Listed for: Mitigation
Licenses on file: see the profile
Call Rocky Mountain Radon Control, LLC at (303) 980-1961No website listed
Locations and reports
Radon in Littleton, Colorado
Littleton lies in 3 counties, in EPA Zone 1; 93.8% of it is in Arapahoe County, where 37.9% of 1,990 reported tests (2023) were at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so the only way to know your home's level is to test it.
Data checked By Radon411Methodology
Share at 4+ pCi/L
37.9%
1.0 pts below CO
- Arapahoe
- 37.9%
- Colorado
- 38.9%
Arapahoe, 23rd of 38 in CO, 2023
Median result
2.5pCi/L
Below action level
- Arapahoe
- 2.5 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of Arapahoe's tests, 2023
Highest county
41.8%
Jefferson
- Jefferson
- 41.8%
- Douglas
- 35.8%
3 counties, 3 with 30+ tests, 2023
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
Arapahoe; Jefferson Zone 1, Douglas Zone 1
Tests reported
1,990
In Arapahoe
- Arapahoe
- 1,990
- Jefferson
- 3,068
Reported to CDC before any fix, 2023
Read a result for Littleton
Starts at Arapahoe County's median, 2.5 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.5 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. Arapahoe County's median reported result, 2023.
The data
Littleton, What is published
What is published for Littleton
Information:
Every figure for Littleton is a county's
Radon data is published by county, not by city, and Littleton reaches into 3 counties: Arapahoe County, Jefferson County and Douglas County. Each has its own EPA zone and its own CDC test figures, set side by side below and each labelled with its county. Only a test tells you about one home.
Littleton covers 12.6 square miles of land across 3 counties: 93.8% in Arapahoe County, 4.4% in Jefferson County and 1.8% in Douglas County. About 46,246 people live there, 3,662 to the square mile.
Littleton, Counties
Littleton's counties, side by side
MeasuredEach county's own EPA zone and its own published CDC figures for 2023, the newest period any of them has. A county without a figure for that period is shown without one, never with a figure from another year.
- Arapahoe County
- EPA zone
- Zone 1: Highest predicted potential
- At or above 4 pCi/L
- 37.9%
- Median result
- 2.5 pCi/L
- Tests reported
- 1,990 tests
- Annual years on file
- 10
- Jefferson County
- EPA zone
- Zone 1: Highest predicted potential
- At or above 4 pCi/L
- 41.8%
- Median result
- 3.2 pCi/L
- Tests reported
- 3,068 tests
- Annual years on file
- 10
- Douglas County
- EPA zone
- Zone 1: Highest predicted potential
- At or above 4 pCi/L
- 35.8%
- Median result
- 2.4 pCi/L
- Tests reported
- 1,635 tests
- Annual years on file
- 10
| County | EPA zone | Reported tests at or above 4 pCi/L | Median reported result | Tests reported | Annual years on file |
|---|---|---|---|---|---|
| Arapahoe County | Zone 1: Highest predicted potential | 37.9% | 2.5 pCi/L | 1,990 tests | 10 |
| Jefferson County | Zone 1: Highest predicted potential | 41.8% | 3.2 pCi/L | 3,068 tests | 10 |
| Douglas County | Zone 1: Highest predicted potential | 35.8% | 2.4 pCi/L | 1,635 tests | 10 |
Littleton spans 3 counties, each with its own EPA zone and its own CDC figure: Arapahoe County (Zone 1, 37.9% of 1,990 tests), Jefferson County (Zone 1, 41.8% of 3,068 tests) and Douglas County (Zone 1, 35.8% of 1,635 tests).
Arapahoe County ranks 23rd of 38 Colorado counties with 30 or more tests for that period, 1.0 points below the 38.9% pooled across Colorado's counties, 4.5 points above the national pool of 33.4%. Of the city's other counties, Jefferson County reported 41.8% and Douglas County reported 35.8%.
Measured from the middle of Littleton, the nearest counties with a CDC figure for 2023 are Denver County (14 miles, 35.4% of 2,277 tests), Broomfield County (25 miles, 36.9% of 758 tests) and Gilpin County (33 miles, 26.4% of 129 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 26.4% to 57.5%; the farthest of them, Park County, is 50 miles away at 57.5%.
The directory lists 1 business with an address in Littleton, 1 for mitigation. Colorado's other cities with a page of their own: Colorado Springs, Fort Collins, Grand Junction and Aurora.
Against Colorado and its other counties
Shares of tests people chose to run and report, by county (2023); the state's is its counties' counts added up, calculated by Radon411. Only a test measures a home.
The counties around Littleton
By distance from the middle of Littleton; counties with 30 or more tests.
The median reported pre-mitigation result for 2023 was 2.5 pCi/L in Arapahoe County, 3.2 pCi/L in Jefferson County and 2.4 pCi/L in Douglas County.
Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2023.
Littleton, Geology
The ground under Littleton
PredictedUSGS's geologic map puts all of Littleton's mapped land in one class: high radon potential. 96.2% of it lies in the area the map calls Dawson Arkose, to which USGS gives a radon index of 14, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Dawson Arkose | Consolidated alluvial fan and river deposits sourced in the granite mountains to the west. | High | 14 | 96.2% |
| Rocky Mountains | Precambrian granites, gneiss, amphibolite, variable uranium content, abundant shear zones.Sedimentary rocks shed from the granitic highlands. | High | 15 | 3.8% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Littleton beside its counties and Colorado
All of Littleton, like all of Arapahoe County, is rated high. Littleton 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.
Littleton, Homes
Homes in Littleton
Littleton has 21,506 homes, and many share a building: 36% are in buildings of five or more, 49% are detached houses, against 56% across Arapahoe County. Half of its homes were built before 1981, close to Arapahoe County's 1985: 20% date from before 1960 and 21% from 2000 or later. 61% of occupied homes are lived in by their owner (Arapahoe County: 65%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Littleton | Arapahoe County | Colorado |
|---|---|---|---|
| Housing units | 21,506 | 265,980 | 2,545,124 |
| Detached houses | 49% | 56% | 62% |
| In buildings of 5 or more | 36% | 29% | 22% |
| Mobile homes | 2% | 1% | 4% |
| Built before 1960 | 20% | 9% | 16% |
| Built since 2000 | 21% | 26% | 31% |
| Middle year built | 1981 | 1985 | 1987 |
| Owner-occupied | 61% | 65% | 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
Littleton, Professionals
Radon professionals listed in Littleton
Businesses whose listed city is Littleton, from the state registries and listings in the Radon411 directory, with the same business and certification status the directory shows.
Radon professionals listed in Littleton: 1 of 1
1 listing with Littleton as the city. See radon mitigation in Littleton, or all radon professionals in Colorado.
Littleton, Local resources
Local resources for Littleton
Who to ask in Colorado: its radon program, test kits and professionals.
What it means
Littleton, Questions
Questions about radon in Littleton
What radon zone is Littleton in?
All 3 counties Littleton reaches into (Arapahoe County, Jefferson County and Douglas County) are in Zone 1, the map's highest class: a predicted county average above 4 pCi/L. EPA zones counties, not cities, so that is the zone for every part of Littleton.
What are radon levels in Littleton?
Around Littleton, 37.9% of 1,990 tests reported from Arapahoe County for 2023 reached 4 pCi/L or more, so a high result is no surprise here. The median reported result was 2.5 pCi/L. Jefferson County reported 41.8% of 3,068 tests and Douglas County reported 35.8% of 1,635 tests; the counties are kept apart.
Should I test my home in Littleton?
Yes. Arapahoe County reported about 754 of its 1,990 tests at or above 4 pCi/L. That is about what Colorado as a whole reports (38.9%), and ranks Arapahoe County 23rd of the 38 Colorado counties with 30 or more tests. Which homes they were, no map can say. How to test a home.
What ground is Littleton built on, as far as radon goes?
USGS's geologic map puts all of Littleton on one named area, "Dawson Arkose", rated high for radon potential, radon index 14.
Is radon higher in the counties around Littleton?
It depends which way you go. 3 of the 8 nearest counties with a figure report a larger share than Arapahoe County's 37.9% and 5 a smaller one: from Gilpin County (26.4%, 33 miles off) to Park County (57.5%, 50 miles off).
Who tests for or fixes radon in Littleton?
Littleton is the address of one business in Radon411's directory, listed for mitigation, none for testing. Each entry names the public list it came from. Radon professionals in Littleton.
The answers use the published figures of Arapahoe County, Jefferson County and Douglas County, the counties Littleton lies in.
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