In January 2024 a homeowner in Bethel Park, south of Pittsburgh, called about a radon test result of 7.2 pCi/L from his home inspection. His real estate agent had said “it’s just a little over the limit, easy fix.” The EPA action level is 4 pCi/L. At 7.2 pCi/L, the agency’s own risk table shows a significantly elevated lifetime lung cancer risk. The phrase “easy fix” is accurate mechanically — mitigation is well-established — but the dismissal of 7.2 pCi/L as minor is not supported by the risk data.
What radon is and where it comes from
Radon forms from the decay of uranium in soil and rock and enters homes through foundation cracks, floor-wall joints, and sump pits. It is colorless, odorless, and undetectable without a test. Allegheny County consistently appears in EPA data as a high-radon region, with median indoor levels well above the national average of approximately 1.3 pCi/L. The EPA recommends testing every home, fixing any above 4 pCi/L, and considering mitigation between 2 and 4 pCi/L. Retesting every two years in high-radon areas is also recommended, as soil conditions and house pressure dynamics shift with seasons and renovations.
Testing: which kind, where, and when
The two common test types are short-term (2 to 7 days) and long-term (90 days to 1 year). Short-term tests are used at real estate transactions and for quick screening; they are less representative of the annual average because radon concentrations vary with barometric pressure, temperature, and wind. Long-term charcoal electret or alpha track tests give a more accurate annual average and cost $25 to $45 per kit from state radon programs or national suppliers.
Test at the lowest occupied level of the house — if the basement is used even as a laundry room, test there. Place the device in a room used at least eight hours a week, away from exterior walls and high-airflow areas. Short-term tests require closed-house conditions, which is why winter real estate tests sometimes read higher than the annual average: cold-weather closed-house conditions accumulate radon faster than a summer house with open windows.
Mitigation: how it works and what it costs
Sub-slab depressurization is the standard mitigation method for most residential situations. A contractor core-drills through the slab floor, inserts a PVC pipe, connects it to a continuously running fan mounted outside the house, and exhausts the soil gas above the roofline. The fan creates a slight negative pressure under the slab, drawing radon-laden soil gas up through the pipe and outside before it can enter the house. Properly installed, this reduces indoor radon levels by 80 to 99 percent in most cases.
Cost in the Pittsburgh metro area runs $800 to $1,800 for a typical single-family house with an accessible slab and crawlspace configuration. Homes with finished basements, complex slab sections, or multiple foundation types cost more — $1,500 to $2,500 is common for harder installations. The fans used in mitigation systems draw $15 to $40 per year in electricity at current Pennsylvania rates. They run continuously and are rated for 10 to 15 years of operation.
Post-mitigation testing and long-term monitoring
Test 24 hours after the system is operational, and again with a long-term test 90 days later. The short test confirms the system is running and achieving a basic reduction; the long-term test gives the annual average picture. An ongoing radon monitor — a digital device that measures continuously and logs data — costs $150 to $250 and is worth having in a house in a high-radon county. These devices show radon in real time and alert if levels rise, which can happen if the mitigation fan fails or if a renovation opens new pathways. The article on indoor combustion sources in a DC row house touches on a related point: house depressurization from exhaust fans can also affect radon levels by changing the pressure differential between interior and soil.
Frequently asked questions
Is 4 pCi/L really a safe level, or is it just the regulatory limit? The EPA’s 4 pCi/L action level is not a safety threshold — it is a pragmatic line above which the agency recommends action. The EPA itself acknowledges that there is no completely safe level of radon exposure, and estimates that radon causes about 21,000 lung cancer deaths per year in the United States. At 2 pCi/L, the risk is still above zero. The 4 pCi/L action level reflects where mitigation is consistently cost-effective relative to the risk reduction achieved.
How much does a radon mitigation system cost to run per year? The fan draws 30 to 75 watts continuously. At the national average electricity rate of roughly $0.13 per kilowatt-hour, a 50-watt fan costs about $57 per year to run. Maintenance is minimal — check the pressure gauge indicator every few months and plan to replace the fan every 10 to 15 years at a cost of $150 to $300.
Can I install a radon mitigation system myself? The mechanical work — drilling, PVC pipe, fan mounting — is within the skill range of an experienced DIYer in states that do not require licensed contractor installation. Pennsylvania does not require contractor licensing for radon mitigation, though the EPA recommends using a certified mitigator. A certified professional brings diagnostic tools to determine the sub-slab communication pattern before drilling, which affects pipe placement. DIY kit materials run $200 to $400; professional installation adds $600 to $1,200 in labor and diagnostic work.