Is radon high in ZIP 99133?

Moderate. The model's predicted long-term basement average for ZIP 99133 is 2.8 pCi/L (SD 0.06), with above-ground floors at 1.7 pCi/L. That is about 1.3× the average US ZIP code (2.2) and about 1.4× the Douglas County average of 2.0. It ranks 1 of 9 ZIPs in the county.

Do I need to test my home in 99133?

Yes. 99133's predicted average falls in the EPA's 2-4 pCi/L "consider fixing" band, and a meaningful share of individual homes in such areas test above 4. Test with a short-term kit and confirm anything at 2 or higher with a long-term test.

What EPA radon zone is ZIP 99133 in?

ZIP 99133 lies mostly in Douglas County, which the EPA classifies as Radon Zone 2 (moderate potential (2-4 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 99133

ModerateEPA Zone 2

ZIP 99133 (Douglas County, Washington): predicted long-term basement average of 2.8 pCi/L (model estimate), about 1.3× the average US ZIP (2.2) and about 1.7× the Washington average (1.6).

Test ZIP 99133 - the EPA says "consider fixing" in this range

The predicted basement average here is 2.8 pCi/L, in the 2-4 pCi/L band where the EPA recommends considering mitigation. Plenty of individual homes in a moderate area test above 4. Start with a short-term test; if it comes back at 2 or higher, follow up with a long-term test or a continuous monitor.

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

Already tested at 4 pCi/L or higher? Find a certified mitigation professional (EPA). A mitigation system typically runs $800-$2,500 installed.

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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.

2.8 ± 0.06

pCi/L predicted basement mean (model SD)

1.7 ± 0.07

pCi/L predicted upstairs mean

2.3 ± 0.07

pCi/L predicted typical screening test

How 99133 compares

Within Douglas County, ZIP 99133 ranks #1 of 9 ZIPs by predicted basement level; the county average is 2.0 pCi/L and its ZIPs run from 1.7 to 2.8. The county is EPA Radon Zone 2. About 1,493 people lived in this ZIP at the 2010 Census.

Above-ground floors are predicted at 1.7 pCi/L, below the action level, while basements sit in the 2-4 band. If you spend time in a finished basement, test there first.

Other ZIP codes in Douglas County

988021.9
988132.5
988431.7
988501.7
988582.3
991152.1
988302.1
988452.0

ZIP 99133 radon questions

Is radon high in ZIP 99133?: Moderate. The model's predicted long-term basement average for ZIP 99133 is 2.8 pCi/L (SD 0.06), with above-ground floors at 1.7 pCi/L. That is about 1.3× the average US ZIP code (2.2) and about 1.4× the Douglas County average of 2.0. It ranks 1 of 9 ZIPs in the county.
Do I need to test my home in 99133?: Yes. 99133's predicted average falls in the EPA's 2-4 pCi/L "consider fixing" band, and a meaningful share of individual homes in such areas test above 4. Test with a short-term kit and confirm anything at 2 or higher with a long-term test.
What EPA radon zone is ZIP 99133 in?: ZIP 99133 lies mostly in Douglas County, which the EPA classifies as Radon Zone 2 (moderate potential (2-4 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.