Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Smith County, Kansas
EPA puts Smith County in Zone 1, its highest radon zone, and only 9 radon tests from it are on file with CDC (2022). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
63.0%
25.7 pts above KS
- Smith
- 63.0%
- Kansas
- 37.3%
46 tests, 2017
Median result
5.5pCi/L
Action level reached
- Smith
- 5.5 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2017
Tests reported
46
34th of 45 by tests
- Smith
- 46
- Johnson
- 9,462
Reported to CDC before any fix, 2017
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Kansas
3 of 45
Top quarter
- Smith
- 63.0%
- Sheridan
- 67.7%
By share, of 45 with 30+ tests
Read a result for Smith County
Starts at Smith County's median, 5.5 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 5.5 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Smith County's median reported result, 2017.
The data
Smith County, At a glance
Smith County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Smith County in
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 Smith County, 2022
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2016 | 87.5% |
| 2017 | 63.0% |
| 2018 | 80.0% |
| 2019 | 75.0% |
| 2020 | 75.0% |
| 2021 | 87.5% |
| 2022 | 33.3% |
2022: 33.3%. Across these years the share ran from 33.3% to 87.5%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 9 tests were reported to CDC for Smith County over 2022, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.
Measured: CDC tracking data. Figure above: 2022. Measured data period: 2016 to 2022 (every CDC figure on file).
Smith County, Compared
Smith County radon figures, compared
Calculated by Radon411More than half: 63.0% of the 46 radon tests reported to CDC for Smith County in 2017 read at least 4 pCi/L. That places it 3rd of 45 Kansas counties with 30 or more tests for the same period. That is 25.7 points above the 37.3% pooled from 97 Kansas counties.
The newest figure, in 2022, counts only 9 tests (33.3% at or above 4 pCi/L), too few to compare, so this reading uses the 46-test figure.
The median result, 5.5 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 24.4 pCi/L. The rest split 26.1% under 2 pCi/L and 10.9% from 2 to 4 (Kansas: 39.5% and 23.2%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 63.0% share point the same way here.
1 of its 3 bordering counties with figures ran higher, led by Webster County, NE at 84.6%; Franklin County, NE reported 50.0%. Statewide for the same period, Sheridan County reported the highest share (67.7%) and Reno County the lowest (21.6%).
The busiest year on file was 2017, with 46 tests reported; the quietest, 2020, had 4.
Nationally, every county with a figure for the same period pools to 31.7%; Smith County sits 31.3 points above it. CDC also counts 6 tests taken after mitigation in Smith County for the same period: tests in homes where a fix was already in.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Smith County, Geology
The ground under Smith County
PredictedUSGS's geologic map puts all of Smith County's mapped land in one class: high radon potential. 96.9% of it lies in the area the map calls Smoky Hills, to which USGS gives a radon index of 12, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Smoky Hills | Cretaceous marine sandstone, shale, and siltstone covered by discontinuous loess deposits. | High | 12 | 96.9% |
| Ogallala Formation | Tertiary sandstone, in part covered by windblown eolian sand and loess deposits. | High | 12 | 3.1% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Smith County beside the ground around it
Smith County has more high-potential ground than Kansas as a whole: 100% of its land against 59.9%. Of the 6 counties that border it, none has as large a share of high-potential ground; Jewell County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Smith County, Local resources
Radon testing and mitigation in Smith County
- Kansas Radon ProgramKansas Radon Program answers questions about testing, mitigation and the rules in Kansas.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsAsk the program whether it has free or discounted kits, or compare kits you can buy.
- Compare kits
- Professionals in Kansas178 professionals are listed in Kansas.
What Kansas's program says
- Phone
- (800) 693-5343
What it means
Smith County, Questions
Questions about radon in Smith County
Are radon levels high in Smith County?
In 2022, 33.3% of the radon tests reported to CDC for Smith County, Kansas were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.9 pCi/L. Of 45 Kansas counties with 30 or more tests for the same period, 2 reported a higher share; pooled, the state comes to 37.3%.
Which counties border Smith County?
Smith County borders 6 counties: Osborne County, KS, Franklin County, NE, Phillips County, KS, Jewell County, KS, Webster County, NE and Rooks County, KS.
Products
Smith County, Products
Testing a home in Smith County
In Smith County, 63.0% of 46 tests reported to CDC in 2017 reached 4 pCi/L, against 37.3% pooled across Kansas. In Zone 1 the year-round level in Smith County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.
Test kits and monitors3
See every kit and monitor
Monitor
Wave Radon battery smart radon monitor
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- App only
Method: Alpha spectrometry
Short-term kitFirst Alert
RD1 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 2 to 4 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Smith County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Smith County
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Smith County, Bordering counties
Counties bordering Smith County
Calculated by Radon411- Radon levels in Webster County, NEEPA zone 1
84.6%at or above 4 pCi/L
Median 6.0 pCi/L · 78 tests · 21.6 points above Smith County
- Radon levels in Osborne County, KSEPA zone 1
75.0%at or above 4 pCi/L
Median 6.2 pCi/L · 12 tests · 12.0 points above Smith County
- Radon levels in Phillips County, KSEPA zone 1
68.4%at or above 4 pCi/L
Median 5.0 pCi/L · 19 tests · 5.4 points above Smith County
- Radon levels in Jewell County, KSEPA zone 1
59.2%at or above 4 pCi/L
Median 6.6 pCi/L · 49 tests · 3.8 points below Smith County
- Radon levels in Franklin County, NEEPA zone 1
50.0%at or above 4 pCi/L
Median 3.6 pCi/L · 66 tests · 13.0 points below Smith County
- Radon levels in Rooks County, KSEPA zone 1
50.0%at or above 4 pCi/L
Median 3.8 pCi/L · 6 tests · 13.0 points below Smith County
Smith County, Cities and towns
Cities and towns in Smith County
Smith County's population has barely moved since 2020: 3,566 residents on July 1, 2025 against 3,566 then, by the Census Bureau's estimates. Spread over its land, that is 4.0 people to the square mile. Its largest town, Smith Center, has 1,575 residents, 44.2% of the total. Together its 6 incorporated places hold 64.5% of those residents; the other 35.5% live outside any of them. Testing is reported here more often than across the state: CDC's 46 reported tests for 2017 come to 12.9 for every 1,000 residents (2025 estimate), against 8.0 for Kansas.
From Smith Center to Cedar, CDC publishes no figure by town: each reads Smith County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Smith Center | 1,575 | +0.1% | 44.2% |
| Kensington | 400 | Level | 11.2% |
| Lebanon | 183 | Level | 5.1% |
| Gaylord | 90 | +1.1% | 2.5% |
| Athol | 40 | −2.4% | 1.1% |
| Cedar | 12 | Level | 0.3% |
6 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).
Smith County, Homes
Homes in Smith County
Smith County is a place of houses on their own lots: 90% of its 2,023 homes are detached single-family houses, against 72% across Kansas. The homes are older than Kansas' as a whole: half were built before 1954 (1975 for Kansas), and 56% date from before 1960. Owners live in 83% of the occupied homes (Kansas: 67%), so for most households a test and a fix are their own to order.
| Homes | Smith County | Kansas |
|---|---|---|
| Housing units | 2,023 | 1,285,221 |
| Detached houses | 90% | 72% |
| In buildings of 5 or more | 2% | 13% |
| Mobile homes | 2% | 4% |
| Built before 1960 | 56% | 33% |
| Built since 2000 | 5% | 20% |
| Middle year built | 1954 | 1975 |
| Owner-occupied | 83% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.