Locations and reports
Radon Levels in Loudoun County, Virginia
What this means for you
- Your area: EPA rates Loudoun County Zone 2, the middle of its three radon zones. That is a prediction for the whole county, and homes with elevated levels occur in all three zones.
- Local tests: Of 4,457 radon tests reported to CDC for Loudoun County (2008 to 2017), 27.4% were at or above 4 pCi/L, EPA's action level.
- Your home: The only way to know your home’s level is to test it.
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.
Over the 2008 to 2017 laboratory totals, 27.4% of the radon tests reported to CDC for Loudoun County, Virginia came back at or above the EPA action level of 4 pCi/L, and the median result was 1.8 pCi/L. EPA's Map of Radon Zones places the county in Zone 2, moderate predicted potential. Radon levels vary from home to home, so only a test measures the level in yours.
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
EPA predicts an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³) across the county as a whole.
This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.
USGS geologic potential: Moderate across 99% of the county's land area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Loudoun County, 2008 to 2017, laboratory
- Tests reported
- 4,457
- At or above 4 pCi/L
- 27.4%
- Median result
- 1.8 pCi/L
Of 4,457 pre-mitigation tests reported to CDC, not homes in this area. CDC publishes the share in each band, not a count per band, so the per-band counts in the table are calculated by Radon411 and rounded to add up to the published total.
| Result band | Tests Calculated by Radon411 | Share Measured |
|---|---|---|
| Under 2 pCi/L | 2,304 | 51.7% |
| 2 to 4 pCi/L | 932 | 20.9% |
| 4 pCi/L and above | 1,221 | 27.4% |
Distribution of tested buildings, not this house. People testing before a sale, or because they suspect a problem, are over-represented in any reported testing data.
Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Loudoun County, In figures
Loudoun County in figures
What the published data says about Loudoun County, in words. A zone and a share of tests describe an area, never the level in any one home.
Predicted
PredictedEPA places Loudoun County in Zone 2, moderate predicted potential, as it does 27 other counties of Virginia's 133.
Of the 8 bordering counties, EPA places Clarke County, Fairfax County, Frederick County, Jefferson County, Montgomery County and Washington County in Zone 1 and Fauquier County and Prince William County in Zone 2.
Reported tests
MeasuredCDC publishes no annual figure for Loudoun County; its figure is a laboratory total for 2008 to 2017: 27.4% of 4,457 reported tests were at or above 4 pCi/L.
Local record
Virginia's radon program is the VDH Radon Program, run by Virginia Department of Health; its contacts are under Local resources.
The county's largest incorporated places are Leesburg, Herndon and Purcellville; the figures here cover them as part of the county.
Loudoun County, Comparison
How Loudoun County compares
MeasuredLoudoun County's own published CDC figures beside those of the counties that border it, for the same period.
Share of reported tests at or above 4 pCi/L
Measured2008 to 2017, laboratory, highest first. Each county’s own published CDC figure.
- Washington CountyMD1,259 tests56.0%
- Jefferson CountyWV898 tests53.2%
- Clarke CountyVA350 tests47.7%
- Prince William CountyVA4,441 tests31.7%
- Fauquier CountyVA1,199 tests30.2%
- Frederick CountyMD3,933 tests28.1%
- Loudoun CountyThis page4,457 tests27.4%
- Fairfax CountyVA8,657 tests18.7%
- Montgomery CountyMD10,969 tests18.0%
Median reported result
Measured2008 to 2017, laboratory, highest first. Each county’s own published CDC figure.
- Washington CountyMD1,259 tests5.2 pCi/L
- Jefferson CountyWV898 tests4.4 pCi/L
- Clarke CountyVA350 tests3.5 pCi/L
- Fauquier CountyVA1,199 tests2.5 pCi/L
- Prince William CountyVA4,441 tests2.3 pCi/L
- Loudoun CountyThis page4,457 tests1.8 pCi/L
- Fairfax CountyVA8,657 tests1.5 pCi/L
- Frederick CountyMD3,933 tests1.5 pCi/L
- Montgomery CountyMD10,969 tests1.3 pCi/L
Each figure is that county’s own published CDC figure for 2008 to 2017, laboratory, counting radon tests reported to CDC, not homes. Loudoun County is this page. Nothing is averaged or combined across counties. The test count beside each county is CDC’s published number of pre-mitigation tests behind its figures. Figures from few tests can swing widely from year to year. Every Virginia county’s own figure is in the Virginia county table.
CDC publishes this figure only for counties here, so there is no state or national number to compare Loudoun County, Virginia with.
Loudoun County, Bordering counties
Counties bordering Loudoun County
Calculated by Radon4118 counties share a boundary with Loudoun County, computed from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county’s report can be worth reading alongside this one.
- Clarke CountyVAZone 1: Highest predicted potential
- Jefferson CountyWVZone 1: Highest predicted potential
- Fairfax CountyVAZone 1: Highest predicted potential
- Montgomery CountyMDZone 1: Highest predicted potential
- Prince William CountyVAZone 2: Moderate predicted potential
- Fauquier CountyVAZone 2: Moderate predicted potential
- Washington CountyMDZone 1: Highest predicted potential
- Frederick CountyMDZone 1: Highest predicted potential
Loudoun County, Local resources
Local resources in Virginia
Who to ask in Virginia: the state's radon program, test kits and professionals.
VDH Radon Program
Virginia Department of Health
Virginia’s radon program answers questions about testing, mitigation and the rules where you live.
- Phone
- (804) 864-8161
- Radon@vdh.virginia.gov
- Licensing of radon professionals
The Code of Virginia requires that Radon testers and mitigators be currently certified by either the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB).
Test kits
The program says: Virginia Department of Health is offering a limited supply of short-term, do-it-yourself radon test kits available for only a $4 shipping fee.
Radon professionals
4 professionals are listed in Virginia.
Professionals in VirginiaLoudoun County, Cities and towns
Cities and towns in Loudoun County
The radon figures on this page are for Loudoun County as a whole. They do not differ by city or town.
- Leesburg
- Herndon (part)
- Purcellville
- Lovettsville
- Round Hill
- Middleburg
- Hamilton
- Hillsboro
8 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county.
Loudoun County, Questions
Questions about radon in Loudoun County
Common questions8 questions, answered from the figures above
Who does radon mitigation in Loudoun County?
No listed mitigator names Loudoun County as a service area yet; the Virginia directory lists 4 companies. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional. Your state radon program is the place to check whether Virginia requires one.
How radon mitigation worksWhat mitigation costsMitigators in Virginia
How do I get a radon test in Loudoun County?
EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. No certified tester listed on Radon411 names Loudoun County as a service area yet. The Virginia radon program is the place to ask about certified testers and any test kit offer it runs.
How to test a homeTest kits comparedFree and low-cost kits by stateVirginia radon program
Are radon levels high in Loudoun County?
In 2017, 27.4% of the radon tests reported to CDC for Loudoun County, Virginia were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.8 pCi/L. That is a share of reported tests, not of homes. EPA places Loudoun County in Zone 2, moderate predicted potential, a predicted average indoor screening level 2 to 4 pCi/L. Homes with elevated levels occur in all three zones, so the figures describe the area, not your house. Testing is the only way to know the radon level in a specific building.
What EPA radon zone is Loudoun County in?
EPA places Loudoun County, Virginia in Zone 2, which EPA describes as moderate predicted potential for the area. A zone is a prediction for the whole county and never determines whether a particular home should be tested. EPA recommends testing every home regardless of zone.
Should I test my home in Loudoun County?
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.
When is the best time of year to test?
EPA says short-term tests stay in the home from 2 to 90 days and that all radon tests should run a minimum of 48 hours; long-term tests stay more than 90 days. EPA's guides do not name a best season: they say radon levels tend to vary from day to day and season to season, so a long-term test is more likely than a short-term test to tell you the year-round average.
What does it cost to test?
EPA's Citizen's Guide calls testing easy and inexpensive, and EPA's Home Buyer's and Seller's Guide says passive short-term and long-term devices are generally inexpensive, while active devices may cost more. No national average price is published for this, so Radon411 does not give one. What testing costs.
Which counties border Loudoun County?
Loudoun County borders 8 counties, derived from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county's report can be relevant.
What these figures mean if you own, buy, sell or rent
The reported-test figures on this page describe Loudoun County, Virginia in 2017. They describe tests other people carried out in other buildings, and none of them measures yours.
- How to test a home
If you own your home
Test the lowest lived-in level; a short-term kit screens in days, a long-term kit reflects the year.
- Buying a house: radon guide
If you are buying
Ask for past results and any system's post-mitigation test, and test during the sale.
- Selling a house: radon guide
If you are selling
Testing before you list puts the timing in your hands; disclosure rules differ by state.
- Radon in rental homes
If you rent, or rent out a home
A tenant can test; a fix is the owner's to make, and duties differ by state.
How long a test has to run, under what conditions, and what EPA says a result means: the testing standard, in full.
Loudoun County, Products
Testing and mitigation products
Whatever the figures for Loudoun County show, only a test tells you about one home.
Testing
- Short-term test kitsPassive detectors exposed for a few days under closed-building conditions, then analyzed by a lab.
- Long-term test kitsDetectors exposed for more than 90 days, for a closer picture of the annual average.
- Continuous monitorsPowered devices that log radon on a repeating cycle, often used for transaction tests.
- Digital detectorsConsumer devices that display a running radon reading without a lab.
- Water radon testsKits for radon dissolved in well water, analyzed by a lab.
Mitigation
- Mitigation fansThe inline fan that keeps a soil depressurization system running, sized by the installer.
- System indicatorsU-tube manometers and fan alarms that show whether a mitigation system is still working.
- Sealing materialsCrack, joint and sump sealing used alongside a mitigation system, not instead of one.
Loudoun County / Next steps
What to do next
Learn
Know what radon is
What radon is, how it gets indoors, and why a county zone is not a reading for your home.
Learn about radonTest
Test the building you live in
Short-term or long-term, where the device goes, and closed-house conditions.
How to testFix
Bring a high level down
How a mitigation system works, and the retest that confirms it.
How mitigation worksFind a pro
Hire a certified professional
Measurement and mitigation professionals by state, with their certifications.
Find a professional
Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.