Why Electret Ion Chambers Have Industry-Leading Accuracy
Electret Ion Chambers are one of two types of radon measurement devices that have been shown to be the most accurate and reliable tools to test for radon in homes, based on EPA-led research over the last three decades. Both types have been used world-wide since the 1990s. Both have saved countless lives.
Electret Ion Chambers are manufactured by Rad Elec Inc. under the brand name “E-PERM.” They are one of the most accurate radon testing devices available to radon testing professionals. In fact, when the USEPA conducted intercomparison tests of all radon testing devices, E-PERMs outperformed all passive and active radon testing devices (USDOE Inter-comparison Results For Radon Technologies – REF: EML-566 (1995)). Unlike some other passive radon testing methods, E-PERMs also have distinct advantages:
1. E-PERMs will detect equipment malfunctions, because they usually are deployed in duplicates for home tests. A few measurements are taken with single monitors, usually in “sequential testing,” an approved process that is rare in home uses. Most other testing devices are deployed as a single standalone device, without a duplicate or back-up, so equipment errors cannot be detected;
2. They are not affected by temperature or humidity, and can provide the radon professional same day test results;
3. E-PERMs are true integrating devices, yielding highly accurate measures of radon levels in a home; and
4. E-PERMs do not depend on electrical power supplies to function.
For all of those reasons, E-PERMs are recognized world-wide as one of the most accurate radon testing devices available to the radon professional, and are listed by the U.S. Environmental Protection Agency (USEPA), the World Health Organization (WHO), the National Radon Safety Board (NRSB), and the National Radon Proficiency Program (NRPP).
The two basic methods for radon gas testing are active testing devices and passive testing devices. Active radon testing (often called CRMs, or continuous radon monitor) report hourly radon measurements. In contrast, passive devices integrate radon measurements over the testing period (usually 48 hours in homes) and report a single average radon concentration for the duration of the radon test. There is a misconception that CRMs are “more accurate” than passive devices. Not true. Both methods of radon testing provide accurate and reproducible radon test results. Both methods of radon testing have been approved by the USEPA and the NRSB/NRPP. Additionally, all radon testing devices used for real estate transactions sanctioned by the NRSB/NRPP must have been tested and listed by these organizations to validate that they meet the required standards for accuracy. However, home owners typically have little or no use for hourly radon readings or temperatures, etc. It is the radon concentration in the home over the full 48 hour test that matters. E-PERMs excel by this measure and are not affected by humidity.
In evaluating the “accuracy” of a radon test, the single most important factor is that the recommended testing protocols be followed, since both types of test equipment will produce accurate results under standard protocols. Almost all “errors” associated with radon testing are caused by “manipulation” or not maintaining the required “closed house” conditions during the testing period, and not by some defect in the testing device. No test device guarantees tampering never occurs. Yet experience shows it is far from common. Although all test devices can be subjected to tampering to one degree or another, tampering often is recognizable in test results that are improbably far from norms.
In short, electret ion chambers are extremely accurate passive testing devices that provide an integrated radon concentration, and can be deployed in challenging environments that may experience a loss of electricity or climate control. Their lower limit of detection (LLD) is between 0.2 and 0.3 pCi/L, and deploying them in duplicate provides ample confidence that the radon test results are both accurate and precise. They have been a tried and true methodology for over 30 years, and continue to be deployed all across the world.
Rad Elec Inc.