Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Montezuma County, Colorado
EPA puts Montezuma County in Zone 1, its highest radon zone, and 33.3% of its 72 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
33.3%
5.6 pts below CO
- Montezuma
- 33.3%
- Colorado
- 38.9%
72 tests, 2023
Median result
3.0pCi/L
Below action level
- Montezuma
- 3.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
72
31st of 38 by tests
- Montezuma
- 72
- Jefferson
- 3,068
Reported to CDC before any fix, 2023
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Colorado
33 of 38
Lowest quarter
- Montezuma
- 33.3%
- Park
- 57.5%
By share, of 38 with 30+ tests
Read a result for Montezuma County
Starts at Montezuma County's median, 3.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.0 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. Montezuma County's median reported result, 2023.
The data
Montezuma County, At a glance
Montezuma County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Montezuma County in
USGS geologic potential: High across 75% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Montezuma County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 27.8% |
| 2015 | 38.2% |
| 2016 | 59.4% |
| 2017 | 35.1% |
| 2018 | 34.9% |
| 2019 | 22.4% |
| 2020 | 23.5% |
| 2021 | 29.3% |
| 2022 | 14.3% |
| 2023 | 33.3% |
2023: 33.3%. Across these years the share ran from 14.3% to 59.4%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 72 tests reported to CDC for Montezuma 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).
Montezuma County, Compared
Montezuma County radon figures, compared
Calculated by Radon411In Montezuma County, about 3 in 10 reported tests in 2023 (24 of 72) were at or above EPA's action level. Against the national pool of 33.4%, the gap is 0.1 points lower. Across 61 Colorado counties pooled together, 38.9% of tests reached that level, so Montezuma County runs 5.6 points below its state.
La Plata County, the one bordering county with a figure for the same period, reported 39.3%. By share, Montezuma County is 33rd of 38 Colorado counties with 30 or more tests for the same period.
Year by year, 2015 opened at 38.2% and 2023 closed at 33.3% (down 4.9 points), with 2016 the high at 59.4%. Half the tests came in under 3.0 pCi/L and half over it; the single highest reached 107.6 pCi/L. Below the action level, 20 tests (27.8%) came in under 2 pCi/L, against 39.2% statewide, and 28 tests (38.9%) fell between 2 and 4, against 22.0% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 33.3% share point the same way here. USGS geology rates 75% of the county's land high radon potential.
The busiest year on file was 2018, with 169 tests reported; the quietest, 2014, had 18.
Montezuma CountyColorado, pooled
| Year | Tests | Montezuma County, at or above 4 pCi/L | Colorado, pooled |
|---|---|---|---|
| 2015 | 34 | 38.2% | 47.2% |
| 2016 | 32 | 59.4% | 38.5% |
| 2017 | 57 | 35.1% | 41.0% |
| 2018 | 169 | 34.9% | 44.2% |
| 2019 | 161 | 22.4% | 44.1% |
| 2020 | 102 | 23.5% | 41.9% |
| 2021 | 41 | 29.3% | 47.3% |
| 2022 | 84 | 14.3% | 38.6% |
| 2023 | 72 | 33.3% | 38.9% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Montezuma County, State data
Colorado's own radon test data
MeasuredWhat Colorado's own agencies publish about radon tests in Montezuma 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 Montezuma 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
26.9%
211 of 784 tests
Median result
2.4 pCi/L
Highest result
107.6 pCi/L
Tests behind these figures
784 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.
Montezuma County, Geology
The ground under Montezuma County
PredictedMost of the ground under Montezuma County is one class on USGS's geologic map: 75.5% of its land is high radon potential, with 24.5% moderate. The map puts 75.5% of Montezuma County in the area it calls Uravan Belt and 24.5% in San Juan Basin. USGS gives the first a radon index of 13, in the high band (12 to 17), and the second 11, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Uravan Belt | Uranium-bearing Cretaceous and Jurassic sedimentary rocks of the Uravan mineral belt. | High | 13 | 75.5% |
| San Juan Basin | Mesozoic marine and non-marine sedimentary rocks including sandstone, siltstone, shale, minor limestone. | Moderate | 11 | 24.5% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Montezuma County beside the ground around it
On high-potential ground Montezuma County is close to Colorado as a whole: 75.5% of its land against 74.8%. Of the 6 counties that border it, 1 has more high-potential ground, Dolores County the most at 93.1%.
The map rates the ground, not the air in any home.
Local help
Montezuma County, Local resources
Radon testing and mitigation in Montezuma County
- Colorado's radon programColorado Department of Public Health and EnvironmentColorado's radon program licenses or certifies radon professionals, offers free or discounted test kits and states the rule for disclosing radon when a home is sold, and answers questions about testing and mitigation in Colorado.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 Colorado25 professionals are listed in Colorado.
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
Montezuma County, Questions
Questions about radon in Montezuma County
Are radon levels high in Montezuma County?
In 2023, 33.3% of the radon tests reported to CDC for Montezuma County, Colorado were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.0 pCi/L. Of 38 Colorado counties with 30 or more tests for the same period, 32 reported a higher share; pooled, the state comes to 38.9%.
Which counties border Montezuma County?
Montezuma County borders 6 counties: Dolores County, CO, La Plata County, CO, San Juan County, CO, San Juan County, NM, San Juan County, UT and Apache County, AZ.
Products
Montezuma County, Products
Testing a home in Montezuma County
In Montezuma County, 33.3% of 72 tests reported to CDC in 2023 reached 4 pCi/L, against 38.9% pooled across Colorado. In Zone 1 the year-round level in Montezuma 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
Monitor
RadonScan USB-powered radon monitor with a color screen
- C-NRPP 2024/25: Not included
- Plug-in
- Alarm
- Screen
First reading: Within 5 minutes
Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Montezuma County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Montezuma County
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Montezuma County, Bordering counties
Counties bordering Montezuma County
Calculated by Radon411- Radon levels in San Juan County, UTEPA zone 2
52.6%at or above 4 pCi/L
Median 4.0 pCi/L · 19 tests · 19.3 points above Montezuma County
- Radon levels in San Juan County, COEPA zone 2
46.2%at or above 4 pCi/L
Median 3.6 pCi/L · 13 tests · 12.9 points above Montezuma County
- Radon levels in La Plata County, COEPA zone 1
39.3%at or above 4 pCi/L
Median 3.1 pCi/L · 224 tests · 6.0 points above Montezuma County
- Radon levels in Dolores County, COEPA zone 1
0.0%at or above 4 pCi/L
Median 0.5 pCi/L · 2 tests · 33.3 points below Montezuma County
- Radon levels in San Juan County, NMEPA zone 2
No CDC figure for 2023; its page reads it against its own neighbours.
- Radon levels in Apache County, AZEPA zone 2
No CDC figure for 2023; its page reads it against its own neighbours.
Montezuma County, Cities and towns
Cities and towns in Montezuma County
The Census Bureau estimates 26,678 residents in Montezuma County for July 1, 2025, 788 more than in 2020 (+3.0%). That works out to 13 people per square mile of land. Its largest town, Cortez, has 9,126 residents, 34.2% of the total. Together its 3 incorporated places hold 42.5% of those residents; the other 57.5% live outside any of them. CDC's 72 reported tests for 2023 work out to 2.7 per 1,000 residents (2025 estimate), close to Colorado's 3.6.
From Cortez to Dolores, CDC publishes no figure by town: each reads Montezuma County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Cortez | 9,126 | +3.9% | 34.2% |
| Mancos | 1,266 | +5.7% | 4.7% |
| Dolores | 933 | +4.1% | 3.5% |
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).
Montezuma County, Homes
Homes in Montezuma County
Of Montezuma County's 12,314 homes, 70% are detached houses, against 62% across Colorado; 18% are mobile homes. Half of its homes were built before 1985, close to Colorado's 1987: 21% date from before 1960 and 25% from 2000 or later. 75% 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 | Montezuma County | Colorado |
|---|---|---|
| Housing units | 12,314 | 2,545,124 |
| Detached houses | 70% | 62% |
| In buildings of 5 or more | 3% | 22% |
| Mobile homes | 18% | 4% |
| Built before 1960 | 21% | 16% |
| Built since 2000 | 25% | 31% |
| Middle year built | 1985 | 1987 |
| Owner-occupied | 75% | 66% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.