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lung.com

Environmental lung risk · 3,143 US counties

What the air where
you live is doing
to you.

Radon seeps out of the ground into 1,071 counties’ worth of basements and kills about 21,000 Americans a year. Wildfire smoke crosses half a continent. Neither shows up in a doctor’s appointment, and both are measured, published and free to look up.

This site reports those measurements, county by county, from the federal releases they come from. It sells nothing to patients and tracks nothing about your health.

Zone 1 · > 4 pCi/LZone 2 · 2 - 4 pCi/LZone 3 · < 2 pCi/L
3,143
Counties
1,071
In Zone 1
1,012
Air monitors

The national picture

Where the ground produces radon

Each state shaded by the share of its counties in the EPA’s highest radon zone. The band from the Great Plains through the upper Midwest into the Appalachians is where uranium-bearing bedrock meets basements.

Hover a state · click to open it

Share of counties in EPA Radon Zone 1, by state

Indoors

Radon

The second leading cause of lung cancer, and the leading cause among people who have never smoked. The EPA places 34% of US counties in its highest-potential zone. Look up yours, then test the house.

3,143 county pages →

Outdoors

Air quality

Five years of EPA monitor data for 1,012 counties: how many days were good, how many were not, and how bad the bad ones got. The other 2,131 are unmeasured, not clean.

1,012 county pages →

Highest potential

The biggest Zone 1 counties

Radon coverage tends to be organised by geology, which puts rural counties first. Ranked by population instead, this is where the most people live above ground the EPA predicts is producing radon above the action level.

Population figures accompany the CDC PLACES county estimates. Ranking by population says nothing about which county has the worst radon; it says where the most people are exposed to the same predicted level.

How this site works

A publication, not a clinic

Every number comes from a row

Nothing here is written by a model or estimated by us. Each figure traces to an EPA, CDC or NCI release, and the source sits under the table it fills.

We do not track your health

No advertising pixels, no behavioural profiling, no sharing what you read with an ad platform. Looking up your county's COPD rate is nobody else's business.

We sell remediation, not treatment

Where this site makes money it is from home services - radon testing and mitigation, filtration - which are contractors for your building, never referrals for your care.

Browse

Radon zones by state

Sources

Where the data comes from

EPA Map of Radon ZonesRadon potential for all 3,143 counties
EPA Air Quality SystemAnnual county AQI summaries, 2021-2025
CDC PLACESAdult asthma, COPD and smoking prevalence, 2022 and 2023 BRFSS
NCI State Cancer ProfilesLung cancer incidence and mortality, 2019-2023
US Census BureauCounty names, FIPS codes and adjacency

Full methodology and download links →