Article Summary

Radon is a colorless and odorless radioactive gas that has been found in homes all over Arizona. Radon is estimated to cause 21,000 lung cancer deaths a year in the United States. According to the EPA, “nearly 1 out of every 15 homes in the United States is estimated to have an elevated radon level of 4 picocuries per liter of air (4pCi/L) or more. If your home has a radon levels above the EPA threshold to take action, 4 pCi/L or higher, we can help you mitigate this problem. At Advantage Home Performance we have had consistent success reducing radon levels in homes to well below the EPA recommended action level.

How does radon get in my home?

Radon can build up to dangerous levels in homes. In can enter through crawlspaces, slab on grade foundations and basements. Air pressure inside your home is usually lower than pressure in the soil around your home’s foundation. Because of this difference in pressure, your home acts like a vacuum, drawing radon in through foundation cracks and other openings. The amount of radon that escapes from the soil to enter the house depends on the weather, soil porosity, soil moisture and the suction within the house.

Radon Levels

In the United States radon is measured in picocuries per liter of air (pCi/L) which is a measure of radioactivity. 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. The EPA action level is 4 pCi/L. Health authorities like the Centers for Disease Control (CDC), the Surgeon General, the American Lung Association, the American Medical Association and others agree that we know enough now to recommend radon testing and to encourage public action when levels are above 4 pCi/L.” The EPA recommends that you consider repairs at radon levels between 2 pCi/L and 4 pCi/L.

How do I test for radon?

The only way to know if your home has a radon problem is to test for it. Short-term and long-term radon test kits are widely available on-line and at the big box home improvement stores. The short-term radon test kits are inexpensive. The problem with the short-term charcoal radon test kits is that they have to sit for three to seven days and then get sent back to a lab to determine the test results. It takes a couple of weeks to get results which deters many homeowners from taking the initiative to have the test performed.

The second problem with a short-term charcoal canister is that it may not provide an accurate account of the long-term radon level in a home. The season and outdoor temperature can have a large bearing on the radon level. We have seen rain cause indoor levels of radon to spike to elevated levels and that is why we prefer a long-term test result that does continuous averaging over a sustained period of time.

A short-term radon test is probably a good place to start, but if you have radon levels above 4 pCi/L your next step might be to invest in a long-term radon test. We much prefer a long-term radon test result with an electronic radon tester that provides a continuous readout (see photo above) We really like the Corentium Home by Airthings that can be purchased online for $179. Make sure you get the USA version.

Radon Reduction Techniques

As an HVAC contractor, spray foam contractor and energy audit company, Advantage Home Performance has many options at our disposal to reduce radon levels. The solution we propose is often based on the level of radon in the home, type of foundation (crawl space, slab on grade or basement) age of home, budget and if a real estate sale is contingent on us getting great results. Obviously if a sale of a house in contingent on us getting a great result, we propose a multi-pronged solution that will get us the best result in the shortest period of time.

In the photos below you can see two of our radon mitigation strategies. The plastic air barrier has a perforated hose running underneath it which is connected to an in-line fan which exhausts to the outdoors (see photo of inline fan at beginning of article). We create a negative pressure underneath the air barrier to eliminate radon entry into the crawl space. We also sealed the air distribution system so the return side would not suck radon into the home. On a slab on grade home we again would use a combination of strategies from a sub slab depressurization, duct sealing and energy recovery ventilator.

Fee for radon inspection

We charge a diagnostic fee to inspect homes that have elevated radon levels. The fee for a radon inspection is $200. The reason we charge this fee in order to slow down our inspectors. Our goal will be to arrive at a mitigation strategy that will reduce radon levels well below the EPA action level of 4 picocuries per liter of air (4pCi/L). To accomplish this goal we need to thoroughly understand the home before we write a proposal and repairs start. The fee covers our time to inspect the house and generate a quote. We will not commence work on a house with a radon level unless we are confident that we can achieve accomplish the goal.

We also offer a radon inspection coupled with short-term radon testing for $350. We will leave a radon testing device at your home for five to seven days to determine your home’s average radon level during this period of time. The fee is non-refundable if you choose not to proceed with repairs. However if you choose to proceed with radon mitigation repairs we will provide short-term testing for a two week period after work is completed at no charge. We will be as interested as you, if not more, to make sure that we accomplished our goal of reducing radon levels below 4 picocuries per liter of air (4pCi/L).

Our radon mitigation results

We have reduced radon levels below 2 pCi/L on our two most recent radon mitigation projects. One of the projects involved a real estate transaction in which we had to get the house below 2.5 pCi/L as a condition for of the sale to proceed forward. For this client the sale of their house was pending on achieving a very low radon test result. We have very strong local references who know how successful our multi-pronged approach is to radon mitigation.


The EPA has several outstanding publications dealing with radon. We suggest you start with their radon fact sheet.

1. EPA Publications on radon

2. EPA Basic Radon Facts

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