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Radon in Washington, District of Columbia

EPA puts District of Columbia, where Washington is, in Zone 3, its lowest radon zone, and most reported tests there come back low, though 8.7% of 2,126 (2008 to 2017, laboratory totals) reached 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    8.7%

    0.0 pts below DC

    District of Columbia
    8.7%
    DC
    8.7%

    District of Columbia, 2008 to 2017

  • Median result

    1.2pCi/L

    Below action level

    District of Columbia
    1.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of District of Columbia's tests, 2008 to 2017

  • Tests reported

    2,126

    In District of Columbia

    District of Columbia
    2,126

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 3

    Low potential

    1. 1
    2. 2
    3. Zone 3

    1 highest, 3 lowest

    District of Columbia, where Washington is

  • Tests reported

    2,126

    In District of Columbia

    Reported to CDC before any fix, 2008 to 2017

Read a result for Washington

Starts at District of Columbia's median, 1.2 pCi/L

1.2pCi/L

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

EPA’s reading of 1.2 pCi/L

Below 2 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 below 2 pCi/L, the level at which EPA says a fix should be considered. District of Columbia's median reported result, 2008 to 2017.

Interpret this reading

The data

Washington, What is published

What is published for Washington

Information:

Every figure for Washington is a county's

Radon data is published by county, not by city, so for Washington it is District of Columbia's: its EPA zone (Zone 3) and the 2,126 tests reported to CDC for 2008 to 2017, laboratory. Only a test tells you about one home.

Washington covers 61.1 square miles of land, all of it in District of Columbia. Its 693,645 residents live 11,348 to the square mile.

Washington, Counties

The county Washington lies in

Measured

District of Columbia's EPA zone and the figures CDC publishes for it, 2008 to 2017, laboratory.

District of ColumbiaZone 3Lower predicted potential

8.7%
Reported tests at or above 4 pCi/L
1.2 pCi/L
Median reported result
2,126 tests
Tests reported to CDC
None
Yearly figures on file

District of Columbia runs 0.0 points below the 8.7% pooled across District of Columbia's counties, 27.0 points below the national pool of 35.7%.

No business in the directory gives Washington as its address; the District of Columbia list covers it.

Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2008 to 2017, laboratory.

Washington, Geology

The ground under Washington

Predicted

USGS's geologic map splits Washington: 72.3% of its land is moderate radon potential and 16.3% high and 1.0% low. The map puts 72.3% of Washington in the area it calls Western Shore and 16.3% in Eastern Piedmont, with one smaller area beside them. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 12, in the high band (12 to 17).

USGS's geologic areas under Washington
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Western ShoreCretaceous, Quaternary, minor Tertiary gravel, sand, silt, clay.Moderate1072.3%
Eastern PiedmontPrecambrian igneous and metamorphic rocks (schist and gneiss).High1216.3%
Cretaceous Coastal Plain SedimentsCretaceous Coastal Plain sand, silt, clay.Low81.0%

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

Washington beside its county and District of Columbia

The ground under Washington is close to District of Columbia's as a whole: 16.3% rated high against 16.6%. On high-potential ground Washington is close to District of Columbia as a whole: 16.3% of its land against 16.6%.

Share of land by USGS radon potential: Washington, the county it lies in and District of Columbia
AreaEPA zoneLow potentialModerate potentialHigh potential
WashingtonBy county1.0%72.3%16.3%
District of ColumbiaZone 31.0%72.3%16.6%
District of Columbia1 county, pooled by land areaVaries1.0%72.3%16.6%

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

Washington, Homes

Homes in Washington

Washington has 356,101 homes, and many share a building: 56% are in buildings of five or more, 11% are detached houses, against 11% across District of Columbia. Half of its homes were built before 1957, close to District of Columbia's 1957: 54% date from before 1960 and 22% from 2000 or later. Most occupied homes here are rented: owners live in 41% (District of Columbia: 41%). A tenant can run a test; a fix is the landlord's to make.

Homes in Washington, District of Columbia, District of Columbia, 2019 to 2023
HomesWashingtonDistrict of ColumbiaDistrict of Columbia
Housing units356,101356,101356,101
Detached houses11%11%11%
In buildings of 5 or more56%56%56%
Mobile homesunder 1%under 1%under 1%
Built before 196054%54%54%
Built since 200022%22%22%
Middle year built195719571957
Owner-occupied41%41%41%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.

Local help

Washington, Local resources

Local resources for Washington

Who to ask in District of Columbia: its radon program, test kits and professionals.

The program's own words on licensing are on the District of Columbia page.

What it means

Washington, Questions

Questions about radon in Washington

What radon zone is Washington in?

EPA's map puts District of Columbia, and with it Washington, in Zone 3, the map's lowest class: a predicted county average under 2 pCi/L. A low zone does not clear a house: homes over the action level are found in all three.

What are radon levels in Washington?

Only 8.7% of 2,126 tests from District of Columbia for 2008 to 2017 (laboratory totals) reached 4 pCi/L, so reported levels around Washington run low. The median reported result was 1.2 pCi/L. Low is not none.

Should I test my home in Washington?

Yes, even here. 185 of 2,126 tests reported from District of Columbia were at or above 4 pCi/L. That is about what District of Columbia as a whole reports (8.7%). Those homes were found by testing, not by the county's low share. How to test a home.

What ground is Washington built on, as far as radon goes?

72.3% of Washington sits on what USGS's map calls "Western Shore", rated moderate for radon potential, radon index 10; another 16.3% is "Eastern Piedmont", rated high for radon potential, radon index 12. One smaller area makes up the rest. So the ground changes within Washington itself.

The answers use the published figures of District of Columbia, the county Washington lies in.

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