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Radon Levels in Mesa County, Colorado

EPA puts Mesa County in Zone 1, its highest radon zone, and 18.9% of its 567 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

    18.9%

    20.0 pts below CO

    Mesa
    18.9%
    Colorado
    38.9%

    567 tests, 2023

  • Median result

    2.2pCi/L

    Below action level

    Mesa
    2.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    567

    11th of 38 by tests

    Mesa
    567
    Jefferson
    3,068

    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 Colorado

    37 of 38

    Lowest quarter

    Mesa
    18.9%
    Park
    57.5%

    By share, of 38 with 30+ tests

Read a result for Mesa County

Starts at Mesa County's median, 2.2 pCi/L

2.2pCi/L

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

EPA’s reading of 2.2 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. Mesa County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Mesa County, At a glance

Mesa County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Mesa 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 99% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Mesa County, 2023

Share of reported tests at or above 4 pCi/L, by year, Mesa County
Share of reported tests at or above 4 pCi/L, by year, Mesa County
YearShare of reported tests at or above 4 pCi/L
201430.2%
201534.8%
201633.1%
201728.5%
201824.0%
201937.1%
202018.1%
202130.8%
202216.1%
202318.9%

2023: 18.9%. Across these years the share ran from 16.1% to 37.1%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 567 tests reported to CDC for Mesa 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

Mesa County, Compared

Mesa County radon figures, compared

Calculated by Radon411

Mesa County's 567 reported tests in 2023 had a middle value of 2.2 pCi/L and a maximum of 52.4 pCi/L, and 18.9% reached 4 pCi/L. Colorado as a whole (61 Colorado counties, pooled) comes to 38.9%: 20.0 points higher than here.

Among its state's counties it ranks 37th of 38 Colorado counties with 30 or more tests for the same period. Statewide for the same period, Park County reported the highest share (57.5%) and Bent County the lowest (3.7%).

Below the action level, 268 tests (47.3%) came in under 2 pCi/L, against 39.2% statewide, and 192 tests (33.9%) fell between 2 and 4, against 22.0% statewide. The busiest year on file was 2019, with 596 tests reported; the quietest, 2014, had 116.

EPA's 1993 zone map puts Mesa County in Zone 1, a predicted county average above 4 pCi/L. USGS geology rates 99% of the county's land high radon potential.

Next door, the shares run from 23.9% in Grand County, UT to 55.6% in Delta County. Over 10 years of annual figures the share fell 11.3 points, from 30.2% in 2014 to 18.9% in 2023; its peak was 37.1% in 2019.

CDC also counts 15 tests taken after mitigation in Mesa 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, Mesa County against Colorado2014 to 2023, years with 30 or more tests: Mesa County 30.2% to 18.9%, the state's pooled share 38.9% in 2023.
Mesa CountyColorado, pooled
Share of reported tests at or above 4 pCi/L by year, Mesa County against Colorado: data table
YearTestsMesa County, at or above 4 pCi/LColorado, pooled
201411630.2%46.5%
201531934.8%47.2%
201616333.1%38.5%
201715128.5%41.0%
201845024.0%44.2%
201959637.1%44.1%
202038718.1%41.9%
202129530.8%47.3%
202250316.1%38.6%
202356718.9%38.9%
Mesa County against Colorado, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Mesa County
Mesa County56718.9%2.2 pCi/LThis county
Colorado, pooled61 counties, pooled21,80238.9%Not pooled+20.0 points
United States, pooled642 counties, pooled128,74033.4%Not pooled+14.5 points
Park Countyhighest in the state10657.5%4.6 pCi/L+38.6 points
Bent Countylowest in the state1083.7%0.1 pCi/L−15.2 points
Delta County, COborders it12455.6%4.6 pCi/L+36.7 points
Montrose County, COborders it21555.3%4.5 pCi/L+36.4 points
San Juan County, UTborders it1952.6%4.0 pCi/L+33.7 points
Garfield County, COborders it22439.3%2.9 pCi/L+20.4 points
Pitkin County, COborders it16436.6%2.5 pCi/L+17.7 points
Gunnison County, COborders it14734.7%2.5 pCi/L+15.8 points
Grand County, UTborders it4623.9%1.9 pCi/L+5.0 points
Where Mesa County's reported results fell, 2023, beside Colorado and the United States
ResultMesa County testsMesa County shareColorado shareU.S. shareAgainst Colorado
Under 2 pCi/L26847.3%39.2%41.4%+8.1 points
2 to 4 pCi/L19233.9%22.0%25.2%+11.9 points
4 pCi/L and above10718.9%38.9%33.4%−20.0 points
Mesa County ranked among the 38 Colorado counties with 30 or more tests, by share at or above 4 pCi/L, 2023
CountyRankTestsAt or above 4 pCi/LMedian
Douglas County28 of 381,63535.8%2.4 pCi/L
Denver County29 of 382,27735.4%2.8 pCi/L
Gunnison County30 of 3814734.7%2.5 pCi/L
El Paso County31 of 381,84434.4%2.5 pCi/L
Boulder County32 of 381,96334.2%2.5 pCi/L
Montezuma County33 of 387233.3%3.0 pCi/L
Huerfano County34 of 385328.3%1.3 pCi/L
Gilpin County35 of 3812926.4%1.1 pCi/L
Las Animas County36 of 389319.4%1.1 pCi/L
Mesa County37 of 3856718.9%2.2 pCi/L
Bent County38 of 381083.7%0.1 pCi/L
Mesa County radon tests by year, against Colorado's pooled share
YearTestsAt or above 4 pCi/LMedianHighestColorado, pooledChange from the row before
202356718.9%2.2 pCi/L52.4 pCi/L38.9%+2.8 points
202250316.1%1.8 pCi/L44.0 pCi/L38.6%−14.7 points
202129530.8%1.9 pCi/L268.0 pCi/L47.3%+12.7 points
202038718.1%1.4 pCi/L16.9 pCi/L41.9%−19.0 points
201959637.1%3.1 pCi/L142.5 pCi/L44.1%+13.1 points
201845024.0%2.1 pCi/L65.0 pCi/L44.2%−4.5 points
201715128.5%2.3 pCi/L22.8 pCi/L41.0%−4.6 points
201616333.1%3.0 pCi/L49.4 pCi/L38.5%−1.7 points
201531934.8%2.7 pCi/L25.7 pCi/L47.2%+4.6 points
201411630.2%2.5 pCi/L55.7 pCi/L46.5%First on file

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

Mesa County, State data

Colorado's own radon test data

Measured

What Colorado's own agencies publish about radon tests in Mesa County, with their period. These are not CDC's figures and are never added to them.

MeasuredState figures, not CDC's

What Colorado CDPHE reports for Mesa County

Radon data (county results): radon test results received from radon testing labs, primarily short-term household tests taken by the homeowner. Period: 2005-2025.

Share over 4 pCi/L

33.5%

1,445 of 4,318 tests

Median result

2.7 pCi/L

Highest result

301.0 pCi/L

Tests behind these figures

4,318 tests

  • CDPHE says these data do not give actual radon levels in homes that have not been tested.
  • When possible, only tests conducted before a mitigation system was installed are used.
  • Some counties have very small numbers of test results, and their summaries may be less representative.
  • These figures describe tests reported to Colorado CDPHE in this area. They count a different set of tests than CDC's figures and are not a reading of any one home.

Measured: Colorado CDPHE data, 2005-2025.

Mesa County, Geology

The ground under Mesa County

Predicted

Most of the ground under Mesa County is one class on USGS's geologic map: 99.5% of its land is high radon potential, with 0.6% moderate. The map puts 46.3% of Mesa County in the area it calls Uravan Belt and 29.1% in Paradox Basin, with 2 smaller areas beside them. USGS gives both a radon index of 13, in the high band (12 to 17).

USGS's geologic areas under Mesa County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Uravan BeltUranium-bearing Cretaceous and Jurassic sedimentary rocks of the Uravan mineral belt.High1346.3%
Paradox BasinTertiary sandstone, siltstone and shale.High1329.1%
Mancos Shale LowlandsMarine shales (Mancos Shale) and Tertiary sandstones.High1324.1%
Colorado PlateauPaleozoic and Mesozoic sandstone, shale, limestone.Moderate90.5%

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

Mesa County beside the ground around it

Mesa County has more high-potential ground than Colorado as a whole: 99.5% of its land against 74.8%. Of the 7 counties that border it, 2 have more high-potential ground, Delta County the most at 100%.

Share of land by USGS radon potential: Mesa County, the 7 counties bordering it and Colorado
AreaEPA zoneLow potentialModerate potentialHigh potential
Mesa CountyZone 1None0.6%99.5%
Montrose CountyZone 1NoneNone100%
Delta CountyZone 1NoneNone100%
Grand County, UTZone 1None32.1%67.9%
Garfield CountyZone 1None42.5%57.5%
Gunnison CountyZone 1None25.9%74.1%
Pitkin CountyZone 1None67.2%32.8%
San Juan County, UTZone 2None78.3%21.7%
Colorado64 counties, pooled by land areaVariesNone25.2%74.8%

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

Local help

Mesa County, Local resources

Radon testing and mitigation in Mesa County

What Colorado's program says
Licensing of radon professionals
Listed contractors are certified by the National Radon Proficiency Program or the National Radon Safety Board, and must be licensed by the Colorado Department of Regulatory Agencies.
Disclosure when a home is sold or rented
As of August 7, 2023, landlords in Colorado are required to disclose radon information when a tenant signs a lease agreement.

What it means

Mesa County, Questions

Questions about radon in Mesa County

Are radon levels high in Mesa County?

In 2023, 18.9% of the radon tests reported to CDC for Mesa County, Colorado were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.2 pCi/L. Of 38 Colorado counties with 30 or more tests for the same period, 36 reported a higher share; pooled, the state comes to 38.9%.

Which counties border Mesa County?

Mesa County borders 7 counties: Montrose County, CO, Delta County, CO, Grand County, UT, Garfield County, CO, Gunnison County, CO, Pitkin County, CO and San Juan County, UT.

Products

Mesa County, Products

Testing a home in Mesa County

In Mesa County, 18.9% of 567 tests reported to CDC in 2023 reached 4 pCi/L, against 38.9% pooled across Colorado. In Zone 1 the year-round level in Mesa 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

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

Explore

Mesa County, Bordering counties

Counties bordering Mesa County

Calculated by Radon411

Mesa County, Cities and towns

Cities and towns in Mesa County

The Census Bureau estimates 162,845 residents in Mesa County for July 1, 2025, 6,838 more than in 2020 (+4.4%). That works out to 49 people per square mile of land. Its largest town, Grand Junction, has 71,827 residents, 44.1% of the total. Together its 5 incorporated places hold 54.8% of those residents; the other 45.2% live outside any of them. CDC's 567 reported tests for 2023 work out to 3.5 per 1,000 residents (2025 estimate), close to Colorado's 3.6.

From Grand Junction to Collbran, CDC publishes no figure by town: each reads Mesa County's.

The cities and towns in Mesa County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Grand Junction71,827+9.2%44.1%
Fruita14,003+4.3%8.6%
Palisade2,599+1.4%1.6%
De Beque476−2.7%0.3%
Collbran355−2.5%0.2%

5 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).

Mesa County, Homes

Homes in Mesa County

Of Mesa County's 68,861 homes, 71% are detached houses, against 62% across Colorado; 9% are in buildings of five or more homes. Half of its homes were built before 1987, close to Colorado's 1987: 16% date from before 1960 and 29% from 2000 or later. 72% of occupied homes are lived in by their owner (Colorado: 66%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Mesa County, Colorado, 2019 to 2023
HomesMesa CountyColorado
Housing units68,8612,545,124
Detached houses71%62%
In buildings of 5 or more9%22%
Mobile homes8%4%
Built before 196016%16%
Built since 200029%31%
Middle year built19871987
Owner-occupied72%66%

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