Where radon tests run highest

Story · Land, air and risk

Where radon tests run highest

937 of 1,233 Ohio ZIP codes have a figure; the median one has 4.3 pCi/L.

Open this topic on the map Radon by ZIP code

Radon is a radioactive gas that seeps up from uranium decaying in soil and bedrock, and it collects indoors, worst in basements with the doors and windows shut. Ohio sits on some of the country's higher radon potential, mostly where glacial soils overlie uranium-bearing shale, but the level under one house can differ tenfold from the house next door, so a ZIP code average is a reason to test, not a verdict on any address.

This ranks the 25 Ohio ZIP codes with the highest average radon reading, among ZIP codes with at least five tests on file with the Ohio Department of Health since 2010, before any mitigation. EPA's action level is 4 pCi/L, and at or above it the agency recommends fixing it.

Across the state

One dot per ZIP code, colored the way the map colors this topic; larger dots are more populous ZIP codes.

Under 2 pCi/L (64) 2 to 4 pCi/L (346) 4 to 8 pCi/L (422) 8 to 12 pCi/L (82) 12 pCi/L and up (23) Too few tests (296)

The 25 highest ZIP code averages

Highest first; every ZIP code links to its own page.

43014 · Union Township and DanvilleKnox County35.3 pCi/L
44431 · LeetoniaColumbiana County20.5 pCi/L
43837 · Port WashingtonTuscarawas County18.6 pCi/L
44864 · Green Township and PerrysvilleAshland County18.6 pCi/L
44637 · Killbuck Township and KillbuckHolmes County17.9 pCi/L
43844 · Jefferson Township and WarsawCoshocton County16.6 pCi/L
43755 · Madison Township and Lore CityGuernsey County16.4 pCi/L
43749 · Monroe Township and KimboltonGuernsey County16.3 pCi/L
43080 · UticaLicking County16.1 pCi/L
44669 · Paris Township and ParisStark County16.1 pCi/L
43028 · Howard Township and HowardKnox County15.8 pCi/L
43149 · Good Hope Township and RockbridgeHocking County15.7 pCi/L
45111 · Symmes Township and Camp DennisonHamilton County15.7 pCi/L
43945 · SalinevilleColumbiana County15.5 pCi/L
44455 · Middleton Township and RogersColumbiana County15.1 pCi/L
44427 · East Township and KensingtonColumbiana County14.8 pCi/L
43071 · Eden Township and Saint LouisvilleLicking County14.8 pCi/L
43986 · Rumley Township and JewettHarrison County14.2 pCi/L
43360 · Jefferson Township and ZanesfieldLogan County13.2 pCi/L
44627 · Salt Creek Township and FredericksburgWayne County13.0 pCi/L
43107 · Rushcreek Township and BremenFairfield County12.3 pCi/L
43005 · Jackson Township and BladensburgKnox County12.1 pCi/L
44813 · Jefferson Township and BellvilleRichland County12.1 pCi/L
44626 · Pike Township and East SpartaStark County11.9 pCi/L
44842 · LoudonvilleAshland County11.8 pCi/L

How this was measured

Ohio Department of Health, radon levels by ZIP code: every test reported by Ohio-licensed radon professionals since 2010, before any mitigation, updated monthly. The map shows the ZIP's average; ZIPs with fewer than five tests are left grey. A ZIP average says nothing about one house, and EPA's advice is the same everywhere: test, and fix at 4 pCi/L or more.

937 of 1,233 ZIP codes have a figure; ZIP codes without one are left off the list, not counted as zero. Ties are broken by ZIP code.

Every ZIP code's own page carries the full detail behind its figure, and the Radon topic page ranks the whole state.

Sources

Ohio Department of Health radon test results by ZIP code since 2010 (pre-mitigation), ZIPs with five or more tests.

ODH radon program

The figures behind this page are open data: the open JSON, CC BY 4.0 for the compilation. Report a correction.

Cite this page as:

Cracked Buckeye (Open Shower Co), "Where radon tests run highest", https://crackedbuckeye.com/stories/radon-highest/, built 2026-09-16, accessed [date].

One figure from it:

Cracked Buckeye (Open Shower Co), "Where radon tests run highest", https://crackedbuckeye.com/stories/radon-highest/, built 2026-09-16, accessed [date]; Radon from ODH radon program.

How to cite · Report a correction · Built 2026-09-16