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 Radon Measurement Guide for Homeowners & Home Inspectors
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InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
Best ways to measure radon: this article explains procedures for measuring the indoor exposure to radon gas in air or water, and we describe the proper steps to remove radon and improve indoor air quality in homes. 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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Guide to Measuring Radon - Sources of Home Test Kits for Radon & Radon Action Level Definition
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 This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.
While some regions of the country
have more homes with elevated radon levels, high indoor
levels can occur anywhere.
For that reason, the EPA
recommends that all homes be tested. Although soil testing
is possible prior to building, there is currently no reliable
way to predict what household levels will be until a
home is completed.
Testing indoor levels is straightforward,
using inexpensive test kits available from hardware
stores or by mail order.
Select a radon test kit that is nationally or
state-certified. Our photo (page top) shows an economical radon test kit available from RTCA - the Radon Testing Corporation of America. Home test kits for radon typically cost $20. for one test canister.
The “action level” established by the EPA
for remediation in homes is 4 pCi/L, although it recommends
that people consider taking action at 2 pCi/L or
above—since no exposure level is without risk. The average
indoor level in the U.S. is 1.3 pCi/L, while outdoor
levels average 0.4 pCi/L.
Really, what is the health hazard from breathing air in which radon gas is detected at 4 picocuries per liter?
As we explain in more detail at Effects of Radon on Home Sales, the original EPA radon gas testing recommendation was for further long term testing if a short term test for radon showed 4 pCi/L of radon in indoor air. The level of radon gas in air, if present at all, can vary significantly over time due to a variety of building conditions such as indoor convective air current changes, building temperature variation, and variations in buildng ventilation. Because real estate sales transactions often do not welcome a year long radon remedy escrow fund impeding the sale of a property, 4 picocuries became an "action level for radon." Readers should note this additional explanation of the hazard level of breathing air contaminated at a level of 4 picocuries of radon:
If you breathe air contaminated with radon gas at an average level of 4 picocuries per liter of air for eighteen hours a day for seventy years, then IFyou contract lung cancer after that time, you can assert that the lung cancer could have been caused by the radon gas exposure. In other words, for 4 pCi/L radon gas exposure for any time period less than 18 hours a day for 70 years, the occurrence of lung cancer in an individual cannot be distinguished from random occurrences in the population and so cannot be asserted to be due to the radon gas exposure - Ed. .
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Radon Testing Methods & Procedures
Radon tests should be conducted away
from drafts, high heat, and high humidity in a
regularly used room on the lowest level in the home
that is used as living space, or in radon-testing lingo: test the lowest habitable space. So if your home has a full-height ceiling basement that is presently un-finished but that could be made into living space, it's reasonable to perform the test there.
Short-term radon tests last for
2 to 90 days, and long-term tests run for up to a year. Place the radon test canister 2-3 feet above the floor on a chair, box, or table, in a house that has been closed for at least 24 hours before starting the test and that will be kept closed for the duration of the test period.
Place the radon test canister close to the center of the room, not by a window, door, or masonry such as a brick fireplace that can cause abnormal readings (some bricks contain and emit radon).
Do not place the radon test kit in a dead-air space, and do not place the canister where the building's HVAC system will blow on or across it.
Because radon levels vary daily and seasonally,
longer test periods are better indicators of the average
level. However, if two short-term tests yield an average
result greater than 4 pCi/L, the EPA recommends
taking steps to lower the level to 2 pCi/L or lower.
Since 1985, millions of homes have been tested for
radon, and an estimated 800,000 homes have been
mitigated.
-- 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.
- "Radon's Threat Can Be Subdued", part 1 - William Turner, Terry Brennan, Solar Age Magazine Radon and its progeny are the slipperiest pollutants in the indoor environment, but there are simple ways to keep radon and its relations at bay.
- "Radon's Threat Can Be Subdued", part 2 - what is radon, where does radon come from, how does radon get indoors, and why is radon a problem in buildings.
- "Radon's Threat Can Be Subdued", part 3 - standards for airborne radon levels in buildings and recommended levels of radon for action, how radon is best detected, and radon action plan.
- "Radon's Threat Can Be Subdued", part 4 - radon prevention advice for new construction, radon in well water - how it is removed, sources of information about radon gas and radon contamination.
- "Defeating Radon" part 1- Terry Brennan, Bill Turner, Solar Age Magazine - How does radon get into buildings, how do I know if a building has a radon gas problem, how can I solve radon problems in existing homes, and what can I do to prevent radon from entering new homes. Part 1: where Radon comes from, how to diagnose radon
- "Defeating Radon" part 2- Guide to keeping radon out of new houses - design details
- "Defeating Radon" part 3- Key spots to seal, to stop radon gas leaks into buildings
- "Defeating Radon" part 4- Data on radon levels in buildings before & after radon mitigation treatment
- "Defeating Radon" part 5- Air filtering, testing after radon mitigation, where to buy radon tests
Frequently Asked Questions (FAQs)
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
- RTCA, the Radon Testing Corporation of America, is in Elmsford, NY - 800-457-2366
- US EPA Radon level maps for the United States (747 K PDF file) - US EPA data on radon risk by geographic area - original source http://www.epa.gov/radon/zonemap.html
- Granite Countertops and Radiation Hazards, U.S. EPA (PDF), retrieved 12/15/2010, original source: http://www.epa.gov/rpdweb00/tenorm/granite-countertops.html
- RTCA, the Radon Testing Corporation of America, is in Elmsford, NY - 800-457-2366
- "Radon Basics", Q&A article, Solar Age, April 1984, includes advice for radon-resistant construction for an underground house built of concrete
- "Radon Basics-PDF", Q&A article, Solar Age, April 1984, includes advice for radon-resistant construction for an underground house built of concrete
- ...
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
 The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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