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Radon in Tucson, Arizona

EPA puts Pima County, where Tucson is, in Zone 2, its middle radon zone, and most reported tests there come back low, though 6.8% of 410 (2008 to 2017, laboratory totals) reached 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

    6.8%

    10.0 pts below AZ

    Pima
    6.8%
    Arizona
    16.8%

    Pima, 5th of 6 in AZ, 2008 to 2017

  • Median result

    1.1pCi/L

    Below action level

    Pima
    1.1 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of Pima's tests, 2008 to 2017

  • Nearest county

    8.9%

    Pinal, 58 miles

    Pinal
    8.9%
    Pima
    6.8%

    101 tests, 2008 to 2017

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    Pima, where Tucson is

  • Tests reported

    410

    In Pima

    Pima
    410
    Pinal
    101

    Reported to CDC before any fix, 2008 to 2017

Read a result for Tucson

Starts at Pima County's median, 1.1 pCi/L

1.1pCi/L

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

EPA’s reading of 1.1 pCi/L

Below 2 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 below 2 pCi/L, the level at which EPA says a fix should be considered. Pima County's median reported result, 2008 to 2017.

Interpret this reading

The data

Tucson, What is published

What is published for Tucson

Information:

Every figure for Tucson is a county's

Radon data is published by county, not by city, so for Tucson it is Pima County's: its EPA zone (Zone 2) and the 410 tests reported to CDC for 2008 to 2017, laboratory. Only a test tells you about one home.

Tucson covers 241 square miles of land, all of it in Pima County. About 548,371 people live there, 2,275 to the square mile.

Tucson, Counties

The county Tucson lies in

Measured

Pima County's EPA zone and the figures CDC publishes for it, 2008 to 2017, laboratory.

Pima CountyZone 2Moderate predicted potential

6.8%
Reported tests at or above 4 pCi/L
1.1 pCi/L
Median reported result
410 tests
Tests reported to CDC
None
Yearly figures on file

Pima County ranks 5th of 6 Arizona counties with 30 or more tests for that period, 10.0 points below the 16.8% pooled across Arizona's counties, 28.9 points below the national pool of 35.7%.

The counties nearest Tucson with a CDC figure for 2008 to 2017, laboratory, measured from the middle of the city: Pinal County (58 miles, 8.9% of 101 tests), Maricopa County (125 miles, 17.4% of 2,393 tests) and Yavapai County (194 miles, 16.2% of 265 tests). Across the 5 nearest, the share at or above 4 pCi/L runs from 4.1% to 30.0%; the farthest of them, Mohave County, is 295 miles away at 4.1%.

No business in the directory gives Tucson as its address; the Arizona list covers it. Arizona's other cities with a page of their own: Phoenix and Scottsdale.

The counties around Tucson

By distance from the middle of Tucson; counties with 30 or more tests.

Nearest counties to Tucson with 30 or more tests
CountyDistanceTestsAt or above 4 pCi/LMedian
Pinal County58 mi1018.9%0.9 pCi/L
Maricopa County125 mi2,39317.4%1.6 pCi/L
Yavapai County194 mi26516.2%1.6 pCi/L
Coconino County259 mi27330.0%2.3 pCi/L
Mohave County295 mi494.1%0.2 pCi/L

Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2008 to 2017, laboratory.

Tucson, Geology

The ground under Tucson

Predicted

USGS's geologic map puts all of Tucson's mapped land in one class: low radon potential. All of it lies in the area the map calls Basin and Range/Sonoran Desert, to which USGS gives a radon index of 8, in the low band (5 to 8).

USGS's geologic areas under Tucson
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Basin and Range/Sonoran DesertQuaternary to Tertiary sediments, with uranium-bearing Tertiary volcanic rocks, highly variable volcanic, metamorphic, and sedimentary rocks, and eolian depositsLow8100%

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

Tucson beside its county and Arizona

Neither Tucson nor Pima County as a whole has any land USGS rates above low potential. Across Arizona 0.1% of the land is rated high; none of Tucson's is.

Share of land by USGS radon potential: Tucson, the county it lies in and Arizona
AreaEPA zoneLow potentialModerate potentialHigh potential
TucsonBy county100%NoneNone
Pima CountyZone 2100%NoneNone
Arizona15 counties, pooled by land areaVaries42.8%57.1%0.1%

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

Tucson, Homes

Homes in Tucson

Fewer than six in ten of Tucson's 245,836 homes are detached houses (52%, against 60% across Pima County); the rest are attached, in shared buildings or mobile. Half of its homes were built before 1979, close to Pima County's 1986: 21% date from before 1960 and 18% from 2000 or later. 52% of occupied homes are lived in by their owner (Pima County: 65%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Tucson, Pima County, Arizona, 2019 to 2023
HomesTucsonPima CountyArizona
Housing units245,836475,3783,142,443
Detached houses52%60%64%
In buildings of 5 or more26%18%16%
Mobile homes6%10%10%
Built before 196021%13%8%
Built since 200018%27%35%
Middle year built197919861992
Owner-occupied52%65%67%

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

Local help

Tucson, Local resources

Local resources for Tucson

Who to ask in Arizona: its radon program, test kits and professionals.

What it means

Tucson, Questions

Questions about radon in Tucson

What radon zone is Tucson in?

Tucson takes its zone from Pima County, which EPA puts in Zone 2, the map's middle class: a predicted county average of 2 to 4 pCi/L.

What are radon levels in Tucson?

Only 6.8% of 410 tests from Pima County for 2008 to 2017 (laboratory totals) reached 4 pCi/L, so reported levels around Tucson run low. The median reported result was 1.1 pCi/L. Low is not none.

Should I test my home in Tucson?

Yes, even here. 28 of 410 tests reported from Pima County were at or above 4 pCi/L. That is below Arizona's pooled 16.8%, and still not a reason to skip it, and ranks Pima County 5th of the 6 Arizona counties with 30 or more tests. Those homes were found by testing, not by the county's low share. How to test a home.

What ground is Tucson built on, as far as radon goes?

USGS's geologic map puts all of Tucson on one named area, "Basin and Range/Sonoran Desert", rated low for radon potential, radon index 8.

Is radon higher in the counties around Tucson?

Some are and some are not. Against Pima County's 6.8%, 4 of the 5 nearest counties with a figure report more and 1 less, from Mohave County (4.1%, 295 miles off) to Coconino County (30.0%, 259 miles off).

The answers use the published figures of Pima County, the county Tucson lies in.

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