It’s simple: the test is voided and must be run again. No exceptions. The parameters for a radon test are that it has be a minimum of 48-hours, the HVAC system remains on and thermostat set between 67º and 76º F, windows stay closed, and doors opened only briefly for entry and exit from the house. Even if the test runs longer than the minimum 48-hours and, for example, a window is opened after the first two days, the results are voided. 

Tamper Detection Built-In

    The type of radon test device used for most real estate transactions is a continuous electronic monitor. It reports hourly radon readings, signals any movement of the device, and notes temperature and humidity fluctuations, along with changes in interior pressure of the home that indicate any opening of doors or windows. So this type of radon testing device is good for being sure the results are “honest.”

Passive Devices Easier To Fool

    Another group of radon testing devices are the “passive” type. These include the charcoal canisters that consumers can buy at hardware and home improvement stores, and electret ion chambers that utilize electrically-charged strips for testing. They are equal in accuracy to continuous electronic monitors, but do not have the tamper-resistant features. Some testing services use a tamper-resistant tape that secures the test canister in place, but any opening of windows or change in temperature or humidity of the testing area cannot be determined with a passive monitor.

    Although the passive radon test devices are excellent for homeowners that want to check their own house and have no reason to try to change the test results, they are not as tamperproof for a real estate transaction. Also, see our blog post Can a radon test result be wrong?

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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? 

• Can the seller tamper with a homebuyer's radon test to change the results?

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

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

• How was it determined that between 15,000 and 22,000 lung cancer deaths each year are caused by radon?

• 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? 

• 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?

• 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?

    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.