Is radon high in Charleston, South Carolina?

Low. Averaging the model's ZIP-code predictions across Charleston (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.4 pCi/L - about 23% below the US average of 1.8 and about 15% below the South Carolina average of 1.6. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Charleston ranks 4 of 9 South Carolina cities on this site.

Which Charleston ZIP codes have the highest radon?

Predictions for the 8 modeled ZIP codes in Charleston range from 1.1 to 1.6 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 0% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.

Should I test for radon in Charleston?

Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Charleston's low predicted average describes the typical home, not yours.

What does EPA Radon Zone 3 mean for Charleston?

Charleston sits mainly in Charleston County, which the EPA classifies as Zone 3 - low potential (< 2 pCi/L). The zone map dates from 1993 and covers whole counties. The 2001-2021 model agrees with the zone for the city. Neither replaces a test of your own home.

Radon levels in Charleston, South Carolina

LowEPA Zone 3

Predicted long-term basement average of 1.4 pCi/L (model estimate) across the 8 modeled ZIP codes in Charleston - about 23% below the US average of 1.8, about 15% below the South Carolina average of 1.6. Ranked #4 of 9 South Carolina cities on this site. Most of the city lies in Charleston County (its ZIPs also reach into 1 other county).

Test Charleston, SC once anyway - radon varies house to house

The predicted basement average here is 1.4 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.

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Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.

1.4 ± 0.07

pCi/L predicted basement mean (model SD)

0.7 ± 0.10

pCi/L predicted upstairs (above-ground) mean

1.1-1.6

range of ZIP-level basement predictions in the city

of Charleston ZIPs predicted ≥ 4 pCi/L (0% ≥ 2)

What this means for Charleston

The typical Charleston home is predicted below 2 pCi/L, the lowest band. That describes the average house; the ZIP-level predictions inside the city still span 1.1 to 1.6 pCi/L.

The city figure is not a separate estimate: it is the mean of the model's ZIP-code predictions, weighted by the share of the city's land in each ZIP (Census 2020 ZCTA-to-place relationship file). The 1993 EPA zone (3) for Charleston and the 2001-2021 model agree here.

Comparable South Carolina cities: Summerville (1.4), Mount Pleasant (1.4), Goose Creek (1.4), Columbia (1.3).

ZIP codes in Charleston

ZIPs that overlap the city, largest share of its land first. Predicted basement and upstairs means are model estimates; ZIPs the model does not cover show a dash.

ZIP	Share of city	Basement	Upstairs	Grade
29492	30%	1.4 ± 0.07	0.7	Low
29414	20%	1.4 ± 0.07	0.7	Low
29412	18%	1.5 ± 0.06	0.7	Low
29455	14%	1.6 ± 0.07	0.8	Low
29407	11%	1.2 ± 0.07	0.6	Low
29403	5%	1.1 ± 0.06	0.6	Low
29401	1%	1.1 ± 0.06	0.7	Low
29405	1%	1.1 ± 0.06	0.6	Low
29409	<1%	—	—	no model
29424	<1%	—	—	no model
29425	<1%	—	—	no model

Testing help in South Carolina

We link only state program pages we could verify, and South Carolina's did not respond when we checked, so start from the EPA state radon contacts page. If a test comes back at 4 pCi/L or higher, mitigation typically costs $800-$2,500 installed; use EPA find-a-professional and read the mitigation guide.

Charleston radon questions

Is radon high in Charleston, South Carolina?: Low. Averaging the model's ZIP-code predictions across Charleston (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.4 pCi/L - about 23% below the US average of 1.8 and about 15% below the South Carolina average of 1.6. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Charleston ranks 4 of 9 South Carolina cities on this site.
Which Charleston ZIP codes have the highest radon?: Predictions for the 8 modeled ZIP codes in Charleston range from 1.1 to 1.6 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 0% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.
Should I test for radon in Charleston?: Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Charleston's low predicted average describes the typical home, not yours.
What does EPA Radon Zone 3 mean for Charleston?: Charleston sits mainly in Charleston County, which the EPA classifies as Zone 3 - low potential (< 2 pCi/L). The zone map dates from 1993 and covers whole counties. The 2001-2021 model agrees with the zone for the city. Neither replaces a test of your own home.

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