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Radon Levels in Sevier County, Utah

EPA puts Sevier County in Zone 1, its highest radon zone, and high results are common there: 57.4% of the 101 radon tests reported to CDC (2023) came back at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    57.4%

    21.3 pts above UT

    Sevier
    57.4%
    Utah
    36.1%

    101 tests, 2023

  • Median result

    4.9pCi/L

    Action level reached

    Sevier
    4.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    101

    15th of 22 by tests

    Sevier
    101
    Salt Lake
    9,658

    Reported to CDC before any fix, 2023

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Utah

    7 of 22

    Middle half

    Sevier
    57.4%
    Beaver
    66.7%

    By share, of 22 with 30+ tests

Read a result for Sevier County

Starts at Sevier County's median, 4.9 pCi/L

4.9pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 4.9 pCi/L

At or above 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 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. Sevier County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Sevier County, At a glance

Sevier County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Sevier County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

USGS geologic potential: High across 97% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Sevier County, 2023

Share of reported tests at or above 4 pCi/L, by year, Sevier County
Share of reported tests at or above 4 pCi/L, by year, Sevier County
YearShare of reported tests at or above 4 pCi/L
201433.3%
201552.4%
201661.9%
201752.2%
201862.1%
201966.7%
202045.0%
202128.6%
202249.1%
202357.4%

2023: 57.4%. Across these years the share ran from 28.6% to 66.7%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 101 tests reported to CDC for Sevier County over 2023, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.

Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Sevier County, Compared

Sevier County radon figures, compared

Calculated by Radon411

More than half: 57.4% of the 101 radon tests reported to CDC for Sevier County in 2023 read at least 4 pCi/L. That places it 7th of 22 Utah counties with 30 or more tests for the same period. That is 21.3 points above the 36.1% pooled from 29 Utah counties.

The median result, 4.9 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 121.2 pCi/L. The rest split 26.7% under 2 pCi/L and 15.8% from 2 to 4 (Utah: 35.4% and 28.5%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 57.4% share point the same way here.

3 of its 4 bordering counties with figures ran higher, led by Beaver County at 66.7%; Emery County reported 38.5%. Statewide for the same period, Beaver County reported the highest share (66.7%) and Washington County the lowest (9.9%).

The busiest year on file was 2022, with 159 tests reported; the quietest, 2014, had 6.

Over 3 years of annual figures the share fell 4.5 points, from 61.9% in 2016 to 57.4% in 2023; its peak was 61.9% in 2016. Nationally, every county with a figure for the same period pools to 33.4%; Sevier County sits 24.0 points above it. CDC also counts 14 tests taken after mitigation in Sevier County for the same period: tests in homes where a fix was already in.

Share of reported tests at or above 4 pCi/L by year, Sevier County against Utah2016 to 2023, years with 30 or more tests: Sevier County 61.9% to 57.4%, the state's pooled share 36.1% in 2023.
Sevier CountyUtah, pooled
Share of reported tests at or above 4 pCi/L by year, Sevier County against Utah: data table
YearTestsSevier County, at or above 4 pCi/LUtah, pooled
20164261.9%39.8%
202215949.1%37.7%
202310157.4%36.1%
Sevier County against Utah, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Sevier County
Sevier County10157.4%4.9 pCi/LThis county
Utah, pooled29 counties, pooled27,42236.1%Not pooled−21.3 points
United States, pooled642 counties, pooled128,74033.4%Not pooled−24.0 points
Juab Countyhighest in the state4963.3%5.0 pCi/L+5.9 points
Washington Countylowest in the state6579.9%1.3 pCi/L−47.5 points
Wayne County, UTborders it2770.4%5.5 pCi/L+13.0 points
Beaver County, UTborders it4266.7%9.3 pCi/L+9.3 points
Sanpete County, UTborders it15060.0%4.6 pCi/L+2.6 points
Millard County, UTborders it5558.2%4.4 pCi/L+0.8 points
Emery County, UTborders it3938.5%2.7 pCi/L−18.9 points
Piute County, UTborders it10.0%3.3 pCi/L−57.4 points
Where Sevier County's reported results fell, 2023, beside Utah and the United States
ResultSevier County testsSevier County shareUtah shareU.S. shareAgainst Utah
Under 2 pCi/L2726.7%35.4%41.4%−8.7 points
2 to 4 pCi/L1615.8%28.5%25.2%−12.7 points
4 pCi/L and above5857.4%36.1%33.4%+21.3 points
Sevier County ranked among the 22 Utah counties with 30 or more tests, by share at or above 4 pCi/L, 2023
CountyRankTestsAt or above 4 pCi/LMedian
Juab County2 of 224963.3%5.0 pCi/L
Sanpete County3 of 2215060.0%4.6 pCi/L
Morgan County4 of 2220759.4%5.0 pCi/L
Millard County5 of 225558.2%4.4 pCi/L
Box Elder County6 of 2244957.9%4.9 pCi/L
Sevier County7 of 2210157.4%4.9 pCi/L
Cache County8 of 2299453.8%4.4 pCi/L
Wasatch County9 of 2232451.9%4.2 pCi/L
Uintah County10 of 2210451.0%4.2 pCi/L
Tooele County11 of 2257351.0%4.1 pCi/L
Utah County12 of 227,83340.6%3.2 pCi/L
Sevier County radon tests by year, against Utah's pooled share
YearTestsAt or above 4 pCi/LMedianHighestUtah, pooledChange from the row before
202310157.4%4.9 pCi/L121.2 pCi/L36.1%+8.3 points
202215949.1%3.5 pCi/L990.0 pCi/L37.7%+20.5 points
20211428.6%2.5 pCi/L9.1 pCi/L34.2%−16.4 points
20202045.0%3.5 pCi/L14.2 pCi/L37.6%−21.7 points
20191266.7%4.3 pCi/L19.0 pCi/L37.7%+4.6 points
20182962.1%5.8 pCi/L64.5 pCi/L36.6%+9.9 points
20172352.2%4.4 pCi/L20.9 pCi/L38.2%−9.7 points
20164261.9%4.4 pCi/L56.5 pCi/L39.8%+9.5 points
20152152.4%5.2 pCi/L31.3 pCi/L42.3%+19.1 points
2014633.3%3.3 pCi/L11.7 pCi/L43.4%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Sevier County, Geology

The ground under Sevier County

Predicted

Most of the ground under Sevier County is one class on USGS's geologic map: 96.7% of its land is high radon potential, with 3.3% moderate. The map puts 45.4% of Sevier County in the area it calls High Plateau and 35.7% in Northern High Plateau, with 2 smaller areas beside them. USGS gives the first a radon index of 13 and the second 12, both in the high band (12 to 17).

USGS's geologic areas under Sevier County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
High PlateauTertiary volcanic and volcaniclastic rocks.High1345.4%
Northern High PlateauTertiary and Cretaceous sedimentary rocks.High1235.7%
Mancos Shale LowlandsMarine rocks of the Mancos shale.High1315.6%
Colorado PlateauPaleozoic and Mesozoic sandstone, shale, limestone.Moderate93.3%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Sevier County beside the ground around it

Sevier County has more high-potential ground than Utah as a whole: 96.7% of its land against 32.8%. Of the 6 counties that border it, 2 have more high-potential ground, Piute County the most at 100%.

Share of land by USGS radon potential: Sevier County, the 6 counties bordering it and Utah
AreaEPA zoneLow potentialModerate potentialHigh potential
Sevier CountyZone 1None3.3%96.7%
Piute CountyZone 1NoneNone100%
Sanpete CountyZone 1NoneNone100%
Wayne CountyZone 2None85.7%14.3%
Emery CountyZone 2None56.3%43.7%
Millard CountyZone 2None90.7%9.3%
Beaver CountyZone 2None85.3%14.7%
Utah29 counties, pooled by land areaVariesNone67.2%32.8%

The map rates the ground, not the air in any home.

Local help

Sevier County, Local resources

Radon testing and mitigation in Sevier County

What Utah's program says
Phone
(801) 536-0091
Disclosure when a home is sold or rented
Utah requires that sellers disclose "Hazardous Conditions: Are there any hazardous conditions on the Property such as Radon gas in house or well?"

What it means

Sevier County, Questions

Questions about radon in Sevier County

Are radon levels high in Sevier County?

In 2023, 57.4% of the radon tests reported to CDC for Sevier County, Utah were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.9 pCi/L. Of 22 Utah counties with 30 or more tests for the same period, 6 reported a higher share; pooled, the state comes to 36.1%.

Which counties border Sevier County?

Sevier County borders 6 counties: Piute County, Sanpete County, Wayne County, Emery County, Millard County and Beaver County.

Products

Sevier County, Products

Testing a home in Sevier County

In Sevier County, 57.4% of 101 tests reported to CDC in 2023 reached 4 pCi/L, against 36.1% pooled across Utah. In Zone 1 the year-round level in Sevier 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

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

Explore

Sevier County, Bordering counties

Counties bordering Sevier County

Calculated by Radon411

Sevier County, Cities and towns

Cities and towns in Sevier County

Sevier County is growing: the Census Bureau puts it at 22,827 residents on July 1, 2025, up 5.9% from 21,554 in 2020. That works out to 12 people per square mile of land. Its largest town, Richfield, has 8,478 residents, 37.1% of the total. Together its 12 incorporated places hold 86.7% of those residents; the other 13.3% live outside any of them. Reported testing is thin here: 101 tests over 2023, or 4.4 for every 1,000 residents (2025 estimate), where Utah as a whole comes to 7.7.

From Richfield to Joseph, CDC publishes no figure by town: each reads Sevier County's.

The cities and towns in Sevier County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Richfield8,478+4.0%37.1%
Monroe2,738+8.8%12.0%
Salina2,640+6.8%11.6%
Aurora1,062+6.6%4.7%
Elsinore906+7.0%4.0%
Annabella898+6.8%3.9%
Redmond820+6.8%3.6%
Central Valley690+6.2%3.0%
Glenwood496+6.9%2.2%
Sigurd431+6.9%1.9%
Koosharem316Level1.4%
Joseph310+6.9%1.4%

12 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).

Sevier County, Homes

Homes in Sevier County

Sevier County is a place of houses on their own lots: 80% of its 8,705 homes are detached single-family houses, against 67% across Utah. The homes are older than Utah's as a whole: half were built before 1978 (1991 for Utah), and 31% date from before 1960. Owners live in 80% of the occupied homes (Utah: 71%), so for most households a test and a fix are their own to order.

Homes in Sevier County, Utah, 2019 to 2023
HomesSevier CountyUtah
Housing units8,7051,193,082
Detached houses80%67%
In buildings of 5 or more4%16%
Mobile homes8%3%
Built before 196031%16%
Built since 200022%37%
Middle year built19781991
Owner-occupied80%71%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.