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Radon Levels in San Juan County, Utah

EPA puts San Juan County in Zone 2, its middle radon zone, and only 19 radon tests from it are on file with CDC (2023). 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

    46.2%

    8.5 pts above UT

    San Juan
    46.2%
    Utah
    37.7%

    39 tests, 2022

  • Median result

    2.7pCi/L

    Below action level

    San Juan
    2.7 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2022

  • Tests reported

    39

    23rd of 24 by tests

    San Juan
    39
    Salt Lake
    15,201

    Reported to CDC before any fix, 2022

  • 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

    11 of 24

    Middle half

    San Juan
    46.2%
    Beaver
    88.9%

    By share, of 24 with 30+ tests

Read a result for San Juan County

Starts at San Juan County's median, 2.7 pCi/L

2.7pCi/L

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

EPA’s reading of 2.7 pCi/L

Between 2 and 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. San Juan County's median reported result, 2022.

Interpret this readingWhat a fix costs

The data

San Juan County, At a glance

San Juan County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

San Juan 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 78% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for San Juan County, 2023

Share of reported tests at or above 4 pCi/L, by year, San Juan County
Share of reported tests at or above 4 pCi/L, by year, San Juan County
YearShare of reported tests at or above 4 pCi/L
201450.0%
20150.0%
201650.0%
201750.0%
201890.0%
20190.0%
202116.7%
202246.2%
202352.6%

2023: 52.6%. Across these years the share ran from 0.0% to 90.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 19 tests were reported to CDC for San Juan County over 2023, 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: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

San Juan County, Compared

San Juan County radon figures, compared

Calculated by Radon411

In San Juan County, about 5 in 10 reported tests in 2022 (18 of 39) were at or above EPA's action level. Against the national pool of 23.9%, the gap is 22.3 points higher. Across 28 Utah counties pooled together, 37.7% of tests reached that level, so San Juan County runs 8.5 points above its state.

The newest figure, in 2023, counts only 19 tests (52.6% at or above 4 pCi/L), too few to compare, so this reading uses the 39-test figure.

Of 6 neighbours with a figure, 1 reported a larger share at or above 4 pCi/L and 5 a smaller one; the spread is 14.3% (Montezuma County, CO) to 52.2% (Montrose County, CO). By share, San Juan County is 11th of 24 Utah counties with 30 or more tests for the same period.

Half the tests came in under 2.7 pCi/L and half over it; the single highest reached 10.8 pCi/L. Below the action level, 12 tests (30.8%) came in under 2 pCi/L, against 33.5% statewide, and 9 tests (23.1%) fell between 2 and 4, against 28.8% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 46.2% share point the same way here. USGS geology rates 78% of the county's land moderate radon potential.

The busiest year on file was 2022, with 39 tests reported; the quietest, 2019, had 2.

San Juan County against Utah, the United States and nearby counties, 2022
AreaTestsAt or above 4 pCi/LMedianDifference from San Juan County
San Juan County3946.2%2.7 pCi/LThis county
Utah, pooled28 counties, pooled41,00437.7%Not pooled−8.5 points
United States, pooled853 counties, pooled333,14023.9%Not pooled−22.3 points
Beaver Countyhighest in the state8188.9%18.0 pCi/L+42.7 points
Washington Countylowest in the state9249.4%1.4 pCi/L−36.8 points
Wayne County, UTborders it1560.0%6.2 pCi/L+13.8 points
Montrose County, COborders it13652.2%4.3 pCi/L+6.0 points
San Miguel County, COborders it1936.8%2.2 pCi/L−9.4 points
Dolores County, COborders it333.3%0.3 pCi/L−12.9 points
Garfield County, UTborders it3633.3%2.7 pCi/L−12.9 points
Emery County, UTborders it17732.2%3.3 pCi/L−14.0 points
Kane County, UTborders it2128.6%1.4 pCi/L−17.6 points
Grand County, UTborders it41117.5%1.7 pCi/L−28.7 points
Mesa County, COborders it50316.1%1.8 pCi/L−30.1 points
Montezuma County, COborders it8414.3%1.1 pCi/L−31.9 points
Where San Juan County's reported results fell, 2022, beside Utah and the United States
ResultSan Juan County testsSan Juan County shareUtah shareU.S. shareAgainst Utah
Under 2 pCi/L1230.8%33.5%54.5%−2.7 points
2 to 4 pCi/L923.1%28.8%21.7%−5.7 points
4 pCi/L and above1846.2%37.7%23.9%+8.5 points
San Juan County ranked among the 24 Utah counties with 30 or more tests, by share at or above 4 pCi/L, 2022
CountyRankTestsAt or above 4 pCi/LMedian
Tooele County6 of 2497555.1%4.6 pCi/L
Cache County7 of 241,36552.7%4.2 pCi/L
Wasatch County8 of 2460951.7%4.2 pCi/L
Duchesne County9 of 2412951.2%4.8 pCi/L
Sevier County10 of 2415949.1%3.5 pCi/L
San Juan County11 of 243946.2%2.7 pCi/L
Uintah County12 of 2429445.9%3.7 pCi/L
Utah County13 of 2410,77342.9%3.3 pCi/L
Carbon County14 of 2438440.6%3.0 pCi/L
Summit County15 of 241,04140.3%2.9 pCi/L
Salt Lake County16 of 2415,20134.4%2.8 pCi/L
San Juan County radon tests by year, against Utah's pooled share
YearTestsAt or above 4 pCi/LMedianHighestUtah, pooledChange from the row before
20231952.6%4.0 pCi/L11.4 pCi/L36.1%+6.4 points
20223946.2%2.7 pCi/L10.8 pCi/L37.7%+29.5 points
2021616.7%3.2 pCi/L7.3 pCi/L34.2%+16.7 points
201920.0%1.1 pCi/L1.9 pCi/L37.7%−90.0 points
20181090.0%9.7 pCi/L24.8 pCi/L36.6%+40.0 points
2017850.0%4.3 pCi/L10.3 pCi/L38.2%Level
20161050.0%4.4 pCi/L12.7 pCi/L39.8%+50.0 points
201530.0%2.8 pCi/L3.3 pCi/L42.3%−50.0 points
2014650.0%4.6 pCi/L32.2 pCi/L43.4%First on file

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

San Juan County, Geology

The ground under San Juan County

Predicted

Most of the ground under San Juan County is one class on USGS's geologic map: 78.3% of its land is moderate radon potential, with 21.7% high. The map puts 78.2% of San Juan County in the area it calls Colorado Plateau and 21.7% in Uravan Belt. USGS gives the first a radon index of 9, in the moderate band (9 to 11), and the second 13, in the high band (12 to 17).

USGS's geologic areas under San Juan County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Colorado PlateauPaleozoic and Mesozoic sandstone, shale, limestone.Moderate978.2%
Uravan BeltUranium-bearing Cretaceous and Jurassic sedimentary rocks of the Uravan mineral belt.High1321.7%

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

San Juan County beside the ground around it

Utah as a whole has more high-potential ground than San Juan County: 32.8% of its land, against 21.7% here. Of the 14 counties that border it, 8 have more high-potential ground, Montrose County, CO the most at 100%.

Share of land by USGS radon potential: San Juan County, the 14 counties bordering it and Utah
AreaEPA zoneLow potentialModerate potentialHigh potential
San Juan CountyZone 2None78.3%21.7%
Montezuma County, COZone 1None24.5%75.5%
Dolores County, COZone 1None6.9%93.1%
Wayne CountyZone 2None85.7%14.3%
San Miguel County, COZone 1None3.5%96.5%
Grand CountyZone 1None32.1%67.9%
Montrose County, COZone 1NoneNone100%
Garfield CountyZone 2None67.9%32.1%
Mesa County, COZone 1None0.6%99.5%
Emery CountyZone 2None56.3%43.7%
Kane CountyZone 2None96.3%3.7%
San Juan County, NMZone 2None81.8%18.2%
Navajo County, AZZone 2None100%None
Apache County, AZZone 2None99.0%1.0%
Coconino County, AZZone 2None100%None
Utah29 counties, pooled by land areaVariesNone67.2%32.8%

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

Local help

San Juan County, Local resources

Radon testing and mitigation in San Juan 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

San Juan County, Questions

Questions about radon in San Juan County

Are radon levels high in San Juan County?

In 2023, 52.6% of the radon tests reported to CDC for San Juan County, Utah were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.0 pCi/L. Of 24 Utah counties with 30 or more tests for the same period, 10 reported a higher share; pooled, the state comes to 37.7%.

Which counties border San Juan County?

San Juan County borders 14 counties: Montezuma County, CO, Dolores County, CO, Wayne County, UT, San Miguel County, CO, Grand County, UT, Montrose County, CO, Garfield County, UT, Mesa County, CO, Emery County, UT, Kane County, UT, San Juan County, NM, Navajo County, AZ, Apache County, AZ and Coconino County, AZ.

Products

San Juan County, Products

Testing a home in San Juan County

In San Juan County, 46.2% of 39 tests reported to CDC in 2022 reached 4 pCi/L, against 37.7% pooled across Utah. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in San Juan County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for San Juan County homes, compared

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San Juan County, Bordering counties

Counties bordering San Juan County

Calculated by Radon411
View all 14 counties bordering San Juan County

San Juan County, Cities and towns

Cities and towns in San Juan County

San Juan County's population has barely moved since 2020: 14,542 residents on July 1, 2025 against 14,521 then, by the Census Bureau's estimates. Spread over its land, that is 1.9 people to the square mile. Its largest town, Blanding, has 3,199 residents, 22.0% of the total. Together its 3 incorporated places hold 35.7% of those residents; the other 64.3% live outside any of them. Reported testing is thin here: 39 tests over 2022, or 2.7 for every 1,000 residents (2025 estimate), where Utah as a whole comes to 11.6.

From Blanding to Bluff, CDC publishes no figure by town: each reads San Juan County's.

The cities and towns in San Juan County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Blanding3,199−5.5%22.0%
Monticello1,737−4.9%11.9%
Bluff252+3.3%1.7%

3 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).

San Juan County, Homes

Homes in San Juan County

San Juan County is a place of houses on their own lots: 77% of its 5,612 homes are detached single-family houses, against 67% across Utah. Half of its homes were built before 1987, close to Utah's 1991: 14% date from before 1960 and 23% from 2000 or later. 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 San Juan County, Utah, 2019 to 2023
HomesSan Juan CountyUtah
Housing units5,6121,193,082
Detached houses77%67%
In buildings of 5 or more1%16%
Mobile homes19%3%
Built before 196014%16%
Built since 200023%37%
Middle year built19871991
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.