Radon Measurement Guide for Homeowners & Home Inspectors
RADON MEASUREMENT GUIDE - CONTENTS: Advice for making accurate measurements of indoor radon levels in buildings. Where to buy radon test kits & how to use a radon test kit. Health effects of exposure to radon gas in homes - a consumer summary. Table of lung cancer risk from radon exposure in air or water. An easy guide to Radon Remediation in Homes
While some regions of the country
have more homes with elevated radon levels, high indoor
levels can occur anywhere.
[Click to enlarge any image]
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 RADON IMPACT 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 building 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. .
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
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