Skip to content
RADON411

Locations and reports

Radon Levels in Box Elder County, Utah

EPA puts Box Elder County in Zone 2, its middle radon zone, and high results are common there: 57.9% of the 449 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

    57.9%

    21.8 pts above UT

    Box Elder
    57.9%
    Utah
    36.1%

    449 tests, 2023

  • Median result

    4.9pCi/L

    Action level reached

    Box Elder
    4.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    449

    8th of 22 by tests

    Box Elder
    449
    Salt Lake
    9,658

    Reported to CDC before any fix, 2023

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in Utah

    6 of 22

    Top quarter

    Box Elder
    57.9%
    Beaver
    66.7%

    By share, of 22 with 30+ tests

Read a result for Box Elder County

Starts at Box Elder 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. Box Elder County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Box Elder County, At a glance

Box Elder County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Box Elder County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

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

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Box Elder County, 2023

Share of reported tests at or above 4 pCi/L, by year, Box Elder County
Share of reported tests at or above 4 pCi/L, by year, Box Elder County
YearShare of reported tests at or above 4 pCi/L
201481.3%
201562.1%
201653.1%
201756.8%
201854.3%
201934.6%
202055.4%
202160.0%
202263.5%
202357.9%

2023: 57.9%. Across these years the share ran from 34.6% to 81.3%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 449 tests reported to CDC for Box Elder 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

Box Elder County, Compared

Box Elder County radon figures, compared

Calculated by Radon411

More than half: 57.9% of the 449 radon tests reported to CDC for Box Elder County in 2023 read at least 4 pCi/L. That places it 6th of 22 Utah counties with 30 or more tests for the same period. That is 21.8 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 125.3 pCi/L. The rest split 22.5% under 2 pCi/L and 19.6% from 2 to 4 (Utah: 35.4% and 28.5%). The reported tests do not follow EPA's Zone 2 label for Box Elder County (predicted average between 2 and 4 pCi/L): 57.9% of them reached 4 pCi/L, fewer than that label suggests.

No bordering county with a figure for the same period reported a higher share; the closest is Cache County at 53.8%, the lowest Davis County at 28.4%. 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 2023, with 449 tests reported; the quietest, 2019, had 26.

Over 9 years of annual figures the share fell 23.4 points, from 81.3% in 2014 to 57.9% in 2023; its peak was 81.3% in 2014. Nationally, every county with a figure for the same period pools to 33.4%; Box Elder County sits 24.5 points above it. CDC also counts 61 tests taken after mitigation in Box Elder 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, Box Elder County against Utah2014 to 2023, years with 30 or more tests: Box Elder County 81.3% to 57.9%, the state's pooled share 36.1% in 2023.
Box Elder CountyUtah, pooled
Share of reported tests at or above 4 pCi/L by year, Box Elder County against Utah: data table
YearTestsBox Elder County, at or above 4 pCi/LUtah, pooled
20148081.3%43.4%
20159562.1%42.3%
20169653.1%39.8%
20178156.8%38.2%
20184654.3%36.6%
20207455.4%37.6%
20214060.0%34.2%
202244463.5%37.7%
202344957.9%36.1%
Box Elder County against Utah, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Box Elder County
Box Elder County44957.9%4.9 pCi/LThis county
Utah, pooled29 counties, pooled27,42236.1%Not pooled−21.8 points
United States, pooled642 counties, pooled128,74033.4%Not pooled−24.5 points
Beaver Countyhighest in the state4266.7%9.3 pCi/L+8.8 points
Washington Countylowest in the state6579.9%1.3 pCi/L−48.0 points
Cache County, UTborders it99453.8%4.4 pCi/L−4.1 points
Tooele County, UTborders it57351.0%4.1 pCi/L−6.9 points
Weber County, UTborders it1,66928.6%2.1 pCi/L−29.3 points
Davis County, UTborders it3,59428.4%2.4 pCi/L−29.5 points
Where Box Elder County's reported results fell, 2023, beside Utah and the United States
ResultBox Elder County testsBox Elder County shareUtah shareU.S. shareAgainst Utah
Under 2 pCi/L10122.5%35.4%41.4%−12.9 points
2 to 4 pCi/L8819.6%28.5%25.2%−8.9 points
4 pCi/L and above26057.9%36.1%33.4%+21.8 points
Box Elder 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
Beaver County1 of 224266.7%9.3 pCi/L
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
Box Elder County radon tests by year, against Utah's pooled share
YearTestsAt or above 4 pCi/LMedianHighestUtah, pooledChange from the row before
202344957.9%4.9 pCi/L125.3 pCi/L36.1%−5.6 points
202244463.5%5.7 pCi/L68.6 pCi/L37.7%+3.5 points
20214060.0%5.7 pCi/L27.2 pCi/L34.2%+4.6 points
20207455.4%4.3 pCi/L52.3 pCi/L37.6%+20.8 points
20192634.6%2.7 pCi/L42.5 pCi/L37.7%−19.7 points
20184654.3%5.7 pCi/L34.1 pCi/L36.6%−2.5 points
20178156.8%4.7 pCi/L27.5 pCi/L38.2%+3.7 points
20169653.1%4.5 pCi/L43.9 pCi/L39.8%−9.0 points
20159562.1%6.1 pCi/L90.4 pCi/L42.3%−19.2 points
20148081.3%9.1 pCi/L50.6 pCi/L43.4%First on file

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

Box Elder County, Geology

The ground under Box Elder County

Predicted

Most of the ground under Box Elder County is one class on USGS's geologic map: 97.4% of its land is moderate radon potential, with 2.6% high. 97.3% of it lies in the area the map calls Basin and Range, to which USGS gives a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Box Elder County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Basin and RangeQuaternary sedimentary and igneous rocks.Moderate1197.3%
Wasatch RangePrecambrian granite and gneiss and Tertiary igneous rocks that have relatively low uranium concentrations.High142.6%

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

Box Elder County beside the ground around it

Utah as a whole has more high-potential ground than Box Elder County: 32.8% of its land, against 2.6% here. Of the 7 counties that border it, 4 have more high-potential ground, Cache County the most at 44.7%.

Share of land by USGS radon potential: Box Elder County, the 7 counties bordering it and Utah
AreaEPA zoneLow potentialModerate potentialHigh potential
Box Elder CountyZone 2None97.4%2.6%
Davis CountyZone 2None85.9%14.1%
Oneida County, IDZone 2None99.6%0.4%
Weber CountyZone 2None56.7%43.3%
Cache CountyZone 2None55.3%44.7%
Tooele CountyZone 2None100%None
Cassia County, IDZone 2None100%None
Elko County, NVZone 2None88.5%11.5%
Utah29 counties, pooled by land areaVariesNone67.2%32.8%

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

Local help

Box Elder County, Local resources

Radon testing and mitigation in Box Elder 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

Box Elder County, Questions

Questions about radon in Box Elder County

Are radon levels high in Box Elder County?

In 2023, 57.9% of the radon tests reported to CDC for Box Elder 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, 5 reported a higher share; pooled, the state comes to 36.1%.

Which counties border Box Elder County?

Box Elder County borders 7 counties: Davis County, UT, Oneida County, ID, Weber County, UT, Cache County, UT, Tooele County, UT, Cassia County, ID and Elko County, NV.

Products

Box Elder County, Products

Testing a home in Box Elder County

In Box Elder County, 57.9% of 449 tests reported to CDC in 2023 reached 4 pCi/L, against 36.1% pooled across Utah. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Box Elder County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Box Elder County homes, compared

Explore

Box Elder County, Bordering counties

Counties bordering Box Elder County

Calculated by Radon411

Box Elder County, Cities and towns

Cities and towns in Box Elder County

Box Elder County is growing: the Census Bureau puts it at 65,320 residents on July 1, 2025, up 12.7% from 57,944 in 2020. That works out to 11 people per square mile of land. Its largest town, Brigham City, has 20,633 residents, 31.6% of the total. Together its 16 incorporated places hold 82.5% of those residents; the other 17.5% live outside any of them. CDC's 449 reported tests for 2023 work out to 6.9 per 1,000 residents (2025 estimate), close to Utah's 7.7.

From Brigham City to Snowville, CDC publishes no figure by town: each reads Box Elder County's.

The 12 largest cities and towns in Box Elder County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Brigham City20,633+4.8%31.6%
Tremonton12,934+29.7%19.8%
Perry6,226+11.5%9.5%
Garland2,915+12.6%4.5%
Willard2,486+23.4%3.8%
Honeyville1,806+11.7%2.8%
Mantua1,389+24.7%2.1%
Elwood1,375+16.8%2.1%
Bear River City918+4.6%1.4%
Corinne881+6.8%1.3%
Fielding626+12.4%1.0%
Plymouth517+20.2%0.8%
  • Deweyville
  • Portage
  • Howell
  • Snowville

16 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).

Box Elder County, Homes

Homes in Box Elder County

Box Elder County is a place of houses on their own lots: 78% of its 20,280 homes are detached single-family houses, against 67% across Utah. The homes are older than Utah's as a whole: half were built before 1981 (1991 for Utah), and 24% date from before 1960. Owners live in 76% of the occupied homes (Utah: 71%), so for most households a test and a fix are their own to order.

Homes in Box Elder County, Utah, 2019 to 2023
HomesBox Elder CountyUtah
Housing units20,2801,193,082
Detached houses78%67%
In buildings of 5 or more6%16%
Mobile homes4%3%
Built before 196024%16%
Built since 200029%37%
Middle year built19811991
Owner-occupied76%71%

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