Radon levels in Washington, District of Columbia
LowEPA Zone 3Predicted long-term basement average of 1.1 pCi/L (model estimate) across the 22 modeled ZIP codes in Washington - about 40% below the US average of 1.8, close to the District of Columbia average of 1.1. Ranked #1 of 1 District of Columbia cities on this site. Most of the city lies in District of Columbia.
Test Washington, DC once anyway - radon varies house to house
The predicted basement average here is 1.1 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.
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Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.
1.1 ± 0.06
pCi/L predicted basement mean (model SD)
0.8 ± 0.08
pCi/L predicted upstairs (above-ground) mean
0.9-1.2
range of ZIP-level basement predictions in the city
0%
of Washington ZIPs predicted ≥ 4 pCi/L (0% ≥ 2)
What this means for Washington
The typical Washington home is predicted below 2 pCi/L, the lowest band. That describes the average house; the ZIP-level predictions inside the city still span 0.9 to 1.2 pCi/L.
The city figure is not a separate estimate: it is the mean of the model's ZIP-code predictions, weighted by the share of the city's land in each ZIP (Census 2020 ZCTA-to-place relationship file). The 1993 EPA zone (3) for District of Columbia and the 2001-2021 model agree here.
Comparable District of Columbia cities: Baltimore (1.0), Columbia (1.1), Germantown (1.1), Frederick (1.1).
ZIP codes in Washington
ZIPs that overlap the city, largest share of its land first. Predicted basement and upstairs means are model estimates; ZIPs the model does not cover show a dash.
| ZIP | Share of city | Basement | Upstairs | Grade |
|---|---|---|---|---|
| 20019 | 10% | 1.0 ± 0.07 | 0.7 | Low |
| 20011 | 9% | 1.1 ± 0.07 | 0.8 | Low |
| 20032 | 9% | 1.1 ± 0.06 | 0.8 | Low |
| 20002 | 8% | 1.0 ± 0.07 | 0.8 | Low |
| 20020 | 8% | 1.1 ± 0.07 | 0.8 | Low |
| 20016 | 7% | 1.1 ± 0.06 | 0.8 | Low |
| 20015 | 6% | 1.2 ± 0.06 | 1.1 | Low |
| 20007 | 5% | 1.2 ± 0.05 | 0.7 | Low |
| 20008 | 5% | 1.2 ± 0.06 | 0.9 | Low |
| 20018 | 5% | 1.2 ± 0.06 | 0.9 | Low |
| 20003 | 4% | 1.0 ± 0.06 | 0.8 | Low |
| 20017 | 4% | 1.1 ± 0.06 | 0.8 | Low |
| 20024 | 4% | 0.9 ± 0.06 | 0.7 | Low |
| 20012 | 3% | 1.2 ± 0.06 | 0.9 | Low |
| 20001 | 3% | 1.1 ± 0.07 | 0.8 | Low |
| 20009 | 2% | 0.9 ± 0.07 | 0.8 | Low |
| 20010 | 2% | 1.1 ± 0.07 | 0.8 | Low |
| 20037 | 1% | 1.0 ± 0.07 | 0.7 | Low |
| 20373 | 1% | — | — | no model |
| 20005 | 1% | 0.9 ± 0.08 | 0.6 | Low |
| 20006 | 1% | 0.9 ± 0.06 | 0.6 | Low |
| 20317 | 1% | — | — | no model |
| 20036 | 1% | 0.9 ± 0.07 | 0.7 | Low |
| 20004 | <1% | 1.0 ± 0.07 | 0.6 | Low |
| 20057 | <1% | — | — | no model |
| 20064 | <1% | — | — | no model |
| 20059 | <1% | — | — | no model |
| 20230 | <1% | — | — | no model |
| 20319 | <1% | — | — | no model |
| 20422 | <1% | — | — | no model |
| 20560 | <1% | — | — | no model |
| 20565 | <1% | — | — | no model |
| 20052 | <1% | — | — | no model |
| 20388 | <1% | — | — | no model |
| 20515 | <1% | — | — | no model |
| 20520 | <1% | — | — | no model |
| 20540 | <1% | — | — | no model |
| 20566 | <1% | — | — | no model |
| 20045 | <1% | — | — | no model |
| 20204 | <1% | — | — | no model |
| 20220 | <1% | — | — | no model |
| 20240 | <1% | — | — | no model |
| 20245 | <1% | — | — | no model |
| 20250 | <1% | — | — | no model |
| 20260 | <1% | — | — | no model |
| 20390 | <1% | — | — | no model |
| 20408 | <1% | — | — | no model |
| 20415 | <1% | — | — | no model |
| 20418 | <1% | — | — | no model |
| 20427 | <1% | — | — | no model |
| 20431 | <1% | — | — | no model |
| 20510 | <1% | — | — | no model |
| 20530 | <1% | — | — | no model |
| 20535 | <1% | — | — | no model |
| 20542 | <1% | — | — | no model |
| 20551 | <1% | — | — | no model |
| 20591 | <1% | — | — | no model |
Testing help in District of Columbia
District of Columbia's radon program page is at doee.dc.gov and, when we checked it, offered free radon test kits for District residents. EPA state radon contacts page. If a test comes back at 4 pCi/L or higher, mitigation typically costs $800-$2,500 installed; use EPA find-a-professional and read the mitigation guide.
Washington radon questions
- Is radon high in Washington, District of Columbia?
- Low. Averaging the model's ZIP-code predictions across Washington (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.1 pCi/L - about 40% below the US average of 1.8 and close to the District of Columbia average of 1.1. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Washington ranks 1 of 1 District of Columbia cities on this site.
- Which Washington ZIP codes have the highest radon?
- Predictions for the 22 modeled ZIP codes in Washington range from 0.9 to 1.2 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 0% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.
- Should I test for radon in Washington?
- Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Washington's low predicted average describes the typical home, not yours.
- What does EPA Radon Zone 3 mean for Washington?
- Washington sits mainly in District of Columbia, which the EPA classifies as Zone 3 - low potential (< 2 pCi/L). The zone map dates from 1993 and covers whole counties. The 2001-2021 model agrees with the zone for the city. Neither replaces a test of your own home.
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