Colorado state data suggests about half of Colorado homes have radon above the EPA action level of 4 pCi/L. DORA calls all of Colorado high risk, “not just the mountains or foothills” ^[CO-2]. 53 of 64 counties, home to 97.6% of Coloradans, are in EPA Radon Zone 1 ^[EPA-5][CEN].

RadonCosts lists 146 radon mitigation companies in Colorado. For 113 of them, we matched a mitigation professional to an active DORA “Radon Mitigation Professional” license ^[CO-5]. The other 33 hold NRPP or NRSB mitigation certification, but we couldn’t match a DORA license to them. Colorado has required a license since July 1, 2022 ^[CO-2], so ask those companies for their DORA license number.

Colorado at a glance

Colorado radon rules

• Licensing: DORA’s Office of Radon Professionals licenses radon measurement and mitigation professionals. Mitigation applicants must hold mitigation certification from a proficiency program such as NRPP or NRSB ^[CO-4]. Exemptions include owners working on the single-family home they own and live in, and assistants directly supervised by a licensee ^[CO-3]. Look up a license with DORA’s online license lookup, linked from the Office of Radon Professionals ^[CO-5].
• Real estate and rentals: CDPHE says its “Radon and Real Estate” brochure is “required for real estate transactions and rental agreements” ^[CO-1]. Ask your agent or landlord for it.
• Complaints: report unlicensed practice through the Office of Radon Professionals ^[CO-2].

Radon zones in Colorado’s largest counties

All Zone 1: El Paso (Colorado Springs), Denver, Arapahoe, Jefferson, Adams, Douglas, Larimer, Weld, Boulder, Pueblo ^[EPA-5].

Colorado county test data isn’t in this version yet.

Installers in Colorado

Cities with the most listed companies: Colorado Springs (13), Aurora (12), Littleton (7), Fort Collins (7), Centennial (6), Denver, Parker and Loveland (5 each).

Each listing shows whether we matched an active DORA mitigation license. Some companies list a person under a different name than the one on their license, so “not matched” doesn’t mean unlicensed. Ask, and check on DORA’s site.

What radon mitigation costs in Colorado

• CDPHE: $1,300–$3,000. Activating a passive (radon-ready) system costs about $500, and a professional test about $150 ^[CO-1].
• National surveys: $805–$1,326, average $1,043. Angi’s Denver figure is about $800 (estimate) ^[ANGI]. That’s well below the state health department’s range, so get more than one quote.
• What Colorado installers post online: 8 of 76 CO-listed websites we could read state a mitigation-system price or price range (crawl Nov 2, 2026). The lowest figure each one posts has a median of $1,200 (range $800–$1,450). These are the companies’ own advertised figures, sometimes for a specific job type (for example new construction or activating a passive system). They aren’t quotes:
  • Centennial Radon Solutions LLC: $800–$2,500 (source)
  • Rapid Response: $1,000–$3,000 (source)
  • Breathe Easy Radon Solutions LLC: $1,200–$2,200 (source)
  • Evergreen RCS: $1,200–$1,500 (source)
  • ExperTech Environmental: $1,200–$2,200 (source)
  • RDS Environmental, Inc.: $1,200–$2,200 (source)
  • HousePrep LLC: $1,400–$2,800 (source)
  • Aristeia Radon: $1,450 (source)
• RadonCosts homeowner reports: not enough yet. Report what you paid.

FAQ

Does my installer need a Colorado license? Yes, for paid work since July 1, 2022 ^[CO-2]. Owners mitigating their own owner-occupied home are exempt ^[CO-3].

Does a new home with a radon pipe need anything? Many newer Colorado homes have a passive pipe. CDPHE puts adding a fan at about $500 ^[CO-1]. Test first.

Data: DORA licensee roster, Radon Mitigation Professional (Nov 2, 2026), NRPP and NRSB searches (Nov 2, 2026), EPA radon zones, US Census 2024 estimates.