Radon Testing in Central Ohio: What Buyers Should Know
Franklin County sits in the EPA's highest radon zone, and the EPA recommends fixing a home at 4 pCi/L or higher. A short-term test during your inspection window takes at least 48 hours, so schedule it early and plan how you'd handle a high result.
If you're relocating to Central Ohio from a state where radon rarely comes up in a home purchase, this is one inspection item that deserves your attention here. Radon is a colorless, odorless gas that comes from the soil and can build up indoors, and the Ohio Department of Health notes that the only way to know how much is in a home is to test.
It's also one of the most fixable issues a home inspection can uncover, which is why it's worth understanding before you're under contract and watching the calendar.
Why Does Radon Matter So Much in Central Ohio?
Franklin County is classified by the EPA as Radon Zone 1, the highest-potential category, meaning the predicted average indoor level is above 4 pCi/L. Ohio overall has a high potential for radon, with more than 50 counties in Zone 1. The Ohio Department of Health says the EPA's action level is 4 pCi/L, and at or above that level it highly recommends installing a mitigation system. ODH also cites an estimated 21,000 U.S. lung cancer deaths a year from radon exposure, and notes that any level carries some risk.
Local test data points the same direction. According to a summary of ODH program data, more than 112,000 radon tests in Franklin County have averaged 7.47 pCi/L. Statewide, the 2026 Ohio Radon Report Card from the American Association of Radon Scientists and Technologists found that 52% of nearly 99,000 tests came back at or above 4.0 pCi/L, and another 25% landed between 2.0 and 4.0. None of that means a particular home is a problem. It does mean a high result is common enough that you should expect to test.
How Does a Radon Test Work During a Home Purchase?
A short-term test is the usual approach. ODH guidance says the device should be placed in the lowest level of the home that could be occupied, the test must run for at least 48 hours, the home's HVAC should be operating, and windows and exterior doors should stay closed. If the home already has a mitigation system, it should not be turned off during the test. Results are reported as an average for the testing period, because radon levels move up and down by the hour, day, and season.
The practical takeaway is timing. Because the test takes at least two days and the lab or device needs time to report, it should be scheduled at the start of your inspection window, not the end. Using an Ohio-licensed radon professional is the safest way to keep the test consistent with state protocols, and your inspector can often coordinate it.
What Do the Results Mean?
The EPA's action level is 4 pCi/L. At or above that number, fixing the home is recommended. Between 2.0 and 4.0, the EPA suggests considering mitigation, especially if you'll spend a lot of time in a lower level, such as a finished basement or a basement office. Below 2.0 is generally considered lower, though ODH notes there's no level that is completely risk-free.
One test is a snapshot. If a result is borderline or something about the testing conditions changed, a second test can be worth the short delay. Radon enters through cracks in floors and walls and openings like drains and sump pumps, so basements and ground-contact rooms usually run highest.
What Does Fixing a High Radon Level Involve?
A mitigation system uses a vent pipe and fan to draw radon from beneath the foundation and release it outside. According to radon professionals in Ohio, installation can often be completed in about a day, and a properly installed system can bring levels well below the action level and keep them there. Costs vary by home, foundation type, and system design, and they're often quoted in the range of roughly a thousand dollars to a few thousand, so it's worth getting written quotes from licensed professionals rather than relying on a general number.
After installation, a follow-up test confirms the system is working. If a seller has already installed a system, ask for the test results and any documentation so you know how it was verified.
How Should You Handle Radon in Your Contract?
Treat it as an optional inspection item that you add on purpose. Ohio doesn't require radon testing as a condition of sale, but ODH recommends that sellers test before listing, and many buyers include it in their inspection period. Work with your agent to make sure the contract gives you time to receive results, and to decide in advance how you'd respond to a high number. Options typically include asking the seller to install a mitigation system, negotiating a credit or price reduction, or installing a system yourself after closing.
If you're selling, a pre-listing radon test can remove a negotiation surprise, and ODH's own guidance supports testing before you list. Ask your agent how radon results are handled under Ohio's disclosure form and your specific contract.
Frequently Asked Questions
Is radon a problem in Columbus and Central Ohio?
Franklin County is in the EPA's Radon Zone 1, the highest-potential category, and local test data shows high results are common. A test is the only way to know a specific home's level.
What radon level should I worry about?
The EPA action level is 4 pCi/L, and the Ohio Department of Health highly recommends a mitigation system at or above that level. The EPA also suggests considering mitigation between 2.0 and 4.0 pCi/L.
How long does a radon test take?
A short-term test must run at least 48 hours under closed-home conditions in the lowest occupiable level, so it should be scheduled early in your inspection window.
Can high radon be fixed?
Yes. A mitigation system with a vent pipe and fan typically can be installed in about a day and can bring levels below the action level. A follow-up test confirms it is working.
Does Ohio require radon testing when you sell a home?
Ohio does not require testing as a condition of sale, but the Ohio Department of Health recommends testing before selling, and many buyers add radon testing to their inspection period.
If you're getting ready to buy or sell in Central Ohio, I'm always happy to walk you through how to build radon testing into your inspection timeline so there are no surprises under contract.
This content is provided for informational purposes only and does not constitute legal or financial advice. All real estate services are provided in compliance with Fair Housing laws, RESPA, TCPA, the REALTOR® Code of Ethics, and Ohio Real Estate Commission advertising regulations. Equal Housing Opportunity. Chrisi Hagan, Collins Lassiter Group, Red 1 Realty.
