even when the seller-supplied kit reads at or near 4.0 pCi/L.

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