Radon Levels in Montana
Montana is classified as an EPA Zone 1 state with a high risk for radon. Average indoor radon levels range from 2 to 8 pCi/L, and approximately 38% of Montana homes test above the EPA action level of 4.0 pCi/L.
Montana Radon Summary
High Radon Risk State
Montana is among the higher-risk states for residential radon. The Montana Department of Health strongly recommends that all residents test their homes. If you have not tested your home, consider ordering a test kit or radon detector today.
Key Facts About Radon in Montana
- Montana has widespread high radon levels due to its Rocky Mountain geology
- Granite and uranium-rich mineral deposits cover much of the state
- Montana DPHHS actively promotes radon testing
Montana Testing Requirements & Recommendations
No mandate. Montana DPHHS strongly recommends testing all homes.
Montana's building conditions and geology make sub-slab depressurization highly effective.
Major Cities in Montana
Radon levels can vary significantly within Montana depending on local geology. All residents — regardless of city — should test their specific home, as neighborhood-level radon varies independently of broader state and county averages.
What Should Montana Residents Do?
Test Your Home
Use a short-term charcoal test kit ($15–$25) for an initial reading, or a continuous radon detector for ongoing monitoring. Test in your basement or lowest livable area.
Understand Your Result
If your result is below 2.0 pCi/L: monitor periodically. Between 2.0–4.0 pCi/L: consider mitigation. Above 4.0 pCi/L: the EPA recommends mitigation. Above 8.0 pCi/L: take action promptly.
Hire a Certified Contractor if Needed
Look for NRPP or NRSB-certified radon mitigation contractors in Montana. Mitigation systems typically cost $800–$2,500 and can reduce radon levels by 50–99%.
Verify with a Follow-Up Test
After mitigation, test again to confirm the system is working. Retest every 2 years, or after significant home renovations.
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