Radon Testing CompaniesWashington file — NRPP / NRSB
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Chapter 04 — The Washington file

Radon testing & mitigation in Washington

This site imports no Washington 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.

30current listings
23testing
7mitigation
Fig. 4 — 30 of 30 current listings are mapped. 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 Washington

We have not confirmed whether Washington requires a state radon credential. Treat this as unknown, not as "none required", and ask the Washington radon program. Listings here are current NRPP or NRSB certifications, which are national and are not a state license.

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

§ 4.4

Questions about radon credentials in Washington

Does Washington license radon testers and mitigators?

We have not confirmed whether Washington requires a state radon credential. That means unknown, not that none is required. We do not guess at state law, so this site publishes no answer it has not checked. Ask the Washington radon program.

How do I verify a radon credential in Washington?

The 30 listings shown here are current NRPP or NRSB certifications, verifiable on those programs' public finders. The latest record check was September 14, 2026; check each listing for its own date. If Washington also requires a state credential, ask the provider for it and check it with the state agency.

Is an NRPP or NRSB certification enough in Washington?

We cannot say for Washington, because we have not confirmed whether the state requires its own credential. A national certification is never a state license anywhere. Treat NRPP or NRSB as evidence of training, then ask the state radon program what else is required.