Short-term kit
RA100 short-term liquid scintillation radon test kit
- Lab fee extra
Method: Liquid scintillation
In home: 48 to 96 hours
Locations and reports
Radon Levels in Coconino County, Arizona
EPA puts Coconino County in Zone 2, its middle radon zone, and 30.0% of its 273 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
30.0%
13.2 pts above AZ
- Coconino
- 30.0%
- Arizona
- 16.8%
273 tests, 2008 to 2017
Median result
2.3pCi/L
Below action level
- Coconino
- 2.3 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
273
3rd of 6 by tests
- Coconino
- 273
- Maricopa
- 2,393
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 Arizona
1 of 6
Top quarter
- Coconino
- 30.0%
- Coconino
- 30.0%
By share, of 6 with 30+ tests
Read a result for Coconino County
Starts at Coconino 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. Coconino County's median reported result, 2008 to 2017.
The data
Coconino County, At a glance
Coconino County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Coconino County is a
USGS geologic potential: Moderate across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Coconino County, 2008 to 2017, laboratory
Under 2 pCi/L: 41%2 to 4 pCi/L: 29%4 pCi/L and above: 30%
Of 273 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 111 | 40.7% |
| 2 to 4 pCi/L | 80 | 29.3% |
| 4 pCi/L and above | 82 | 30.0% |
What these figures count
These are the 273 tests reported to CDC for Coconino 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).
Coconino County, Compared
Coconino County radon figures, compared
Calculated by Radon411In Coconino County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (82 of 273) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 5.7 points lower. Across 13 Arizona counties pooled together, 16.8% of tests reached that level, so Coconino County runs 13.2 points above its state.
Of 2 neighbours with a figure, none reported a larger share at or above 4 pCi/L; the spread is 4.1% (Mohave County) to 16.2% (Yavapai County). By share, Coconino County is 1st of 6 Arizona 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 66.0 pCi/L. Below the action level, 111 tests (40.7%) came in under 2 pCi/L, against 60.1% statewide, and 80 tests (29.3%) fell between 2 and 4, against 23.2% statewide.
Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 30.0% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential. CDC also counts 23 tests taken after mitigation in Coconino County for the same period: tests in homes where a fix was already in.
CDC's ten-year totals for Coconino County went from 181 tests (2005 to 2014) to 273 (2008 to 2017), the share going from 38.1% to 30.0%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Coconino County, Geology
The ground under Coconino County
PredictedUSGS's geologic map puts all of Coconino County's mapped land in one class: moderate radon potential. The map puts 63.2% of Coconino County in the area it calls Colorado Plateau and 19.5% in Colorado Plateau, with 4 smaller areas beside them. USGS gives both a radon index of 9, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Colorado Plateau | Paleozoic sadstone, shale, and limestones, some Precambrian gneiss, metasedimentary rocks, granites. | Moderate | 9 | 63.2% |
| Colorado Plateau | Triassic and Jurassic eolian sandstones. | Moderate | 9 | 19.5% |
| Colorado Plateau | Jurassic-Triassic nonmarine sandstones and shales. | Moderate | 11 | 13.6% |
| Black Mesa | Cretaceous marine sandstones and shales. | Moderate | 11 | 2.5% |
| Colorado Plateau | Paleozoic and Mesozoic sandstone, shale, limestone. | Moderate | 9 | 0.7% |
| Transition Zone | Precambrian igneous, metamorphic and sedimentary rocks and Tertiary volcanic rocks. | Moderate | 10 | 0.5% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Coconino County beside the ground around it
Across Arizona 0.1% of the land is rated high; none of Coconino County's is. Of the 6 counties that border it, 2 have more high-potential ground, San Juan County, UT the most at 21.7%.
The map rates the ground, not the air in any home.
Local help
Coconino County, Local resources
Radon testing and mitigation in Coconino County
- Arizona's radon programArizona Department of Health ServicesArizona's radon program answers questions about testing, mitigation and the rules in Arizona.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
- See the Arizona directoryNo professionals are listed in Arizona yet. The state program can point you to registered testers and mitigators.
What it means
Coconino County, Questions
Questions about radon in Coconino County
Are radon levels high in Coconino County?
Over the 2008 to 2017 laboratory totals, 30.0% of the radon tests reported to CDC for Coconino County, Arizona were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.3 pCi/L. Of 6 Arizona counties with 30 or more tests for the same period, none reported a higher share; pooled, the state comes to 16.8%.
Which counties border Coconino County?
Coconino County borders 6 counties: Yavapai County, AZ, Navajo County, AZ, Mohave County, AZ, Kane County, UT, Gila County, AZ and San Juan County, UT.
Products
Coconino County, Products
Testing a home in Coconino County
In Coconino County, 30.0% of 273 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 16.8% pooled across Arizona. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Coconino 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
MonitorAEGTEST
HOUND-3699 radon monitor with a 2.1-inch touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
First reading: Within 1 hour
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Coconino County, Bordering counties
Counties bordering Coconino County
Calculated by Radon411- Radon levels in San Juan County, UTEPA zone 2
66.7%at or above 4 pCi/L
Median 5.1 pCi/L · 15 tests · 36.7 points above Coconino County
- Radon levels in Gila County, AZEPA zone 2
64.7%at or above 4 pCi/L
Median 5.7 pCi/L · 17 tests · 34.7 points above Coconino County
- Radon levels in Kane County, UTEPA zone 2
38.9%at or above 4 pCi/L
Median 2.5 pCi/L · 18 tests · 8.9 points above Coconino County
- Radon levels in Yavapai County, AZEPA zone 2
16.2%at or above 4 pCi/L
Median 1.6 pCi/L · 265 tests · 13.8 points below Coconino County
- Radon levels in Mohave County, AZEPA zone 2
4.1%at or above 4 pCi/L
Median 0.2 pCi/L · 49 tests · 25.9 points below Coconino County
- Radon levels in Navajo County, AZEPA zone 2
0.0%at or above 4 pCi/L
Median 1.1 pCi/L · 16 tests · 30.0 points below Coconino County
Coconino County, Cities and towns
Cities and towns in Coconino County
About 144,368 people live in Coconino County by the Census Bureau's estimate for July 1, 2025, 814 fewer than in 2020 (−0.6%). Spread over its land, that is 7.8 people to the square mile. Flagstaff alone is home to 77,260 of them, 53.5% of the total. Testing is reported here more often than across the state: CDC's 273 reported tests for 2008 to 2017 come to 1.9 for every 1,000 residents (2025 estimate), against 0.5 for Arizona.
From Flagstaff to Tusayan, CDC publishes no figure by town: each reads Coconino County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Flagstaff | 77,260 | +0.2% | 53.5% |
| Sedonaextends beyond Coconino County | 9,619 | −0.7% | Counted whole |
| Page | 7,147 | −3.6% | 5.0% |
| Williams | 3,473 | +8.0% | 2.4% |
| Fredonia | 1,290 | −1.7% | 0.9% |
| Tusayan | 581 | −3.2% | 0.4% |
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 Coconino County is counted whole, so it has no share.
Coconino County, Homes
Homes in Coconino County
Of Coconino County's 69,907 homes, 59% are detached houses, against 64% across Arizona; 16% are in buildings of five or more homes. Half of its homes were built before 1990, close to Arizona's 1992: 7% date from before 1960 and 30% from 2000 or later. 59% of occupied homes are lived in by their owner (Arizona: 67%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Coconino County | Arizona |
|---|---|---|
| Housing units | 69,907 | 3,142,443 |
| Detached houses | 59% | 64% |
| In buildings of 5 or more | 16% | 16% |
| Mobile homes | 13% | 10% |
| Built before 1960 | 7% | 8% |
| Built since 2000 | 30% | 35% |
| Middle year built | 1990 | 1992 |
| Owner-occupied | 59% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.