Air Quality

Published on November 20th, 2012 | by Henri


Radon testing

Q.      We are getting ready to look for a smaller house this spring now that our children are gone. What is your opinion about radon testing, and what other advice can you give us?

A.      It is a good idea to have any house tested for radon. But there are different ways of doing it.

First, to give you a good idea of the potential radon contamination of your house, the testing should be done when the house is going to be closed for an extended period of time and when there is a big difference between indoor and outdoor temperatures – that is, during the winter or the air-conditioning season. If you test your home for radon when it is warm outside, the reading is likely to be the same as it is outdoors because the windows will be open. There is nothing to be done about outdoor radon, and we have all been exposed to it from the day we were born, anyway.

As for the types of testing available, short-term testing can be done with charcoal canisters, but they test the radon level over only the preceding few days. I favor the longer-term alpha track system, which gives you readings over several months. This is the system I used at my house. I installed it in September and stopped the testing in March. Using this method, I was sure that I got a reading over a long period of time, through many temperature fluctuations and other variables.

When my clients ask me about the results of radon testing, I ask them: “Would you still buy the house if it showed a high reading?”

If your answer is no, then go for the quick-but-limited testing with charcoal canisters or with one of the fancy, expensive devices that gives instantaneous readings. Many inspectors carry them, but they charge an additional fee to use the equipment.

If the answer is yes, then buy the house and test for radon over the next heating season. If the reading is over the health limit set by the government, consider having mitigation measures done by experienced professionals.

More information on this subject, from the Environmental Protection Agency, can be found at

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