Radon levels in Missouri: Moderate
The model predicts a population-weighted basement average of 2.2 pCi/L (model estimate) across Missouri's 115 counties - about 1.2× the US average of 1.8 pCi/L. Above-ground floors average 1.3 pCi/L.
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.
11 / 115
EPA Zone 1 counties (10%)
97 / 7
Zone 2 / Zone 3 counties
1
counties predicted ≥ 4 pCi/L
1.3%
of ZIP codes predicted ≥ 4 pCi/L
Test Missouri - the EPA says "consider fixing" in this range
The predicted basement average here is 2.2 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.
Monitor link goes to the Airthings store - use code RADONGRADE-10OFF at checkout for 10% off any Airthings 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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What the data says about radon in Missouri
11 of Missouri's 115 counties are EPA Zone 1 (10%), 97 are Zone 2 and 7 are Zone 3 on the EPA's county-level map. Zone 2 (predicted screening average of 2-4 pCi/L) is the most common designation, with the 11 Zone 1 counties marking where the EPA expected the highest potential. The zones were drawn once, from geology and the tests available in 1993, and the EPA itself notes that homes with elevated radon exist in all three zones.
Weighted by where people live, Missouri's predicted basement average is 2.2 pCi/L - 1.2× the US population-weighted average of 1.8 - which puts the state in the moderate range. Of the 115 counties with predictions, 1 are predicted at or above 4 pCi/L, 98 in the 2-4 band and 16 below 2. The highest predicted county is Atchison County at 4.4 pCi/L; the lowest is Dunklin County at 1.4 - a 3.0 pCi/L spread that means a statewide average tells you little about any one county.
Nationally 4.2% of ZIPs are predicted at 4+ pCi/L and 48.7% at 2+; in Missouri it is 1.3% and 73.2% - below the US share at the action level but above it at 2 pCi/L. With more than half of ZIPs above 2, a test is worth doing before any purchase or renovation here.
Missouri counties by predicted radon
Sorted highest to lowest predicted basement average (model estimate). 115 counties.
| County | Predicted basement | Upstairs | Grade | EPA zone | ZIPs |
|---|---|---|---|---|---|
| Atchison County | 4.4 pCi/L | 2.5 | High | EPA Zone 1 | 5 |
| Holt County | 3.8 pCi/L | 2.2 | Moderate | EPA Zone 1 | 5 |
| Andrew County | 3.8 pCi/L | 2.3 | Moderate | EPA Zone 1 | 10 |
| Nodaway County | 3.5 pCi/L | 1.9 | Moderate | EPA Zone 1 | 15 |
| Clinton County | 3.1 pCi/L | 2.0 | Moderate | EPA Zone 1 | 6 |
| Buchanan County | 3.1 pCi/L | 1.9 | Moderate | EPA Zone 1 | 10 |
| Iron County | 2.9 pCi/L | 1.6 | Moderate | EPA Zone 1 | 8 |
| Madison County | 2.7 pCi/L | 1.6 | Moderate | EPA Zone 2 | 2 |
| Cass County | 2.6 pCi/L | 1.7 | Moderate | EPA Zone 1 | 11 |
| Platte County | 2.6 pCi/L | 1.7 | Moderate | EPA Zone 1 | 12 |
| Jackson County | 2.5 pCi/L | 1.7 | Moderate | EPA Zone 1 | 52 |
| Howell County | 2.5 pCi/L | 1.4 | Moderate | EPA Zone 2 | 7 |
| Pettis County | 2.5 pCi/L | 1.4 | Moderate | EPA Zone 2 | 7 |
| Lewis County | 2.5 pCi/L | 1.4 | Moderate | EPA Zone 2 | 8 |
| Putnam County | 2.4 pCi/L | 1.6 | Moderate | EPA Zone 2 | 5 |
| Worth County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 2 | 4 |
| Vernon County | 2.4 pCi/L | 1.3 | Moderate | EPA Zone 2 | 11 |
| Bates County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 2 | 6 |
| Mercer County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 2 | 3 |
| DeKalb County | 2.4 pCi/L | 1.6 | Moderate | EPA Zone 2 | 6 |
| Barton County | 2.4 pCi/L | 1.3 | Moderate | EPA Zone 2 | 4 |
| Harrison County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 2 | 8 |
| Lawrence County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 2 | 8 |
| Barry County | 2.4 pCi/L | 1.3 | Moderate | EPA Zone 2 | 12 |
| Cooper County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 2 | 6 |
| Gasconade County | 2.4 pCi/L | 1.3 | Moderate | EPA Zone 2 | 5 |
| Gentry County | 2.4 pCi/L | 1.5 | Moderate | EPA Zone 2 | 6 |
| Marion County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 2 | 6 |
| Webster County | 2.4 pCi/L | 1.3 | Moderate | EPA Zone 2 | 4 |
| Daviess County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 2 | 8 |
| Livingston County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 2 | 7 |
| Maries County | 2.4 pCi/L | 1.3 | Moderate | EPA Zone 2 | 7 |
| Sullivan County | 2.4 pCi/L | 1.3 | Moderate | EPA Zone 2 | 7 |
| Ray County | 2.3 pCi/L | 1.6 | Moderate | EPA Zone 2 | 7 |
| Clay County | 2.3 pCi/L | 1.7 | Moderate | EPA Zone 1 | 17 |
| Jefferson County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 14 |
| Johnson County | 2.3 pCi/L | 1.4 | Moderate | EPA Zone 2 | 7 |
| Lafayette County | 2.3 pCi/L | 1.5 | Moderate | EPA Zone 2 | 12 |
| Caldwell County | 2.3 pCi/L | 1.4 | Moderate | EPA Zone 2 | 7 |
| Christian County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 12 |
| Dade County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 6 |
| Grundy County | 2.3 pCi/L | 1.4 | Moderate | EPA Zone 2 | 4 |
| Cedar County | 2.3 pCi/L | 1.2 | Moderate | EPA Zone 2 | 3 |
| Moniteau County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 7 |
| Texas County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 14 |
| Linn County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 8 |
| Polk County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 10 |
| Ste. Genevieve County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 3 |
| Henry County | 2.3 pCi/L | 1.4 | Moderate | EPA Zone 2 | 7 |
| Howard County | 2.2 pCi/L | 1.4 | Moderate | EPA Zone 2 | 5 |
| Macon County | 2.2 pCi/L | 1.4 | Moderate | EPA Zone 2 | 10 |
| Montgomery County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 6 |
| Osage County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 8 |
| Saline County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 9 |
| Dallas County | 2.2 pCi/L | 1.2 | Moderate | EPA Zone 2 | 7 |
| Greene County | 2.2 pCi/L | 1.4 | Moderate | EPA Zone 2 | 16 |
| Jasper County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 11 |
| Laclede County | 2.2 pCi/L | 1.2 | Moderate | EPA Zone 2 | 5 |
| Morgan County | 2.2 pCi/L | 1.2 | Moderate | EPA Zone 2 | 8 |
| Pike County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 9 |
| St. Francois County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 8 |
| Callaway County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 10 |
| Crawford County | 2.2 pCi/L | 1.2 | Moderate | EPA Zone 2 | 8 |
| Stone County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 8 |
| Schuyler County | 2.2 pCi/L | 1.4 | Moderate | EPA Zone 2 | 5 |
| Chariton County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 9 |
| Franklin County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 19 |
| Wright County | 2.2 pCi/L | 1.2 | Moderate | EPA Zone 2 | 7 |
| Newton County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 7 |
| Benton County | 2.2 pCi/L | 1.2 | Moderate | EPA Zone 2 | 5 |
| Hickory County | 2.2 pCi/L | 1.2 | Moderate | EPA Zone 2 | 8 |
| Randolph County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 7 |
| Audrain County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 9 |
| Dent County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 4 |
| Miller County | 2.2 pCi/L | 1.2 | Moderate | EPA Zone 2 | 9 |
| Ralls County | 2.2 pCi/L | 1.4 | Moderate | EPA Zone 2 | 3 |
| Shelby County | 2.2 pCi/L | 1.4 | Moderate | EPA Zone 2 | 7 |
| Clark County | 2.1 pCi/L | 1.3 | Moderate | EPA Zone 2 | 5 |
| McDonald County | 2.1 pCi/L | 1.2 | Moderate | EPA Zone 2 | 9 |
| Lincoln County | 2.1 pCi/L | 1.4 | Moderate | EPA Zone 2 | 8 |
| St. Clair County | 2.1 pCi/L | 1.3 | Moderate | EPA Zone 2 | 5 |
| Carroll County | 2.1 pCi/L | 1.4 | Moderate | EPA Zone 2 | 7 |
| Washington County | 2.1 pCi/L | 1.1 | Moderate | EPA Zone 2 | 9 |
| Oregon County | 2.1 pCi/L | 1.2 | Moderate | EPA Zone 2 | 5 |
| Monroe County | 2.1 pCi/L | 1.3 | Moderate | EPA Zone 2 | 6 |
| Scotland County | 2.1 pCi/L | 1.4 | Moderate | EPA Zone 2 | 3 |
| Shannon County | 2.1 pCi/L | 1.2 | Moderate | EPA Zone 2 | 5 |
| Knox County | 2.1 pCi/L | 1.3 | Moderate | EPA Zone 2 | 7 |
| Douglas County | 2.1 pCi/L | 1.1 | Moderate | EPA Zone 2 | 5 |
| Ozark County | 2.1 pCi/L | 1.1 | Moderate | EPA Zone 2 | 13 |
| Adair County | 2.1 pCi/L | 1.4 | Moderate | EPA Zone 2 | 6 |
| Perry County | 2.1 pCi/L | 1.5 | Moderate | EPA Zone 2 | 5 |
| Phelps County | 2.0 pCi/L | 1.1 | Moderate | EPA Zone 2 | 6 |
| Warren County | 2.0 pCi/L | 1.3 | Moderate | EPA Zone 2 | 5 |
| Reynolds County | 2.0 pCi/L | 1.1 | Moderate | EPA Zone 2 | 5 |
| Pulaski County | 2.0 pCi/L | 1.1 | Moderate | EPA Zone 2 | 7 |
| Taney County | 2.0 pCi/L | 1.2 | Moderate | EPA Zone 2 | 14 |
| Bollinger County | 2.0 pCi/L | 1.2 | Moderate | EPA Zone 2 | 8 |
| St. Charles County | 2.0 pCi/L | 1.2 | Moderate | EPA Zone 2 | 13 |
| Cape Girardeau County | 1.9 pCi/L | 1.4 | Low | EPA Zone 2 | 9 |
| Boone County | 1.9 pCi/L | 1.2 | Low | EPA Zone 2 | 9 |
| Carter County | 1.9 pCi/L | 1.1 | Low | EPA Zone 2 | 4 |
| Cole County | 1.9 pCi/L | 1.2 | Low | EPA Zone 2 | 6 |
| Wayne County | 1.9 pCi/L | 1.0 | Low | EPA Zone 2 | 10 |
| Ripley County | 1.9 pCi/L | 1.1 | Low | EPA Zone 2 | 5 |
| Camden County | 1.8 pCi/L | 1.2 | Low | EPA Zone 2 | 10 |
| St. Louis County | 1.8 pCi/L | 1.1 | Low | EPA Zone 2 | 42 |
| Butler County | 1.8 pCi/L | 1.1 | Low | EPA Zone 3 | 6 |
| Scott County | 1.7 pCi/L | 0.9 | Low | EPA Zone 3 | 5 |
| St. Louis city | 1.6 pCi/L | 0.7 | Low | EPA Zone 2 | 18 |
| Stoddard County | 1.6 pCi/L | 0.9 | Low | EPA Zone 3 | 8 |
| Mississippi County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 3 |
| Pemiscot County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 5 |
| Dunklin County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 10 |
| New Madrid County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 8 |
Radon levels in Missouri cities
The 15 most-populous Missouri places among the 1,000 largest US cities (Census incorporated places and CDPs), by population. City figures are ZIP-land-weighted means of the model's ZIP predictions (model estimate).
| City | Population | Predicted basement | Upstairs | Grade | ZIPs ≥ 4 |
|---|---|---|---|---|---|
| Kansas City | 510,704 | 2.5 pCi/L | 1.6 | Moderate | 0% |
| St. Louis | 281,754 | 1.6 pCi/L | 0.7 | Low | 0% |
| Springfield | 170,188 | 2.2 pCi/L | 1.4 | Moderate | 0% |
| Columbia | 129,330 | 1.9 pCi/L | 1.2 | Low | 0% |
| Independence | 120,922 | 2.7 pCi/L | 1.8 | Moderate | 0% |
| Lee's Summit | 104,184 | 2.6 pCi/L | 1.8 | Moderate | 0% |
| O'Fallon | 94,074 | 1.9 pCi/L | 0.9 | Low | 0% |
| St. Charles | 71,800 | 2.1 pCi/L | 1.2 | Moderate | 0% |
| St. Joseph | 70,634 | 3.3 pCi/L | 2.0 | Moderate | 0% |
| Blue Springs | 60,539 | 2.5 pCi/L | 1.8 | Moderate | 0% |
| St. Peters | 59,413 | 2.0 pCi/L | 1.3 | Moderate | 0% |
| Joplin | 53,095 | 2.1 pCi/L | 1.2 | Moderate | 0% |
| Florissant | 51,128 | 1.8 pCi/L | 1.2 | Low | 0% |
| Chesterfield | 49,166 | 1.9 pCi/L | 1.2 | Low | 0% |
| Wentzville | 47,497 | 2.0 pCi/L | 1.3 | Moderate | 0% |
Highest-radon ZIP codes in Missouri
The 10 Missouri ZIP codes with the highest predicted basement average (model estimate), out of 960 modeled. A ZIP average is still an area figure - neighboring homes routinely test several pCi/L apart.
| ZIP | County | Predicted basement | Upstairs | Grade |
|---|---|---|---|---|
| 64491 | Atchison County | 4.5 pCi/L | 2.6 | High |
| 64428 | Nodaway County | 4.5 pCi/L | 2.3 | High |
| 64446 | Atchison County | 4.4 pCi/L | 2.6 | High |
| 64498 | Atchison County | 4.4 pCi/L | 2.4 | High |
| 64487 | Nodaway County | 4.4 pCi/L | 2.5 | High |
| 64445 | Nodaway County | 4.3 pCi/L | 2.3 | High |
| 64482 | Atchison County | 4.3 pCi/L | 2.5 | High |
| 64466 | Holt County | 4.2 pCi/L | 2.3 | High |
| 64476 | Nodaway County | 4.2 pCi/L | 2.4 | High |
| 64431 | Nodaway County | 4.1 pCi/L | 2.2 | High |
Missouri radon questions
- Is radon high in Missouri?
- Missouri's population-weighted predicted basement average is 2.2 pCi/L, about 1.2× the US average of 1.8. 1 of its 115 modeled counties are predicted at or above the EPA action level of 4 pCi/L, 98 are in the 2-4 "consider fixing" range and 16 are below 2. 1.3% of Missouri ZIP codes are predicted at 4 or higher.
- Which Missouri county has the highest radon?
- Atchison County has the highest predicted basement average in Missouri at 4.4 pCi/L (EPA Zone 1). The lowest is Dunklin County at 1.4 pCi/L. These are area figures; individual homes in any county can test far higher.
- How many EPA Zone 1 counties are in Missouri?
- 11 of Missouri's 115 counties (10%) are EPA Zone 1 (highest potential), 97 are Zone 2 and 7 are Zone 3. The EPA zone map dates from 1993; the predicted values on this page come from a 2001-2021 model built on millions of actual tests, so the two can disagree for a given county.
- Should I test for radon in Missouri?
- Yes - with some urgency. Missouri's predicted average is in the moderate range, and 73.2% of its ZIP codes are predicted at 2 pCi/L or higher. A short-term charcoal kit or a continuous digital monitor will tell you your actual level within days.
Missouri radon program
Missouri's radon program page is at health.mo.gov and, when we checked it, offered free radon test kits for Missouri residents. The EPA also keeps a directory of every state radon contact: EPA state radon contacts page. Then read how to test and what mitigation costs.