Radon from the ground

Radon gas indoors

Q. Who most needs to test for radon?
A. Radon testing is sometimes required for real estate sales, or for leasing to the government.  Or often requested in buildings or regions with high previous readings, such as in Oregon around Portland and up the Willamette river to Salem, or in Washington mainly around Spokane or somewhat around Steilacoom/Lakewood, or along the Cascade foothills.

Q. What is radon?
A. Radon is an odorless radioactive gas that can travel and enter building air. It comes from the radioactive decay of uranium in rocks and soils.

Q. Why is radon a problem?
A. Radon can cause lung cancer. Radon decays radioactively to form charged decay products that attach to dust particles.  We inhale the particles, which may become trapped in our lungs. Radiation from further decay damages lung tissue.

Q. How does radon get indoors?
A. Radon enters with soil gases (or sometimes from interior rock or masonry, or well water) into basements or crawl spaces.  It can be sucked up into the building by exhaust fans, combustion appliances, or the “stack effect” of warm air rising.

Q. How high is the radon level in Seattle?
A. Radon is usually very low near Puget Sound.  Expect higher in the foothills, or around Steilacoom/Lakewood, or especially Spokane.

Q. How do we test for radon?
A. See the page on how to test:  conditions, methods, tools, re-testing.

Q. How high is my radon concentration?
A. Compare levels, measured in picoCuries of radiation per liter of air (pCi/L), with these levels:

 (pCi/L)      Range   –   Air Quality Guidelines

  • (4.0 to 20)  HIGH – Test again to verify levels; take action to reduce.
  • (4.0)  “ACTION LEVEL” recommended by the USEPA for indoor air.
  • (2.0 to 4.0)  MEDIUM – (just below the USEPA “action level”.)
  • (0.5 to 2.0)  LOW – (1.3 is the national average indoors.)
  • (below 0.5)  VERY LOW – (0.4 is the national average outdoors.)

Q. How can I reduce radon levels?
A. Find the source and stop the pathways (see reduction page), such as in summary:

  • Basement:  sealed openings, subslab ventilation.
  • Crawl space:  soil vapor barrier and perimeter vents.
  • Exposed masonry:  sealed with paint.

Finding sources and pathways

  • Test again in more and different locations, to find the source: soil gases? (most common), interior masonry, granite, rocks?, well water?
  • Test also to find the entry pathways: basement? (most common) (more in one end or corner?), crawl space? well water?

Get more info from the US EPA.

©Richard Knights, Blue Sky Testing, http://www.inyourair.com