Skip to content
RADON411

Locations and reports

Radon Levels in Plymouth County, Iowa

EPA puts Plymouth County in Zone 1, its highest radon zone. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

Predicted
Zone 1Highest predicted potential
Measured
82.3%of 1,405 tests reported to CDC (2008 to 2017) were at or above 4 pCi/L
Your home
Test to knowNo area figure here is a reading of your home.
How to test this homeFind a certified tester

The data

Plymouth County, At a glance

Plymouth County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.

What EPA predicts hereScreening level, geology

EPA predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county as a whole.

USGS geologic potential: High across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Tests reported
1,405
At or above 4 pCi/L
82.3%
Median result
8.6 pCi/L
Reported results by concentration band, Plymouth County, 2008 to 2017, laboratory
Under 2 pCi/L: 8%2 to 4 pCi/L: 10%4 pCi/L and above: 82%

Of 1,405 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Plymouth County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L1067.5%
2 to 4 pCi/L14310.2%
4 pCi/L and above1,15682.3%

CDC publishes this figure only for counties here, so there is no state or national number to compare Plymouth County, Iowa with.

What these figures count

Distribution of radon tests reported to CDC, not this house. People testing before a sale, or because they suspect a problem, are over-represented in any reported testing data.

The figures at the top are for 2008 to 2017 (laboratory totals): a percentage there is a share of radon tests reported to CDC for Plymouth County over 2008 to 2017, laboratory, and a percentage in a view below is a share of the tests reported for the year or period it names. It is not a share of homes in Plymouth County, and it is not a random sample: it counts only the tests people chose to run and that were reported.

CDC works out the shares and the median over pre-mitigation tests, counting a test not marked as before or after mitigation as one of them (1,405 for 2008 to 2017, laboratory). The median is the middle result of those tests, not of buildings. CDC also reports the number of buildings tested (903), a different count, so the two totals are not interchangeable.

Plymouth County's own published CDC figures beside those of the counties that border it, for the same period.

Each figure is that county’s own published CDC figure for 2008 to 2017, laboratory, counting radon tests reported to CDC, not homes. Plymouth County is this page. Nothing is averaged or combined across counties. The test count beside each county is CDC’s published number of pre-mitigation tests behind its figures. Figures from few tests can swing widely from year to year. Every Iowa county’s own figure is in the Iowa county table.

Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

Radon Action Brief

National Radon Action MonthPre-sale

Plymouth County's radon brief, in one dated file.

  • Your area's radon record, explained.
  • Your plan to test this week.
  • Fix costs and pros near you.

Save 64%Sale price: $8.99Price after the sale: $25Ends Jan 31Then $25

Get the Plymouth County BriefSee a free sample

Area data, not a test of the building.

Local help

Plymouth County, Local resources

Radon testing and mitigation in Plymouth County

Who tests and fixes radon in Plymouth County: listed businesses, Iowa's radon program and test kits.

Listed radon businesses with an address in Plymouth County:

Listed radon professionals by town: Sioux City, Le Mars

What Iowa's program says
Phone
(515) 281-4928
Licensing of radon professionals
Iowa’s radon program approves applications for persons who wish to become certified to perform radon testing or credentialed to perform mitigation and laboratories that provide radon testing devices and analytical services.
Disclosure when a home is sold or rented
However, per Iowa Code chapters 543B.9 and 543B.18 and Iowa Administrative Code 193E Chapter 14 administered by the Iowa Real Estate Commission, a seller must disclose any known tests for the presence of radon and if yes, provide the date of last report and the result(s).

What it means

Plymouth County, Questions

Questions about radon in Plymouth County

Common questions

8 questions, answered from the figures above

Are radon levels high in Plymouth County?

Over the 2008 to 2017 laboratory totals, 82.3% of the radon tests reported to CDC for Plymouth County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 8.6 pCi/L. That is a share of reported tests, not of homes. EPA places Plymouth County in Zone 1, highest predicted potential, a predicted average indoor screening level greater than 4 pCi/L. Homes with elevated levels occur in all three zones, so the figures describe the area, not your house. Testing is the only way to know the radon level in a specific building.

Radon levels: what a result meansWhat is radon?Radon levels in Iowa

How do I get a radon test in Plymouth County?

EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. No radon testing business listed on Radon411 has an address in Plymouth County or names it as a service area yet. The Iowa radon program is the place to ask about certified testers and any test kit offer it runs.

Radon testing: how to test a homeRadon test kits comparedFree and low-cost kits by stateRadon Action Month checklistIowa radon program

Who does radon mitigation in Plymouth County?

No listed mitigator names Plymouth County as a service area yet; the Iowa directory lists 186 companies. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional. Your state radon program is the place to check whether Iowa requires one.

Radon mitigation: how it worksRadon mitigation costRadon mitigation systemsMitigators in Iowa

What EPA radon zone is Plymouth County in?

EPA places Plymouth County, Iowa in Zone 1, which EPA describes as highest predicted potential for the area. A zone is a prediction for the whole county and never determines whether a particular home should be tested. EPA recommends testing every home regardless of zone.

Should I test my home in Plymouth County?

Yes. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. How to test a home.

When is the best time of year to test?

EPA says short-term tests stay in the home from 2 to 90 days and that all radon tests should run a minimum of 48 hours; long-term tests stay more than 90 days. EPA's guides do not name a best season: they say radon levels tend to vary from day to day and season to season, so a long-term test is more likely than a short-term test to tell you the year-round average.

What does it cost to test?

EPA's Citizen's Guide calls testing easy and inexpensive, and EPA's Home Buyer's and Seller's Guide says passive short-term and long-term devices are generally inexpensive, while active devices may cost more. No national average price is published for this, so Radon411 does not give one. What testing costs.

Which counties border Plymouth County?

Plymouth County borders 5 counties, derived from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county's report can be relevant.

If you own, buy, sell or rent

What these figures mean for each reader, with the guide that covers it

The reported-test figures on this page describe Plymouth County, Iowa over the 2008 to 2017 laboratory totals. They describe tests other people carried out in other buildings, and none of them measures yours.

Plymouth County in figures

The figures above, said in words

What the published data says about Plymouth County, in words. A zone and a share of tests describe an area, never the level in any one home.

    • Predicted

      Predicted

      EPA places Plymouth County in Zone 1, highest predicted potential, as it does 98 other counties of Iowa's 99.

      Of the 5 bordering counties, EPA places Cherokee County, O'Brien County, Sioux County, Union County, SD and Woodbury County in Zone 1.

  • Reported tests

    Measured

    CDC publishes no annual figure for Plymouth County; its figure is a laboratory total for 2008 to 2017: 82.3% of 1,405 reported tests were at or above 4 pCi/L.

  • Local record

    Iowa's radon program is the Iowa HHS Radon Program, run by Iowa Department of Health and Human Services; its contacts are under Local resources.

    The county's largest incorporated places are Sioux City, Le Mars and Remsen; the figures here cover them as part of the county.

Products

Plymouth County, Products

Testing and mitigation products

Whatever the figures for Plymouth County show, only a test tells you about one home.

Test kits and monitors42

See all products

As an Amazon Associate, Radon411 earns from qualifying purchases.

Plymouth County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Plymouth County

Testing

5

Mitigation

3

Explore

Plymouth County, Bordering counties

Counties bordering Plymouth County

Calculated by Radon411
Why bordering counties matter

5 counties share a boundary with Plymouth County, computed from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county’s report can be worth reading alongside this one.

Plymouth County, Cities and towns

Cities and towns in Plymouth County

The radon figures on this page are for Plymouth County as a whole. They do not differ by city or town.

  • Sioux City (part)
  • Le Mars
  • Remsen
  • Akron
  • Kingsley
  • Hinton
  • Merrill
  • Brunsville
  • Westfield
  • Oyens
  • Craig
  • Struble

12 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county.

Plymouth County, Next steps

What to do next

  1. LearnKnow what radon isWhat radon is, how it gets indoors, and why a county zone is not a reading for your home.Learn about radon
  2. TestTest the building you live inShort-term or long-term, where the device goes, and closed-house conditions.How to test
  3. FixBring a high level downHow a mitigation system works, and the retest that confirms it.How mitigation works
  4. Find a proHire a certified professionalMeasurement and mitigation professionals by state, with their certifications.Find a professional

Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.