Preface
About
This is a directory of people and firms with a current radon testing or mitigation credential on an official US state file or a current NRPP or NRSB certification. It is not a radon contractor. We do not test homes, install systems, or match you to a salesperson.
The Canadian section lists current C-NRPP testing and mitigation credentials, with separate Canadian sources, expiry dates and province/territory coverage. The US directory and its ZIP search retain their US scope.
Every listing shows the credential number, the issuing body, the date we last checked the file, and a link to that official source. We do not publish star ratings, “top 10” lists, or EPA-certified badges. EPA does not certify radon contractors.
City and listing maps mark the city or county named on the source file. Official rosters usually do not include a street, so pins are labeled approximate. We do not invent an office address.
Masthead
Who maintains this directory
Scott Foster publishes Radon Testing Companies as an independent directory publisher. This directory is not a radon contractor, not a lead broker, and not affiliated with EPA, NRPP, NRSB, or any state agency whose files it imports.
No listing here is paid, sponsored, or advertised. There is no way to buy a listing, a better position, or a highlight. Every listing is imported from an official credential file and links back to that file, and the only listings that exist are ones the file shows as current.
The roster is rebuilt monthly from those official files. Someone appears here only while the source shows a current credential; once the credential leaves the file, the listing leaves this site at the next refresh. That is why every page carries the date it was last verified. See the methodology for each source and credentials by state for who issues them.
Diagrams
Reusing our diagrams
The diagrams in our homeowner guides are licensed under CC BY-ND 4.0. You may republish them, including commercially, without changes and with the credit “Diagram: Radon Testing Companies” linked to the page where the diagram appears. Each diagram is simplified and cites the agency guidance it is based on; it is not installation or testing instructions, and it does not imply endorsement by EPA or any other agency.
Errata
Telling us something is wrong
Email corrections@radontestingcompanies.com with the credential number and what the official file says. We check the source before changing anything, and we correct or remove a listing that the source no longer supports. We cannot add someone who is not on that file. Removal requests are reviewed against the linked official source.