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Radon Levels in Grand County, Utah

EPA puts Grand County in Zone 1, its highest radon zone, and 23.9% of its 46 reported radon tests (2023) were 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

    23.9%

    12.2 pts below UT

    Grand
    23.9%
    Utah
    36.1%

    46 tests, 2023

  • Median result

    1.9pCi/L

    Below action level

    Grand
    1.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    46

    20th of 22 by tests

    Grand
    46
    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

    19 of 22

    Lowest quarter

    Grand
    23.9%
    Beaver
    66.7%

    By share, of 22 with 30+ tests

Read a result for Grand County

Starts at Grand County's median, 1.9 pCi/L

1.9pCi/L

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

EPA’s reading of 1.9 pCi/L

Below 2 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 below 2 pCi/L, the level at which EPA says a fix should be considered. Grand County's median reported result, 2023.

Interpret this reading

The data

Grand County, At a glance

Grand County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Grand 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 68% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Grand County, 2023

Share of reported tests at or above 4 pCi/L, by year, Grand County
Share of reported tests at or above 4 pCi/L, by year, Grand County
YearShare of reported tests at or above 4 pCi/L
20145.9%
201550.0%
20160.0%
20170.0%
20185.0%
201911.1%
20200.0%
202121.2%
202217.5%
202323.9%

2023: 23.9%. Across these years the share ran from 0.0% to 50.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 46 tests reported to CDC for Grand 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

Grand County, Compared

Grand County radon figures, compared

Calculated by Radon411

Grand County's 46 reported tests in 2023 had a middle value of 1.9 pCi/L and a maximum of 41.1 pCi/L, and 23.9% reached 4 pCi/L. Utah as a whole (29 Utah counties, pooled) comes to 36.1%: 12.2 points higher than here.

Among its state's counties it ranks 19th of 22 Utah counties with 30 or more tests for the same period. Statewide for the same period, Beaver County reported the highest share (66.7%) and Washington County the lowest (9.9%).

Below the action level, 27 tests (58.7%) came in under 2 pCi/L, against 35.4% statewide, and 8 tests (17.4%) fell between 2 and 4, against 28.5% statewide. The busiest year on file was 2022, with 411 tests reported; the quietest, 2017, had 3.

EPA's 1993 zone map puts Grand County in Zone 1, a predicted county average above 4 pCi/L. USGS geology rates 68% of the county's land high radon potential.

Next door, the shares run from 18.9% in Mesa County, CO to 55.3% in Montrose County, CO, with Carbon County and Mesa County, CO below Grand County. Over 3 years of annual figures the share rose 2.7 points, from 21.2% in 2021 to 23.9% in 2023; its peak was 23.9% in 2023.

Share of reported tests at or above 4 pCi/L by year, Grand County against Utah2021 to 2023, years with 30 or more tests: Grand County 21.2% to 23.9%, the state's pooled share 36.1% in 2023.
Grand CountyUtah, pooled
Share of reported tests at or above 4 pCi/L by year, Grand County against Utah: data table
YearTestsGrand County, at or above 4 pCi/LUtah, pooled
20213321.2%34.2%
202241117.5%37.7%
20234623.9%36.1%
Grand County against Utah, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Grand County
Grand County4623.9%1.9 pCi/LThis county
Utah, pooled29 counties, pooled27,42236.1%Not pooled+12.2 points
United States, pooled642 counties, pooled128,74033.4%Not pooled+9.5 points
Beaver Countyhighest in the state4266.7%9.3 pCi/L+42.8 points
Washington Countylowest in the state6579.9%1.3 pCi/L−14.0 points
Wayne County, UTborders it2770.4%5.5 pCi/L+46.5 points
Montrose County, COborders it21555.3%4.5 pCi/L+31.4 points
San Juan County, UTborders it1952.6%4.0 pCi/L+28.7 points
Uintah County, UTborders it10451.0%4.2 pCi/L+27.1 points
Garfield County, COborders it22439.3%2.9 pCi/L+15.4 points
Emery County, UTborders it3938.5%2.7 pCi/L+14.6 points
Carbon County, UTborders it6923.2%2.3 pCi/L−0.7 points
Mesa County, COborders it56718.9%2.2 pCi/L−5.0 points
Where Grand County's reported results fell, 2023, beside Utah and the United States
ResultGrand County testsGrand County shareUtah shareU.S. shareAgainst Utah
Under 2 pCi/L2758.7%35.4%41.4%+23.3 points
2 to 4 pCi/L817.4%28.5%25.2%−11.1 points
4 pCi/L and above1123.9%36.1%33.4%−12.2 points
Grand 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
Utah County12 of 227,83340.6%3.2 pCi/L
Duchesne County13 of 228139.5%3.2 pCi/L
Emery County14 of 223938.5%2.7 pCi/L
Salt Lake County15 of 229,65833.1%2.6 pCi/L
Summit County16 of 2241732.6%2.4 pCi/L
Weber County17 of 221,66928.6%2.1 pCi/L
Davis County18 of 223,59428.4%2.4 pCi/L
Grand County19 of 224623.9%1.9 pCi/L
Carbon County20 of 226923.2%2.3 pCi/L
Iron County21 of 2221321.1%2.1 pCi/L
Washington County22 of 226579.9%1.3 pCi/L
Grand County radon tests by year, against Utah's pooled share
YearTestsAt or above 4 pCi/LMedianHighestUtah, pooledChange from the row before
20234623.9%1.9 pCi/L41.1 pCi/L36.1%+6.4 points
202241117.5%1.7 pCi/L14.6 pCi/L37.7%−3.7 points
20213321.2%2.4 pCi/L9.2 pCi/L34.2%+21.2 points
202040.0%1.4 pCi/L2.0 pCi/L37.6%−11.1 points
2019911.1%1.8 pCi/L6.9 pCi/L37.7%+6.1 points
2018205.0%1.5 pCi/L7.5 pCi/L36.6%+5.0 points
201730.0%0.9 pCi/L2.2 pCi/L38.2%Level
2016150.0%1.2 pCi/L3.4 pCi/L39.8%−50.0 points
2015450.0%3.9 pCi/L44.5 pCi/L42.3%+44.1 points
2014175.9%1.1 pCi/L4.2 pCi/L43.4%First on file

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

Grand County, Geology

The ground under Grand County

Predicted

USGS's geologic map splits Grand County: 67.9% of its land is high radon potential and 32.1% moderate. The map puts 37.4% of Grand County in the area it calls Mancos Shale Lowlands and 32.1% in Colorado Plateau, with 2 smaller areas beside them. USGS gives the first a radon index of 13, in the high band (12 to 17), and the second 9, in the moderate band (9 to 11).

USGS's geologic areas under Grand County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Mancos Shale LowlandsMarine rocks of the Mancos shale.High1337.4%
Colorado PlateauPaleozoic and Mesozoic sandstone, shale, limestone.Moderate932.1%
Uinta BasinUranium-bearing Tertiary sandstone and siltstone.High1323.9%
Uravan BeltUranium-bearing Cretaceous and Jurassic sedimentary rocks of the Uravan mineral belt.High136.7%

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

Grand County beside the ground around it

Grand County has more high-potential ground than Utah as a whole: 67.9% of its land against 32.8%. Of the 8 counties that border it, 4 have more high-potential ground, Carbon County the most at 100%.

Share of land by USGS radon potential: Grand County, the 8 counties bordering it and Utah
AreaEPA zoneLow potentialModerate potentialHigh potential
Grand CountyZone 1None32.1%67.9%
Mesa County, COZone 1None0.6%99.5%
Emery CountyZone 2None56.3%43.7%
Carbon CountyZone 1NoneNone100%
Uintah CountyZone 1None30.5%69.5%
Montrose County, COZone 1NoneNone100%
Wayne CountyZone 2None85.7%14.3%
San Juan CountyZone 2None78.3%21.7%
Garfield County, COZone 1None42.5%57.5%
Utah29 counties, pooled by land areaVariesNone67.2%32.8%

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

Local help

Grand County, Local resources

Radon testing and mitigation in Grand 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

Grand County, Questions

Questions about radon in Grand County

Are radon levels high in Grand County?

In 2023, 23.9% of the radon tests reported to CDC for Grand County, Utah were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.9 pCi/L. Of 22 Utah counties with 30 or more tests for the same period, 18 reported a higher share; pooled, the state comes to 36.1%.

Which counties border Grand County?

Grand County borders 8 counties: Mesa County, CO, Emery County, UT, Carbon County, UT, Uintah County, UT, Montrose County, CO, Wayne County, UT, San Juan County, UT and Garfield County, CO.

Products

Grand County, Products

Testing a home in Grand County

In Grand County, 23.9% of 46 tests reported to CDC in 2023 reached 4 pCi/L, against 36.1% pooled across Utah. In Zone 1 the year-round level in Grand 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

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

Explore

Grand County, Bordering counties

Counties bordering Grand County

Calculated by Radon411

Grand County, Cities and towns

Cities and towns in Grand County

The Census Bureau estimates 9,790 residents in Grand County for July 1, 2025, 107 more than in 2020 (+1.1%). Spread over its land, that is 2.7 people to the square mile. Moab alone is home to 5,206 of them, 53.2% of the total. Together its 2 incorporated places hold 56.9% of those residents; the other 43.1% live outside any of them. Reported testing is thin here: 46 tests over 2023, or 4.7 for every 1,000 residents (2025 estimate), where Utah as a whole comes to 7.7.

From Moab to Castle Valley, CDC publishes no figure by town: each reads Grand County's.

The cities and towns in Grand County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Moab5,206−3.0%53.2%
Castle Valley369+5.7%3.8%

2 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).

Grand County, Homes

Homes in Grand County

Of Grand County's 5,333 homes, 66% are detached houses, against 67% across Utah; 13% are mobile homes. Half of its homes were built before 1987, close to Utah's 1991: 15% date from before 1960 and 30% from 2000 or later. 70% of occupied homes are lived in by their owner (Utah: 71%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Grand County, Utah, 2019 to 2023
HomesGrand CountyUtah
Housing units5,3331,193,082
Detached houses66%67%
In buildings of 5 or more10%16%
Mobile homes13%3%
Built before 196015%16%
Built since 200030%37%
Middle year built19871991
Owner-occupied70%71%

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