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Should I Test For Radon During My Home Inspection?




The answer 99% of the time is YES.  But before we get to all that, for those who may not know, we need to start with the question – What is radon?  Radon is an invisible radioactive gas that has no taste, smell or color. Over time, the uranium in rocks and soil decays and radon gas is released. The gas lets off radioactive particles. Because radon is a gas, it can enter buildings through openings or cracks in the foundation. The radon gas itself decays into radioactive solids, called radon daughters or radon progeny. The radon progeny attach to dust particles in the air and can be inhaled.”  As the EPA states, ”Any radon exposure has some risk of causing lung cancer. The lower the radon level in your home, the lower your family’s risk of lung cancer. Based on a national residential radon survey completed in 1991, the average indoor radon level is about 1.3 picocuries per liter (pCi/L) in air in the United States. The average outdoor level is about 0.4 pCi/L.”  So those are some radon facts…..




Now on to the radon test….  Typically, the radon test is a two-day process in which canisters or a machine are placed in the lowest-level of a home that is habitable.  And so, for a home with finished space in the basement, the test would be placed in the basement.  For a home without a basement or with only a 4-foot foundation rather than a full basement, the test would be placed on the first floor.  Radon is always present, but its level fluctuates constantly.  After 48 hours, the average radon level is taken, and if the radon level is found to be at or above 4.0 pCi/L, it is considered “unsafe” by the EPA.  If this is the case, the situation can be remedied by a Radon Mitigation System, which can cost anywhere from approximately $1,000 – $2,000 (at least this has been my experience) depending of the type of system and the specific characteristics of the home.


The cost of the actual radon test itself is not expensive.  Some home inspectors will provide a Canister kit to test the radon for which they charge their clients $100′ish (give or take), while others bring a machine for which they charge $125′ish (give or take).  The canisters have to be sent to a lab to be processed, and so it can take up to a week from when the canisters are placed until you receive the results.  The machine, on the other hand, provides its results two days after the administration of the test or as soon as the machine is picked up.  When my buyers ask if they should test for radon during the home inspection, in almost every case, I say yes.  And I answer this way even if no one is going to be using or spending any time in the finished room in the basement….  Even if a test was done six months before and the result was 2.0 pCi/L, for example.  According to the RSSI, “Radon levels vary in daily and seasonal cycles and in response to weather conditions and ventilation patterns,” and so a six-month window might present too many variations to the testing conditions….  And even if the home currently has a radon mitigation system, which “seems” to be working properly.  The only time that I might advise not to conduct a radon test is if a previous test was done within the last 30 days, there weren’t any structural changes to the home or its ventilating, heating and/or cooling systems during that 30-day time period, and the test result was 2.0 pCi/L or below.  In this case, given the 2.0 pCi/L level of the prior test results and the fact that the conditions are fairly consistent with those of the previous test given the short 30-day window combined with my client’s desire to waive administering the test, I would concur.  But only after we had reviewed, verified and were comfortable with the prior test results.


The last thing I want to say on the subject of testing for radon is a tip to sellers whose home is being tested for the gas – do not do anything to the windows, doors, etc. to try to influence the test.   Many people think that by airing the basement, they can make the levels of the radon decrease, but this is not necessarily true.  In fact, doing this may have the opposite effect on the radon levels.  So follow the instructions of the radon test, and try to keep the opening and closing of doors and windows to a minimum – basically live in the house as you normally would….