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Radon Levels in District of Columbia

EPA puts District of Columbia 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

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  • Share at 4+ pCi/L

    8.7%

    0.0 pts above DC

    District of Columbia
    8.7%
    DC
    8.7%

    2,126 tests, 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 the tests, 2008 to 2017

  • Tests reported

    2,126

    Most tested in DC

    District of Columbia
    2,126

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 3

    Lower potential

    1. 1
    2. 2
    3. Zone 3

    1 highest, 3 lowest

    EPA predicts under 2 pCi/L indoors

Read a result for District of Columbia

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

District of Columbia, At a glance

District of Columbia at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for District of Columbia as a whole is an average indoor of less than 2 pCi/L (less than 75 Bq/m³). A low zone clears no address in it: homes above EPA's turn up in all three zones.

USGS geologic potential: Moderate across 72% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for District of Columbia, 2008 to 2017, laboratory

Reported results by concentration band, District of Columbia, 2008 to 2017, laboratory
Under 2 pCi/L: 71%2 to 4 pCi/L: 20%4 pCi/L and above: 9%

Of 2,126 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, District of Columbia, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L1,51671.3%
2 to 4 pCi/L42419.9%
4 pCi/L and above1868.7%
What these figures count

These are the 2,126 tests reported to CDC for District of Columbia over 2008 to 2017 (laboratory totals), many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.

Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

District of Columbia, Compared

District of Columbia radon figures, compared

Calculated by Radon411

District of Columbia reports fewer high tests than District of Columbia overall. 8.7% of its 2,126 tests over the 2008 to 2017 laboratory totals were at or above 4 pCi/L. Pooled across 1 District of Columbia counties, the share is the same 8.7%.

Nationally, every county with a figure for the same period pools to 35.7%; District of Columbia sits 27.0 points below it.

Next door, the shares run from 7.3% in Alexandria city, VA to 19.0% in Prince George's County, MD, with Alexandria city, VA below District of Columbia. Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 8.7% share point the same way here.

Half the tests came in under 1.2 pCi/L and half over it; the single highest reached 82.2 pCi/L. The rest split 71.3% under 2 pCi/L and 19.9% from 2 to 4 (District of Columbia: 71.3% and 19.9%).

CDC's ten-year totals for District of Columbia went from 1,735 tests (2005 to 2014) to 2,126 (2008 to 2017), the share going from 8.0% to 8.7%.

District of Columbia against District of Columbia, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from District of Columbia
District of Columbia2,1268.7%1.2 pCi/LThis county
District of Columbia, pooled1 counties, pooled2,1268.7%Not pooledLevel
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+27.0 points
Prince George's County, MDborders it1,60319.0%1.4 pCi/L+10.3 points
Fairfax County, VAborders it8,65718.7%1.5 pCi/L+10.0 points
Montgomery County, MDborders it10,96918.0%1.3 pCi/L+9.3 points
Arlington County, VAborders it1,10113.7%1.4 pCi/L+5.0 points
Alexandria city, VAborders it4107.3%1.0 pCi/L−1.4 points
Where District of Columbia's reported results fell, 2008 to 2017, laboratory, beside District of Columbia and the United States
ResultDistrict of Columbia testsDistrict of Columbia shareDistrict of Columbia shareU.S. shareAgainst District of Columbia
Under 2 pCi/L1,51671.3%71.3%39.6%Level
2 to 4 pCi/L42419.9%19.9%24.7%Level
4 pCi/L and above1868.7%8.7%35.7%Level
District of Columbia ten-year laboratory totals, against District of Columbia's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestDistrict of Columbia, pooledChange from the row before
2008 to 20172,1268.7%1.2 pCi/L82.2 pCi/L8.7%+0.1 points
2007 to 20162,2828.6%1.2 pCi/L82.2 pCi/L8.6%+0.1 points
2006 to 20151,9878.5%1.1 pCi/L82.2 pCi/L8.5%+0.5 points
2005 to 20141,7358.0%1.1 pCi/L82.2 pCi/L8.0%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

District of Columbia, Geology

The ground under District of Columbia

Predicted

USGS's geologic map splits District of Columbia: 72.3% of its land is moderate radon potential and 16.6% high and 1.0% low. The map puts 72.3% of District of Columbia 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 District of Columbia
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.

District of Columbia beside the ground around it

On high-potential ground District of Columbia is close to District of Columbia as a whole: 16.6% of its land against 16.6%. Of the 5 counties that border it, 4 have more high-potential ground, Montgomery County, MD the most at 80.2%.

Share of land by USGS radon potential: District of Columbia, the 5 counties bordering it and District of Columbia
AreaEPA zoneLow potentialModerate potentialHigh potential
District of ColumbiaZone 31.0%72.3%16.6%
Arlington County, VAZone 254.9%None44.8%
Alexandria city, VAZone 399.5%NoneNone
Prince George's County, MDZone 20.1%58.7%38.8%
Montgomery County, MDZone 1None19.8%80.2%
Fairfax County, VAZone 125.2%12.7%61.1%
District of Columbia1 county, pooled by land areaVaries1.0%72.3%16.6%

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

Local help

District of Columbia, Local resources

Radon testing and mitigation in District of Columbia

What District of Columbia's program says
Phone
(202) 535-2302

What it means

District of Columbia, Questions

Questions about radon in District of Columbia

Are radon levels high in District of Columbia?

Over the 2008 to 2017 laboratory totals, 8.7% of the radon tests reported to CDC for District of Columbia were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.2 pCi/L.

Which counties border District of Columbia?

District of Columbia borders 5 counties: Arlington County, VA, Alexandria city, VA, Prince George's County, MD, Montgomery County, MD and Fairfax County, VA.

Products

District of Columbia, Products

Testing a home in District of Columbia

In District of Columbia, 8.7% of 2,126 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 8.7% pooled across District of Columbia. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in District of Columbia.

Test kits and monitors3

See every kit and monitor

Best radon monitors for District of Columbia homes, compared

Explore

District of Columbia, Bordering counties

Counties bordering District of Columbia

Calculated by Radon411

District of Columbia, Cities and towns

Cities and towns in District of Columbia

The Census Bureau estimates 693,645 residents in District of Columbia for July 1, 2025, 22,687 more than in 2020 (+3.4%). Packed into its land, that is 11,348 people per square mile. Washington, its one incorporated place, has 693,645 residents, 100.0% of the total. CDC's 2,126 reported tests for 2008 to 2017 work out to 3.1 per 1,000 residents (2025 estimate), close to District of Columbia's 3.1.

Washington is the one incorporated place here; CDC publishes no figure by town, so it reads District of Columbia's.

Washington, District of Columbia: residents on July 1, 2025
PlaceResidentsSince 2020Share of residents
Washington693,645+3.4%100.0%

One incorporated place, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).

District of Columbia, Homes

Homes in District of Columbia

District of Columbia 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 District of Columbia, District of Columbia, 2019 to 2023
HomesDistrict of ColumbiaDistrict of Columbia
Housing units356,101356,101
Detached houses11%11%
In buildings of 5 or more56%56%
Mobile homesunder 1%under 1%
Built before 196054%54%
Built since 200022%22%
Middle year built19571957
Owner-occupied41%41%

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