Radon in Arizona
About 1 in 6 homes tested in Arizona were at or above the EPA action level of 4 pCi/L.
- Below 2 pCi/L: 60%
- 2 to 4 pCi/L: 23%
- 4 pCi/L or more: 17%
The EPA puts 0 of Arizona's 15 counties in Zone 1, its highest radon category, 15 in Zone 2 and 0 in Zone 3.
Every county in Arizona
Sorted by the share of homes tested at or above 4 pCi/L. Select a county for local details and costs.
| County | Homes tested | At or above 4 | Median | EPA zone |
|---|---|---|---|---|
| Gila County | 8 tests | – | – | 2 |
| Graham County | 6 tests | – | – | 2 |
| Coconino County | 30% | 2.3 pCi/L | 2 | |
| Cochise County | 27% | 2.8 pCi/L | 2 | |
| Maricopa County | 17% | 1.6 pCi/L | 2 | |
| Yavapai County | 16% | 1.6 pCi/L | 2 | |
| Pinal County | 9% | 0.9 pCi/L | 2 | |
| Pima County | 7% | 1.1 pCi/L | 2 | |
| Mohave County | 4% | 0.2 pCi/L | 2 | |
| Apache County | 1 tests | – | – | 2 |
| Navajo County | 12 tests | – | – | 2 |
| Santa Cruz County | 5 tests | – | – | 2 |
| Yuma County | 8 tests | – | – | 2 |
| Greenlee County | No data | – | – | 2 |
| La Paz County | No data | – | – | 2 |
"–" means fewer than 20 tests or no lab data, too few for a reliable figure.
Sources
- EPA Map of Radon Zones (public domain).
- CDC Environmental Public Health Tracking Network, radon tests from labs, 2008–2017. Pre-mitigation tests only.
Last updated October 2026. How we calculate these numbers.