Is radon high in Tacoma, Washington?

Low. Averaging the model's ZIP-code predictions across Tacoma (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.4 pCi/L - about 21% below the US average of 1.8 and close to the Washington average of 1.6. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Tacoma ranks 15 of 29 Washington cities on this site.

Which Tacoma ZIP codes have the highest radon?

Predictions for the 13 modeled ZIP codes in Tacoma range from 1.3 to 1.6 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 0% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.

Should I test for radon in Tacoma?

Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Tacoma's low predicted average describes the typical home, not yours.

What does EPA Radon Zone 3 mean for Tacoma?

Tacoma sits mainly in Pierce County, which the EPA classifies as Zone 3 - low potential (< 2 pCi/L). The zone map dates from 1993 and covers whole counties. The 2001-2021 model agrees with the zone for the city. Neither replaces a test of your own home.

Radon levels in Tacoma, Washington

LowEPA Zone 3

Predicted long-term basement average of 1.4 pCi/L (model estimate) across the 13 modeled ZIP codes in Tacoma - about 21% below the US average of 1.8, close to the Washington average of 1.6. Ranked #15 of 29 Washington cities on this site. Most of the city lies in Pierce County.

Test Tacoma, WA once anyway - radon varies house to house

The predicted basement average here is 1.4 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.

1.4 ± 0.07

pCi/L predicted basement mean (model SD)

0.6 ± 0.09

pCi/L predicted upstairs (above-ground) mean

1.3-1.6

range of ZIP-level basement predictions in the city

of Tacoma ZIPs predicted ≥ 4 pCi/L (0% ≥ 2)

What this means for Tacoma

The typical Tacoma home is predicted below 2 pCi/L, the lowest band. That describes the average house; the ZIP-level predictions inside the city still span 1.3 to 1.6 pCi/L.

The city figure is not a separate estimate: it is the mean of the model's ZIP-code predictions, weighted by the share of the city's land in each ZIP (Census 2020 ZCTA-to-place relationship file). The 1993 EPA zone (3) for Pierce and the 2001-2021 model agree here.

Comparable Washington cities: Kent (1.4), Olympia (1.4), South Hill (1.5), Bellevue (1.4).

ZIP codes in Tacoma

ZIPs that overlap the city, largest share of its land first. Predicted basement and upstairs means are model estimates; ZIPs the model does not cover show a dash.

ZIP	Share of city	Basement	Upstairs	Grade
98409	15%	1.6 ± 0.07	0.6	Low
98421	13%	—	—	no model
98404	12%	1.5 ± 0.07	0.7	Low
98407	11%	1.3 ± 0.07	0.6	Low
98422	10%	1.3 ± 0.07	0.6	Low
98406	9%	1.4 ± 0.07	0.6	Low
98405	8%	1.4 ± 0.07	0.6	Low
98408	7%	1.5 ± 0.06	0.7	Low
98418	4%	1.5 ± 0.06	0.7	Low
98465	3%	1.4 ± 0.07	0.6	Low
98444	3%	1.6 ± 0.07	0.7	Low
98402	2%	1.3 ± 0.06	0.7	Low
98403	2%	1.3 ± 0.07	0.6	Low
98466	2%	1.4 ± 0.06	0.6	Low
98416	<1%	—	—	no model

Testing help in Washington

Washington's radon program page is at doh.wa.gov and, when we checked it, offered a limited supply of free radon test kits. EPA state radon contacts page. If a test comes back at 4 pCi/L or higher, mitigation typically costs $800-$2,500 installed; use EPA find-a-professional and read the mitigation guide.

Tacoma radon questions

Is radon high in Tacoma, Washington?: Low. Averaging the model's ZIP-code predictions across Tacoma (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.4 pCi/L - about 21% below the US average of 1.8 and close to the Washington average of 1.6. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Tacoma ranks 15 of 29 Washington cities on this site.
Which Tacoma ZIP codes have the highest radon?: Predictions for the 13 modeled ZIP codes in Tacoma range from 1.3 to 1.6 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 0% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.
Should I test for radon in Tacoma?: Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Tacoma's low predicted average describes the typical home, not yours.
What does EPA Radon Zone 3 mean for Tacoma?: Tacoma sits mainly in Pierce County, which the EPA classifies as Zone 3 - low potential (< 2 pCi/L). The zone map dates from 1993 and covers whole counties. The 2001-2021 model agrees with the zone for the city. Neither replaces a test of your own home.

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