Minnesota radon map, by census tract
This is the finest radon map on this site. Minnesota publishes its results by census tract, which is a smaller area than a ZIP code, across 1,331 tracts and roughly 250,734 home tests. Statewide, 40.3% of tested Minnesota homes are at or above the EPA action level, the highest share of the three states mapped here.
250,734
recorded 2010-2020, approximate
3.1 pCi/L
across every test
40.3%
the EPA action level
1,331
1,283 with enough tests to colour
What this map deliberately does not show
Minnesota's tract file includes a column for the percentage of homes above 4 pCi/L, and it would have been the obvious thing to colour this map with. It is a county figure repeated on every tract in that county. We checked: not one of the 87 counties has more than a single distinct value across its tracts, and the state's own documentation describes the field as being by county.
So this map is coloured on the tract median, which genuinely varies tract by tract, and the percentage appears only in the county table below, where it is honest. A tract map shaded by a county number would look far more precise than it is, and precision you have not got is the one thing a map like this must never fake.
Read this before you use a number from this map
Sample sizes here are approximate. Minnesota publishes tests per year rather than a total, so the counts shown are that figure across the eleven years the data covers. Close enough to judge whether a tract means anything, not exact.
48 tracts are grey. Either they have fewer than 30 tests or the state itself flagged them unstable. Minnesota's own rule is that anywhere with twenty or fewer tests should be read with caution, and we take their flag at face value rather than colouring over it.
The data ends in 2020 and has not been refreshed. It covers 2010 to 2020. Radon in the ground does not change on that timescale, but the housing stock and the testing rate do, so treat it as a strong picture of a decade rather than a live feed.
A tract is still not a house. Even at this resolution, the difference between two neighbouring homes is routinely larger than the difference between two tracts. The map tells you how common a problem is around you. Only a test tells you about your house.
The highest census tracts
Ranked by median, restricted to tracts with enough tests to be worth ranking. County is shown because a tract number on its own tells you nothing about where it is.
| Tract | County | Tests | Median pCi/L |
|---|---|---|---|
| 27119020300 | Polk | 99 | 11.1 |
| 27119020100 | Polk | 77 | 9.9 |
| 27117460500 | Pipestone | 66 | 9.6 |
| 27105105200 | Nobles | 66 | 8.9 |
| 27063480200 | Jackson | 88 | 8.4 |
| 27027030106 | Clay | 99 | 8.2 |
| 27119020400 | Polk | 77 | 8.1 |
| 27129790300 | Renville | 77 | 7.7 |
| 27133570200 | Rock | 99 | 7.6 |
| 27133570300 | Rock | 66 | 7.6 |
| 27063480300 | Jackson | 77 | 7.5 |
| 27101900300 | Murray | 143 | 7.5 |
By county
The county view, where the share above the action level is a real county figure rather than a repeated one. The 95th percentile column is the reading that only one home in twenty exceeds, and it is a better guide to the worst case than a single maximum.
| County | Tests | Median pCi/L | At or above 4.0 | 95th percentile |
|---|---|---|---|---|
| Rock | 242 | 7.3 | 78.6% | 24.3 |
| Murray | 341 | 7 | 79.7% | 22.2 |
| Jackson | 517 | 6.8 | 73.8% | 20.6 |
| Lincoln | 187 | 6.5 | 69.8% | 26.6 |
| Nobles | 418 | 6.5 | 73.5% | 25.8 |
| Renville | 506 | 6.5 | 74.1% | 22.5 |
| Polk | 638 | 6.2 | 70% | 19.9 |
| Cottonwood | 539 | 6.1 | 70.8% | 21.7 |
| Brown | 1,881 | 5.9 | 71.5% | 18.4 |
| Redwood | 528 | 5.8 | 69.3% | 18.4 |
| Pipestone | 286 | 5.7 | 68.2% | 26.2 |
| Chippewa | 385 | 5.6 | 69.9% | 19.8 |
What the numbers mean
The EPA acts at 4.0 pCi/L and suggests considering action between 2.0 and 4.0. The World Health Organization's reference level is 100 Bq/m³, roughly 2.7 pCi/L. All of them are action levels rather than safety guarantees, and no level of radon is known to be harmless.
Minnesota's state median is 3.1 pCi/L, which sits inside the range where the EPA says to consider acting, and 40.3% of tested homes are at or above the action level outright. In a state this cold, homes are sealed and heated for much of the year, which is exactly the condition under which soil gas accumulates indoors.
If your reading is high
Mitigation is a pipe and a fan venting soil gas above the roofline, usually a day's work. Measuring and mitigating are separate certifications, and plenty of companies hold only the first, so it is worth knowing which you are calling. Our Minnesota directory lists every certified company in the state split by what each is actually certified to do.
Minnesota law also requires a seller to give the buyer the Department of Health's radon booklet along with a written disclosure covering whether the home has been tested, what the readings were, and whether a mitigation system is installed. A seller who stays silent can be liable for two years after the sale. A disclosure is still not a test.
Source. Radon data published by the Minnesota Department of Health through its Environmental Public Health Tracking programme, covering 2010-2020, at census tract and county level. Tract boundaries are MDH's own published geometry rather than a current Census file, because tract lines were redrawn at the 2020 census and joining to the newer boundaries would have silently dropped 164 tracts from the map.
This page is an educational summary of public records. It is not a health assessment of any individual property, and no reading here should be used to price a house or to decide against testing one.