Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
Locations and reports
Radon Levels in Union County, New Mexico
EPA puts Union County in Zone 2, its middle radon zone, and only 2 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
Highest bordering
64.5%
Baca County
- Baca
- 64.5%
- Las Animas
- 63.9%
2 of 8 neighbours have 30+ tests, 2006 to 2015
Nearest county
44.4%
San Miguel County, 102 miles
- San Miguel
- 44.4%
- New Mexico
- 30.3%
Share at 4+ pCi/L, 36 tests, 2006 to 2015
Ground above low
100.0%
7.4 pts above New Mexico
- Union
- 100.0%
- New Mexico
- 92.6%
Share of land USGS rates moderate or high potential
Tests reported
3
Too few for a share
- Union
- 3
- Needed
- 30
2005 to 2014, laboratory
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Read a result for Union 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
Union County, At a glance
Union County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Union County is a
USGS geologic potential: Moderate across 67% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Union County, 2008 to 2017, laboratory
CDC holds 2 reported tests for Union County over the 2008 to 2017 laboratory totals, with a median of 5.5 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Union County beside the counties around it is how this page reads it.
What these figures count
Only 2 tests were reported to CDC for Union 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).
Union County, Compared
Union County radon figures, compared
Calculated by Radon411CDC's largest figure for Union County rests on 3 tests over the 2005 to 2014 laboratory totals, 1 of them at or above 4 pCi/L, so each test moves its share by 33.3 points and no rank or comparison is drawn from it. Results reached as high as 4.1 pCi/L, with a middle value of 2.8 pCi/L.
Of the counties bordering it, 2 have a figure over the 2006 to 2015 laboratory totals: Baca County, CO reported the largest share at or above 4 pCi/L, 64.5%, and Las Animas County, CO the smallest, 63.9%. Farther out, San Miguel County (102 miles away) at 44.4%, Taos County (120 miles away) at 71.9% and Santa Fe County (156 miles away) at 32.5% have figures too. Pooled across 30 New Mexico counties, 30.3% of reported tests reached that level; across every county in the country with a figure, 36.3%.
Statewide for the same period, Taos County reported the highest share (71.9%) and Otero County the lowest (10.7%). EPA's 1993 map puts Union County in Zone 2, its middle label: a predicted county average between 2 and 4 pCi/L. USGS geology rates 67% of the county's land moderate radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Union County, Geology
The ground under Union County
PredictedUSGS's geologic map splits Union County: 67.0% of its land is moderate radon potential and 33.0% high. The map puts 36.1% of Union County in the area it calls Southern Great Plains and 33.0% in High Plains, with 2 smaller areas beside them. USGS gives the first a radon index of 10, 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 |
|---|---|---|---|---|
| Southern Great Plains | Cretaceous sedimentary rocks including sandstone and shale. | Moderate | 10 | 36.1% |
| High Plains | Quaternary deposits and Cretaceous marine shales that locally have a high radiometric signature. | High | 12 | 33.0% |
| High Plains | Sandstone, siltstone, minor shale-Tertiary Ogallala Formation. | Moderate | 9 | 27.3% |
| Great Plains Pecos Valley Section | Triassic sandstone, siltstone, mudstone, Quaternary alluvial and eolian sand and silt. | Moderate | 9 | 3.6% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Union County beside the ground around it
Union County has more high-potential ground than New Mexico as a whole: 33.0% of its land against 19.2%. Of the 8 counties that border it, 2 have more high-potential ground, Baca County, CO the most at 97.8%.
The map rates the ground, not the air in any home.
Local help
Union County, Local resources
Radon testing and mitigation in Union County
- New Mexico Indoor Radon Outreach ProgramNew Mexico Indoor Radon Outreach Program, run by New Mexico Environment Department, does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in New Mexico.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
The New Mexico Environment Department seasonally distributes free radon testing kits to the public on a first-come, first-served basis.
- Compare kits
- See the New Mexico directoryNo professionals are listed in New Mexico yet. The state program can point you to registered testers and mitigators.
What New Mexico's program says
- Phone
- (505) 476-8600
- radon.questions@env.nm.gov
- Licensing of radon professionals
There is not currently a certification program within the state.
What it means
Union County, Questions
Questions about radon in Union County
Are radon levels high in Union County?
Over the 2008 to 2017 laboratory totals, 100.0% of the radon tests reported to CDC for Union County, New Mexico were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.5 pCi/L. Of the counties bordering it, 2 have a figure over the 2006 to 2015 laboratory totals: Baca County, CO reported the largest share at or above 4 pCi/L, 64.5%, and Las Animas County, CO the smallest, 63.9%.
Which counties border Union County?
Union County borders 8 counties: Harding County, NM, Dallam County, TX, Cimarron County, OK, Hartley County, TX, Colfax County, NM, Las Animas County, CO, Baca County, CO and Quay County, NM.
Products
Union County, Products
Testing a home in Union County
No CDC figure names Union County; the nearest county with one, San Miguel County (102 miles away), reported 44.4% of its tests at or above 4 pCi/L over the 2006 to 2015 laboratory totals, the only reading nearby until a test of this home. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Union County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
MonitorX-Sense
XR0A-iR Wi-Fi battery radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Wi-Fi
- Screen, app
Method: Alpha spectrometry
First reading: Within 24 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Union County, Bordering counties
Counties bordering Union County
Calculated by Radon411- Radon levels in Dallam County, TXEPA zone 2
100.0%at or above 4 pCi/L
Median 4.2 pCi/L · 1 test
- Radon levels in Cimarron County, OKEPA zone 2
100.0%at or above 4 pCi/L
Median 11.5 pCi/L · 1 test
- Radon levels in Quay County, NMEPA zone 2
66.7%at or above 4 pCi/L
Median 5.0 pCi/L · 3 tests
- Radon levels in Baca County, COEPA zone 1
64.5%at or above 4 pCi/L
Median 4.7 pCi/L · 31 tests
- Radon levels in Las Animas County, COEPA zone 1
63.9%at or above 4 pCi/L
Median 5.5 pCi/L · 183 tests
- Radon levels in Colfax County, NMEPA zone 1
61.1%at or above 4 pCi/L
Median 5.7 pCi/L · 18 tests
- Radon levels in Hartley County, TXEPA zone 2
50.0%at or above 4 pCi/L
Median 6.1 pCi/L · 2 tests
- Radon levels in Harding County, NMEPA zone 2
0.0%at or above 4 pCi/L
Median 3.3 pCi/L · 1 test
Union County, Cities and towns
Cities and towns in Union County
Union County has been losing residents: from 4,070 in 2020 to 3,844 on July 1, 2025, a fall of 5.6% by the Census Bureau's estimates. Spread over its land, that is 1.0 people to the square mile. Clayton alone is home to 2,510 of them, 65.3% of the total. Together its 4 incorporated places hold 69.8% of those residents; the other 30.2% live outside any of them. Reported testing is thin here: 3 tests over 2005 to 2014, or 0.8 for every 1,000 residents (2025 estimate), where New Mexico as a whole comes to 2.2.
From Clayton to Grenville, CDC publishes no figure by town: each reads Union County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Clayton | 2,510 | −5.2% | 65.3% |
| Des Moines | 105 | −7.9% | 2.7% |
| Folsom | 46 | −6.1% | 1.2% |
| Grenville | 24 | −4.0% | 0.6% |
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).
Union County, Homes
Homes in Union County
Of Union County's 2,091 homes, 73% are detached houses, against 65% across New Mexico; 20% are mobile homes. The homes are older than New Mexico's as a whole: half were built before 1965 (1984 for New Mexico), and 44% date from before 1960. 68% of occupied homes are lived in by their owner (New Mexico: 69%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Union County | New Mexico |
|---|---|---|
| Housing units | 2,091 | 949,524 |
| Detached houses | 73% | 65% |
| In buildings of 5 or more | 3% | 10% |
| Mobile homes | 20% | 16% |
| Built before 1960 | 44% | 17% |
| Built since 2000 | 13% | 24% |
| Middle year built | 1965 | 1984 |
| Owner-occupied | 68% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.