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Radon Levels in York County, South Carolina

EPA puts York County in Zone 2, its middle radon zone, and most reported tests there come back low, though 13.6% of 1,412 (2008 to 2017, laboratory totals) reached 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

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  • Share at 4+ pCi/L

    13.6%

    5.8 pts below SC

    York
    13.6%
    SC
    19.4%

    1,412 tests, 2008 to 2017

  • Median result

    1.2pCi/L

    Below action level

    York
    1.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    1,412

    6th of 24 by tests

    York
    1,412
    Greenville
    12,004

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in SC

    10 of 24

    Middle half

    York
    13.6%
    Oconee
    42.6%

    By share, of 24 with 30+ tests

Read a result for York County

Starts at York County's median, 1.2 pCi/L

1.2pCi/L

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

EPA’s reading of 1.2 pCi/L

Below 2 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 below 2 pCi/L, the level at which EPA says a fix should be considered. York County's median reported result, 2008 to 2017.

Interpret this reading

The data

York County, At a glance

York County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

York County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Low across 79% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, York County, 2008 to 2017, laboratory
Under 2 pCi/L: 67%2 to 4 pCi/L: 19%4 pCi/L and above: 14%

Of 1,412 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, York County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L94867.1%
2 to 4 pCi/L27219.3%
4 pCi/L and above19213.6%
What these figures count

These are the 1,412 tests reported to CDC for York 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

York County, Compared

York County radon figures, compared

Calculated by Radon411

York County reports fewer high tests than South Carolina overall. 13.6% of its 1,412 tests over the 2008 to 2017 laboratory totals were at or above 4 pCi/L. That is 5.8 points below the 19.4% pooled from 46 South Carolina counties.

Ordered from highest share down, it comes 10th of 24 South Carolina counties with 30 or more tests for the same period. Nationally, every county with a figure for the same period pools to 35.7%; York County sits 22.1 points below it.

Next door, the shares run from 8.5% in Mecklenburg County, NC to 39.5% in Cleveland County, NC, with Mecklenburg County, NC below York County. Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 13.6% share point the same way here.

Half the tests came in under 1.2 pCi/L and half over it; the single highest reached 40.7 pCi/L. The rest split 67.1% under 2 pCi/L and 19.3% from 2 to 4 (South Carolina: 57.4% and 23.1%).

CDC's ten-year totals for York County went from 986 tests (2005 to 2014) to 1,412 (2008 to 2017), the share going from 12.7% to 13.6%.

York County against South Carolina, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from York County
York County1,41213.6%1.2 pCi/LThis county
South Carolina, pooled46 counties, pooled26,48119.4%Not pooled+5.8 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+22.1 points
Oconee Countyhighest in the state2,46942.6%3.3 pCi/L+29.0 points
Florence Countylowest in the state590.0%0.7 pCi/L−13.6 points
Cleveland County, NCborders it51139.5%2.8 pCi/L+25.9 points
Chester County, SCborders it1822.2%1.1 pCi/L+8.6 points
Gaston County, NCborders it59319.1%1.5 pCi/L+5.5 points
Cherokee County, SCborders it15313.7%1.6 pCi/L+0.1 points
Lancaster County, SCborders it37413.6%1.6 pCi/LLevel
Mecklenburg County, NCborders it3,7538.5%0.9 pCi/L−5.1 points
Union County, SCborders it270.0%1.0 pCi/L−13.6 points
Where York County's reported results fell, 2008 to 2017, laboratory, beside South Carolina and the United States
ResultYork County testsYork County shareSouth Carolina shareU.S. shareAgainst South Carolina
Under 2 pCi/L94867.1%57.4%39.6%+9.7 points
2 to 4 pCi/L27219.3%23.1%24.7%−3.8 points
4 pCi/L and above19213.6%19.4%35.7%−5.8 points
York County ranked among the 24 South Carolina counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Spartanburg County5 of 243,28019.1%1.7 pCi/L
Newberry County6 of 247516.0%1.1 pCi/L
Laurens County7 of 2424413.9%1.3 pCi/L
Cherokee County8 of 2415313.7%1.6 pCi/L
Lancaster County9 of 2437413.6%1.6 pCi/L
York County10 of 241,41213.6%1.2 pCi/L
Aiken County11 of 2424113.3%1.3 pCi/L
Lexington County12 of 2459112.5%0.9 pCi/L
Sumter County13 of 244211.9%1.3 pCi/L
Anderson County14 of 241,73311.1%1.1 pCi/L
Greenwood County15 of 241137.1%1.0 pCi/L
York County ten-year laboratory totals, against South Carolina's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestSouth Carolina, pooledChange from the row before
2008 to 20171,41213.6%1.2 pCi/L40.7 pCi/L19.4%+1.1 points
2007 to 20161,42212.5%1.1 pCi/L40.7 pCi/L19.3%Level
2006 to 20151,21612.5%1.1 pCi/L40.7 pCi/L19.8%−0.2 points
2005 to 201498612.7%1.1 pCi/L20.9 pCi/L19.8%First on file

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

York County, Geology

The ground under York County

Predicted

Most of the ground under York County is one class on USGS's geologic map: 79.0% of its land is low radon potential, with 21.0% moderate. The map puts 78.7% of York County in the area it calls Charlotte Belt and 12.2% in Kings Mountain Belt, with one smaller area beside them. USGS gives the first a radon index of 8, in the low band (5 to 8), and the second 11, in the moderate band (9 to 11).

USGS's geologic areas under York County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Charlotte BeltBiotite gneiss and schist, metavolcanic rocks, mica gneiss.Low878.7%
Kings Mountain BeltProterozoic-Cambrain metasedimentary and metavolcanic rocks.Moderate1112.2%
Carolina and Charlotte Belt GranitesGranite and granite gneissModerate118.8%

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

York County beside the ground around it

Across South Carolina 0.2% of the land is rated high; none of York County's is. Of the 7 counties that border it, 4 have more moderate-potential ground, Cleveland County, NC the most at 100%.

Share of land by USGS radon potential: York County, the 7 counties bordering it and South Carolina
AreaEPA zoneLow potentialModerate potentialHigh potential
York CountyZone 279.0%21.0%None
Gaston County, NCZone 236.5%63.5%None
Chester CountyZone 384.0%16.0%None
Cherokee CountyZone 22.4%97.6%None
Mecklenburg County, NCZone 3100%NoneNone
Lancaster CountyZone 383.7%16.3%None
Union CountyZone 346.4%53.6%None
Cleveland County, NCZone 2None100%None
South Carolina46 counties, pooled by land areaVaries80.8%18.2%0.2%

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

Local help

York County, Local resources

Radon testing and mitigation in York County

What South Carolina's program says
Phone
1-800-768-0362
Email
radon@des.sc.gov

What it means

York County, Questions

Questions about radon in York County

Are radon levels high in York County?

Over the 2008 to 2017 laboratory totals, 13.6% of the radon tests reported to CDC for York County, South Carolina were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.2 pCi/L. Of 24 South Carolina counties with 30 or more tests for the same period, 9 reported a higher share; pooled, the state comes to 19.4%.

Which counties border York County?

York County borders 7 counties: Gaston County, NC, Chester County, SC, Cherokee County, SC, Mecklenburg County, NC, Lancaster County, SC, Union County, SC and Cleveland County, NC.

Products

York County, Products

Testing a home in York County

In York County, 13.6% of 1,412 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 19.4% pooled across South Carolina. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in York County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for York County homes, compared

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York County, Bordering counties

Counties bordering York County

Calculated by Radon411

York County, Cities and towns

Cities and towns in York County

York County is growing: the Census Bureau puts it at 306,887 residents on July 1, 2025, up 8.1% from 283,833 in 2020. That works out to 451 people per square mile of land. Its largest town, Rock Hill, has 75,911 residents, 24.7% of the total. CDC's 1,412 reported tests for 2008 to 2017 work out to 4.6 per 1,000 residents (2025 estimate), close to South Carolina's 4.8.

From Rock Hill to Smyrna, CDC publishes no figure by town: each reads York County's.

The cities and towns in York County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Rock Hill75,911+1.7%24.7%
Fort Mill38,673+53.5%12.6%
Tega Cay14,457+12.4%4.7%
York10,620+24.1%3.5%
Clover7,659+12.9%2.5%
Sharon480+2.6%0.2%
Hickory Grove478+3.0%0.2%
McConnells288+2.9%Under 0.1%
Smyrnaextends beyond York County56LevelCounted whole

9 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 York County is counted whole, so it has no share.

York County, Homes

Homes in York County

Of York County's 118,063 homes, 68% are detached houses, against 64% across South Carolina; 14% are in buildings of five or more homes. Much of York County is recent building: 48% of its homes have gone up since 2000 and the middle year built is 1999, against 1991 for South Carolina. 73% of occupied homes are lived in by their owner (South Carolina: 71%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in York County, South Carolina, 2019 to 2023
HomesYork CountySouth Carolina
Housing units118,0632,401,638
Detached houses68%64%
In buildings of 5 or more14%13%
Mobile homes9%15%
Built before 19609%13%
Built since 200048%35%
Middle year built19991991
Owner-occupied73%71%

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