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Take the data
These are the same tables the site is built from: the federal sources joined onto the Census county spine, with the naming and boundary problems already resolved. Both are derived from public federal data and carry no additional licence.
Data build 2026-08-21. Please cite the original agencies - EPA, CDC and NCI - rather than this site.
3,143 rows · CSV
us-county-radon-zones.csv
One row per county: EPA radon zone, population, adult asthma, COPD and smoking prevalence, and lung cancer incidence and mortality rates.
Columns
| fips | 5-digit county FIPS code |
| county, state, state_name | Census county name and state |
| epa_radon_zone | 1, 2 or 3 |
| population | County population accompanying the CDC PLACES estimate |
| asthma_pct, copd_pct, smoking_pct | Crude adult prevalence, CDC PLACES |
| lung_cancer_death_rate | Age-adjusted per 100,000, 2019-2023 |
| lung_cancer_death_count | Average annual deaths over the period |
| lung_cancer_trend | NCI trend classification: rising, falling or stable |
| lung_cancer_incidence_rate | Age-adjusted per 100,000, 2018-2022 |
| places_year, places_release | Which BRFSS year and PLACES release the prevalence came from |
5,060 rows · CSV
us-county-air-quality.csv
One row per county per year, 2021 to 2025, for the 1012 counties with a reporting EPA monitor.
Columns
| fips, county, state | County identity |
| year | 2021-2025 |
| days_with_aqi | Days the county had a valid AQI |
| good_days … hazardous_days | Day counts in each of the six AQI categories |
| max_aqi, p90_aqi, median_aqi | Annual maximum, 90th percentile and median AQI |
| days_ozone, days_pm25 | Days on which each pollutant set the index |
Before you use it
Three things to carry with the data
A radon zone describes a county, not a house. Do not use this file to tell anyone their home is safe or unsafe.
Air quality rows exist only for the 1012 counties with a monitor. Absence of a row is absence of measurement, not absence of pollution.
Prevalence figures are model-based small-area estimates with confidence intervals this file does not carry. They are not counts of diagnosed people.
Full source list, vintages and join methodology on the methodology page.