Is radon high in Sioux County, Iowa?

High. The model predicts a long-term basement average of 6.3 pCi/L in Sioux County (about 3.5× the US average of 1.8 and about 1.8× the Iowa average of 3.5). That is at or above the EPA action level of 4 pCi/L, so the typical home here would qualify for mitigation. Ranked 1 of 99 Iowa counties.

Should I test for radon in Sioux County?

Yes, soon. With a predicted average of 6.3 pCi/L and at least one ZIP predicted at 7.3, many homes in Sioux County will test above the 4 pCi/L action level. Use a short-term kit first; if it reads 2 or higher, confirm with a long-term test or continuous monitor before deciding on mitigation.

What does EPA Radon Zone 1 mean for Sioux County?

Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and classifies whole counties. The 2001-2021 model agrees with the zone here. Neither replaces a test of your own home.

How much does radon mitigation cost in Sioux County?

A standard active sub-slab depressurization system typically runs $800-$2,500 installed nationally; Iowa quotes vary with foundation type (slab, crawlspace, basement), home size and local labor. Get two or three bids from certified mitigators listed by your state radon program or the EPA's find-a-professional page.

Radon levels in Sioux County, Iowa

HighEPA Zone 1

Predicted long-term basement average of 6.3 pCi/L (model estimate) across 12 ZIP codes - about 3.5× the US average of 1.8, about 1.8× the Iowa average of 3.5. Ranked #1 of 99 Iowa counties.

Test Sioux County, IA now - and consider a continuous monitor

The model predicts a long-term basement average of 6.3 pCi/L here, at or above the EPA action level of 4. Homes in the same ZIP still vary widely, so a real test is the only way to know your number. A continuous digital monitor shows how your level swings with weather and season, which matters when you're near the action level.

Get a continuous radon monitor →Or start with a short-term test kit

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.

6.3 ± 0.08

pCi/L predicted basement mean (model SD)

3.1 ± 0.08

pCi/L predicted upstairs (above-ground) mean

3.9-7.3

range of ZIP-level basement predictions in the county

What this means for Sioux

The typical home in Sioux County is predicted to sit at or above the EPA action level of 4 pCi/L in the basement. In practice that means a large share of houses here would qualify for mitigation if tested, and buyers routinely ask for radon tests in Iowa transactions.

The 1993 EPA zone (1) and the 2001-2021 model agree for Sioux. County figures weight each ZIP by its 2010 Census population, so they describe where people live rather than empty land.

Comparable Iowa counties: Shelby County (6.1), Cherokee County (6.0), Ida County (6.0), Plymouth County (5.9).

ZIP codes in Sioux County

Predicted basement and upstairs means by ZIP (model estimate). ZIPs whose land is mostly in this county.

ZIP	Basement	Upstairs	Grade
51250	7.3 ± 0.10	3.3	High
51041	6.8 ± 0.10	3.5	High
51201	5.7 ± 0.06	2.8	High
51247	5.3 ± 0.07	2.7	High
51023	4.8 ± 0.06	2.6	High
51239	7.0 ± 0.07	3.4	High
51003	6.2 ± 0.07	3.4	High
51234	6.7 ± 0.06	3.3	High
51027	5.7 ± 0.06	3.1	High
51238	6.5 ± 0.07	3.3	High
51036	6.1 ± 0.06	2.9	High
51011	3.9 ± 0.06	2.2	Moderate

If your test comes back at 4 pCi/L or higher

Mitigation is a routine job: a fan-driven pipe that vents soil gas from under the slab to above the roofline, typically $800-$2,500 installed (typical range; local quotes vary). Use certified professionals: EPA find-a-professional. Read the full mitigation guide.

Sioux County radon questions

Is radon high in Sioux County, Iowa?: High. The model predicts a long-term basement average of 6.3 pCi/L in Sioux County (about 3.5× the US average of 1.8 and about 1.8× the Iowa average of 3.5). That is at or above the EPA action level of 4 pCi/L, so the typical home here would qualify for mitigation. Ranked 1 of 99 Iowa counties.
Should I test for radon in Sioux County?: Yes, soon. With a predicted average of 6.3 pCi/L and at least one ZIP predicted at 7.3, many homes in Sioux County will test above the 4 pCi/L action level. Use a short-term kit first; if it reads 2 or higher, confirm with a long-term test or continuous monitor before deciding on mitigation.
What does EPA Radon Zone 1 mean for Sioux County?: Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and classifies whole counties. The 2001-2021 model agrees with the zone here. Neither replaces a test of your own home.
How much does radon mitigation cost in Sioux County?: A standard active sub-slab depressurization system typically runs $800-$2,500 installed nationally; Iowa quotes vary with foundation type (slab, crawlspace, basement), home size and local labor. Get two or three bids from certified mitigators listed by your state radon program or the EPA's find-a-professional page.

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