Chapter 04 — The Delaware file

Certified radon testers & mitigators in Delaware

This site imports no Delaware state roster, so these are current NRPP and NRSB certifications from those programs’ public finders. A national certification is not a state license. We group people by the city on that file. We do not invent neighborhoods. Source: NRPP.

Latest credential check September 14, 2026. Methodology Individual record dates may be earlier.

5current listings
4testing
1mitigation
Fig. 45 current listings. Each pin is a current listing at the Census city or county centroid on the file, approximate. Pins that share a place are spread so you can click them. Not street addresses.

§ 4.1

Cities with listings

A city appears only when at least one current listing serves it.

§ 4.3

How to verify a radon credential in Delaware

DE DPH registers radon work in Delaware but publishes no list with credential numbers that we can import, so listings here are national NRPP or NRSB certifications instead. A national certification is not the Delaware credential. Ask the agency directly: 302-744-4546.

NRPP finder · NRSB finder · EPA guidance · All fifty states · reviewed September 8, 2026

§ 4.4

Questions about radon credentials in Delaware

Does Delaware license radon testers and mitigators?

Yes. DE DPH registers radon work in Delaware. It publishes no current list with credential numbers that we can import, so this site cannot show the Delaware credential itself.

How do I verify a radon credential in Delaware?

Ask DE DPH directly: 302-744-4546. The 5 listings shown here are current NRPP or NRSB certifications, which you can check on those programs' public finders, but they are not the Delaware credential.

Is an NRPP or NRSB certification enough in Delaware?

No. Delaware credentials radon work separately through DE DPH. A national certification does not satisfy that requirement. Ask any provider for their Delaware credential and verify it with the agency before you hire.