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Why Radon Testing Should be done in Multiple Locations

Radon electrets for testing in multiple locations

The real estate market is moving along in the Chicagoland area and it is the prime season for radon testing.  We have covered in prior blogs the importance of knowing the radon levels. We have also reviewed why it is so important to test.  But occasionally, I get questions regarding why I test in multiple locations in the property (typically in four areas). Don’t most radon companies typically leave one device for 48 hours and call it a day?  What’s the point in testing a number of locations?

Multiple foundations – Multiple pathways for radon

One reason for testing multiple locations would be if there were multiple foundations. Testing should be performed in each lowest area suitable for occupancy regardless of what devices you use 1.  For instance, if you have a partial basement and a crawlspace, the measurement devices should be placed in the basement and in the living area above the crawl. Or maybe the property has a basement but the addition is on a slab foundation. In that case, the basement and addition need to be tested separately.

Results can vary from place to place

Second, radon will not be evenly distributed in the property. Testing in multiple locations may reveal a radon problem in a single area where the other devices show acceptable levels.  I performed a radon test last year where one device exceeded the 4.0 Picocurie level in a large wine cellar but radon levels were much lower throughout the rest of the basement. The client reported that he liked to spend his free time in this cellar and smoke.  As an aside, when smoking is combined with elevated levels of radon, it significantly increases your chances of getting lung cancer 2. In his case, the radon problem would never have been discovered had we just performed a single test in the middle of the basement.  Testing multiple locations can catch these issues limited to one corner of the property.

Fixing the problem near the source

Another reason for performing multiple radon tests is to aid in the placement of a radon mitigation system.  Again, if there are elevated levels of radon found in just one section of the home, it greatly helps to know where the mitigation system should be placed to aid in more efficiently removing the gas.  

And finally, since it is well established that radon is the second leading cause of lung cancer 3, four tests are better than one!  Multiple testing can give a homeowner a greater sense of confidence that their home is safe from this dangerous gas.

Peace of mind

Whether purchasing a new home or just wanting the peace of mind knowing that your property is safe from elevated levels of radon, we generally recommend testing in a number of locations.  If a basement is very small, one location is probably acceptable. However, we would recommend testing in multiple locations if the home is particularly large, especially if it is older in age.  Cracks in the foundation of an older home can more easily allow radon gas to make its way into your living space. Since radon is an odorless, colorless gas, the only way to know for certain is to test.  Be sure to ask your radon professional if testing in multiple locations is a possible option.

  1. https://www2.illinois.gov/iema/NRS/Radon/documents/radontestguidelineforrealestate.pdf
  2. https://www.epa.gov/radon/health-risk-radon#riskcharts
  3. https://www.epa.gov/radon/health-risk-radon

Ian Cull

Ian Cull is a nationally recognized expert in the field of indoor air quality. He is the Chief Science Officer of Indoor Science, a company he started in 2004. He speaks around the world on air quality topics and is a training provider of the Indoor Air Quality Association. Mr. Cull is a Licensed Professional Engineer (PE) and Certified Industrial Hygienist (CIH). His degree is in Environmental Engineering from the University of Illinois - Urbana Champaign. Mr. Cull has developed 50 air quality related courses for the IAQA University and is the author of the book, “Fundamentals of Mold Remediation”. In his words… “Besides being passionate about indoor air quality, I enjoy cycling, music, the Chicago Bulls, and having fun with my three kids.”

3 thoughts on “Why Radon Testing Should be done in Multiple Locations

    I like how you said that radon won’t be evenly distributed because I have a lot of areas in my house I’d like to test. We haven’t had it tested yet so who knows what kind of radon we’re dealing with? Luckily neither of us are smokers so we’re not as at risk for getting cancer.

    It made sense when you said that testing in multiple locations can help determine the best placement for a radon mitigation system. My husband and I want to have our home’s air and water tested for radon. Reading your article helped me feel prepared to identify a radon mitigation service that’s thorough and knowledgable!

    It’s really good that you explained that performing multiple radon tests is important because it helps in the placement of the system, especially if there are different levels of elevation throughout the house, like a basement and upstairs. I was talking with my husband the other day, and he said he was thinking about having our home tested for radon. After reading this, I think I will have a professional run multiple radon tests throughout our house.