You may be surprised to learn that millions of Americans are at risk for radon exposure. You may not even know what radon is or why it’s dangerous. If that describes you, please keep reading. You will not only learn what radon is, but also why testing for radon is necessary, regardless of your location.

What is Radon?

Radon is a radioactive gas that is naturally occurring. The gas is produced from the breakdown of uranium that is in the soil and rock underneath us. This gas can be drawn into your house due to the differences in air pressure. The gas makes its way into the home through cracks and openings. This gas, in high concentrations, can be detrimental to the occupants health. The Surgeon General warns that radon is the second leading cause of lung cancer in the United States. It is estimated it is responsible for 21,000 lung cancer deaths in the US every year. Smoking remains the leading cause of lung cancer, but smoking in the presence of radon can increase the risk of cancer. 

“Indoor radon is the second leading cause of lung cancer in the United States and breathing it over prolonged periods can present a significant health risk to families all over the country. It’s important to know that this threat is completely preventable. Radon can be detected with a simple test and fixed through well-established venting techniques.” – January 2005

Where is Radon Found?

Radon can be found in all 50 states, but is more prevalent in certain areas.  The EPA has published an interactive map that displays the radon zones around the United States. While homes in any area are susceptible, homes in zone 1 are at increased risk. Radon is found naturally outdoors at an average 0.4 pCi/L. In comparison, the average indoor level is 1.3 pCi/L and the EPA strongly recommends action when indoor levels are above 4.0 pCi/L.

Radon is most heavily concentrated in the lower levels of your home, but can be detected on upper levels as well. Since radon is pulled into your home through cracks in the foundation or exposed soil in the crawlspace, the areas closest to the soil will contain the highest levels.  Many people believe that homes without a basement are at lower risk. This is not the case. While a well built home may have mitigation naturally built in, all homes can be at risk. This risk can be higher in certain homes based on the soil conditions underneath the home.  Homes with high radon levels may be just up the street or in the same neighborhood with homes with low radon levels.  Without testing, you don’t know.

How to Test for Radon

Testing for radon is relatively easy. You can test for radon yourself or you can hire a testing professional. Each method can have some pros and cons. We will cover each. 

Self Testing

Test kits can be purchased at your local home improvement stores. You may have seen them near home safety equipment such as smoke and carbon monoxide detectors. First Alert Test Kits are charcoal activated sample kits that can be used to place in your home for at least 48 hours. These are often referred to as passive radon detection kits. Once the kits have been exposed for at least 48 hours, they are placed in a protective envelope and sent back to the Alpha Energy Lab for analysis. While each box only contains one test kit, it is recommended that you put out two tests side by side (follow stated directions). This will give you confidence in test data provided by the lab. Two kits, shipping and rush results will cost about $60.00 or so. Including sampling time, it will take about 4-5 days to get your test results.

Care must be taken in how and where samples are placed. Improper placement or home conditions can cause test inaccuracy. Due to the nature of charcoal sampling, shipping and testing, there can be some inherent error. If you decide to go this route, please carefully follow all of the instructions. If you want a trained professional, with professional testing equipment, that is definitely an option.

Professional Testing

Professional radon testing can be found across the country. Home Inspection companies may offer this testing as a service as well as radon mitigation companies. In both cases, always ask for their qualifications and ensure that it meets your states’ requirements or laws. Professional testing often involves a testing device that is placed in the home. These devices are referred to as active testing devices and require power.  While they are still placed for a minimum of 48 hours, these devices report hourly radon values as well as overall averages. Continuous active monitors can also be placed if on-going radon level monitoring is necessary. The cost of these tests are generally more expensive, but you are paying for the inspectors time, travel, expertise, test equipment and insurance coverage. You are also getting a higher level of accuracy and the assurance that comes with a professional test result. 

I have My Radon Results, Now What?

Your results are in hand… If the results are below 2 pCi/L, relax. It is recommended that you just consider bi-annual testing or testing when the home structure or systems have changed. If your results are between 2 and 4 pCi/L you should consider retesting as radon levels in your home can vary seasonally or due to weather conditions. You may also want to consider mitigation, especially if your results are closer to 4 pCi/L. What if your radon levels are above 4 pCi/L?  Relax, your home is not condemned.  There are options!


Now that you have your results, you should discuss with your testing professional to determine if there were any mitigation efforts already installed. A vapor barrier that has been moved, a radon vent that is uncovered or an inoperable fan could have a detrimental effect on your testing results. If there were issues found with the current mitigation system, then have those corrected and re-test. You should wait at least 24 hours after the systems are functional and then have your home retested.  If your test results are still above 4 pCi/L or if your home did not have any mitigation efforts installed prior to testing, you should consider your mitigation options. 

The most common type of mitigation on a slab or basement is a form of soil suction. There are several methods for the soil suction mitigation technique.  A mitigation professional will evaluate and determine the best technique to use based on your home construction and conditions. For homes built on crawlspaces, a plastic sheet (sometimes referred to as the vapor barrier), a vent pipe and fan are used to draw the radon into the vent and to the outdoors. Passive or active crawlspace ventilation can also be used to vent the crawlspace, which can lower radon levels in the home as well. There are also sealing and pressurization methods that can be employed in certain situations.

If all of these things sound like more than a weekend DIY project, you’re right. With your family’s health on the line, always hire a professional radon mitigation firm to do the work. Don’t always go with the cheapest solution. Call around, ask for client reviews and ensure that retesting to confirm the work is included. 


Radon is a deadly, silent killer. Knowing about its existence is a good start, but understanding that it can be impacting your home is critical. Testing for radon is not difficult or all that expensive, but knowing you have high levels of radon can be a literal life saver. You don’t have to look at your home as a death trap if you have the proper mitigation methods employed. That is the good news! With proper mitigation, you can return your home back to radon levels that are safe for you and your family. So now that you know all about radon, its impact on your health, how to test for it and how to fix it, don’t you think testing for radon is necessary?

Brandon Vaughn

Brandon Vaughn

Brandon is a licensed home inspector in the state of South Carolina.

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