Short-term kitempowerDX
Standard Radon Test short-term mail-in radon test kit
- Lab fee included
Method: Passive sampler
In home: 48 to 96 hours
Locations and reports
Radon Levels in Prince William County, Virginia
EPA puts Prince William County in Zone 2, its middle radon zone, and 31.7% of its 4,441 reported radon tests (2008 to 2017, laboratory totals) were at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
31.7%
1.3 pts above VA
- Prince William
- 31.7%
- Virginia
- 30.4%
4,441 tests, 2008 to 2017
Median result
2.3pCi/L
Below action level
- Prince William
- 2.3 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
4,441
3rd of 84 by tests
- Prince William
- 4,441
- Fairfax
- 8,657
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Rank in Virginia
49 of 84
Middle half
- Prince William
- 31.7%
- Russell
- 67.3%
By share, of 84 with 30+ tests
Read a result for Prince William County
Starts at Prince William County's median, 2.3 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.3 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Prince William County's median reported result, 2008 to 2017.
The data
Prince William County, At a glance
Prince William County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Prince William County is a
USGS geologic potential: Moderate across 45% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Prince William County, 2008 to 2017, laboratory
Under 2 pCi/L: 44%2 to 4 pCi/L: 24%4 pCi/L and above: 32%
Of 4,441 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 1,959 | 44.1% |
| 2 to 4 pCi/L | 1,073 | 24.2% |
| 4 pCi/L and above | 1,409 | 31.7% |
What these figures count
These are the 4,441 tests reported to CDC for Prince William County 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).
Prince William County, Compared
Prince William County radon figures, compared
Calculated by Radon411In Prince William County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (1,409 of 4,441) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 4.0 points lower. Across 131 Virginia counties pooled together, 30.4% of tests reached that level, so Prince William County runs 1.3 points above its state.
Of 5 neighbours with a figure, none reported a larger share at or above 4 pCi/L; the spread is 15.9% (Manassas city) to 31.4% (Stafford County). By share, Prince William County is 49th of 84 Virginia counties with 30 or more tests for the same period.
Half the tests came in under 2.3 pCi/L and half over it; the single highest reached 66.6 pCi/L. Below the action level, 1,959 tests (44.1%) came in under 2 pCi/L, against 44.7% statewide, and 1,073 tests (24.2%) fell between 2 and 4, against 24.9% statewide.
Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 31.7% share point the same way here. USGS geology rates 45% of the county's land moderate radon potential. CDC also counts 351 tests taken after mitigation in Prince William County for the same period: tests in homes where a fix was already in.
CDC's ten-year totals for Prince William County went from 3,100 tests (2005 to 2014) to 4,441 (2008 to 2017), the share going from 31.7% to 31.7%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Prince William County, Geology
The ground under Prince William County
PredictedNo class of ground holds half of Prince William County on USGS's geologic map: 44.8% of its land is moderate radon potential, 40.6% high and 14.1% low. The map puts 44.8% of Prince William County in the area it calls Mesozoic Basins and 40.6% in Inner Piedmont, with one smaller area beside them. USGS gives the first a radon index of 11, in the moderate band (9 to 11), and the second 12, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Mesozoic Basins | Sandstone, siltstone and lacustrine black shale. | Moderate | 11 | 44.8% |
| Inner Piedmont | Granite, pegmatites, granitic gneiss, schist and gneiss, slate, and phyllite. | High | 12 | 40.6% |
| Cretaceous Coastal Plain Sediments | Cretaceous Coastal Plain sand, silt, clay. | Low | 8 | 14.1% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Prince William County beside the ground around it
On high-potential ground Prince William County is close to Virginia as a whole: 40.6% of its land against 47.9%. Of the 6 counties that border it, 3 have more high-potential ground, Manassas Park city the most at 77.7%.
The map rates the ground, not the air in any home.
Local help
Prince William County, Local resources
Radon testing and mitigation in Prince William County
- VDH Radon ProgramVDH Radon Program answers questions about testing, mitigation and the rules in Virginia.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsAsk the program whether it has free or discounted kits, or compare kits you can buy.
- Compare kits
- Professionals in Virginia2 professionals are listed in Virginia.
What Virginia's program says
- 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).
What it means
Prince William County, Questions
Questions about radon in Prince William County
Are radon levels high in Prince William County?
Over the 2008 to 2017 laboratory totals, 31.7% of the radon tests reported to CDC for Prince William County, Virginia were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.3 pCi/L. Of 84 Virginia counties with 30 or more tests for the same period, 48 reported a higher share; pooled, the state comes to 30.4%.
Which counties border Prince William County?
Prince William County borders 6 counties: Manassas city, Manassas Park city, Fairfax County, Fauquier County, Stafford County and Loudoun County.
Products
Prince William County, Products
Testing a home in Prince William County
In Prince William County, 31.7% of 4,441 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 30.4% pooled across Virginia. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Prince William County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
MonitorAEGTEST
HOUND-1011 rechargeable radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Best radon monitors for Prince William County homes, compared
Explore
Prince William County, Bordering counties
Counties bordering Prince William County
Calculated by Radon411- Radon levels in Stafford CountyEPA zone 1
31.4%at or above 4 pCi/L
Median 2.5 pCi/L · 2,758 tests · 0.3 points below Prince William County
- Radon levels in Fauquier CountyEPA zone 2
30.2%at or above 4 pCi/L
Median 2.5 pCi/L · 1,199 tests · 1.5 points below Prince William County
- Radon levels in Loudoun CountyEPA zone 2
27.4%at or above 4 pCi/L
Median 1.8 pCi/L · 4,457 tests · 4.3 points below Prince William County
- Radon levels in Manassas Park cityEPA zone 1
20.0%at or above 4 pCi/L
Median 1.4 pCi/L · 25 tests · 11.7 points below Prince William County
- Radon levels in Fairfax CountyEPA zone 1
18.7%at or above 4 pCi/L
Median 1.5 pCi/L · 8,657 tests · 13.0 points below Prince William County
- Radon levels in Manassas cityEPA zone 1
15.9%at or above 4 pCi/L
Median 1.9 pCi/L · 145 tests · 15.8 points below Prince William County
Prince William County, Cities and towns
Cities and towns in Prince William County
The Census Bureau estimates 502,966 residents in Prince William County for July 1, 2025, 20,128 more than in 2020 (+4.2%). Packed into its land, that is 1,500 people per square mile. No town dominates: Dumfries, the largest, has 6,405 residents, 1.3% of the total. CDC's 4,441 reported tests for 2008 to 2017 work out to 8.8 per 1,000 residents (2025 estimate), close to Virginia's 6.0.
From Dumfries to Quantico, CDC publishes no figure by town: each reads Prince William County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Dumfries | 6,405 | +12.0% | 1.3% |
| Haymarket | 1,602 | +4.2% | 0.3% |
| Occoquanextends beyond Prince William County | 1,078 | +4.1% | Counted whole |
| Quantico | 597 | +3.1% | 0.1% |
4 incorporated places, 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). A place that extends beyond Prince William County is counted whole, so it has no share.
Prince William County, Homes
Homes in Prince William County
Fewer than six in ten of Prince William County's 160,256 homes are detached houses (55%, against 61% across Virginia); the rest are attached, in shared buildings or mobile. Much of Prince William County is recent building: 40% of its homes have gone up since 2000 and the middle year built is 1994, against 1984 for Virginia. 74% of occupied homes are lived in by their owner (Virginia: 67%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Prince William County | Virginia |
|---|---|---|
| Housing units | 160,256 | 3,654,784 |
| Detached houses | 55% | 61% |
| In buildings of 5 or more | 16% | 19% |
| Mobile homes | 1% | 4% |
| Built before 1960 | 5% | 19% |
| Built since 2000 | 40% | 25% |
| Middle year built | 1994 | 1984 |
| Owner-occupied | 74% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.