Colorado · Adams County
Radon Levels in Adams County, Colorado
In Adams County, Colorado, 46.8% of pre-mitigation home radon tests came back at or above the EPA action level of 4 pCi/L — based on 11,212 tests collected by the Colorado Department of Public Health and Environment between 2005 and 2024. The county’s median pre-mitigation reading was 3.6 pCi/L, with a maximum recorded result of 279 pCi/L.
EPA recommends mitigation when long-term indoor radon measures at or above 4 pCi/L. Counties with elevated medians and large test counts — like Adams — typically warrant testing during real-estate transactions and seasonal retesting in occupied homes.
Adams County by the numbers
Source: Colorado Department of Public Health and Environment. Pre-mitigation indoor radon tests, 2005–2024.
- Tests above 4 pCi/L
- 46.8%
- Total tests recorded
- 11,212
- Median result
- 3.6 pCi/L
- Maximum recorded
- 279 pCi/L
EPA action level
CDPHE 2005–2024
pre-mitigation
outlier high
How Adams compares to Colorado as a whole
Both bars show the percentage of pre-mitigation tests that came back at or above the EPA action level of 4 pCi/L.
CDPHE 2005–2024
Get a free quote for radon mitigation in Adams County.
We’re NRPP-certified and Colorado state-licensed. A typical sub-slab depressurization install runs about $1,500 and reduces indoor radon by 95%+ in most Adams County homes.
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- Post-install re-test included
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Adams County radon questions
- What level of radon is dangerous?
- The EPA recommends mitigation at 4 pCi/L or higher. Between 2 and 4 pCi/L, you should consider mitigation — long-term exposure at this range still carries lung-cancer risk. Below 2 pCi/L, the EPA suggests retesting every two years.
- How much does radon mitigation cost in Colorado?
- A standard sub-slab depressurization system in Colorado typically runs $1,200–$2,500, with $1,500 the most common all-in price. That single system reduces indoor radon by 95% or more in the majority of homes. Crawlspace installs cost more ($2,000–$5,000) because the membrane and tie-ins are more involved.
- Why are radon levels elevated in Adams County?
- Geology drives most of it. Granitic bedrock and uranium-bearing soils — common across Colorado — release radon as they decay, and Front Range building style (basements, tight envelopes, forced-air systems) concentrates that gas indoors. Higher-elevation counties also tend to have lower atmospheric pressure, which can pull radon up through the foundation more aggressively.