Locations and reports
Radon in Erie, Colorado
Erie lies in 2 counties, in EPA Zone 1; 71.4% of it is in Weld County, where 46.0% of 663 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
46.0%
7.1 pts above CO
- Weld
- 46.0%
- Colorado
- 38.9%
Weld, 10th of 38 in CO, 2023
Median result
3.5pCi/L
Below action level
- Weld
- 3.5 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of Weld's tests, 2023
Highest county
46.0%
Weld
- Weld
- 46.0%
- Boulder
- 34.2%
2 counties, 2 with 30+ tests, 2023
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
Weld; Boulder Zone 1
Tests reported
663
In Weld
- Weld
- 663
- Boulder
- 1,963
Reported to CDC before any fix, 2023
Read a result for Erie
Starts at Weld County's median, 3.5 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.5 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. Weld County's median reported result, 2023.
The data
Erie, What is published
What is published for Erie
Every figure for Erie is a county's
Radon data is published by county, not by city, and Erie reaches into 2 counties: Weld County and Boulder 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.
Erie covers 19.7 square miles of land: 71.4% of it lies in Weld County and 28.6% in Boulder County. About 40,904 people live there, 2,072 to the square mile.
Erie, Counties
Erie'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.
- Weld County
- EPA zone
- Zone 1: Highest predicted potential
- At or above 4 pCi/L
- 46.0%
- Median result
- 3.5 pCi/L
- Tests reported
- 663 tests
- Annual years on file
- 10
- Boulder County
- EPA zone
- Zone 1: Highest predicted potential
- At or above 4 pCi/L
- 34.2%
- Median result
- 2.5 pCi/L
- Tests reported
- 1,963 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 |
|---|---|---|---|---|---|
| Weld County | Zone 1: Highest predicted potential | 46.0% | 3.5 pCi/L | 663 tests | 10 |
| Boulder County | Zone 1: Highest predicted potential | 34.2% | 2.5 pCi/L | 1,963 tests | 10 |
Erie spans 2 counties, each with its own EPA zone and its own CDC figure: Weld County (Zone 1, 46.0% of 663 tests) and Boulder County (Zone 1, 34.2% of 1,963 tests).
Weld County ranks 10th of 38 Colorado counties with 30 or more tests for that period, 7.1 points above the 38.9% pooled across Colorado's counties, 12.6 points above the national pool of 33.4%. Of the city's other county, Boulder County reported 34.2%.
The counties nearest Erie with a CDC figure for 2023, measured from the middle of the city: Broomfield County (6 miles, 36.9% of 758 tests), Denver County (21 miles, 35.4% of 2,277 tests) and Gilpin County (29 miles, 26.4% of 129 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 26.4% to 49.4%; the farthest of them, Larimer County, is 49 miles away at 49.4%.
No business in the directory gives Erie as its address; the Colorado list covers it. 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 Erie
By distance from the middle of Erie; counties with 30 or more tests.
The median reported pre-mitigation result for 2023 was 3.5 pCi/L in Weld County and 2.5 pCi/L in Boulder County.
Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2023.
Erie, Geology
The ground under Erie
PredictedUSGS's geologic map puts all of Erie's mapped land in one class: high radon potential. All of it lies in the area the map calls High Plains, to which USGS gives a radon index of 12, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| High Plains | Quaternary deposits and Cretaceous marine shales that locally have a high radiometric signature. | High | 12 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Erie beside its counties and Colorado
Erie sits on more high-potential ground than Weld County as a whole: 100% of the city against 66.2% of the county. Erie 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.
Erie, Homes
Homes in Erie
Erie is a place of houses on their own lots: 87% of its 11,277 homes are detached single-family houses, against 73% across Weld County. Half of its homes were built before 2007, close to Weld County's 2000: 2% date from before 1960 and 78% from 2000 or later. Owners live in 88% of the occupied homes (Weld County: 76%), so for most households a test and a fix are their own to order.
| Homes | Erie | Weld County | Colorado |
|---|---|---|---|
| Housing units | 11,277 | 125,033 | 2,545,124 |
| Detached houses | 87% | 73% | 62% |
| In buildings of 5 or more | 4% | 11% | 22% |
| Mobile homes | 1% | 7% | 4% |
| Built before 1960 | 2% | 12% | 16% |
| Built since 2000 | 78% | 49% | 31% |
| Middle year built | 2007 | 2000 | 1987 |
| Owner-occupied | 88% | 76% | 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
Erie, Local resources
Local resources for Erie
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
Erie, Questions
Questions about radon in Erie
What radon zone is Erie in?
Both counties Erie reaches into (Weld County and Boulder 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 Erie.
What are radon levels in Erie?
46.0% of the 663 tests reported from Weld County for 2023 were at or above 4 pCi/L, the level at which EPA says to fix a home: high results are ordinary around Erie. The median reported result was 3.5 pCi/L. Boulder County reported 34.2% of 1,963 tests; the counties are kept apart.
Should I test my home in Erie?
Yes. About 305 of the 663 tests reported from Weld County were at or above 4 pCi/L. That is above Colorado's pooled 38.9%, and ranks Weld County 10th of the 38 Colorado counties with 30 or more tests. No map says which homes those are. How to test a home.
What ground is Erie built on, as far as radon goes?
USGS's geologic map puts all of Erie on one named area, "High Plains", rated high for radon potential, radon index 12.
Is radon higher in the counties around Erie?
Some are and some are not. Against Weld County's 46.0%, 1 of the 8 nearest counties with a figure report more and 7 less, from Gilpin County (26.4%, 29 miles off) to Larimer County (49.4%, 49 miles off).
The answers use the published figures of Weld County and Boulder County, the counties Erie lies in.
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