Is radon high in Sioux Falls, South Dakota?

Moderate. Averaging the model's ZIP-code predictions across Sioux Falls (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 3.0 pCi/L - about 1.7× the US average of 1.8 and about 22% below the South Dakota average of 3.9. That is in the 2-4 pCi/L range where the EPA says to consider fixing. Sioux Falls ranks 2 of 2 South Dakota cities on this site.

Which Sioux Falls ZIP codes have the highest radon?

Predictions for the 7 modeled ZIP codes in Sioux Falls range from 2.7 to 3.4 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 100% 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 Sioux Falls?

Yes, soon. With a predicted basement average of 3.0 pCi/L, a meaningful share of Sioux Falls homes will test above the 4 pCi/L action level. Start with a short-term kit; if it reads 2 or higher, confirm with a long-term test or a continuous monitor before paying for mitigation.

What does EPA Radon Zone 1 mean for Sioux Falls?

Sioux Falls sits mainly in Minnehaha County, which the EPA classifies as Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and covers whole counties. The newer model's city average of 3.0 pCi/L does not line up with Zone 1, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.

Radon levels in Sioux Falls, South Dakota

ModerateEPA Zone 1

Predicted long-term basement average of 3.0 pCi/L (model estimate) across the 7 modeled ZIP codes in Sioux Falls - about 1.7× the US average of 1.8, about 22% below the South Dakota average of 3.9. Ranked #2 of 2 South Dakota cities on this site. Most of the city lies in Minnehaha County (its ZIPs also reach into 1 other county).

Test Sioux Falls, SD - the EPA says "consider fixing" in this range

The predicted basement average here is 3.0 pCi/L, in the 2-4 pCi/L band where the EPA recommends considering mitigation. Plenty of individual homes in a moderate area test above 4. Start with a short-term test; if it comes back at 2 or higher, follow up with a long-term test or a continuous monitor.

Get a short-term test kit →Or track it with a continuous monitor

Already tested at 4 pCi/L or higher? Find a certified mitigation professional (EPA). A mitigation system typically runs $800-$2,500 installed.

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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.

3.0 ± 0.08

pCi/L predicted basement mean (model SD)

1.9 ± 0.07

pCi/L predicted upstairs (above-ground) mean

2.7-3.4

range of ZIP-level basement predictions in the city

of Sioux Falls ZIPs predicted ≥ 4 pCi/L (100% ≥ 2)

What this means for Sioux Falls

The typical Sioux Falls home is predicted in the 2-4 pCi/L band. The EPA's guidance for this range is to consider fixing, because there is no known safe level and a meaningful minority of homes in a moderate area will test above 4.

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). Note that the EPA classifies Minnehaha County as Zone 1 while the newer model predicts 3.0 pCi/L for Sioux Falls; where they disagree, we grade on the model but show both.

Comparable South Dakota cities: Rapid City (4.8), Cheyenne (2.4), Casper (3.2), Billings (2.9).

ZIP codes in Sioux Falls

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
57104	20%	2.9 ± 0.06	1.7	Moderate
57108	15%	2.7 ± 0.09	1.9	Moderate
57106	15%	3.3 ± 0.10	2.0	Moderate
57107	14%	3.4 ± 0.06	2.0	Moderate
57110	14%	3.0 ± 0.07	1.8	Moderate
57103	12%	2.8 ± 0.08	1.7	Moderate
57105	10%	3.3 ± 0.07	2.2	Moderate
57117	<1%	—	—	no model
57197	<1%	—	—	no model

Testing help in South Dakota

South Dakota's radon program page is at danr.sd.gov and, when we checked it, offered a limited number of free radon test kits (500 announced). 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.

Sioux Falls radon questions

Is radon high in Sioux Falls, South Dakota?: Moderate. Averaging the model's ZIP-code predictions across Sioux Falls (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 3.0 pCi/L - about 1.7× the US average of 1.8 and about 22% below the South Dakota average of 3.9. That is in the 2-4 pCi/L range where the EPA says to consider fixing. Sioux Falls ranks 2 of 2 South Dakota cities on this site.
Which Sioux Falls ZIP codes have the highest radon?: Predictions for the 7 modeled ZIP codes in Sioux Falls range from 2.7 to 3.4 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 100% 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 Sioux Falls?: Yes, soon. With a predicted basement average of 3.0 pCi/L, a meaningful share of Sioux Falls homes will test above the 4 pCi/L action level. Start with a short-term kit; if it reads 2 or higher, confirm with a long-term test or a continuous monitor before paying for mitigation.
What does EPA Radon Zone 1 mean for Sioux Falls?: Sioux Falls sits mainly in Minnehaha County, which the EPA classifies as Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and covers whole counties. The newer model's city average of 3.0 pCi/L does not line up with Zone 1, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.

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