Evidence policy
RadonVerdict is built around a simple rule: official radon evidence comes before calculators. County pages use public EPA, state, CDC, NJ DEP, Census, ZIP, and cost-reference data to decide whether a page has enough local evidence for search and what next step a user should see.
Open data download
The CSV contains one normalized row per official measurement or radon-potential record. It includes county FIPS, EPA zone, source URL, reporting period, retrieval date, available metrics, the source caveat, and a stable county evidence URL.
This is a transformed index of public-source records, not a replacement for the primary datasets. Preserve the source URL and caveat when quoting a row, and verify decisions against the linked agency source.
Suggested citation
RadonVerdict. “US County Radon Evidence Dataset.” Accessed from radonverdict.com/radon-data-sources.
Download CSV (3,057 records)Citation-ready local records
These are direct, stable pages for the local evidence selected for this recovery pass. Each record names the official source and period, links to the complete county page, and states what the aggregate cannot prove about one home.
Schenectady County, New York · 2015–2019
New York State Department of Health residential test data reports 16.0% of submitted tests at or above 4.0 pCi/L. It is a county-level submitted-test summary, not a prediction for an individual basement.
Falls Church, Virginia · 2016–2024
Virginia Department of Health data is a citywide result record after its published exclusions. It is not a basement-only measurement and cannot substitute for testing the lowest regularly occupied level of a specific home.
Ulster County, New York · 2015–2019
New York State Department of Health data supplies the county context. The linked testing page explains how to obtain the measurement that decides what this particular home needs.
How to test a home in Ulster CountyOfficial county evidence
3,057
Measurement or tier-backed county summaries loaded for radon-level decisions.
Measurement summaries
3,036
County rows from official health, tracking, or state radon datasets.
ZIP mappings
40,965
ZIP-to-primary-county mappings used to route cost and credit searches.
Reference anchors
8
EPA, CDC, HUD, and cost-reference sources used across guides and calculators.
Evidence hierarchy
The hierarchy matters because EPA zone maps, state measurements, and cost models answer different questions. We keep them separate so a county page does not overstate what any single source can prove.
1. Official measured radon data
State health departments, CDC tracking exports, public dashboards, and official county or ZIP aggregates come first when available.
2. Official tier or potential data
For New Jersey, DEP municipal radon-potential tiers are used as testing-priority evidence, not as a county pCi/L average.
3. EPA zone and state program context
EPA zones explain predicted county potential. State program pages explain testing, disclosure, and credential expectations.
4. Census housing and cost references
Housing stock, home value, foundation assumptions, and national cost references support budgeting, but they never replace a home test.
Official source inventory
Counts below describe source-backed rows currently loaded into the application, not a claim that every county page should be indexed.
CDC county summaries are based on national radon testing laboratories and participating state feeds; they are not a statistically designed survey of every home.
Evidence type
County measurement summary
2008-2017
Loaded counties
1,924
VDH says the map displays indoor air radon results received by its Radon Program from 2016-2024, using voluntary reports from five major radon test-kit vendors and professional testers after removing duplicates, post-mitigation tests, inappropriate locations, upper-floor tests, and incomplete addresses. VDH suppresses locality averages when fewer than 25 tests are available. RadonVerdict normalized the rendered VDH Tableau table because Tableau Public summary data, crosstab, and workbook export are permission-denied.
Evidence type
County measurement summary
2016-2024
Loaded counties
133
Missouri DHSS publishes residential radon testing through a public ArcGIS dashboard. County totals, average final result, and maximum final result come from the county summary layer. RadonVerdict computes the 4.0+ share from non-negative point-level Final_Result records because the point layer also contains -999 privacy/suppression sentinel values. These are reported test records, not a statistically designed survey of every home.
Evidence type
County measurement summary
2005-2017
Loaded counties
115
Kansas EPHT county summaries are based on radon tests reported to KDHE; they are public-health surveillance summaries and cannot predict an individual home's result.
Evidence type
County measurement summary
2020
Loaded counties
105
IEMA-OHS says the dashboard is not intended to decide whether a specific home should be tested; all homes should be tested. The measurement data are annual reports submitted by licensed measurement and mitigation professionals for calendar years 2003-2019, using the highest submitted measurement for each address. RadonVerdict stores only county-level aggregates, excludes invalid tests and negative result sentinels, and does not store address-level records.
Evidence type
County measurement summary
2003-2019
Loaded counties
100
NCDHHS says the public map shows the highest measured radon level in each county from two test kit companies and one continuous-monitor leasing company. RadonVerdict stores that value only as a high-end county signal, not as a county average or a prediction for a particular building.
Evidence type
County measurement summary
updated 2025-08-06
Loaded counties
100
Iowa HHS/IDPH publishes county median radon values through a public Tableau CSV export. RadonVerdict stores the median county test result as a county context signal; it is not a prediction for any individual home, and Iowa HHS still recommends testing because high levels can be found in any type of home.
Evidence type
County measurement summary
current dashboard export
Loaded counties
99
Tennessee Health Data says county and ZIP values come from radon test kit and mitigation company data; results before about 2015 may not be included, and county or ZIP averages cannot predict an individual home's radon level. RadonVerdict uses the official county average layer and rolls the official ZIP 4.0+ layer up to primary counties.
Evidence type
County measurement summary
through 2020
Loaded counties
95
Minnesota county summaries are based on reported commercial and residential radon tests, mostly single-family homes, and exclude most continuous-monitor real-estate tests.
Evidence type
County measurement summary
2010-2020
Loaded counties
87
Wisconsin DHS ZIP-level summaries are based on indoor radon test results from 1995-2016 and are aggregated to county by RadonVerdict using test-count weighting.
Evidence type
County measurement summary
1995-2016
Loaded counties
72
Colorado county summaries are based on pre-mitigation indoor radon tests reported to CDPHE and are not a statistically designed survey of every home.
Evidence type
County measurement summary
2005-2024
Loaded counties
64
NY DOH county summaries are based on submitted residential radon tests and are not a statistically designed survey of every home.
Evidence type
County measurement summary
2015-2019
Loaded counties
62
Indexing discipline
RadonVerdict does not try to submit every possible county or ZIP combination to search engines. A county page can be useful to a direct user and still stay out of search if the available evidence is weak, missing, too similar to other pages, or not supported by enough demand yet.
Submit pages with distinct evidence
Official evidence, housing context, state rules, clear related pages, and a distinct user task must support the page.
Hold thin or low-signal pages back
Zone-only, duplicate, unknown-zone, or unsupported county pages are kept out of the sitemap until they earn a stronger reason to rank.
Bottom line
Public radon data can tell you whether a county deserves urgency. It cannot diagnose a property. That boundary is why our county pages separate evidence, testing guidance, cost planning, and lead capture.