Is radon high in ZIP 78666?

Low. The model's predicted long-term basement average for ZIP 78666 is 1.3 pCi/L (SD 0.08), with above-ground floors at 0.5 pCi/L. That is about 39% below the average US ZIP code (2.2) and close to the Hays County average of 1.5. It ranks 7 of 7 ZIPs in the county.

Do I need to test my home in 78666?

Yes, once. Even in a low-predicted ZIP the EPA recommends every home be tested; a single house's foundation and ventilation can put it several times above its neighbors. One short-term kit answers it.

What EPA radon zone is ZIP 78666 in?

ZIP 78666 lies mostly in Hays County, which the EPA classifies as Radon Zone 3 (low potential (< 2 pCi/L)). Zones are county-wide and date from 1993; the ZIP-level prediction above is from a 2001-2021 model built on millions of tests.

Radon levels in ZIP 78666

LowEPA Zone 3

ZIP 78666 (Hays County, Texas): predicted long-term basement average of 1.3 pCi/L (model estimate), about 39% below the average US ZIP (2.2) and close to the Texas average (1.5). This is the most populous ZIP in Hays County.

Test ZIP 78666 once anyway - radon varies house to house

The predicted basement average here is 1.3 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.

Get a short-term test kit →Or track it with a continuous monitor

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Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.

1.3 ± 0.08

pCi/L predicted basement mean (model SD)

0.5 ± 0.19

pCi/L predicted upstairs mean

0.5 ± 0.18

pCi/L predicted typical screening test

How 78666 compares

Within Hays County, ZIP 78666 ranks #7 of 7 ZIPs by predicted basement level; the county average is 1.5 pCi/L and its ZIPs run from 1.3 to 1.9. The county is EPA Radon Zone 3. About 63,836 people lived in this ZIP at the 2010 Census.

Both basement (1.3) and upstairs (0.5) predictions are under 2 pCi/L. That is reassuring for the area, but the model's own uncertainty (± 0.08) and house-to-house variation mean a test is still the only way to know your home.

Other ZIP codes in Hays County

786401.6
786101.6
786201.8
786761.9
787371.6
786191.7

ZIP 78666 radon questions

Is radon high in ZIP 78666?: Low. The model's predicted long-term basement average for ZIP 78666 is 1.3 pCi/L (SD 0.08), with above-ground floors at 0.5 pCi/L. That is about 39% below the average US ZIP code (2.2) and close to the Hays County average of 1.5. It ranks 7 of 7 ZIPs in the county.
Do I need to test my home in 78666?: Yes, once. Even in a low-predicted ZIP the EPA recommends every home be tested; a single house's foundation and ventilation can put it several times above its neighbors. One short-term kit answers it.
What EPA radon zone is ZIP 78666 in?: ZIP 78666 lies mostly in Hays County, which the EPA classifies as Radon Zone 3 (low potential (< 2 pCi/L)). Zones are county-wide and date from 1993; the ZIP-level prediction above is from a 2001-2021 model built on millions of tests.

ZIP pages are generated for ZIPs predicted at or above 2.5 pCi/L and for the most populous ZIP in each county; all other ZIPs appear in their county table. Methodology.