South Dakota Cities Ranked by Indoor Radon Levels
Measured averages from Airthings devices across South Dakota, USA. Action level: 4 pCi/L — the threshold at which remediation is recommended.
Deadwood has the highest measured indoor radon in South Dakota at 12.5 pCi/L, based on Airthings measurements across 31 cities.
Updated September 28, 2026
Highest city
12.5pCi/L
Deadwood
South Dakota city average
5.7pCi/L
across 31 cities
Above action level
23/ 31
cities
| # | Location | Avg level | vs action level |
|---|---|---|---|
| 1 | Deadwood | 12.5 pCi/L | 3.1× over |
| 2 | Chamberlain | 9.4 pCi/L | 2.4× over |
| 3 | Box Elder | 9.1 pCi/L | 2.3× over |
| 4 | Sturgis | 9.1 pCi/L | 2.3× over |
| 5 | Custer | 8.4 pCi/L | 2.1× over |
| 6 | Parkston | 8.1 pCi/L | 2.0× over |
| 7 | Elk Point | 8.0 pCi/L | 2.0× over |
| 8 | Faulkton | 6.7 pCi/L | 1.7× over |
| 9 | Hot Springs | 6.5 pCi/L | 1.6× over |
| 10 | Volga | 6.4 pCi/L | 1.6× over |
| 11 | Spearfish | 6.3 pCi/L | 1.6× over |
| 12 | Mitchell | 6.3 pCi/L | 1.6× over |
| 13 | Brandon | 5.8 pCi/L | 1.5× over |
| 14 | Blackhawk | 5.8 pCi/L | 1.4× over |
| 15 | Madison | 5.7 pCi/L | 1.4× over |
| 16 | Watertown | 4.8 pCi/L | 1.2× over |
| 17 | Rapid City | 4.8 pCi/L | 1.2× over |
| 18 | Salem | 4.7 pCi/L | 1.2× over |
| 19 | Pierre | 4.7 pCi/L | 1.2× over |
| 20 | Rapid Valley | 4.5 pCi/L | 1.1× over |
| 21 | Sioux Falls | 4.2 pCi/L | 1.0× over |
| 22 | North Sioux City | 4.2 pCi/L | 1.0× over |
| 23 | Huron | 4.1 pCi/L | 1.0× over |
| ✓ Below EPA action level (4 pCi/L) | |||
| 24 | Harrisburg | 3.9 pCi/L | 1.0× under |
| 25 | Aberdeen | 3.7 pCi/L | 0.9× under |
| 26 | Brookings | 3.6 pCi/L | 0.9× under |
| 27 | Yankton | 3.4 pCi/L | 0.8× under |
| 28 | Tea | 3.4 pCi/L | 0.8× under |
| 29 | Colonial Pine Hills | 3.3 pCi/L | 0.8× under |
| 30 | Milbank | 3.0 pCi/L | 0.8× under |
| 31 | Vermillion | 1.6 pCi/L | 0.4× under |