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Radon in Seneca, South Carolina

EPA puts Oconee County, where Seneca is, in Zone 2, its middle radon zone, and high results are common there: 42.6% of the 2,469 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

    42.6%

    23.2 pts above SC

    Oconee
    42.6%
    SC
    19.4%

    Oconee, 1st of 24 in SC, 2008 to 2017

  • Median result

    3.3pCi/L

    Below action level

    Oconee
    3.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of Oconee's tests, 2008 to 2017

  • Nearest county

    23.6%

    Pickens, 19 miles

    Pickens
    23.6%
    Oconee
    42.6%

    1,717 tests, 2008 to 2017

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    Oconee, where Seneca is

  • Tests reported

    2,469

    In Oconee

    Oconee
    2,469
    Pickens
    1,717

    Reported to CDC before any fix, 2008 to 2017

Read a result for Seneca

Starts at Oconee County's median, 3.3 pCi/L

3.3pCi/L

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

EPA’s reading of 3.3 pCi/L

Between 2 and 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Oconee County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Seneca, What is published

What is published for Seneca

Information:

Every figure for Seneca is a county's

Radon data is published by county, not by city, so for Seneca it is Oconee County's: its EPA zone (Zone 2) and the 2,469 tests reported to CDC for 2008 to 2017, laboratory. Only a test tells you about one home.

Seneca covers 8.2 square miles of land, all of it in Oconee County. About 9,424 people live there, 1,150 to the square mile.

Seneca, Counties

The county Seneca lies in

Measured

Oconee County's EPA zone and the figures CDC publishes for it, 2008 to 2017, laboratory.

Oconee CountyZone 2Moderate predicted potential

42.6%
Reported tests at or above 4 pCi/L
3.3 pCi/L
Median reported result
2,469 tests
Tests reported to CDC
None
Yearly figures on file

Oconee County ranks 1st of 24 South Carolina counties with 30 or more tests for that period, 23.2 points above the 19.4% pooled across South Carolina's counties, 6.9 points above the national pool of 35.7%.

The counties nearest Seneca with a CDC figure for 2008 to 2017, laboratory, measured from the middle of the city: Pickens County (19 miles, 23.6% of 1,717 tests), Anderson County (22 miles, 11.1% of 1,733 tests) and Greenville County (37 miles, 19.6% of 12,004 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 7.1% to 23.6%; the farthest of them, Cherokee County, is 80 miles away at 13.7%.

No business in the directory gives Seneca as its address; the South Carolina list covers it.

The counties around Seneca

By distance from the middle of Seneca; counties with 30 or more tests.

Nearest counties to Seneca with 30 or more tests
CountyDistanceTestsAt or above 4 pCi/LMedian
Pickens County19 mi1,71723.6%1.8 pCi/L
Anderson County22 mi1,73311.1%1.1 pCi/L
Greenville County37 mi12,00419.6%1.7 pCi/L
Abbeville County43 mi6622.7%1.8 pCi/L
Laurens County56 mi24413.9%1.3 pCi/L
Spartanburg County58 mi3,28019.1%1.7 pCi/L
Greenwood County60 mi1137.1%1.0 pCi/L
Cherokee County80 mi15313.7%1.6 pCi/L

Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2008 to 2017, laboratory.

Seneca, Geology

The ground under Seneca

Predicted

USGS's geologic map puts all of Seneca's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Inner Piedmont Belt, to which USGS gives a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Seneca
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Inner Piedmont BeltProterozoic through Cambrian biotite gneiss and schist, and mica schist.Moderate11100%

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

Seneca beside its county and South Carolina

Oconee County as a whole has 11.0% of its land rated high; none of that ground lies under Seneca. Across South Carolina 0.2% of the land is rated high; none of Seneca's is.

Share of land by USGS radon potential: Seneca, the county it lies in and South Carolina
AreaEPA zoneLow potentialModerate potentialHigh potential
SenecaBy countyNone100%None
Oconee CountyZone 2None89.0%11.0%
South Carolina46 counties, pooled by land areaVaries80.8%18.2%0.2%

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

Seneca, Homes

Homes in Seneca

Of Seneca's 4,420 homes, 60% are detached houses, against 68% across Oconee County; 19% are in buildings of five or more homes. The homes are older than Oconee County's as a whole: half were built before 1980 (1990 for Oconee County), and 18% date from before 1960. 53% of occupied homes are lived in by their owner (Oconee County: 75%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Seneca, Oconee County, South Carolina, 2019 to 2023
HomesSenecaOconee CountySouth Carolina
Housing units4,42041,5142,401,638
Detached houses60%68%64%
In buildings of 5 or more19%5%13%
Mobile homes3%21%15%
Built before 196018%12%13%
Built since 200029%31%35%
Middle year built198019901991
Owner-occupied53%75%71%

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

Local help

Seneca, Local resources

Local resources for Seneca

Who to ask in South Carolina: its radon program, test kits and professionals.

The program's own words on licensing are on the South Carolina page.

What it means

Seneca, Questions

Questions about radon in Seneca

What radon zone is Seneca in?

Seneca takes its zone from Oconee County, which EPA puts in Zone 2, the map's middle class: a predicted county average of 2 to 4 pCi/L.

What are radon levels in Seneca?

42.6% of the 2,469 tests reported from Oconee County for 2008 to 2017 (laboratory totals) were at or above 4 pCi/L, the level at which EPA says to fix a home: high results are ordinary around Seneca. The median reported result was 3.3 pCi/L.

Should I test my home in Seneca?

Yes. About 1,052 of the 2,469 tests reported from Oconee County were at or above 4 pCi/L. That is above South Carolina's pooled 19.4%, and ranks Oconee County 1st of the 24 South Carolina counties with 30 or more tests. No map says which homes those are. How to test a home.

What ground is Seneca built on, as far as radon goes?

USGS's geologic map puts all of Seneca on one named area, "Inner Piedmont Belt", rated moderate for radon potential, radon index 11.

Is radon higher in the counties around Seneca?

No. Oconee County's 42.6% is above every one of the 8 nearest counties with a figure: the closest share to it is Pickens County (23.6%, 19 miles off), the lowest Greenwood County (7.1%, 60 miles off).

The answers use the published figures of Oconee County, the county Seneca lies in.

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