Radon Testing & Mitigation in Estes Park

What is radon and why it matters

Radon is a colorless, odorless radioactive gas that forms naturally as uranium in soil and rock breaks down. It can seep into homes through cracks in foundations, sump pits, crawl spaces, and utility penetrations, where it can accumulate—especially in lower levels. Long‑term exposure to elevated radon is the leading cause of lung cancer among non‑smokers and the second leading cause overall in the U.S., responsible for an estimated 21,000 deaths each year.

Sources: CDPHE • World Health Organization • US EPA

Northern Colorado risk levels

Northern Colorado has an especially high potential for radon. Statewide, about half of Colorado homes test above the EPA’s recommended action level of 4.0 pCi/L, and Larimer County reports an average indoor level around 7.8 pCi/L—well above the national average of 1.3 pCi/L. Local geology and common foundation types help soil gas move into buildings, which is why many Front Range areas, including Larimer and Weld counties, see frequent elevated readings.

Sources: CDPHE • Larimer County • US EPA

Which homes are vulnerable?

Any home that touches the ground—old or new, with a basement, slab, or crawl space—can have high radon. It’s less about the age of the house and more about pressure differences and entry points: warm indoor air and slightly lower air pressure draw soil gases in through gaps and cracks. Even tight, energy‑efficient homes can pull in more radon without good sealing and ventilation.

Source: CDPHE

Testing guidelines and action levels

Testing is the only way to know your levels. Short‑term tests typically run 48–120 hours under “closed‑house” conditions; long‑term tests (90+ days) give a better annual average. The EPA recommends fixing a home at 4.0 pCi/L or higher and considers action between 2.0 and 4.0 pCi/L; the WHO suggests a reference level of 2.7 pCi/L. Many local programs also remind residents that levels below 4.0 pCi/L still pose some risk and can often be reduced further.

Sources: CDPHE • US EPA • City of Fort Collins

Mitigation at a glance

The most common, reliable fix is active sub‑slab depressurization: a contractor installs a vent pipe through the slab or crawl space and a quiet, continuously running fan that pulls radon from beneath the home and exhausts it above the roofline. Sealing obvious entry points is part of the job, and new homes can include radon‑resistant features from the start. With current technology, most homes can be brought down to around 2.0 pCi/L or below.

Source: US EPA

Colorado disclosure basics

In Colorado real‑estate transactions, sellers and landlords must disclose known radon information and share the state health department’s brochure; tenants have specific rights around disclosure and mitigation timelines. Regardless of a home’s age or style, the simple first step is the same—test, then fix if needed.

Learn more: Colorado radon disclosure statute (C.R.S. 38-35.7-102)

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