Skip to content
RADON411

Locations and reports

Radon in Arvada, Colorado

Arvada lies in 2 counties, in EPA Zone 1; 98.5% of it is in Jefferson County, where 41.8% of 3,068 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    41.8%

    2.9 pts above CO

    Jefferson
    41.8%
    Colorado
    38.9%

    Jefferson, 17th of 38 in CO, 2023

  • Median result

    3.2pCi/L

    Below action level

    Jefferson
    3.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of Jefferson's tests, 2023

  • Highest county

    41.8%

    Jefferson

    Jefferson
    41.8%
    Adams
    36.6%

    2 counties, 2 with 30+ tests, 2023

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    Jefferson; Adams Zone 1

  • Tests reported

    3,068

    In Jefferson

    Jefferson
    3,068
    Adams
    1,191

    Reported to CDC before any fix, 2023

Read a result for Arvada

Starts at Jefferson County's median, 3.2 pCi/L

3.2pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 3.2 pCi/L

Between 2 and 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 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. Jefferson County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Arvada, What is published

What is published for Arvada

Information:

Every figure for Arvada is a county's

Radon data is published by county, not by city, and Arvada reaches into 2 counties: Jefferson County and Adams 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.

Arvada covers 38.9 square miles of land: 98.5% of it lies in Jefferson County and 1.5% in Adams County. About 122,901 people live there, 3,159 to the square mile.

Arvada, Counties

Arvada's counties, side by side

Measured

Each 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.

  • 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
  • Adams County
    EPA zone
    Zone 1: Highest predicted potential
    At or above 4 pCi/L
    36.6%
    Median result
    2.3 pCi/L
    Tests reported
    1,191 tests
    Annual years on file
    10
The counties Arvada lies in, each with its own EPA zone and its own published CDC figures for 2023
CountyEPA zoneReported tests at or above 4 pCi/LMedian reported resultTests reportedAnnual years on file
Jefferson CountyZone 1: Highest predicted potential41.8%3.2 pCi/L3,068 tests10
Adams CountyZone 1: Highest predicted potential36.6%2.3 pCi/L1,191 tests10

Arvada spans 2 counties, each with its own EPA zone and its own CDC figure: Jefferson County (Zone 1, 41.8% of 3,068 tests) and Adams County (Zone 1, 36.6% of 1,191 tests).

Jefferson County ranks 17th of 38 Colorado counties with 30 or more tests for that period, 2.9 points above the 38.9% pooled across Colorado's counties, 8.4 points above the national pool of 33.4%. Of the city's other county, Adams County reported 36.6%.

The counties nearest Arvada with a CDC figure for 2023, measured from the middle of the city: Broomfield County (10 miles, 36.9% of 758 tests), Denver County (15 miles, 35.4% of 2,277 tests) and Gilpin County (20 miles, 26.4% of 129 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 26.4% to 41.2%; the farthest of them, Summit County, is 53 miles away at 38.3%.

No business in the directory gives Arvada 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

Radon test figures for the counties Arvada lies in
CountyShare of ArvadaTestsAt or above 4 pCi/LMedianColorado, pooledRank in the stateEPA zone
Jefferson County98.5%3,06841.8%3.2 pCi/L38.9%17 of 38Zone 1
Adams County1.5%1,19136.6%2.3 pCi/L38.9%26 of 38Zone 1

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 Arvada

By distance from the middle of Arvada; counties with 30 or more tests.

Nearest counties to Arvada with 30 or more tests
CountyDistanceTestsAt or above 4 pCi/LMedian
Broomfield County10 mi75836.9%2.3 pCi/L
Denver County15 mi2,27735.4%2.8 pCi/L
Gilpin County20 mi12926.4%1.1 pCi/L
Boulder County21 mi1,96334.2%2.5 pCi/L
Clear Creek County28 mi5141.2%3.0 pCi/L
Douglas County37 mi1,63535.8%2.4 pCi/L
Arapahoe County45 mi1,99037.9%2.5 pCi/L
Summit County53 mi29538.3%2.0 pCi/L

The median reported pre-mitigation result for 2023 was 3.2 pCi/L in Jefferson County and 2.3 pCi/L in Adams County.

Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2023.

Arvada, Geology

The ground under Arvada

Predicted

USGS's geologic map puts all of Arvada's mapped land in one class: high radon potential. The map puts 92.7% of Arvada in the area it calls High Plains and 7.3% in Rocky Mountains. USGS gives the first a radon index of 12 and the second 15, both in the high band (12 to 17).

USGS's geologic areas under Arvada
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
High PlainsQuaternary deposits and Cretaceous marine shales that locally have a high radiometric signature.High1292.7%
Rocky MountainsPrecambrian granites, gneiss, amphibolite, variable uranium content, abundant shear zones.Sedimentary rocks shed from the granitic highlands.High157.3%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Arvada beside its counties and Colorado

All of Arvada, like all of Jefferson County, is rated high. Arvada has more high-potential ground than Colorado as a whole: 100% of its land against 74.8%.

Share of land by USGS radon potential: Arvada, the counties it lies in and Colorado
AreaEPA zoneLow potentialModerate potentialHigh potential
ArvadaBy countyNoneNone100%
Jefferson CountyZone 1NoneNone100%
Adams CountyZone 1NoneNone100%
Colorado64 counties, pooled by land areaVariesNone25.2%74.8%

The map rates the ground, not the air in any home.

Arvada, Homes

Homes in Arvada

Of Arvada's 51,655 homes, 70% are detached houses, against 64% across Jefferson County; 18% are in buildings of five or more homes. Half of its homes were built before 1979, close to Jefferson County's 1980: 11% date from before 1960 and 24% from 2000 or later. 75% of occupied homes are lived in by their owner (Jefferson County: 71%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Arvada, Jefferson County, Colorado, 2019 to 2023
HomesArvadaJefferson CountyColorado
Housing units51,655251,1832,545,124
Detached houses70%64%62%
In buildings of 5 or more18%22%22%
Mobile homesunder 1%1%4%
Built before 196011%14%16%
Built since 200024%19%31%
Middle year built197919801987
Owner-occupied75%71%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

Arvada, Local resources

Local resources for Arvada

Who to ask in Colorado: its radon program, test kits and professionals.

The program's own words on licensing and disclosure are on the Colorado page.

What it means

Arvada, Questions

Questions about radon in Arvada

What radon zone is Arvada in?

Both counties Arvada reaches into (Jefferson County and Adams 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 Arvada.

What are radon levels in Arvada?

41.8% of the 3,068 tests reported from Jefferson 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 Arvada. The median reported result was 3.2 pCi/L. Adams County reported 36.6% of 1,191 tests; the counties are kept apart.

Should I test my home in Arvada?

Yes. About 1,282 of the 3,068 tests reported from Jefferson County were at or above 4 pCi/L. That is above Colorado's pooled 38.9%, and ranks Jefferson County 17th 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 Arvada built on, as far as radon goes?

92.7% of Arvada sits on what USGS's map calls "High Plains", rated high for radon potential, radon index 12; another 7.3% is "Rocky Mountains", in the same class.

Is radon higher in the counties around Arvada?

No. Jefferson County's 41.8% is above every one of the 8 nearest counties with a figure: the closest share to it is Clear Creek County (41.2%, 28 miles off), the lowest Gilpin County (26.4%, 20 miles off).

The answers use the published figures of Jefferson County and Adams County, the counties Arvada lies in.

Explore