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Radon Levels in San Juan County, New Mexico

EPA puts San Juan County in Zone 2, its middle radon zone, and 33.9% of its 56 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

    33.9%

    5.4 pts above NM

    San Juan
    33.9%
    New Mexico
    28.5%

    56 tests, 2008 to 2017

  • Median result

    2.4pCi/L

    Below action level

    San Juan
    2.4 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    56

    8th of 8 by tests

    San Juan
    56
    Santa Fe
    1,819

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in New Mexico

    3 of 8

    Middle half

    San Juan
    33.9%
    Taos
    77.1%

    By share, of 8 with 30+ tests

Read a result for San Juan County

Starts at San Juan County's median, 2.4 pCi/L

2.4pCi/L

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

EPA’s reading of 2.4 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. San Juan County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

San Juan County, At a glance

San Juan County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

San Juan County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Moderate across 82% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for San Juan County, 2008 to 2017, laboratory

Reported results by concentration band, San Juan County, 2008 to 2017, laboratory
Under 2 pCi/L: 43%2 to 4 pCi/L: 23%4 pCi/L and above: 34%

Of 56 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, San Juan County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L2442.9%
2 to 4 pCi/L1323.2%
4 pCi/L and above1933.9%
What these figures count

These are the 56 tests reported to CDC for San Juan 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

San Juan County, Compared

San Juan County radon figures, compared

Calculated by Radon411

In San Juan County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (19 of 56) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 1.8 points lower. Across 29 New Mexico counties pooled together, 28.5% of tests reached that level, so San Juan County runs 5.4 points above its state.

Of 4 neighbours with a figure, 2 reported a larger share at or above 4 pCi/L and 2 a smaller one; the spread is 21.4% (Sandoval County) to 46.0% (La Plata County, CO). By share, San Juan County is 3rd of 8 New Mexico counties with 30 or more tests for the same period.

Half the tests came in under 2.4 pCi/L and half over it; the single highest reached 49.9 pCi/L. Below the action level, 24 tests (42.9%) came in under 2 pCi/L, against 41.3% statewide, and 13 tests (23.2%) fell between 2 and 4, against 30.2% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 33.9% share point the same way here. USGS geology rates 82% of the county's land moderate radon potential.

CDC's ten-year totals for San Juan County went from 59 tests (2005 to 2014) to 56 (2008 to 2017), the share going from 33.9% to 33.9%.

San Juan County against New Mexico, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from San Juan County
San Juan County5633.9%2.4 pCi/LThis county
New Mexico, pooled29 counties, pooled3,72128.5%Not pooled−5.4 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+1.8 points
Taos Countyhighest in the state8377.1%8.5 pCi/L+43.2 points
Curry Countylowest in the state1353.7%0.6 pCi/L−30.2 points
San Juan County, UTborders it1566.7%5.1 pCi/L+32.8 points
Rio Arriba County, NMborders it1450.0%3.5 pCi/L+16.1 points
La Plata County, COborders it1,61246.0%3.6 pCi/L+12.1 points
Montezuma County, COborders it17037.6%3.1 pCi/L+3.7 points
Archuleta County, COborders it60031.2%2.3 pCi/L−2.7 points
McKinley County, NMborders it2227.3%2.2 pCi/L−6.6 points
Sandoval County, NMborders it14021.4%1.5 pCi/L−12.5 points
Apache County, AZborders it40.0%1.9 pCi/L−33.9 points
Where San Juan County's reported results fell, 2008 to 2017, laboratory, beside New Mexico and the United States
ResultSan Juan County testsSan Juan County shareNew Mexico shareU.S. shareAgainst New Mexico
Under 2 pCi/L2442.9%41.3%39.6%+1.6 points
2 to 4 pCi/L1323.2%30.2%24.7%−7.0 points
4 pCi/L and above1933.9%28.5%35.7%+5.4 points
San Juan County ranked among the 8 New Mexico counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Taos County1 of 88377.1%8.5 pCi/L
Los Alamos County2 of 87838.5%3.0 pCi/L
San Juan County3 of 85633.9%2.4 pCi/L
Santa Fe County4 of 81,81931.2%2.7 pCi/L
Bernalillo County5 of 81,05224.3%2.1 pCi/L
Sandoval County6 of 814021.4%1.5 pCi/L
Doña Ana County7 of 810412.5%1.3 pCi/L
Curry County8 of 81353.7%0.6 pCi/L
San Juan County ten-year laboratory totals, against New Mexico's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestNew Mexico, pooledChange from the row before
2008 to 20175633.9%2.4 pCi/L49.9 pCi/L28.5%+8.0 points
2007 to 20165425.9%2.0 pCi/L49.9 pCi/L30.0%−4.1 points
2006 to 20156030.0%2.2 pCi/L49.9 pCi/L30.3%−3.9 points
2005 to 20145933.9%2.2 pCi/L49.9 pCi/L29.7%First on file

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

San Juan County, Geology

The ground under San Juan County

Predicted

Most of the ground under San Juan County is one class on USGS's geologic map: 81.8% of its land is moderate radon potential, with 18.2% high. The map puts 77.1% of San Juan County in the area it calls San Juan Basin and 18.2% in Grants Uranium Belt, 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).

USGS's geologic areas under San Juan County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
San Juan BasinMesozoic marine and non-marine sedimentary rocks including sandstone, siltstone, shale, minor limestone.Moderate1077.1%
Grants Uranium BeltUpper Creataceous marine shales and uranium-bearing Jurassic fluvial sandstones of the Grants uranium belt.High1218.2%
Colorado PlateauJurassic-Triassic nonmarine sandstones and shales.Moderate113.2%
Colorado PlateauTriassic and Jurassic eolian sandstones.Moderate91.3%

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

San Juan County beside the ground around it

On high-potential ground San Juan County is close to New Mexico as a whole: 18.2% of its land against 19.2%. Of the 8 counties that border it, 5 have more high-potential ground, Montezuma County, CO the most at 75.5%.

Share of land by USGS radon potential: San Juan County, the 8 counties bordering it and New Mexico
AreaEPA zoneLow potentialModerate potentialHigh potential
San Juan CountyZone 2None81.8%18.2%
McKinley CountyZone 2None67.3%32.7%
Montezuma County, COZone 1None24.5%75.5%
La Plata County, COZone 1None99.9%0.1%
Rio Arriba CountyZone 1None62.1%37.9%
Archuleta County, COZone 2None100%None
Apache County, AZZone 2None99.0%1.0%
Sandoval CountyZone 2None53.2%46.8%
San Juan County, UTZone 2None78.3%21.7%
New Mexico33 counties, pooled by land areaVaries7.4%73.4%19.2%

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

Local help

San Juan County, Local resources

Radon testing and mitigation in San Juan County

What New Mexico's program says
Phone
(505) 476-8600
Email
radon.questions@env.nm.gov
Licensing of radon professionals
There is not currently a certification program within the state.

What it means

San Juan County, Questions

Questions about radon in San Juan County

Are radon levels high in San Juan County?

Over the 2008 to 2017 laboratory totals, 33.9% of the radon tests reported to CDC for San Juan County, New Mexico were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.4 pCi/L. Of 8 New Mexico counties with 30 or more tests for the same period, 2 reported a higher share; pooled, the state comes to 28.5%.

Which counties border San Juan County?

San Juan County borders 8 counties: McKinley County, NM, Montezuma County, CO, La Plata County, CO, Rio Arriba County, NM, Archuleta County, CO, Apache County, AZ, Sandoval County, NM and San Juan County, UT.

Products

San Juan County, Products

Testing a home in San Juan County

In San Juan County, 33.9% of 56 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 28.5% pooled across New Mexico. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in San Juan County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for San Juan County homes, compared

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San Juan County, Bordering counties

Counties bordering San Juan County

Calculated by Radon411

San Juan County, Cities and towns

Cities and towns in San Juan County

About 120,340 people live in San Juan County by the Census Bureau's estimate for July 1, 2025, 1,044 fewer than in 2020 (−0.9%). That works out to 22 people per square mile of land. Its largest town, Farmington, has 46,055 residents, 38.3% of the total. Together its 4 incorporated places hold 49.9% of those residents; the other 50.1% live outside any of them. Reported testing is thin here: 56 tests over 2008 to 2017, or 0.5 for every 1,000 residents (2025 estimate), where New Mexico as a whole comes to 1.8.

From Farmington to Kirtland, CDC publishes no figure by town: each reads San Juan County's.

The cities and towns in San Juan County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Farmington46,055−1.0%38.3%
Bloomfield7,335−1.0%6.1%
Aztec6,091−1.6%5.1%
Kirtland572−1.7%0.5%

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).

San Juan County, Homes

Homes in San Juan County

Mobile homes are 32% of San Juan County's 48,085 homes and detached houses 55%, against 65% across New Mexico. Half of its homes were built before 1986, close to New Mexico's 1984: 11% date from before 1960 and 23% from 2000 or later. 70% 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 in San Juan County, New Mexico, 2019 to 2023
HomesSan Juan CountyNew Mexico
Housing units48,085949,524
Detached houses55%65%
In buildings of 5 or more4%10%
Mobile homes32%16%
Built before 196011%17%
Built since 200023%24%
Middle year built19861984
Owner-occupied70%69%

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