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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Here’s links to a collection of our blog posts about RADON:

• Is a radon mitigation fan required to be on a dedicated circuit breaker/fuse in the electric panel?

• What happens to a radon test result if the windows were opened, the test device moved, or there was any other evidence of tampering during the test? 

• Where do I find the Florida laws regarding radon?

• Can I test vacant land for radon before building a house? 

• Is radon mitigation possible for a condominium?

• Do radon mitigation systems require maintenance?

• What is the average life expectancy of a radon mitigation system?  

• Do older houses have higher radon levels than new houses?  

• How long does it take to get the results of a radon test? 

• Will opening the windows reduce the radon level in a house?

• Can a homebuyer do their own radon test for a real estate transaction with a self-test kit?

• What is the danger of radon in well water?

• What are the symptoms of radon poisoning? 

• Does Florida have radon?

• Where does radon come from?  

• For how many years does an old radon test result remain valid?

• Should homeowners get a pre-listing radon test before selling their home?

• What are a homebuyer's options when the radon test comes back high (4.0 pico-curies/liter or more)? 

• Do granite countertops emit radon?

• How can I tell if a house has a radon mitigation system? 

• Can a mobile/manufactured home have a high radon problem?

• Do I need to test for radon when buying a condominium? 

• What does a radon mitigation contractor do to lower the radon level in a home?

• How can not testing for radon be an expensive mistake for homebuyers? 

• Will the radon test come back sky-high in a house that has been empty and closed-up for months? 

• What is radon? Should I be concerned about it?

• Should I buy a house with a high radon level? 

• What is the average radon level of indoor and outdoor air in America?

• What is the operating cost of a radon mitigation system? 

• Should I buy a house with a radon mitigation system?

• Does the buyer or seller of a home pay for radon mitigation when the radon test comes back high? 

• What is the probability of having high radon in a Florida house?

• How quickly do I need to reduce a high radon level in my house? 

• Does a home inspector check for radon?

• What are the problems with underground return air ducts? 

• What is the probability of having high radon in a Florida house?

• What factors can change radon test levels up or down? 

• How do I know if a radon mitigation system is working? 

• Can I sell a house with a high radon level?

• Does heavy rain change radon levels? 

• Does barometric pressure change radon levels?

• Do high winds affect radon levels? 

• What radon level is dangerous?

    Visit our RADON page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.