Radon Levels Guide helps homeowners, renters and home buyers in the United States and Canada understand radon risk where they live. We turn official radon data into one clear page per state, province, county and city, and explain how to test, what the numbers mean and what fixing a high result usually costs.
Where our data comes from
Every number on this site comes from a public, official source, and each page names its source and the date we checked it:
- U.S. Environmental Protection Agency (EPA): the Map of Radon Zones (Zone 1, 2 or 3 for every U.S. county) and the EPA action level of 4 pCi/L.
- CDC Environmental Public Health Tracking Network: radon test results by county (and by ZIP code where states share them).
- State radon programs: test results and guidance published by state health and environmental agencies.
- Health Canada: the Cross-Canada Survey of Radon Concentrations in Homes and the Canadian guideline of 200 Bq/m³.
- Certification bodies: public lists of certified radon professionals (NRPP and NRSB in the U.S., C-NRPP in Canada).
How we build each page
We collect the official figures, check them against the original publication and present them in tables you can read in a few seconds. Area averages describe a region, not your home: two houses on the same street can have very different radon levels, so every page explains how to test your own home.
We use AI tools to help draft and organize text. A person reviews every page against the original sources before it is published, and numbers are never generated by AI.
Not medical advice
This site is for general information only. For health questions, talk to your doctor or your state or provincial radon program. For testing and mitigation, use a certified radon professional.
Corrections
If you find an error or have newer official data for your area, please contact us with the page and the source. We review every report and update the page and its date.
Independence
Radon Levels Guide is an independent website. We are not affiliated with the EPA, the CDC, Health Canada, any state or provincial agency, or any radon company. The site may show ads and may earn a commission from some product links; this never changes the data we publish.