Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Fremont County, Colorado
EPA puts Fremont County in Zone 1, its highest radon zone, and high results are common there: 50.0% of the 66 radon tests reported to CDC (2023) came back 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
50.0%
11.1 pts above CO
- Fremont
- 50.0%
- Colorado
- 38.9%
66 tests, 2023
Median result
4.0pCi/L
Action level reached
- Fremont
- 4.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
66
32nd of 38 by tests
- Fremont
- 66
- 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
7 of 38
Top quarter
- Fremont
- 50.0%
- Park
- 57.5%
By share, of 38 with 30+ tests
Read a result for Fremont County
Starts at Fremont County's median, 4.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.0 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Fremont County's median reported result, 2023.
The data
Fremont County, At a glance
Fremont County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Fremont County in
USGS geologic potential: High across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Fremont County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 42.9% |
| 2015 | 47.2% |
| 2016 | 34.6% |
| 2017 | 34.6% |
| 2018 | 51.9% |
| 2019 | 40.2% |
| 2020 | 61.3% |
| 2021 | 49.3% |
| 2022 | 41.2% |
| 2023 | 50.0% |
2023: 50.0%. Across these years the share ran from 34.6% to 61.3%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 66 tests reported to CDC for Fremont 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).
Fremont County, Compared
Fremont County radon figures, compared
Calculated by Radon411More than half: 50.0% of the 66 radon tests reported to CDC for Fremont County in 2023 read at least 4 pCi/L. That places it 7th of 38 Colorado counties with 30 or more tests for the same period. That is 11.1 points above the 38.9% pooled from 61 Colorado counties.
The median result, 4.0 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 110.0 pCi/L. The rest split 33.3% under 2 pCi/L and 16.7% from 2 to 4 (Colorado: 39.2% and 22.0%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 50.0% share point the same way here.
3 of its 6 bordering counties with figures ran higher, led by Park County at 57.5%; El Paso County reported 34.4%. Statewide for the same period, Park County reported the highest share (57.5%) and Bent County the lowest (3.7%).
The busiest year on file was 2019, with 117 tests reported; the quietest, 2014, had 14.
Over 8 years of annual figures the share rose 2.8 points, from 47.2% in 2015 to 50.0% in 2023; its peak was 61.3% in 2020. Nationally, every county with a figure for the same period pools to 33.4%; Fremont County sits 16.6 points above it. CDC also counts 18 tests taken after mitigation in Fremont County for the same period: tests in homes where a fix was already in.
Fremont CountyColorado, pooled
50.0% % of tests38.9% % of tests
| Year | Tests | Fremont County, at or above 4 pCi/L | Colorado, pooled |
|---|---|---|---|
| 2015 | 36 | 47.2% | 47.2% |
| 2017 | 52 | 34.6% | 41.0% |
| 2018 | 104 | 51.9% | 44.2% |
| 2019 | 117 | 40.2% | 44.1% |
| 2020 | 75 | 61.3% | 41.9% |
| 2021 | 75 | 49.3% | 47.3% |
| 2022 | 85 | 41.2% | 38.6% |
| 2023 | 66 | 50.0% | 38.9% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Fremont County, State data
Colorado's own radon test data
MeasuredWhat Colorado's own agencies publish about radon tests in Fremont 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 Fremont 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
54.8%
466 of 850 tests
Median result
4.8 pCi/L
Highest result
110.0 pCi/L
Tests behind these figures
850 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.
Fremont County, Geology
The ground under Fremont County
PredictedUSGS's geologic map puts all of Fremont County's mapped land in one class: high radon potential. The map puts 87.0% of Fremont County in the area it calls Rocky Mountains and 13.0% in High Plains. USGS gives the first a radon index of 15 and the second 12, both in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Rocky Mountains | Precambrian granites, gneiss, amphibolite, variable uranium content, abundant shear zones.Sedimentary rocks shed from the granitic highlands. | High | 15 | 87.0% |
| High Plains | Quaternary deposits and Cretaceous marine shales that locally have a high radiometric signature. | High | 12 | 13.0% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Fremont County beside the ground around it
Fremont County has more high-potential ground than Colorado as a whole: 100% of its land against 74.8%. Of the 7 counties that border it, none has as large a share of high-potential ground; El Paso County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Fremont County, Local resources
Radon testing and mitigation in Fremont 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
Fremont County, Questions
Questions about radon in Fremont County
Are radon levels high in Fremont County?
In 2023, 50.0% of the radon tests reported to CDC for Fremont County, Colorado were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.0 pCi/L. Of 38 Colorado counties with 30 or more tests for the same period, 6 reported a higher share; pooled, the state comes to 38.9%.
Which counties border Fremont County?
Fremont County borders 7 counties: Custer County, Teller County, Chaffee County, Park County, Saguache County, El Paso County and Pueblo County.
Products
Fremont County, Products
Testing a home in Fremont County
In Fremont County, 50.0% of 66 tests reported to CDC in 2023 reached 4 pCi/L, against 38.9% pooled across Colorado. In Zone 1 the year-round level in Fremont 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
View Radon Wi-Fi radon monitor with an e-paper display
- C-NRPP 2024/25: Approved
- Battery
- Wi-Fi, Bluetooth
- Screen, app
Method: Alpha spectrometry
Readings: Every 60 minutes
Short-term kit
Radon Short Term Test Kit short-term charcoal radon test kit, lab fee included
- Lab fee included
Method: Charcoal
In home: 2 to 7 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Fremont County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Fremont County
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Fremont County, Bordering counties
Counties bordering Fremont County
Calculated by Radon411- Radon levels in Park CountyEPA zone 1
57.5%at or above 4 pCi/L
Median 4.6 pCi/L · 106 tests · 7.5 points above Fremont County
- Radon levels in Teller CountyEPA zone 1
56.8%at or above 4 pCi/L
Median 4.9 pCi/L · 162 tests · 6.8 points above Fremont County
- Radon levels in Chaffee CountyEPA zone 1
55.2%at or above 4 pCi/L
Median 4.5 pCi/L · 165 tests · 5.2 points above Fremont County
- Radon levels in Custer CountyEPA zone 1
45.7%at or above 4 pCi/L
Median 3.5 pCi/L · 35 tests · 4.3 points below Fremont County
- Radon levels in Pueblo CountyEPA zone 1
44.4%at or above 4 pCi/L
Median 3.5 pCi/L · 342 tests · 5.6 points below Fremont County
- Radon levels in Saguache CountyEPA zone 2
41.7%at or above 4 pCi/L
Median 3.1 pCi/L · 12 tests · 8.3 points below Fremont County
- Radon levels in El Paso CountyEPA zone 1
34.4%at or above 4 pCi/L
Median 2.5 pCi/L · 1,844 tests · 15.6 points below Fremont County
Fremont County, Cities and towns
Cities and towns in Fremont County
The Census Bureau estimates 50,039 residents in Fremont County for July 1, 2025, 1,159 more than in 2020 (+2.4%). That works out to 33 people per square mile of land. Its largest town, Cañon City, has 17,030 residents, 34.0% of the total. Together its 6 incorporated places hold 45.6% of those residents; the other 54.4% live outside any of them. Reported testing is thin here: 66 tests over 2023, or 1.3 for every 1,000 residents (2025 estimate), where Colorado as a whole comes to 3.6.
From Cañon City to Brookside, CDC publishes no figure by town: each reads Fremont County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Cañon City | 17,030 | +0.7% | 34.0% |
| Florence | 3,856 | +0.6% | 7.7% |
| Williamsburg | 789 | +7.6% | 1.6% |
| Rockvale | 530 | +2.9% | 1.1% |
| Coal Creek | 361 | −0.6% | 0.7% |
| Brookside | 235 | +0.9% | 0.5% |
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).
Fremont County, Homes
Homes in Fremont County
Of Fremont County's 20,449 homes, 72% are detached houses, against 62% across Colorado; 14% are mobile homes. Half of its homes were built before 1980, close to Colorado's 1987: 25% date from before 1960 and 21% from 2000 or later. Owners live in 76% of the occupied homes (Colorado: 66%), so for most households a test and a fix are their own to order.
| Homes | Fremont County | Colorado |
|---|---|---|
| Housing units | 20,449 | 2,545,124 |
| Detached houses | 72% | 62% |
| In buildings of 5 or more | 8% | 22% |
| Mobile homes | 14% | 4% |
| Built before 1960 | 25% | 16% |
| Built since 2000 | 21% | 31% |
| Middle year built | 1980 | 1987 |
| Owner-occupied | 76% | 66% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.