- Why does Central Ohio have so much radon?
- Which counties have the highest radon levels?
- Are Columbus suburbs at risk too?
- How does radon get into a home?
- What is a safe radon level?
- How do I test my home for radon?
- DIY radon test vs. professional testing
- How much does radon mitigation cost?
- Radon FAQs
Central Ohio has some of the highest radon levels in the United States because the region sits on uranium-rich glacial deposits and shale. About 38% of Ohio’s 88 counties have average indoor radon levels above the EPA action level of 4.0 pCi/L, and several Central Ohio counties test even higher. The only way to know your home’s radon level is to test.
Radon is invisible, odorless, and naturally occurring. It seeps from the soil into homes, where it becomes the second leading cause of lung cancer in the United States and the leading cause among non-smokers, according to the U.S. Surgeon General.
For Central Ohio homeowners, this is not a distant or theoretical risk. It’s documented, measurable, and rooted in the geology beneath every home in the region.
Why does Central Ohio have so much radon?
The answer is geological. Central Ohio sits on mineral-rich glacial deposits and shale formations that naturally contain uranium. As uranium decays in the soil over time, it produces radium, which then breaks down into radon gas.
That radon moves through cracks, foundation joints, sump pits, and crawl spaces, eventually accumulating inside basements and lower living areas. Because Ohio homes typically operate under negative pressure, especially during the heating season, the home itself acts like a vacuum, pulling soil gas upward.
This is why the U.S. Environmental Protection Agency (EPA) designates Columbus and most of Central Ohio as Zone 1, the highest radon potential category on the EPA’s national map. It’s not bad luck. It’s the ground beneath your foundation.
of Ohio’s 88 counties have an average indoor radon level above the EPA action level of 4.0 pCi/L. Elevated radon has been documented in homes across all 88 Ohio counties.
Source: Ohio Department of Natural Resources, Department of Geological SurveyWhich counties have the highest radon levels?
Indoor radon levels vary widely across Ohio counties based on local geology and soil composition. According to research cited by the Ohio Department of Natural Resources, several Central Ohio counties consistently report some of the highest average indoor radon levels in the state.
| County | Average Indoor Radon Level | Risk Level |
|---|---|---|
| Licking County | Above 8.0 pCi/L | 2x EPA action level |
| Franklin County (Columbus) | 6 to 8 pCi/L | Above action level |
| Fairfield County | 6 to 8 pCi/L | Above action level |
| Pickaway County | 6 to 8 pCi/L | Above action level |
| Knox County | 6 to 8 pCi/L | Above action level |
| Ross County | 6 to 8 pCi/L | Above action level |
| EPA Action Level | 4.0 pCi/L | Mitigation recommended |
For perspective, Newark’s 43055 ZIP code in Licking County is among the highest radon concentrations measured anywhere in the United States. Multiple buildings there have tested far above the EPA action level. This isn’t a fringe issue affecting a handful of homes. It’s a regional pattern.
Are Columbus suburbs at risk too?
Yes. The same geology that affects Columbus extends through every surrounding suburb. Whether you live in a 1920s craftsman in Clintonville or a brand-new build in a developing neighborhood, your home sits on the same radon-producing soil. Two homes on the same street can test very differently based on foundation type, construction details, and seasonal conditions.
Homeowners across the following Central Ohio communities should consider testing:
Newer homes are not safer. In fact, tightly sealed modern construction can sometimes trap radon at higher concentrations than older, draftier homes. Age, neighborhood reputation, and home value have nothing to do with radon risk. Our service area covers 22 Central Ohio counties, and we’ve found elevated radon in every type of home imaginable.
How does radon get into a home?
Radon enters through any opening that connects the home to the soil beneath it. The most common entry points include:
- Cracks in concrete floors and foundation walls
- Construction joints where slabs meet walls
- Sump pits and floor drains
- Crawl spaces with exposed soil
- Loose-fitting pipes and utility penetrations
- Cavities inside concrete block walls
Once inside, radon accumulates fastest in basements and lower-level living areas. Bedrooms, family rooms, and finished basements are typically where exposure happens. If you have a finished basement that’s used regularly, it deserves testing more than almost any other space in the home.
What is a safe radon level?
The EPA has set the action level at 4.0 picocuries per liter (pCi/L). If your home tests at or above this level, mitigation is recommended.
However, no amount of radon is considered completely safe. The EPA also suggests homeowners consider mitigation between 2.0 and 4.0 pCi/L, especially for homes with children, long-term residents, or anyone spending significant time in a basement or lower level.
How do I test my home for radon?
Testing your home for radon is straightforward. Here are the five steps:
- Choose your test type. Decide between a DIY short-term kit or professional testing with a continuous radon monitor.
- Place the device correctly. Position the test in the lowest livable level of your home, away from drafts, exterior walls, and high humidity areas.
- Maintain closed-building conditions. Keep windows and exterior doors closed for 12 hours before and during the test.
- Wait for the test period. Short-term tests run 2 to 7 days. Professional CRMs typically run 48 hours and record hourly data.
- Review and act on results. If levels are at or above 4.0 pCi/L, schedule a mitigation consultation. If below, retest every 2 to 5 years per EPA guidance.
How much does radon mitigation cost in Columbus?
If your home tests above the EPA action level, the next step is radon mitigation: a professionally designed system that vents radon gas from beneath your foundation to the outside, before it can enter your living space.
In Columbus and Central Ohio, most residential radon mitigation systems cost depends on the home’s size, foundation type, and complexity. Most systems can be installed in a single day.
Mitigation systems are highly effective. A properly designed and installed system can reduce indoor radon levels by up to 99%, often bringing concentrations well below the EPA action level. Learn more about radon mitigation systems and how they work.
Radon FAQs for Central Ohio Homeowners
Why is radon so high in Central Ohio?
Central Ohio sits on glacial deposits and shale formations that naturally contain uranium. As uranium decays in the soil, it produces radon gas that seeps into homes through cracks, foundation joints, and crawl spaces. The EPA designates Columbus and most of Central Ohio as Zone 1, the highest radon potential category.
What is a safe level of radon in a home?
The EPA recommends action when indoor radon reaches 4.0 pCi/L or higher. However, no level is considered completely safe. The EPA also suggests considering mitigation between 2.0 and 4.0 pCi/L, especially for homes with children or long-term residents.
Is radon worse in basements?
Yes. Radon enters from the soil and accumulates fastest in basements and lower levels. Basement bedrooms, family rooms, and finished basements are where the most exposure typically occurs.
Do new homes have radon problems?
Yes. Newer homes are not safer from radon. Tightly sealed modern construction can actually trap radon at higher concentrations than older, draftier homes. The only way to know is to test.
Which Ohio county has the highest radon levels?
Licking County has the highest average radon levels in Central Ohio, with averages above 8.0 pCi/L, double the EPA action level. Newark’s 43055 ZIP code is among the highest radon concentrations measured anywhere in the United States.