Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
Locations and reports
Radon Levels in Harrison County, Texas
EPA puts Harrison County in Zone 3, its lowest radon zone, and only 4 radon tests from it are on file with CDC (2008 to 2017, laboratory totals). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Nearest county
9.1%
Smith County, 54 miles
- Smith
- 9.1%
- Texas
- 10.4%
Share at 4+ pCi/L, 33 tests, 2007 to 2016
Ground above low
None
27.3 pts below Texas
- Harrison
- 0.0%
- Texas
- 27.3%
Share of land USGS rates moderate or high potential
Tests reported
5
Too few for a share
- Harrison
- 5
- Needed
- 30
2006 to 2015, laboratory
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Read a result for Harrison County
Starts at EPA's action level
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.0 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher.
The data
Harrison County, At a glance
Harrison County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Harrison County, 2008 to 2017, laboratory
CDC holds 4 reported tests for Harrison County over the 2008 to 2017 laboratory totals, with a median of 0.2 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Harrison County beside the counties around it is how this page reads it.
What these figures count
Only 4 tests were reported to CDC for Harrison County over 2008 to 2017 (laboratory totals), and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.
Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Harrison County, Compared
Harrison County radon figures, compared
Calculated by Radon411CDC's largest figure for Harrison County rests on 5 tests over the 2006 to 2015 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 20.0 points and no rank or comparison is drawn from it. Results reached as high as 0.8 pCi/L, with a middle value of 0.2 pCi/L.
The nearest counties with a figure are Smith County (54 miles away) at 9.1%, Collin County (135 miles away) at 7.7% and Dallas County (141 miles away) at 8.7%. Pooled across 140 Texas counties, 10.4% of reported tests reached that level; across every county in the country with a figure, 35.8%.
Statewide for the same period, Randall County reported the highest share (71.4%) and Nueces County the lowest (0.0%). EPA's 1993 map puts Harrison County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 100% of the county's land low radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Harrison County, Geology
The ground under Harrison County
PredictedUSGS's geologic map puts all of Harrison County's mapped land in one class: low radon potential. All of it lies in the area the map calls East Texas Province, to which USGS gives a radon index of 6, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| East Texas Province | Cretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite. | Low | 6 | 99.8% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Harrison County beside the ground around it
Across Texas 0.5% of the land is rated high; none of Harrison County's is. None of the 6 counties that border it has any moderate-potential ground either.
The map rates the ground, not the air in any home.
Local help
Harrison County, Local resources
Radon testing and mitigation in Harrison County
- Texas Radon GroupTexas Radon Group, run by Texas Tech University, does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Texas.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
The Texas Radon Group offers free radon test kits for Texas individuals who qualify.
- Compare kits
- Professionals in Texas7 professionals are listed in Texas.
What Texas's program says
- Licensing of radon professionals
There are no radon certification requirements for the State of Texas at this time, but the National Radon Proficiency Program lists radon testers and mitigators within Texas that have passed a rigorous national certification program.
What it means
Harrison County, Questions
Questions about radon in Harrison County
Are radon levels high in Harrison County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Harrison County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.2 pCi/L. Of the 8 nearest counties with a figure, within 180 miles, the share of tests at or above 4 pCi/L runs from 0.0% to 17.1%.
Which counties border Harrison County?
Harrison County borders 6 counties: Marion County, TX, Panola County, TX, Gregg County, TX, Caddo Parish, LA, Upshur County, TX and Rusk County, TX.
Products
Harrison County, Products
Testing a home in Harrison County
No CDC figure names Harrison County; the nearest county with one, Smith County (54 miles away), reported 9.1% of its tests at or above 4 pCi/L over the 2007 to 2016 laboratory totals, the only reading nearby until a test of this home. 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 Harrison County.
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
Monitor
View Radon Wi-Fi radon monitor with an e-paper display
- C-NRPP 2024/25: Approved
- Battery
- Wi-Fi, Bluetooth
- Screen, app
Method: Alpha spectrometry
Readings: Every 60 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Harrison County, Bordering counties
Counties bordering Harrison County
Calculated by Radon411- Radon levels in Caddo Parish, LAEPA zone 3
16.7%at or above 4 pCi/L
Median 1.2 pCi/L · 24 tests
- Radon levels in Panola County, TXEPA zone 3
0.0%at or above 4 pCi/L
Median 0.6 pCi/L · 2 tests
- Radon levels in Gregg County, TXEPA zone 3
0.0%at or above 4 pCi/L
Median 0.9 pCi/L · 13 tests
- Radon levels in Upshur County, TXEPA zone 3
0.0%at or above 4 pCi/L
Median 1.6 pCi/L · 4 tests
- Radon levels in Rusk County, TXEPA zone 3
0.0%at or above 4 pCi/L
Median 0.4 pCi/L · 2 tests
- Radon levels in Marion County, TXEPA zone 3
No CDC figure for 2007 to 2016; its page reads it against its own neighbours.
Harrison County, Cities and towns
Cities and towns in Harrison County
The Census Bureau estimates 71,956 residents in Harrison County for July 1, 2025, 3,158 more than in 2020 (+4.6%). That works out to 80 people per square mile of land. Longview, the largest place on its list (83,236 residents in all), extends beyond Harrison County, so no share of the total is worked out for it. Reported testing is thin here: 5 tests over 2006 to 2015, or 0.1 for every 1,000 residents (2025 estimate), where Texas as a whole comes to 0.1.
From Longview to Uncertain, CDC publishes no figure by town: each reads Harrison County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Longviewextends beyond Harrison County | 83,236 | +1.8% | Counted whole |
| Marshall | 24,467 | +4.9% | 34.0% |
| Hallsville | 4,895 | +14.1% | 6.8% |
| Waskom | 1,980 | +3.9% | 2.8% |
| Scottsville | 341 | +2.7% | 0.5% |
| Uncertain | 90 | +1.1% | 0.1% |
6 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 Harrison County is counted whole, so it has no share.
Harrison County, Homes
Homes in Harrison County
Of Harrison County's 29,530 homes, 69% are detached houses, against 65% across Texas; 21% are mobile homes. Half of its homes were built before 1984, close to Texas' 1990: 20% date from before 1960 and 29% from 2000 or later. 75% of occupied homes are lived in by their owner (Texas: 63%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Harrison County | Texas |
|---|---|---|
| Housing units | 29,530 | 11,890,808 |
| Detached houses | 69% | 65% |
| In buildings of 5 or more | 4% | 21% |
| Mobile homes | 21% | 7% |
| Built before 1960 | 20% | 13% |
| Built since 2000 | 29% | 37% |
| Middle year built | 1984 | 1990 |
| Owner-occupied | 75% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.