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 Valley and past Salem, or in NE Washington mainly around Spokane, or somewhat around Steilacoom/Lakewood/Gravelly Lake, 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 can move because it is the first gas in the decay chain, and not chemically reactive.
Radon decays radioactively to form charged decay products which can attach to dust particles that we inhale, and can get trapped in our lungs. Radiation from further decay damages lung tissue.
Q. When is radon a problem?
A. Radon can enter home breathing air, more when the soil contains much uranium, even more when a blanket of snow or soggy soil sends it toward buildings.
Q. How does radon get indoors?
A. Radon enters with other 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. When are radon levels higher?
A. Radon can enter home breathing air more whenever the soil contains much uranium, or a basement is dug, or crawl space perimeter foundation vents are blocked in winter, or a blanket of clay or soggy soil or snow sends it toward buildings.
Q. How high are radon levels around Seattle?
A. Radon is usually very low near Puget Sound, where the glaciers ground up rocks and left a clay cap that slows soil gas rising, allowing much of it to decay to something else not a gas.
Q. How high are radon levels around Salem?
A. Radon is usually higher in the our lower Willamette River Valley, where most homes sit on radioactive Ice Age mudflows periodically swept down from Montana by a series of cataclysmic Missoula Floods after ice dams broke, before 12,000 years ago.
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 level?
A. Compare your 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 LLC, http://www.inyourair.com
Blue Sky Testing LLC 