About RadonGrade

RadonGrade turns two public datasets into a plain-language answer to one question: how likely is radon to be a problem where I live, and how urgently should I test? We publish a page for each of 3,143 US counties and 29,215 ZIP codes.

Where the numbers come from

Predicted radon levels are from the National Radon Exposure Model, a peer-reviewed machine-learning model from researchers at Harvard and Emory that was trained on more than six million real radon tests taken between 2001 and 2021 and released under a CC0 public-domain license. EPA radon zones come from the EPA Map of Radon Zones. Geography comes from the US Census Bureau. For Minnesota we also show measured test results published by the Minnesota Department of Health. We do not collect, estimate or invent any radon values ourselves; see the methodology for exactly how each figure is computed.

What we are not

We are not a testing lab, a mitigation contractor or a government agency, and a predicted value is not a measurement of your home. Every page tells you to test; that is the whole point of the site.

How the site makes money

Through affiliate links to radon test kits and continuous monitors (Amazon Associates and, when enrolled, manufacturer programs), and possibly display advertising in future. Commissions never change which data we show or how an area is graded; the grade thresholds are the EPA's own. Full details are in the disclaimer.

Contact

Corrections, data questions and partnership inquiries: see the contact page.