What the EPA zone map and reported test data say about radon in Pennington, Meade and Lawrence counties, and why your own test is what counts.
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The EPA Map of Radon Zones puts Pennington, Meade and Lawrence counties in Zone 2, which means a predicted average indoor screening level between 2 and 4 pCi/L. South Dakota DANR notes that the eastern part of the state is Zone 1, the rest is Zone 2, and there are no Zone 3 areas in South Dakota (SD DANR).
Zone 2 does not mean your home is safe. The EPA says the zone map is not meant to determine whether individual homes need testing, and DANR says maps are no substitute for an actual test.
| County | EPA zone | Reported tests | Median result | Share at/above 4 pCi/L |
|---|---|---|---|---|
| Pennington (Rapid City, Box Elder, Hill City) | 2 | 1,029 | 4.3 pCi/L | 53.6% |
| Meade (Sturgis, Black Hawk) | 2 | 197 | 4.1 pCi/L | 51.8% |
| Lawrence (Spearfish, Lead, Deadwood) | 2 | 160 | 5.3 pCi/L | 56.9% |
Pre-mitigation radon tests reported to the CDC Environmental Public Health Tracking Network, 2008–2017, as compiled by Radon411 (Pennington/Meade, Lawrence). These count tests people chose to run, not a random sample of homes, so they are not the average for every house. EPA zones from the EPA Map of Radon Zones for South Dakota.
In plain terms: more than half of the radon tests reported from these three counties came back at or above the EPA's 4 pCi/L action level.
Test your home. DANR offers a limited number of free test kits to South Dakota residents, and you can also hire a certified measurement professional. If your result is 4 pCi/L or higher, the EPA recommends fixing your home. Need help? Use the form above and we'll connect you with a local professional.
EPA places Pennington County in Zone 2, meaning a predicted average indoor screening level between 2 and 4 pCi/L. The EPA says the zone map should not be used to decide whether an individual home needs testing; every home should be tested.
Of 1,029 pre-mitigation tests reported to the CDC for Pennington County from 2008 to 2017, 53.6% were at or above 4 pCi/L and the median was 4.3 pCi/L. These are reported tests, not a random sample of homes.
The U.S. EPA recommends fixing your home if radon is 4 pCi/L or higher, and suggests considering a fix between 2 and 4 pCi/L.