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Radon Levels in Summit County, Utah

EPA puts Summit County in Zone 2, its middle radon zone, and 32.6% of its 417 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

    32.6%

    3.5 pts below UT

    Summit
    32.6%
    Utah
    36.1%

    417 tests, 2023

  • Median result

    2.4pCi/L

    Below action level

    Summit
    2.4 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    417

    9th of 22 by tests

    Summit
    417
    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

    16 of 22

    Middle half

    Summit
    32.6%
    Beaver
    66.7%

    By share, of 22 with 30+ tests

Read a result for Summit County

Starts at Summit County's median, 2.4 pCi/L

2.4pCi/L

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

EPA’s reading of 2.4 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. Summit County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Summit County, At a glance

Summit County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Summit 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: High across 56% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Summit County, 2023

Share of reported tests at or above 4 pCi/L, by year, Summit County
Share of reported tests at or above 4 pCi/L, by year, Summit County
YearShare of reported tests at or above 4 pCi/L
201439.2%
201546.5%
201646.1%
201728.8%
201830.2%
201950.0%
202034.3%
202136.1%
202240.3%
202332.6%

2023: 32.6%. Across these years the share ran from 28.8% to 50.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 417 tests reported to CDC for Summit 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

Summit County, Compared

Summit County radon figures, compared

Calculated by Radon411

In Summit County, about 3 in 10 reported tests in 2023 (136 of 417) were at or above EPA's action level. Against the national pool of 33.4%, the gap is 0.8 points lower. Across 29 Utah counties pooled together, 36.1% of tests reached that level, so Summit County runs 3.5 points below its state.

Of 4 neighbours with a figure, all 4 reported a larger share at or above 4 pCi/L; the spread is 33.1% (Salt Lake County) to 59.4% (Morgan County). By share, Summit County is 16th of 22 Utah counties with 30 or more tests for the same period.

Year by year, 2014 opened at 39.2% and 2023 closed at 32.6% (down 6.6 points), with 2019 the high at 50.0%. Half the tests came in under 2.4 pCi/L and half over it; the single highest reached 28.7 pCi/L. Below the action level, 162 tests (38.8%) came in under 2 pCi/L, against 35.4% statewide, and 119 tests (28.5%) fell between 2 and 4, against 28.5% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 32.6% share point the same way here. USGS geology rates 56% of the county's land high radon potential. CDC also counts 105 tests taken after mitigation in Summit County for the same period: tests in homes where a fix was already in.

The busiest year on file was 2022, with 1,041 tests reported; the quietest, 2019, had 66.

Share of reported tests at or above 4 pCi/L by year, Summit County against Utah2014 to 2023, years with 30 or more tests: Summit County 39.2% to 32.6%, the state's pooled share 36.1% in 2023.
Summit CountyUtah, pooled
Share of reported tests at or above 4 pCi/L by year, Summit County against Utah: data table
YearTestsSummit County, at or above 4 pCi/LUtah, pooled
20147439.2%43.4%
201512746.5%42.3%
201621746.1%39.8%
201716328.8%38.2%
201817930.2%36.6%
20196650.0%37.7%
20209934.3%37.6%
202113336.1%34.2%
20221,04140.3%37.7%
202341732.6%36.1%
Summit County against Utah, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Summit County
Summit County41732.6%2.4 pCi/LThis county
Utah, pooled29 counties, pooled27,42236.1%Not pooled+3.5 points
United States, pooled642 counties, pooled128,74033.4%Not pooled+0.8 points
Beaver Countyhighest in the state4266.7%9.3 pCi/L+34.1 points
Washington Countylowest in the state6579.9%1.3 pCi/L−22.7 points
Morgan County, UTborders it20759.4%5.0 pCi/L+26.8 points
Rich County, UTborders it1353.8%4.8 pCi/L+21.2 points
Wasatch County, UTborders it32451.9%4.2 pCi/L+19.3 points
Daggett County, UTborders it450.0%6.3 pCi/L+17.4 points
Duchesne County, UTborders it8139.5%3.2 pCi/L+6.9 points
Salt Lake County, UTborders it9,65833.1%2.6 pCi/L+0.5 points
Where Summit County's reported results fell, 2023, beside Utah and the United States
ResultSummit County testsSummit County shareUtah shareU.S. shareAgainst Utah
Under 2 pCi/L16238.8%35.4%41.4%+3.4 points
2 to 4 pCi/L11928.5%28.5%25.2%Level
4 pCi/L and above13632.6%36.1%33.4%−3.5 points
Summit 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
Tooele County11 of 2257351.0%4.1 pCi/L
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
Summit County radon tests by year, against Utah's pooled share
YearTestsAt or above 4 pCi/LMedianHighestUtah, pooledChange from the row before
202341732.6%2.4 pCi/L28.7 pCi/L36.1%−7.7 points
20221,04140.3%2.9 pCi/L86.1 pCi/L37.7%+4.2 points
202113336.1%2.6 pCi/L29.0 pCi/L34.2%+1.8 points
20209934.3%2.5 pCi/L21.2 pCi/L37.6%−15.7 points
20196650.0%3.9 pCi/L26.5 pCi/L37.7%+19.8 points
201817930.2%2.8 pCi/L18.0 pCi/L36.6%+1.4 points
201716328.8%2.4 pCi/L31.2 pCi/L38.2%−17.3 points
201621746.1%3.7 pCi/L26.9 pCi/L39.8%−0.4 points
201512746.5%3.8 pCi/L25.8 pCi/L42.3%+7.3 points
20147439.2%3.3 pCi/L34.0 pCi/L43.4%First on file

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

Summit County, Geology

The ground under Summit County

Predicted

USGS's geologic map splits Summit County: 56.4% of its land is high radon potential and 43.6% moderate. The map puts 53.7% of Summit County in the area it calls Northern Rocky Mountains and 43.6% in Uinta Mountains, with one smaller area beside them. USGS gives the first a radon index of 13, in the high band (12 to 17), and the second 10, in the moderate band (9 to 11).

USGS's geologic areas under Summit County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Northern Rocky MountainsTertiary sandstone, mudstone, limestone.High1353.7%
Uinta MountainsCretaceous marine shales with Tertiary continental sedimentary rocks on the southern flank.Moderate1043.6%
Wasatch RangePrecambrian granite and gneiss and Tertiary igneous rocks that have relatively low uranium concentrations.High142.8%

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

Summit County beside the ground around it

Summit County has more high-potential ground than Utah as a whole: 56.4% of its land against 32.8%. Of the 8 counties that border it, 5 have more high-potential ground, Morgan County the most at 99.7%.

Share of land by USGS radon potential: Summit County, the 8 counties bordering it and Utah
AreaEPA zoneLow potentialModerate potentialHigh potential
Summit CountyZone 2None43.6%56.4%
Uinta County, WYZone 1None13.9%86.1%
Wasatch CountyZone 2None57.8%42.2%
Duchesne CountyZone 1None29.9%70.1%
Morgan CountyZone 2None0.3%99.7%
Rich CountyZone 2None33.3%66.7%
Daggett CountyZone 2None93.7%6.3%
Salt Lake CountyZone 2None68.3%31.7%
Sweetwater County, WYZone 1None0.4%99.6%
Utah29 counties, pooled by land areaVariesNone67.2%32.8%

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

Local help

Summit County, Local resources

Radon testing and mitigation in Summit 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

Summit County, Questions

Questions about radon in Summit County

Are radon levels high in Summit County?

In 2023, 32.6% of the radon tests reported to CDC for Summit County, Utah were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.4 pCi/L. Of 22 Utah counties with 30 or more tests for the same period, 15 reported a higher share; pooled, the state comes to 36.1%.

Which counties border Summit County?

Summit County borders 8 counties: Uinta County, WY, Wasatch County, UT, Duchesne County, UT, Morgan County, UT, Rich County, UT, Daggett County, UT, Salt Lake County, UT and Sweetwater County, WY.

Products

Summit County, Products

Testing a home in Summit County

In Summit County, 32.6% of 417 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 Summit County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Summit County homes, compared

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Summit County, Bordering counties

Counties bordering Summit County

Calculated by Radon411

Summit County, Cities and towns

Cities and towns in Summit County

The Census Bureau estimates 43,141 residents in Summit County for July 1, 2025, 663 more than in 2020 (+1.6%). That works out to 23 people per square mile of land. Park City, the largest place on its list (8,587 residents in all), extends beyond Summit County, so no share of the total is worked out for it. CDC's 417 reported tests for 2023 work out to 9.7 per 1,000 residents (2025 estimate), close to Utah's 7.7.

From Park City to Henefer, CDC publishes no figure by town: each reads Summit County's.

The cities and towns in Summit County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Park Cityextends beyond Summit County8,587+2.1%Counted whole
Kamas2,086−0.9%4.8%
Francis2,053+27.7%4.8%
Oakley1,538−3.9%3.6%
Coalville1,529+2.7%3.5%
Henefer803−4.7%1.9%

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). A place that extends beyond Summit County is counted whole, so it has no share.

Summit County, Homes

Homes in Summit County

Of Summit County's 26,206 homes, 62% are detached houses, against 67% across Utah; 20% are in buildings of five or more homes. Half of its homes were built before 1995, close to Utah's 1991: 5% date from before 1960 and 39% 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 Summit County, Utah, 2019 to 2023
HomesSummit CountyUtah
Housing units26,2061,193,082
Detached houses62%67%
In buildings of 5 or more20%16%
Mobile homes1%3%
Built before 19605%16%
Built since 200039%37%
Middle year built19951991
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.