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Radon Levels in Ross County, Ohio

EPA puts Ross County in Zone 1, its highest radon zone, and high results are common there: 67.1% of the 368 radon tests reported to CDC (2008 to 2017, laboratory totals) came back at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    67.1%

    14.8 pts above OH

    Ross
    67.1%
    Ohio
    52.3%

    368 tests, 2008 to 2017

  • Median result

    7.0pCi/L

    Action level reached

    Ross
    7.0 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    368

    43rd of 79 by tests

    Ross
    368
    Franklin
    16,142

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Ohio

    11 of 79

    Top quarter

    Ross
    67.1%
    Pickaway
    81.4%

    By share, of 79 with 30+ tests

Read a result for Ross County

Starts at Ross County's median, 7.0 pCi/L

7.0pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 7.0 pCi/L

At or above 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Ross County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Ross County, At a glance

Ross County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Ross County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

USGS geologic potential: High across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Ross County, 2008 to 2017, laboratory

Reported results by concentration band, Ross County, 2008 to 2017, laboratory
Under 2 pCi/L: 17%2 to 4 pCi/L: 16%4 pCi/L and above: 67%

Of 368 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Ross County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L6317.1%
2 to 4 pCi/L5815.8%
4 pCi/L and above24767.1%
What these figures count

These are the 368 tests reported to CDC for Ross County over 2008 to 2017 (laboratory totals), many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.

Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Ross County, Compared

Ross County radon figures, compared

Calculated by Radon411

More than half: 67.1% of the 368 radon tests reported to CDC for Ross County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 11th of 79 Ohio counties with 30 or more tests for the same period. That is 14.8 points above the 52.3% pooled from 88 Ohio counties.

The median result, 7.0 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 201.5 pCi/L. The rest split 17.1% under 2 pCi/L and 15.8% from 2 to 4 (Ohio: 23.1% and 24.6%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 67.1% share point the same way here.

1 of its 5 bordering counties with figures ran higher, led by Pickaway County at 81.4%; Jackson County reported 41.7%. Statewide for the same period, Pickaway County reported the highest share (81.4%) and Cuyahoga County the lowest (21.7%).

CDC's ten-year totals for Ross County went from 332 tests (2005 to 2014) to 368 (2008 to 2017), the share going from 67.5% to 67.1%.

Nationally, every county with a figure for the same period pools to 35.7%; Ross County sits 31.4 points above it. CDC also counts 24 tests taken after mitigation in Ross County for the same period: tests in homes where a fix was already in.

Ross County against Ohio, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Ross County
Ross County36867.1%7.0 pCi/LThis county
Ohio, pooled88 counties, pooled98,84052.3%Not pooled−14.8 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−31.4 points
Fairfield Countyhighest in the state1,17576.8%7.4 pCi/L+9.7 points
Cuyahoga Countylowest in the state10,09221.7%2.0 pCi/L−45.4 points
Pickaway County, OHborders it18381.4%9.5 pCi/L+14.3 points
Fayette County, OHborders it1258.3%5.5 pCi/L−8.8 points
Highland County, OHborders it6756.7%4.8 pCi/L−10.4 points
Pike County, OHborders it5756.1%4.5 pCi/L−11.0 points
Hocking County, OHborders it6053.3%4.0 pCi/L−13.8 points
Jackson County, OHborders it4841.7%3.3 pCi/L−25.4 points
Vinton County, OHborders it425.0%1.9 pCi/L−42.1 points
Where Ross County's reported results fell, 2008 to 2017, laboratory, beside Ohio and the United States
ResultRoss County testsRoss County shareOhio shareU.S. shareAgainst Ohio
Under 2 pCi/L6317.1%23.1%39.6%−6.0 points
2 to 4 pCi/L5815.8%24.6%24.7%−8.8 points
4 pCi/L and above24767.1%52.3%35.7%+14.8 points
Ross County ranked among the 79 Ohio counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Franklin County6 of 7916,14271.9%6.8 pCi/L
Licking County7 of 794,69471.2%7.0 pCi/L
Auglaize County8 of 7913971.2%6.5 pCi/L
Champaign County9 of 7959671.1%6.8 pCi/L
Madison County10 of 7954967.4%5.7 pCi/L
Ross County11 of 7936867.1%7.0 pCi/L
Tuscarawas County12 of 7954766.4%5.6 pCi/L
Marion County13 of 7926565.3%6.4 pCi/L
Miami County14 of 7969065.2%6.1 pCi/L
Morrow County15 of 7917765.0%5.7 pCi/L
Holmes County16 of 796764.2%5.8 pCi/L
Ross County ten-year laboratory totals, against Ohio's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestOhio, pooledChange from the row before
2008 to 201736867.1%7.0 pCi/L201.5 pCi/L52.3%+1.9 points
2007 to 201637165.2%6.6 pCi/L201.5 pCi/L52.8%−0.4 points
2006 to 201536065.6%6.5 pCi/L201.5 pCi/L52.9%−1.9 points
2005 to 201433267.5%6.8 pCi/L201.5 pCi/L52.4%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Ross County, Geology

The ground under Ross County

Predicted

USGS's geologic map puts all of Ross County's mapped land in one class: high radon potential. The map puts 45.1% of Ross County in the area it calls Till Plains and 23.7% in Glaciated Plateau, with 2 smaller areas beside them. USGS gives the first a radon index of 14 and the second 12, both in the high band (12 to 17).

USGS's geologic areas under Ross County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Till PlainsGlacial deposits underlain by Ordovician through Devonian limestone and shale.High1445.1%
Glaciated PlateauPre-Wisconsin glacial deposits derived from high radioactivity marine black shale.High1223.7%
Mississippian LimestoneMississippian limestone exhibiting high gamma radioactivity.High1419.9%
Ohio ShaleDevonian-Mississippian black shale (includes some Ordovician limestone)High1411.3%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Ross County beside the ground around it

Ross County has more high-potential ground than Ohio as a whole: 100% of its land against 62.8%. Of the 7 counties that border it, none has as large a share of high-potential ground; Fayette County comes nearest at 100%.

Share of land by USGS radon potential: Ross County, the 7 counties bordering it and Ohio
AreaEPA zoneLow potentialModerate potentialHigh potential
Ross CountyZone 1NoneNone100%
Pike CountyZone 1None1.5%98.5%
Pickaway CountyZone 1NoneNone100%
Fayette CountyZone 1NoneNone100%
Highland CountyZone 2None67.8%32.2%
Vinton CountyZone 2None80.7%19.3%
Jackson CountyZone 2None88.9%11.1%
Hocking CountyZone 2None49.8%50.2%
Ohio88 counties, pooled by land areaVariesNone37.2%62.8%

The map rates the ground, not the air in any home.

Local help

Ross County, Local resources

Radon testing and mitigation in Ross County

Listed radon businesses with an address in Ross County:

Listed radon professionals by town: Chillicothe

What Ohio's program says
Phone
614-728-0272
Email
indoor.radon@odh.ohio.gov
Licensing of radon professionals
This program licenses companies and persons directly involved with the radon testing and mitigation industry.

What it means

Ross County, Questions

Questions about radon in Ross County

Are radon levels high in Ross County?

Over the 2008 to 2017 laboratory totals, 67.1% of the radon tests reported to CDC for Ross County, Ohio were at or above 4 pCi/L, and the median reported pre-mitigation result was 7.0 pCi/L. Of 79 Ohio counties with 30 or more tests for the same period, 10 reported a higher share; pooled, the state comes to 52.3%.

Which counties border Ross County?

Ross County borders 7 counties: Pike County, Pickaway County, Fayette County, Highland County, Vinton County, Jackson County and Hocking County.

Products

Ross County, Products

Testing a home in Ross County

In Ross County, 67.1% of 368 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 52.3% pooled across Ohio. In Zone 1 the year-round level in Ross County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Ross County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Ross County

Explore

Ross County, Bordering counties

Counties bordering Ross County

Calculated by Radon411

Ross County, Cities and towns

Cities and towns in Ross County

About 76,429 people live in Ross County by the Census Bureau's estimate for July 1, 2025, 638 fewer than in 2020 (−0.8%). That works out to 111 people per square mile of land. Its largest town, Chillicothe, has 21,815 residents, 28.5% of the total. Reported testing is thin here: 368 tests over 2008 to 2017, or 4.8 for every 1,000 residents (2025 estimate), where Ohio as a whole comes to 8.3.

From Chillicothe to South Salem, CDC publishes no figure by town: each reads Ross County's.

The cities and towns in Ross County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Chillicothe21,815−1.0%28.5%
Greenfieldextends beyond Ross County4,329−0.3%Counted whole
Kingston1,236−1.5%1.6%
Frankfort1,094−2.0%1.4%
Bainbridge737−3.3%1.0%
Clarksburg400−1.7%0.5%
Adelphi313−1.6%0.4%
South Salem207−2.4%0.3%

8 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Ross County is counted whole, so it has no share.

Ross County, Homes

Homes in Ross County

Of Ross County's 32,042 homes, 72% are detached houses, against 69% across Ohio; 14% are mobile homes. Half of its homes were built before 1973, close to Ohio's 1970: 35% date from before 1960 and 15% from 2000 or later. 71% of occupied homes are lived in by their owner (Ohio: 67%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Ross County, Ohio, 2019 to 2023
HomesRoss CountyOhio
Housing units32,0425,271,573
Detached houses72%69%
In buildings of 5 or more7%15%
Mobile homes14%4%
Built before 196035%38%
Built since 200015%16%
Middle year built19731970
Owner-occupied71%67%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.