Locations and reports
Radon in Grand Junction, Colorado
EPA puts Mesa County, where Grand Junction is, 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
Share at 4+ pCi/L
18.9%
20.0 pts below CO
- Mesa
- 18.9%
- Colorado
- 38.9%
Mesa, 37th of 38 in CO, 2023
Median result
2.2pCi/L
Below action level
- Mesa
- 2.2 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of Mesa's tests, 2023
Nearest county
55.6%
Delta, 41 miles
- Delta
- 55.6%
- Mesa
- 18.9%
124 tests, 2023
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
Mesa, where Grand Junction is
Tests reported
567
In Mesa
- Mesa
- 567
- Delta
- 124
Reported to CDC before any fix, 2023
Read a result for Grand Junction
Starts at Mesa County's median, 2.2 pCi/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
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 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.
The data
Grand Junction, What is published
What is published for Grand Junction
Every figure for Grand Junction is a county's
Radon data is published by county, not by city, so for Grand Junction it is Mesa County's: its EPA zone (Zone 1) and the 567 tests reported to CDC for 2023. Only a test tells you about one home.
Grand Junction covers 39.6 square miles of land, all of it in Mesa County. About 71,827 people live there, 1,812 to the square mile.
Grand Junction, Counties
The county Grand Junction lies in
MeasuredMesa County's EPA zone and the figures CDC publishes for it, 2023.
Mesa CountyZone 1Highest predicted potential
- 18.9%
- Reported tests at or above 4 pCi/L
- 2.2 pCi/L
- Median reported result
- 567 tests
- Tests reported to CDC
- 10
- Annual years on file
Mesa County ranks 37th of 38 Colorado counties with 30 or more tests for that period, 20.0 points below the 38.9% pooled across Colorado's counties, 14.5 points below the national pool of 33.4%.
The counties nearest Grand Junction with a CDC figure for 2023, measured from the middle of the city: Delta County (41 miles, 55.6% of 124 tests), Montrose County (50 miles, 55.3% of 215 tests) and Garfield County (50 miles, 39.3% of 224 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 34.7% to 55.6%; the farthest of them, Lake County, is 120 miles away at 54.3%.
No business in the directory gives Grand Junction as its address; the Colorado list covers it. Colorado's other cities with a page of their own: Colorado Springs, Fort Collins, Aurora and Longmont.
The counties around Grand Junction
By distance from the middle of Grand Junction; counties with 30 or more tests.
Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2023.
Grand Junction, Geology
The ground under Grand Junction
PredictedUSGS's geologic map puts all of Grand Junction's mapped land in one class: high radon potential. The map puts 79.5% of Grand Junction in the area it calls Mancos Shale Lowlands and 20.5% in Uravan Belt. USGS gives both a radon index of 13, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Mancos Shale Lowlands | Marine shales (Mancos Shale) and Tertiary sandstones. | High | 13 | 79.5% |
| Uravan Belt | Uranium-bearing Cretaceous and Jurassic sedimentary rocks of the Uravan mineral belt. | High | 13 | 20.5% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Grand Junction beside its county and Colorado
The ground under Grand Junction is close to Mesa County's as a whole: 100% rated high against 99.5%. Grand Junction has more high-potential ground than Colorado as a whole: 100% of its land against 74.8%.
The map rates the ground, not the air in any home.
Grand Junction, Homes
Homes in Grand Junction
Of Grand Junction's 30,626 homes, 63% are detached houses, against 71% across Mesa County; 17% are in buildings of five or more homes. Half of its homes were built before 1986, close to Mesa County's 1987: 19% date from before 1960 and 33% from 2000 or later. 63% of occupied homes are lived in by their owner (Mesa County: 72%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Grand Junction | Mesa County | Colorado |
|---|---|---|---|
| Housing units | 30,626 | 68,861 | 2,545,124 |
| Detached houses | 63% | 71% | 62% |
| In buildings of 5 or more | 17% | 9% | 22% |
| Mobile homes | 6% | 8% | 4% |
| Built before 1960 | 19% | 16% | 16% |
| Built since 2000 | 33% | 29% | 31% |
| Middle year built | 1986 | 1987 | 1987 |
| Owner-occupied | 63% | 72% | 66% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.
Local help
Grand Junction, Local resources
Local resources for Grand Junction
Who to ask in Colorado: its radon program, test kits and professionals.
- Colorado's radon programColorado Department of Public Health and Environment.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Order a discounted radon test kit
- Compare kits
- Professionals in ColoradoRadon testers and mitigators in Colorado, each with how its listing was checked.
The program's own words on licensing and disclosure are on the Colorado page.
What it means
Grand Junction, Questions
Questions about radon in Grand Junction
What radon zone is Grand Junction in?
Grand Junction has no zone of its own: it shares Mesa County's, Zone 1, the map's highest class: a predicted county average above 4 pCi/L.
What are radon levels in Grand Junction?
Mesa County's 567 tests for 2023 put 18.9% at or above 4 pCi/L: most tests near Grand Junction come back under EPA's action level, but not all. The median reported result was 2.2 pCi/L.
Should I test my home in Grand Junction?
Yes. Roughly one reported test in 5 in Mesa County reached 4 pCi/L. That is below Colorado's pooled 38.9%, and still not a reason to skip it, and ranks Mesa County 37th of the 38 Colorado counties with 30 or more tests. Only a test puts a number on one house. How to test a home.
What ground is Grand Junction built on, as far as radon goes?
79.5% of Grand Junction sits on what USGS's map calls "Mancos Shale Lowlands", rated high for radon potential, radon index 13; another 20.5% is "Uravan Belt", in the same class.
Is radon higher in the counties around Grand Junction?
Yes, in every direction measured. Each of the 8 nearest counties with a figure reports a larger share of high tests than Mesa County's 18.9%; the highest is Delta County (55.6%, 41 miles off).
The answers use the published figures of Mesa County, the county Grand Junction lies in.
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