How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
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Can a radon test result be wrong?
Friday, November 27, 2020
Yes, it is possible. There are several ways a radon test result could be inaccurate:
•• Cheating or improper test procedure - It’s easier to cheat for a test using a radon canister: cap it, take it outside, or open the windows for part of the test to lower the result. And leaving the canister open longer than reported will elevate the number. The electronic test machines used in most real estate transactions today have sensors that detect the duration of the test, if the machine is moved, how long doors or windows are opened, and temperature or humidity changes. So they are much less likely to be tampered with.
Also, the specific requirements for radon testing must be followed, such as doors and windows closed, locating the test away from a/c ducts, not operating whole-house fans or fireplaces during the test, and keeping the indoor temperature within a normal, comfortable range. Ignoring any of these standards will skew the test results, usually downward.
Forging the test results in the report is also possible. This is why it is always best to have a disinterested, third-party radon tester that is licensed, uses an electronic radon testing machine, and has nothing to gain by adjusting the test results.
•• Short test period - The normal radon test for a real estate transaction lasts for two days. While the test result may be accurate for that time period, weather conditions during the test can cause a brief uptick in radon level, and radon does vary somewhat seasonally. Conversely, a lower than normal reading is also possible.
A radon test that lasts 30 or 60 days, or even longer, is more accurate. This is not feasible during a real estate transaction and, often, a long-term test is not significantly different from a short-term one. But, if the short-term test result is close in either direction to the 4.0 pCi/L level that triggers the EPA’s recommendation for mitigation, then a second short-term test can be a good idea.
Also, see our articles Can the seller tamper with a homebuyer's radon test to change the results? and How was it determined that between 15,000 and 22,000 lung cancer deaths each year are caused by radon?
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