Looking for a radon mitigation pro in Seattle, WA? Describe your project once and up to three certified radon professionals who work in Seattle and King County get back to you with a quote. It's free and there is no obligation.
Seattle is home to about 780,995 people (2024 Census Bureau estimate), a growing community (+6.0% since 2020). With 9,298 people per sq mi, it is a densely built-up area. Radon levels vary from house to house, even next door: testing is the only way to know, and mitigation the standard fix.
Seattle at a glance
- Population (Census Bureau estimate, 2024)
- 780,995 (+6.0% since 2020)
- Rank in Washington
- 1st of 281 cities and towns
- Land area
- 84 sq mi
- Population density
- 9,298 people per sq mi (densely built-up)
- Type
- City (Seattle city)
- Main county
- King County
What to check before hiring in Seattle
- Certification: in Washington, choose a pro certified by the NRPP or NRSB, and licensed by the state where it is required.
- Test after: a post-mitigation test should confirm the new level.
- Fan placement: ask where the fan and the vent pipe will go, especially on the outside of the house.
- Price drivers: foundation type, number of suction points and the pipe route.
Useful official resources
-
EPA: radon
Health risk, testing and fixing your home.
-
NRPP
Find certified radon professionals.
Services available in Seattle
-
Radon mitigation system
Installation of an active soil depressurization system with a post-mitigation test.
-
Radon testing
Professional radon test, for example during a home purchase.
Frequently asked questions in Seattle
How much does radon mitigation cost in Seattle, WA?
It depends mainly on the foundation and the number of suction points. Describe your home: certified pros who serve Seattle reply with a quote.
How long does installation take?
Most residential systems are installed in a day.
Is radon common in Washington?
Radon is found in every state. Only a test of your own home tells you its level.
Which certified radon professionals will contact me?
Up to three independent certified radon professionals who serve Seattle and the surrounding area, chosen for the service you need. Your details are shared only with your consent.
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2024) and Gazetteer Files (public domain), imported on 10/31/2026. Figures describe the incorporated place or county as published; they are shown for information only.