Ohio Radon Map, Levels & Testing Guide
Browse the 88 listed county pages surfaced for Ohio. Open a listed county to compare its EPA zone, source caveats, testing meaning, and when mitigation pricing becomes worth checking.
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Official Evidence in Ohio
88 of 88 listed counties have official evidence
Open a county page to see the official source context: measurement fields, local burden, state percentile, and the next step for no reading, 2.0-3.9, or 4.0+ pCi/L.
100%
covered
Measured
88
State source
0
CDC source
88
Needs source detail
0
Measured Risk Leaders in Ohio
County rankings from actual reported radon tests
These lists rank the visible Ohio county pages by measured radon signals, not by the EPA zone label alone. Use them to spot where the state hub has a real data story before opening individual county pages.
88
measured counties
State-level evidence read
This hub has measured high-burden counties, so the first click should be evidence-led.
The state hub is now doing a decision job: it separates first-click counties, retest counties, and lower-signal counties from 88 visible county measurement rows. 79 counties cross the high measured-burden band, so those pages should answer testing and 4.0+ action questions most directly.
First-click counties
Open Knox County first when you need the strongest local answer. It is tagged Test-now from 72.0% 4.0+ - 23.6 pCi/L primary - 987 tests. 87 visible measured counties are elevated or high enough to review before lower-signal counties.
Buyer/seller lane
Buyer/seller lane: start with the elevated or high counties, require a fresh lowest-level test, and turn any 4.0+ property result into quote or credit math. The hub has 88 CDC-backed county rows to support that routing.
Retest lane
Retest lane: 2.0-3.9 pCi/L deserves more caution in the elevated/high county set than in lower-signal counties. The hub should send those users to county pages before product or cost paths.
Best county pages to open first
Start with these local evidence pages
Ranked by measured burden, 4.0+ share, test volume, and whether the EPA zone understates the measurement signal.
Knox County
CDC Tracking
72.0% 4.0+ - 23.6 pCi/L primary - 987 tests
Knox County is a first-click page: 72.0% of reported tests at or above 4.0 and 23.6 pCi/L primary result. Route no-reading users to a test now and 4.0+ users to quote or credit planning.
Licking County
CDC Tracking
71.2% 4.0+ - 15.5 pCi/L primary - 3,431 tests
Licking County is a first-click page: 71.2% of reported tests at or above 4.0 and 15.5 pCi/L primary result. Route no-reading users to a test now and 4.0+ users to quote or credit planning.
Pickaway County
CDC Tracking
81.4% 4.0+ - 14.8 pCi/L primary - 154 tests
Pickaway County is a first-click page: 81.4% of reported tests at or above 4.0 and 14.8 pCi/L primary result. Route no-reading users to a test now and 4.0+ users to quote or credit planning.
Carroll County
CDC Tracking
57.4% 4.0+ - 16.8 pCi/L primary - 368 tests
Carroll County is a first-click page: 57.4% of reported tests at or above 4.0 and 16.8 pCi/L primary result. Route no-reading users to a test now and 4.0+ users to quote or credit planning.
Highest 4.0+ share
Primary result 14.8 pCi/L - high-end 127.9 pCi/L
CDC Tracking
Primary result 10.9 pCi/L - high-end 481.8 pCi/L
CDC Tracking
Primary result 14.4 pCi/L - high-end 274.8 pCi/L
CDC Tracking
Primary result 8.4 pCi/L - high-end 140.9 pCi/L
CDC Tracking
Primary result 23.6 pCi/L - high-end 610.3 pCi/L
CDC Tracking
Highest high-end reading
4.0+ share 71.2% - primary result 15.5 pCi/L
CDC Tracking
4.0+ share 72.0% - primary result 23.6 pCi/L
CDC Tracking
4.0+ share 49.8% - primary result 9.7 pCi/L
CDC Tracking
4.0+ share 61.8% - primary result 11.9 pCi/L
CDC Tracking
4.0+ share 76.8% - primary result 10.9 pCi/L
CDC Tracking
Most reported tests
4.0+ share 71.9% - primary result 9.5 pCi/L
CDC Tracking
4.0+ share 21.7% - primary result 3.0 pCi/L
CDC Tracking
4.0+ share 38.7% - primary result 4.8 pCi/L
CDC Tracking
4.0+ share 71.2% - primary result 15.5 pCi/L
CDC Tracking
4.0+ share 60.1% - primary result 8.0 pCi/L
CDC Tracking
Measured pattern
Among 88 visible counties with measurement tables, 79 land in the high measured-burden band and 87 land in high or elevated measured-burden bands. That lets this hub rank counties by observed test distribution instead of repeating the EPA map.
Map vs measurements
34 elevated measured counties are not EPA Zone 1. Those are the pages where the actual test distribution matters more than a map-only answer.
Source strategy
The measured rows shown here use CDC Tracking. This is still official evidence, but the hub should keep source caveats visible until a stable state table is available.
Already Tested
View Ohio Cost Estimates
If you already have a radon result, skip the directory and move straight to local price guidance.
Understand the Number
2.0 vs 4.0 vs 8.0 pCi/L
Use the parent levels guide if you need the plain-English meaning of a radon result before browsing counties.
Need a Number First
Read the Testing Guide
Use the fastest valid radon test setup before you compare quotes or ask whether mitigation is worth it.
Browse Counties
Jump to the Directory
Open your county to see its EPA zone, testing meaning, and the point where mitigation becomes worth pricing.
Official State Resource
Ohio radon program and rules
Use the state program link to verify local radon guidance, disclosure language, and contractor credential expectations before you act on an estimate.
Disclosure rule tracked
Ohio requires sellers to disclose known radon levels on the Ohio Residential Property Disclosure Form.
State licensing required
Ohio requires radon testers and mitigators to be licensed by the Ohio Department of Health.
Already tested? Get your itemized mitigation cost estimate.
View Ohio Mitigation Cost Estimates ->