Is radon high in St. Peters, Missouri?

Moderate. Averaging the model's ZIP-code predictions across St. Peters (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 2.0 pCi/L - close to the US average of 1.8 and close to the Missouri average of 2.2. That is in the 2-4 pCi/L range where the EPA says to consider fixing. St. Peters ranks 9 of 15 Missouri cities on this site.

Which St. Peters ZIP codes have the highest radon?

Predictions for the 3 modeled ZIP codes in St. Peters range from 1.8 to 2.2 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 67% 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 St. Peters?

Yes, soon. With a predicted basement average of 2.0 pCi/L, a meaningful share of St. Peters homes will test above the 4 pCi/L action level. Start with a short-term kit; if it reads 2 or higher, confirm with a long-term test or a continuous monitor before paying for mitigation.

What does EPA Radon Zone 2 mean for St. Peters?

St. Peters sits mainly in St. Charles County, which the EPA classifies as Zone 2 - moderate potential (2-4 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 St. Peters, Missouri

ModerateEPA Zone 2

Predicted long-term basement average of 2.0 pCi/L (model estimate) across the 3 modeled ZIP codes in St. Peters - close to the US average of 1.8, close to the Missouri average of 2.2. Ranked #9 of 15 Missouri cities on this site. Most of the city lies in St. Charles County.

Test St. Peters, MO - the EPA says "consider fixing" in this range

The predicted basement average here is 2.0 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.

2.0 ± 0.07

pCi/L predicted basement mean (model SD)

1.3 ± 0.07

pCi/L predicted upstairs (above-ground) mean

1.8-2.2

range of ZIP-level basement predictions in the city

of St. Peters ZIPs predicted ≥ 4 pCi/L (67% ≥ 2)

What this means for St. Peters

The typical St. Peters home is predicted in the 2-4 pCi/L band. The EPA's guidance for this range is to consider fixing, because there is no known safe level and a meaningful minority of homes in a moderate area will test above 4.

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 (2) for St. Charles and the 2001-2021 model agree here.

Comparable Missouri cities: Wentzville (2.0), Joplin (2.1), St. Charles (2.1), O'Fallon (1.9).

ZIP codes in St. Peters

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
63376	86%	2.1 ± 0.07	1.2	Moderate
63304	11%	1.8 ± 0.07	1.4	Low
63303	3%	2.2 ± 0.07	1.4	Moderate

Testing help in Missouri

Missouri's radon program page is at health.mo.gov and, when we checked it, offered free radon test kits for Missouri residents. 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.

St. Peters radon questions

Is radon high in St. Peters, Missouri?: Moderate. Averaging the model's ZIP-code predictions across St. Peters (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 2.0 pCi/L - close to the US average of 1.8 and close to the Missouri average of 2.2. That is in the 2-4 pCi/L range where the EPA says to consider fixing. St. Peters ranks 9 of 15 Missouri cities on this site.
Which St. Peters ZIP codes have the highest radon?: Predictions for the 3 modeled ZIP codes in St. Peters range from 1.8 to 2.2 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 67% 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 St. Peters?: Yes, soon. With a predicted basement average of 2.0 pCi/L, a meaningful share of St. Peters homes will test above the 4 pCi/L action level. Start with a short-term kit; if it reads 2 or higher, confirm with a long-term test or a continuous monitor before paying for mitigation.
What does EPA Radon Zone 2 mean for St. Peters?: St. Peters sits mainly in St. Charles County, which the EPA classifies as Zone 2 - moderate potential (2-4 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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