Understanding Radon Levels: What Your pCi/L Reading Means
Radon is measured in picocuries per liter of air (pCi/L). Here's how to read your number — the EPA's thresholds, what each range means for your home, and where Colorado Springs sits.
Key takeaways
- 4.0 pCi/L is the EPA action level — test results at or above it mean you should mitigate.
- 2–4 pCi/L is the "consider fixing" zone — the EPA recommends considering mitigation here too, especially in Zone 1 areas.
- No level is considered completely safe — risk rises with both level and years of exposure.
- Reported test data in Colorado Springs frequently comes back above the action level, in a Zone 1 county.
- Mitigation works at any level — systems typically bring homes to 2 pCi/L or below.
The pCi/L reference chart
The black marker shows the EPA action level of 4.0 pCi/L. Living at 4.0 carries roughly the lung-cancer risk of smoking half a pack of cigarettes a day, per EPA risk comparisons — which is why the threshold exists where it does.
| Your level (pCi/L) | Category | What to do |
|---|---|---|
| Below 2.0 | Low | No action needed. Retest in 2–5 years, or sooner if you remodel. |
| 2.0 – 4.0 | Moderate | EPA recommends considering mitigation — especially in Zone 1 areas like El Paso County. At minimum, retest to confirm. |
| 4.0 and above | Elevated — action level | Mitigate. Confirm with a second test, then install a mitigation system. |
| 10.0 and above | High | Mitigate promptly. Discuss timing with a licensed professional; very high levels may warrant faster action. |
Why is the action level 4.0?
The EPA set 4.0 pCi/L as the action level based on risk and feasibility: above this level, the lung-cancer risk from long-term exposure becomes comparable to other risks society actively regulates, and mitigation technology reliably brings levels well below it. It's a practical threshold, not a safety boundary — risk exists on a continuum, which is why the EPA also flags the 2–4 range.
How does Colorado Springs compare?
Aggregated homeowner test data frequently shows Colorado Springs readings above the EPA action level. El Paso County carries the EPA's Zone 1 designation, the highest radon-potential category, predicting average indoor screening levels above 4 pCi/L. That doesn't mean every home is elevated — levels vary house to house — but it means testing isn't optional here; it's the single most informative thing a homeowner can do.
Colorado's geology is the reason: uranium-bearing rock and soils across the Front Range generate radon that migrates up through foundations. Newer homes are not exempt — tight, energy-efficient construction can actually trap more radon indoors, which is why some new builds include passive radon piping from the start.
Does radon level affect health risk linearly?
Essentially, yes: the EPA and major health bodies treat lung-cancer risk from radon as increasing with both concentration and duration of exposure, with no known completely safe threshold. That's the scientific basis for "test every home" guidance — a home at 8 pCi/L isn't twice as urgent as one at 4 in any precise clinical sense, but higher sustained exposure means higher lifetime risk, and both should be fixed.
A note on risk framing
Radon causes an estimated 21,000 lung-cancer deaths per year in the U.S., making it the second leading cause after smoking, per the EPA. Smokers exposed to radon face dramatically compounded risk. These are population statistics, not predictions about any individual — but they're the reason testing and mitigation are straightforward, settled public-health guidance rather than a matter of debate.
Know your number?
If your test came back at or above 4.0 pCi/L, get free quotes from local Colorado Springs mitigation professionals today.
Get My Free Quotes or call (719) 555-0147Level guidance follows EPA recommendations; local readings reflect aggregated homeowner-submitted test data, not a measurement of any specific home. Health statistics per EPA. Last updated September 2026.