Radon hazards in underground homes: this article explains the level of radon hazard likely to be found in underground houses, and how to prevent radon gas contamination in concrete and underground houses. See RADON HAZARD TESTS & MITIGATION for details about radon in buildings, its health effects, how to measure radon, the effect of radon contamination on real estate values and home sales, and a guide on how to remove radon from buildings.
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The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.
I plan to build an underground house of concrete. The location will be in the Northwest where there is a lot of granite rock. I would appreciate any information you can give me on radon in underground housing. -- Harold F. Williams, Lakeport CA
Radon is a colorless, odorless gas released during the natural decay of radium, an element found throughout the earth's crust. Concentrations of radon vary greatly from an average of 0.7 picocuries per gram (of soil) in North American soils to seven to ten times that in New Hampshire granites.
Radon enters the home primarily through cracks in the foundation, from unpaved and unvented crawl spaces, and from sump pump pits. Water from deep wells can also be a source of radon gas in air and water in buildings, as can stone and masonry construction materials themselves, particularly when directly exposed to interior spaces. [That's why we don't conduct a radon test indoors by placing the test canister on the brick or stone fireplace mantel--DF].
There is evidence that the average home in the U.S. contains twice the atmospheric level of radon and that basements, on average, contain higher concentrations of radon gas than upper stories.
Radon levels indoors are reduced by good building practices such as thorough sealing and waterproofing, positive drainage, and granular backfill - which keep the radon gas out of the house and allow it a route to the outdoor soil surface.
Indoor air ventilation to 0.5 air changes per hour (ACH) should minimize any radon-related health hazard except under extraordinary conditions, and water borne radon can be filtered out with charcoal.
Medical experts agree that long-term exposure to low-level radon gas increases the likelihood of lung cancer, but the degree of risk is unclear. Radon levels found in problem homes have been compared in risk to smoking one to three cigarettes a day.
If you are concerned about the proposed building site for your underground home, radon detectors from Terradex Corporation can assess the level of radon present in soil at the building site.
This article is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.
The text below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.
Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.
Additional Radon details quoted from How to Remove Indoor Radonare just below.
As reported in Best Practices Guide to Residential Construction:
The EPA and the U.S. Geological Survey have rated every county in the United States as Zone 1 to 3 for radon risk. Links to state maps with county by- county risk levels can be found at www.epa.gov/ radon/zonemap.html.
The EPA recommends that all homes in Zone 1 counties be built with radon-resistant features, which can be easily upgraded to a radon remediation system if needed.
Since homes in Zones 2 and 3 can also have high levels, it is best to check with your state radon office to see if they are aware of any local “hot spots.”
The techniques for radon-resistant building vary for different foundation types and site conditions, but all contain the six basic elements described below.
Following these steps creates a passive soil depressurization system, which sufficiently lowers radon levels in about 50% of homes requiring mitigation.
If radon levels need to be lowered further, the system can be easily converted to an active system by adding an inline fan, which can meet the target levels in nearly all cases (see Figure at above left, showing a typical radon mitigation system installation). The goal of radon remediation is to lower the average indoor radon gas level to less than 4 pCi/L, and preferably 2 pCi/L.
-- Adapted with permission from Best Practices Guide to Residential Construction.
For a Thorough Background in Radon Hazards, Radon Mitigation, & the History of Radon Concerns in the U.S. also see these articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.
The link to the original Q&A article in PDF form immediately below is preceded by an expanded/updated online version of this article.
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