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University of Iowa News Release


June 3, 2008

UI study calls for more rigorous testing of radon detectors

Depending on environmental conditions, commercially available radon detectors can vary substantially in their accuracy and precision, according to a study led by Kainan Sun, a presidential graduate fellow in the University of Iowa College of Public Health. The research was performed in collaboration with the U.S. Environmental Protection Agency (EPA).

The researchers purchased charcoal-based, short-term radon detectors from seven different commercial vendors and blind-tested the detectors under two sets of controlled laboratory conditions. The results were then compared to a previous field study of the same type of commercially available radon detectors.

The investigators found that three out of seven companies' detectors failed to meet former federal guidelines for accuracy, even under ideal exposure conditions (constant temperature, humidity and radon concentration). The study appears in the June 2008 issue of the journal Health Physics.

"Because homeowners often rely on short-term radon measurements to decide if mitigation is necessary, it is important to know whether commercial radon detectors perform reliably under a wide range of environmental conditions encountered in a typical home," said R. William Field, Ph.D., UI professor of occupational and environmental health and a co-author of the study. "Our findings suggest the need for a systematic blind-testing program of radon detectors marketed to the average consumer."

The researchers reported that the detectors from most companies performed better under a moderate relative humidity of 50 percent and exposure to a fairly steady radon gas concentration. However, higher humidity and fluctuations in radon gas concentrations negatively influenced the accuracy and precision of some companies' detectors.

In addition, the study authors noted that the consistent over-reporting or under-reporting trends in the overall results for all three tests suggest a potentially widespread systematic bias for the individual companies that merits further investigation.

"It's important to note that these findings represent a one-time 'snapshot' and may or may not represent the overall reliability of commercially available charcoal-based radon detectors," Sun said. "Nonetheless, the findings suggest the need for improved vigilance to assure that the public can rely on short-term radon detectors to make an informed decision whether or not to perform additional testing or to mitigate."

Despite the findings, Field urges all homeowners to test for radon. He suggests that they perform confirmatory radon testing as outlined by the EPA in the publication, "A Citizen's Guide to Radon," available online at, to assure the measurement reflects the radon concentration within the home.

STORY SOURCE: The University of Iowa College of Public Health Office of Communications and External Relations, 4257 Westlawn, Iowa City, Iowa 52242

MEDIA CONTACT: Hannah Fletcher, College of Public Health, 319-384-4277,; Writer: Debra Venzke