Updated November 2026 · Data: Colorado Department of Public Health and Environment (CDPHE) pre-mitigation radon test results 2005–2025, EPA Map of Radon Zones · Sources and method
Colorado health department data include 3,243 pre-mitigation radon tests from Garfield County homes between 2005 and 2025. Of those, 42.9% (1,390 tests) were above the EPA action level of 4 pCi/L, and the median result was 3.3 pCi/L. That share is close to the Colorado figure of 46.4%, and ranks 43 of 64 Colorado counties. Garfield County is in EPA radon Zone 1 (highest potential).
These are area results, not your home’s level. Homes next to each other can have very different radon levels. The only way to know yours is to test.
How Garfield County compares
| Area | Tests | Above 4 pCi/L | Median (pCi/L) |
|---|---|---|---|
| Garfield County | 3,243 | 42.9% | 3.3 |
| Colorado (all counties) | 237,408 | 46.4% | — |
CDPHE also publishes results by census tract. In Garfield County, 11 census tracts have test data, and in 3 of them (with at least 10 tests) half or more of the tests were above 4 pCi/L. Radon can vary a lot within the same county.
How to test your home in Garfield County
- CDPHE has given away free radon test kits during National Radon Action Month (January), while supplies last; check the CDPHE radon page.
- Short-term kits are also sold at hardware stores and online. Test the lowest lived-in level with windows and doors closed.
- If the result is 4 pCi/L or higher, the EPA recommends fixing the home; between 2 and 4 pCi/L, consider a fix.
- Hire an NRPP- or NRSB-certified mitigator. Low-income homeowners can ask CDPHE about the Low Income Radon Mitigation Assistance (LIRMA) program. See typical prices in our radon mitigation cost guide.
Colorado rules, contacts and every county’s results: Radon in Colorado.
Frequently asked questions
Is radon a problem in Garfield County?
42.9% of 3,243 pre-mitigation radon tests in Garfield County from 2005 to 2025 were above 4 pCi/L, according to CDPHE data. The county is in EPA radon Zone 1. Any home can have high radon, so testing is the only way to know.
What is the average radon level in Garfield County?
The median pre-mitigation test result in Garfield County is 3.3 pCi/L (CDPHE, 2005–2025). The highest result recorded was 276 pCi/L.
How does Garfield County compare with the rest of Colorado?
Garfield County ranks 43 of 64 counties by the share of tests above 4 pCi/L. Statewide, 46.4% of 237,408 tests were above 4 pCi/L.
Sources and method
CDPHE compiles pre-mitigation radon test results reported by radon testing laboratories, mostly short-term tests by homeowners. The numbers describe tested homes only, not every home in the county, and counties with few tests are less reliable. Data covers 2005 to 2025 and was retrieved in November 2026.
- CDPHE Colorado Environmental Public Health Tracking: Radon data (Pre-Mitigation Radon Test Results 2005–2025)
- CDPHE: Radon dataset details
- U.S. EPA: EPA Map of Radon Zones (June 2024 data file)
- CDPHE: Radon