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Radon in Littleton, Colorado

Littleton, Colorado spans 3 counties, Arapahoe County, Douglas County and Jefferson County. Radon data is published by county, so this page sets their figures side by side.

ColoradoAbout 46,246 people

What this means for you

  • Your area: Littleton lies in 3 counties. EPA rates Arapahoe County Zone 1, Douglas County Zone 1 and Jefferson County Zone 1, where Zone 1 is the highest of its three radon zones. Zones are predictions for whole counties, and homes with elevated levels occur in all three zones.
  • Local tests: For 2023, the share of radon tests reported to CDC that were at or above 4 pCi/L was 37.9% in Arapahoe County (1,990 tests), 35.8% in Douglas County (1,635 tests) and 41.8% in Jefferson County (3,068 tests). EPA's action level is 4 pCi/L.
  • Your home: The only way to know your home’s level is to test it.
How to testFind a certified tester

pCi/L (picocuries per liter) is the unit radon is measured in. EPA recommends fixing a home at 4 pCi/L or above, its action level.

Littleton, What is published

What is published for Littleton

Information:

Radon data is published by county, not by city

Radon data is published by county, not by city. EPA assigns radon zones to counties, and CDC publishes radon test figures by county. Neither publishes a figure for Littleton, so every radon figure on this page belongs to a county and is labelled with it. Only a test tells you about one home.

Each county has its own CDC test figures, shown below side by side. About 46,246 people live in Littleton.

Littleton, Counties

Littleton'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.

  • 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
  • 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
  • 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
The counties Littleton 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
Arapahoe CountyZone 1: Highest predicted potential37.9%2.5 pCi/L1,990 tests10
Douglas CountyZone 1: Highest predicted potential35.8%2.4 pCi/L1,635 tests10
Jefferson CountyZone 1: Highest predicted potential41.8%3.2 pCi/L3,068 tests10

The median reported pre-mitigation result for 2023 was 2.5 pCi/L in Arapahoe County, 2.4 pCi/L in Douglas County and 3.2 pCi/L in Jefferson County.

CDC counts radon tests that were reported to it, not homes, and figures from few tests can swing widely from year to year. Each county’s report has its full history.

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

Littleton, Local resources

Local resources for Littleton

Who to ask in Colorado: the state's radon program, test kits and professionals.

Colorado's radon program

Colorado Department of Public Health and Environment

Colorado’s radon program answers questions about testing, mitigation and the rules where you live.

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.
Visit the program's page(opens in a new tab)

Test kits

The program says: Order a free radon test kit

Free and low-cost kitsCompare kits

Radon professionals

Radon testers and mitigators in Colorado, each with how its listing was checked.

Professionals in Colorado

Littleton, Questions

Questions about radon in Littleton

What radon zone is Littleton in?

EPA's Map of Radon Zones classifies counties, not cities. Arapahoe County, Douglas County and Jefferson County are in Zone 1 (highest predicted potential). A zone is a prediction for a whole county and never tells you the level in one home.

How many radon tests come back high in Littleton's counties?

For 2023, the share of radon tests reported to CDC that were at or above 4 pCi/L was 37.9% in Arapahoe County (1,990 tests), 35.8% in Douglas County (1,635 tests) and 41.8% in Jefferson County (3,068 tests). Each is that county's own figure, counting tests reported to CDC, not homes. Radon411 does not average or combine them into a figure for the city.

Should I test my home in Littleton?

Yes. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. How to test a home.

The answers use the published figures of Arapahoe County, Douglas County and Jefferson County, the counties Littleton lies in.

Littleton, Keep reading

Keep reading

Littleton / Next steps

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