This data provided is for informational purposes only. It is compiled by the Oregon Public Health Division from long-term radon tests (more than 90 days), conducted primarily by homeowners.
Indoor radon concentrations are influenced by weather, season, geology, type of construction and heating, ventilation and air conditioning systems. Therefore in general, this data should not be used to substitute for radon tests in homes. The Public Health Division recommends testing all residences, specifically the living areas, on a long-term basis, to evaluate the annual average concentration. When the annual average concentration in a living area of a home exceeds 4 pCi/liter, it is recommended that measures be taken to lower the concentration to below the 4 pCi/liter level.
Additional information on testing, measurement services or mitigation contractors can be obtained from the Oregon Public Health Division, Radon Information Line (971) 673-0490.
Download Radon Concentrations by County (pdf)
Radon Concentrations by County
in pCi/liter
| County |
Total Records |
Max |
Min |
Avg |
> 4 pCi/l |
| BAKER |
24 |
10.0 |
0.1 |
3.6 |
10 |
| BENTON |
184 |
8.7 |
0.1 |
1.2 |
6 |
| CLACKAMAS |
271 |
25.5 |
0.1 |
2.3 |
41 |
| CLATSOP |
38 |
8.7 |
0.1 |
1.7 |
5 |
| COLUMBIA |
10 |
6.0 |
0.6 |
2.4 |
1 |
| COOS |
41 |
15.6 |
0.1 |
1.9 |
4 |
| CROOK |
12 |
3.6 |
0.4 |
2.2 |
0 |
| CURRY |
4 |
0.9 |
0.7 |
0.8 |
0 |
| DESCHUTES |
64 |
7.2 |
0.1 |
0.8 |
1 |
| DOUGLAS |
30 |
7.0 |
0.1 |
1.3 |
2 |
| GILLIAM |
1 |
2.1 |
2.1 |
2.1 |
0 |
| GRANT |
1 |
1.0 |
1.0 |
1.0 |
0 |
| HARNEY |
12 |
3.6 |
0.3 |
1.4 |
0 |
| HOOD RIVER |
45 |
5.9 |
0.2 |
1.6 |
2 |
| JACKSON |
177 |
6.0 |
0.1 |
1.2 |
10 |
| JEFFERSON |
1 |
0.9 |
0.9 |
0.9 |
0 |
| JOSEPHINE |
63 |
15.4 |
0.1 |
1.0 |
2 |
| KLAMATH |
67 |
5.7 |
0.1 |
0.9 |
1 |
| LAKE |
15 |
11.5 |
0.2 |
2.5 |
2 |
| LANE |
116 |
15.4 |
0.1 |
1.7 |
9 |
| LINCOLN |
13 |
4.0 |
0.1 |
1.4 |
0 |
| LINN |
67 |
4.3 |
0.1 |
1.3 |
1 |
| MALHEUR |
14 |
2.7 |
0.6 |
1.3 |
0 |
| MARION * |
222 |
48.8 |
0.1 |
3.3 |
43 |
| MORROW |
4 |
3.2 |
1.0 |
2.2 |
0 |
| MULTNOMAH |
998 |
35.5 |
0.1 |
3.1 |
253 |
| POLK |
33 |
9.4 |
0.1 |
1.8 |
2 |
| TILLAMOOK |
13 |
6.8 |
0.3 |
3.0 |
3 |
| UMATILLA |
52 |
14.0 |
0.1 |
2.7 |
9 |
| UNION |
5 |
3.5 |
0.8 |
2.3 |
0 |
| WALLOWA |
8 |
9.9 |
0.1 |
2.5 |
1 |
| WASCO |
46 |
7.4 |
0.2 |
1.6 |
2 |
| WASHINGTON |
293 |
133.6 |
0.1 |
2.7 |
38 |
| WHEELER |
3 |
4.9 |
0.9 |
2.3 |
1 |
| YAMHILL |
29 |
6.6 |
0.3 |
2.2 |
4 |
* This value was not used to calculate the average for this county
** Includes West Salem