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Colorado · Radon data by zip code

Find Radon Levels for Any Colorado Zip Code

Type any Colorado zip code below and we’ll show you the radon test data for the county that contains it — drawn from 214,362 pre-mitigation tests collected by the Colorado Department of Public Health & Environment between 2005 and 2024. Across the state, 46.9% of those tests came back at or above the EPA action level of 4 pCi/L.

Zip codes are postal routing — they don’t match radon, which follows geology. Every Colorado zip resolves to one (or sometimes more) of the state’s 64 counties, and that’s the data that actually matters. We do that lookup for you below.

Instant lookup — no submit, no email, no waiting. As soon as you type 5 digits we'll show your county's CDPHE radon data.

Popular zips

Don’t know your zip? Try one of these.

Twenty Colorado zip codes that cover roughly half the state’s population. Each card shows the county it belongs to and the CDPHE pre-mitigation data for that county.

How this works

Zip-level radon data doesn’t actually exist

No public radon database — not CDPHE’s, not the EPA’s, not the CDC’s — publishes radon levels by zip code. Every tool that claims to (including the big national ones) is doing exactly what we do: looking up which county your zip lives in and showing you that county’s data.

We’re upfront about it because the framing matters. Radon risk is driven by geology and home construction — what’s in the ground under your foundation, how tight the envelope is, whether you have a basement. None of that follows zip code boundaries. Two homes a half-mile apart on the same street can have very different radon levels. The only way to know yours is to test the actual house.

That said, county-level data does tell you whether you’re in a high-baseline region of Colorado — which informs how seriously to take radon during a home purchase, when to retest after a basement remodel, and whether mitigation is the default expectation in your real-estate market.

Data source

CDPHE

Colorado Department of Public Health & Environment radon database

Sample size

214,362

Pre-mitigation tests collected statewide, 2005–2024

Statewide rate

46.9%

Of those tests came back at or above 4 pCi/L

FAQ

Questions about zip-code radon data

Does zip-code-level radon data actually exist?

No. Every Colorado radon dataset — CDPHE, CDC Tracking, EPA — is published at the county level or coarser. Tools that 'show radon by zip' are looking up your zip's county and displaying that county's data. We do the same lookup, just transparently. To know your specific home's level, you need to test it.

Why is CDPHE data better than CDC Tracking?

CDPHE collects radon test results directly from Colorado homes and certified mitigators. The dataset is denser (214,362 tests vs CDC's smaller subset), more recent (through 2024), and Colorado-specific. CDC Tracking is a national rollup that lags CDPHE by years and aggregates at coarser geography.

What if my zip code spans multiple counties?

About 29% of Colorado zips touch more than one county. We show the primary county prominently (the one with the largest land-area share) and note the others below the result. If your home is near a county line, both data points are relevant. The lookup links you out to every applicable county page.

What does '4 pCi/L' mean?

Picocuries per liter — the standard unit for indoor radon concentration. The EPA's action level is 4 pCi/L: at or above that level, EPA recommends mitigation. Between 2 and 4 pCi/L, you should consider mitigation. Below 2, retest every 2 years. The percentage shown on this page is the share of pre-mitigation tests that came back at 4 pCi/L or higher.

I see a high number for my county — what should I do?

Test your own home. A short-term DIY test kit costs about $15 and takes 3–7 days. CDPHE has a list at coloradoradon.info. If your home tests at 4 pCi/L or higher and you're on the Front Range, get a free mitigation quote from us — a standard sub-slab depressurization system typically runs $1,200–$2,500 and reduces indoor radon by 95% or more.

Why don't you ask for my email?

Because it's public data. Other lookup tools require your email before showing the result — we don't. If you want a mitigation quote, you'll see a CTA; otherwise the data is yours to use however you want.