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Radon Levels in James City County, Virginia

EPA puts James City County in Zone 3, its lowest radon zone, and 37.3% of its 83 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    37.3%

    6.9 pts above VA

    James City
    37.3%
    Virginia
    30.4%

    83 tests, 2008 to 2017

  • Median result

    2.6pCi/L

    Below action level

    James City
    2.6 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    83

    62nd of 84 by tests

    James City
    83
    Fairfax
    8,657

    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

  • Rank in Virginia

    36 of 84

    Middle half

    James City
    37.3%
    Russell
    67.3%

    By share, of 84 with 30+ tests

Read a result for James City County

Starts at James City County's median, 2.6 pCi/L

2.6pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 2.6 pCi/L

Between 2 and 4 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. James City County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

James City County, At a glance

James City County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for James City County 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: Low across 93% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for James City County, 2008 to 2017, laboratory

Reported results by concentration band, James City County, 2008 to 2017, laboratory
Under 2 pCi/L: 44%2 to 4 pCi/L: 19%4 pCi/L and above: 37%

Of 83 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, James City County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L3643.4%
2 to 4 pCi/L1619.3%
4 pCi/L and above3137.3%
What these figures count

These are the 83 tests reported to CDC for James City 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).

How to read these figures

James City County, Compared

James City County radon figures, compared

Calculated by Radon411

In James City County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (31 of 83) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 1.6 points higher. Across 131 Virginia counties pooled together, 30.4% of tests reached that level, so James City County runs 6.9 points above its state.

Newport News city, the one bordering county with a figure for the same period, reported 6.7%. By share, James City County is 36th of 84 Virginia counties with 30 or more tests for the same period.

Half the tests came in under 2.6 pCi/L and half over it; the single highest reached 28.3 pCi/L. Below the action level, 36 tests (43.4%) came in under 2 pCi/L, against 44.7% statewide, and 16 tests (19.3%) fell between 2 and 4, against 24.9% statewide.

The reported tests do not follow EPA's Zone 3 label for James City County (predicted average under 2 pCi/L): 37.3% of them reached 4 pCi/L, more than a low-potential zone suggests. USGS geology rates 93% of the county's land low radon potential.

CDC's ten-year totals for James City County went from 65 tests (2005 to 2014) to 83 (2008 to 2017), the share going from 35.4% to 37.3%.

James City County against Virginia, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from James City County
James City County8337.3%2.6 pCi/LThis county
Virginia, pooled131 counties, pooled53,19930.4%Not pooled−6.9 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−1.6 points
Russell Countyhighest in the state4967.3%6.7 pCi/L+30.0 points
Norfolk citylowest in the state732.7%0.5 pCi/L−34.6 points
New Kent County, VAborders it1330.8%2.4 pCi/L−6.5 points
King and Queen County, VAborders it728.6%2.4 pCi/L−8.7 points
York County, VAborders it2326.1%1.8 pCi/L−11.2 points
Gloucester County, VAborders it825.0%2.0 pCi/L−12.3 points
Williamsburg city, VAborders it1910.5%0.8 pCi/L−26.8 points
Newport News city, VAborders it306.7%1.4 pCi/L−30.6 points
Charles City County, VAborders it20.0%1.1 pCi/L−37.3 points
Where James City County's reported results fell, 2008 to 2017, laboratory, beside Virginia and the United States
ResultJames City County testsJames City County shareVirginia shareU.S. shareAgainst Virginia
Under 2 pCi/L3643.4%44.7%39.6%−1.3 points
2 to 4 pCi/L1619.3%24.9%24.7%−5.6 points
4 pCi/L and above3137.3%30.4%35.7%+6.9 points
James City County ranked among the 84 Virginia counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Brunswick County31 of 843839.5%2.8 pCi/L
Pittsylvania County32 of 8424238.4%3.0 pCi/L
Page County33 of 8414138.3%3.3 pCi/L
Louisa County34 of 8428938.1%2.8 pCi/L
Mecklenburg County35 of 846637.9%3.0 pCi/L
James City County36 of 848337.3%2.6 pCi/L
Warren County37 of 8453636.9%2.7 pCi/L
Amherst County38 of 8424736.8%2.9 pCi/L
Shenandoah County39 of 8439036.4%2.7 pCi/L
Orange County40 of 8446236.1%2.8 pCi/L
Henry County41 of 8411535.7%2.7 pCi/L
James City County ten-year laboratory totals, against Virginia's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestVirginia, pooledChange from the row before
2008 to 20178337.3%2.6 pCi/L28.3 pCi/L30.4%−4.0 points
2007 to 20168041.3%3.2 pCi/L28.3 pCi/L30.6%+2.9 points
2006 to 20157338.4%2.4 pCi/L28.3 pCi/L30.7%+3.0 points
2005 to 20146535.4%2.3 pCi/L28.3 pCi/L30.3%First on file

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

James City County, Geology

The ground under James City County

Predicted

USGS's geologic map puts all of James City County's mapped land in one class: low radon potential. 93.5% of it lies in the area the map calls Tertiary Coastal Plain Sediments, to which USGS gives a radon index of 8, in the low band (5 to 8).

USGS's geologic areas under James City County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Tertiary Coastal Plain SedimentsTertiary Coastal Plain sand, silt, clayLow893.5%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

James City County beside the ground around it

Across Virginia 47.9% of the land is rated high; none of James City County's is. None of the 7 counties that border it has any moderate-potential ground either.

Share of land by USGS radon potential: James City County, the 7 counties bordering it and Virginia
AreaEPA zoneLow potentialModerate potentialHigh potential
James City CountyZone 393.5%NoneNone
Williamsburg cityZone 3100%NoneNone
Gloucester CountyZone 387.5%NoneNone
Charles City CountyZone 392.5%NoneNone
New Kent CountyZone 395.1%NoneNone
York CountyZone 385.4%NoneNone
Newport News cityZone 397.5%NoneNone
King and Queen CountyZone 398.2%NoneNone
Virginia133 counties, pooled by land areaVaries20.6%30.0%47.9%

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

Local help

James City County, Local resources

Radon testing and mitigation in James City County

What Virginia's program says
Phone
(804) 864-8161
Email
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

James City County, Questions

Questions about radon in James City County

Are radon levels high in James City County?

Over the 2008 to 2017 laboratory totals, 37.3% of the radon tests reported to CDC for James City County, Virginia were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.6 pCi/L. Of 84 Virginia counties with 30 or more tests for the same period, 35 reported a higher share; pooled, the state comes to 30.4%.

Which counties border James City County?

James City County borders 7 counties: Williamsburg city, Gloucester County, Charles City County, New Kent County, York County, Newport News city and King and Queen County.

Products

James City County, Products

Testing a home in James City County

In James City County, 37.3% of 83 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 30.4% pooled across Virginia. 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 James City County.

Test kits and monitors3

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Best radon monitors for James City County homes, compared

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James City County, Bordering counties

Counties bordering James City County

Calculated by Radon411

James City County, Residents

Who lives in James City County

James City County is growing: the Census Bureau puts it at 83,326 residents on July 1, 2025, up 6.2% from 78,486 in 2020. That works out to 586 people per square mile of land. Reported testing is thin here: 83 tests over 2008 to 2017, or 1.0 for every 1,000 residents (2025 estimate), where Virginia as a whole comes to 6.0.

Census lists no incorporated place in James City County: every home in it reads the county's figures.

Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).

James City County, Homes

Homes in James City County

Of James City County's 34,400 homes, 68% are detached houses, against 61% across Virginia; 14% are in buildings of five or more homes. Much of James City County is recent building: 44% of its homes have gone up since 2000 and the middle year built is 1997, against 1984 for Virginia. Owners live in 79% of the occupied homes (Virginia: 67%), so for most households a test and a fix are their own to order.

Homes in James City County, Virginia, 2019 to 2023
HomesJames City CountyVirginia
Housing units34,4003,654,784
Detached houses68%61%
In buildings of 5 or more14%19%
Mobile homes2%4%
Built before 19604%19%
Built since 200044%25%
Middle year built19971984
Owner-occupied79%67%

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