Updated November 2026 · Data: EPA Map of Radon Zones · Sources
The District of Columbia is in EPA radon Zone 3, the group with the lowest predicted average indoor radon levels. Even so, the EPA recommends testing every home, because high radon levels are found in every zone. Learn how to test your home and what to do if the result is high.
Your county’s zone is not your home’s radon level. Homes with high radon are found in every zone. The EPA recommends testing every home, whatever its zone.
Map of EPA radon zones by county
Radon zones by county in District of Columbia
The table lists the EPA radon zone for each of the 1 areas in District of Columbia. The zone shows the predicted average indoor radon screening level for homes in that county.
| County | EPA zone | Predicted average indoor level |
|---|---|---|
| District of Columbia | Zone 3 | Below 2 pCi/L |
What the EPA radon zones mean
- Zone 1 (highest potential): predicted average indoor screening level greater than 4 pCi/L. In District of Columbia: 0 areas (0%).
- Zone 2 (moderate potential): predicted average between 2 and 4 pCi/L. In District of Columbia: 0 areas (0%).
- Zone 3 (low potential): predicted average below 2 pCi/L. In District of Columbia: 1 county (100%).
The EPA built the map from indoor radon measurements, geology, soil permeability and type of house foundation. It was made to help governments and builders target resources, not to decide whether a single home needs testing.
How to test for radon in District of Columbia
Testing is the only way to know your home’s radon level. Short-term test kits (2 to 90 days) are sold at hardware stores and online, and some state programs offer kits at low cost; check with the DC Department of Energy & Environment, Radon Program. Test in the lowest lived-in level of the home, with windows and doors closed, and follow the kit instructions.
- Do-it-yourself kits: a simple, low-cost first step for your own home.
- Long-term tests (more than 90 days): give a better picture of your home’s year-round average.
- Certified professionals: look for certification from the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB), and ask the state program whether District of Columbia requires a state license.
- Buying or selling a home: ask for a radon test as part of the home inspection.
DC residents have been able to get a free radon test kit by calling the radon hotline at 202-535-2302 or by requesting one online from the Department of Energy & Environment (DOEE). Check DOEE’s radon page for current availability.
If your radon level is high
The EPA recommends fixing your home if the radon level is 4 pCi/L or higher, and considering a fix between 2 and 4 pCi/L. The most common fix is a radon mitigation system (sub-slab depressurization), which pulls radon from under the foundation and vents it outside, above the roof line.
- The EPA says most homes can be fixed for about the same cost as other common home repairs; the price depends on the size and design of the home.
- Get estimates from more than one qualified, certified mitigation contractor. See our radon mitigation cost guide for typical prices.
- Test again after the system is installed, and retest every few years.
Learn more: safe radon levels · how to test · test kits compared · radon and home sales · radon in well water
District of Columbia radon program
The DC Department of Energy & Environment, Radon Program answers questions from residents about radon testing, results and certified professionals.
- Phone: 202-535-2302
- Website: doee.dc.gov/radon
Contact details as listed by the state radon program directory. Please confirm on the program’s website before calling.
Frequently asked questions
Is radon a problem in Washington, DC?
The District is in EPA Zone 3, the lowest-potential group, but individual homes can still have high radon. The only way to know is to test.
Who can I contact about radon in DC?
The DC Department of Energy & Environment, Radon Program answers questions about radon testing and results: 202-535-2302.
Sources
- SOSRadon.org (CRCPD/EPA): District of Columbia state radon program fact sheet (2018)
- U.S. EPA: EPA Map of Radon Zones (county data file, June 2024)
- U.S. EPA: A Citizen’s Guide to Radon (checked November 2026)
- U.S. EPA: How much can a radon mitigation system cost? (updated September 16, 2026)
- DC Department of Energy & Environment, Radon Program (checked November 2026)
- SOSRadon.org (CRCPD): State radon contacts (checked November 2026)