Radon Levels in Douglas County, Colorado
The average indoor radon level in Douglas County is 6.4 pCi/L — about 4.9× the U.S. average of 1.3 pCi/L, and above the EPA action level of 4.0 pCi/L (statewide estimate; county-specific figure pending). That means the typical home here tests high enough that the EPA recommends installing a radon mitigation system — testing is strongly advised across Castle Rock and the rest of the county.
Douglas County Radon, in Context
Source: CDC National Environmental Public Health Tracking Network — mean pre-mitigation radon level in tested buildings, Colorado, 2008–2017. Classification: Elevated (above EPA 4.0 action level).
What This Means for Douglas County Homeowners
Because the county average sits above the EPA's 4.0 pCi/L action level, radon mitigation is commonly needed here. The fix is routine: an NRPP-certified contractor installs an active sub-slab depressurization system that vents soil gas above the roofline, typically reducing indoor radon by 70–99%. Either way, Colorado Radon Experts routes you to a verified Colorado partner contractor for testing or mitigation.
Cities we serve in Douglas County
See all Colorado counties by radon level · radon FAQ · cost calculator · our services.
Test or Mitigate Radon in Douglas County
Free quote from an NRPP-certified Colorado partner contractor. No upfront cost.