From my experience of nearly 30 years in home inspection, I’ve learned that radon is an often unheard of or confusing topic among home buyers, sellers and real estate agents alike. Many people don’t worry about it like they should, and some don’t believe it’s real, but it’s very real. In fact, radon is number 86 on the periodic table of elements and has been a known health hazard for a long time, even being classified as a human carcinogen in 1988 by the International Agency for Research on Cancer.

While radon testing is outside the scope of a standard home inspection, many home inspectors offer it as an add-on service. Before you hire someone to perform professional radon testing, we highly recommend you check that they are certified or licensed, if required, to conduct the proper testing.

What is Radon?


Radon is a naturally occurring radioactive gas that is created when uranium and radium breakdown. It’s colorless, odorless and tasteless, so it’s virtually impossible to detect it without a Radon Test. Some level of radon is present is virtually every home in the U.S.; however, some regions are prone to higher radon levels than others. How do we know where radon is more commonly found? Years and years of actual test data have been collected from all across the U.S. and show patterns of where higher concentrations of radon are found. High radon levels have also been found in schools and commercial buildings.

Radon is the leading cause of lung cancer among non-smokers and the second leading cause of lung cancer altogether, according to the U.S. Environmental Protection Agency (EPA). It’s estimated that 22,000 American lives are lost every year from radon-induced lung cancer. What’s more surprising is that’s actually six times the number of deaths caused by carbon monoxide poisoning and house fires combined. Moreover, tobacco use can significantly heighten the risk of contracting lung cancer by roughly 15 times. While tobacco use is the main cause of lung cancer, modern research shows that at least 30% of people who have lung cancer have never smoked.

How Radon Enters Your Home

radon exposer

Radon can enter your home in various ways, but the most common way is through cracks and gaps in the home’s foundation. As you may know, warm air rises, so when radon gas is created in the soil, it rises and seeps into the home from the ground up.

Radon is also greatly affected by indoor ventilation, called the ‘stack’ or ‘chimney’ effect. The stack effect is like a natural air circulation system in a building. It happens when warm air goes up, like in a chimney, and needs to be replaced by cooler air from below. Several factors can influence this effect. How we heat our homes, the way the wind blows outside, whether vents or flues are open, and the use of appliances that burn fuel can all play a role. Most often, the air that replaces the rising warm air comes from under the basement. This area is in close contact with the ground, where radon is usually found in the soil. That's why this process is a common way for radon to enter our homes.

Some homeowners and real estate agents are under the impression that homes in city limits, newly constructed homes or homes built on a concrete slab can’t have high levels of radon, but that’s simply not the case. Radon is not discriminatory and can be found in all types of homes in all areas of the U.S., regardless of the age, size or foundation type. While the highest concentration of radon is more commonly found in the basement, if the home has one, it could be concentrated in any area of the home. When testing for radon, I have found high concentrations in homes older than 100 years old, newly built homes and everything in between, which is why it’s critical that every home be tested for radon. In fact, the EPA recommends homes be tested for radon every two years.

What is a “picoCurie”?

Radon levels are typically measured in picoCuries per Liter (pCi/L) of air. Named after Pierre and Marie Curie, a “Curie” is a unit of measurement for radiation. Radiation is a part of our everyday environment - it's widely known as coming from outer space, being within our bodies, and stemming from medical procedures, like X-rays. Interestingly, we're exposed to more radiation from radon and X-rays than from sources like nuclear power plants or cosmic rays. Because we breathe in air all the time, gases like radon can easily enter our bodies, making lung cancer the most common health issue linked to radiation exposure from radon.

Even small amounts of radon and radiation can pose significant health risks. The EPA has gathered a lot of information on how radiation exposure affects people. Based on this data, they recommend taking action immediately if radon levels in a home reach or exceed 4.0 pCi/L. If a radon test shows this level or higher, it's advised to address and mitigate the problem. But remember, even levels below 4.0 pCi/L might not be completely safe. In some homes, reducing these lower levels could be challenging.

It's also worth noting that changes in your home, like remodeling, weatherproofing doors and windows, upgrading windows, changing your heating and cooling system, or even construction work nearby, can either bring in new radon or change how it moves through your house. So, if you've made these kinds of changes, it's a good idea to test for radon again, even if previous tests showed levels below 4.0 pCi/L.

How to Test for Radon

Radon must be tested using advanced equipment or methods. These could include continuous radon (CR) monitors, e-Perms, or activated charcoal. While they each have their pros and cons, the most widely used is the continuous radon monitors. With these testing devices, they are typically placed in a specific area of the home, such as the basement, and left to run for an extended period of time (typically two days) to continuously capture and read radon levels.

To get accurate radon test results, it's important to control air movement inside a building. The EPA has set up specific testing rules known as "Closed House Conditions" to minimize the impact of outside air and ensure reliable results. These conditions require that all exterior doors and windows in the house (and not just those in the basement) be kept closed at least 12 hours before the test begins. It's important to remember that this doesn't mean you should wait to close everything until the inspector shows up. You can still open and close exterior doors briefly for normal coming and going, but they should stay closed otherwise.

For a more realistic scenario, your central heating or air conditioning should be running as usual from 24 hours before the test starts and then throughout the test. However, don't use big fans that pull air from outside, like whole-house fans or window or wall-mounted air conditioners, unless they're just circulating indoor air. Also, keep chimney flue dampers shut, and avoid using fireplaces during the test, unless they're your primary source of heat. All these measures help ensure the test reflects the typical air quality in your home.

It’s important to know that some states have additional standards or requirements in place that radon testing professionals must follow. For example, in Pennsylvania, radon testing must occur at the lowest possible living level - this is different from the EPA’s standard of testing in the lowest possible occupancy level. In most cases, this is the basement level unless the basement has a dirt floor or the ceiling height doesn’t deem the space livable. When your home inspector comes to set up and pick up the testing equipment, we do our best to ensure that the closed house conditions are met per local and state requirements.

Radon Test

Just like there are regulations on where radon testing must occur, there are regulations on where testing cannot occur. Testing should not take place in humid or damp areas of the home, like the kitchen, bathroom or laundry room. The testing equipment must be placed at least 12 inches away from exterior walls and 36 inches away from windows and doors. It also needs to be at least 20 inches off the ground, which is why the monitor is placed on a stand. Finally, radon tests should not occur in enclosed areas (like closets), near heat sources, in the pathway of a draft, or in direct sunlight. All of the conditions could affect the results of the test.

When getting a radon test, the home seller or homeowner is asked to sign a 'non-interference' agreement, which outlines the testing criteria. This agreement is essential in making sure the test is performed properly and not disturbed by the seller or owner. Should there by any indication of interference, the radon test results will be voided, and the test will need to be conducted again.

What if My Home has a High Radon Level?

If your home tests high for radon, don't worry – there are effective ways to reduce it. The most widely used solution is what's called a sub-slab depressurization system. Basically, this involves drilling a hole through the foundation, usually in the concrete floor of the basement. Then, a bit of soil is removed from under the slab, and a PVC pipe with a special fan is installed. This setup directs the radon gas outside, away from doors and windows.

It's important to note that radon fans must be placed either in the attic or on the outside of the house. They're not allowed to be installed inside the living spaces or in the garage. This system is a reliable way to lower radon levels in most homes. In my experience as a home inspector, I've encountered numerous radon remediation systems that weren't installed correctly. Typically, the cost for professional installation ranges from $800 to $1,200. The design and price of these systems can vary, depending on factors like the home's layout, radon levels, type of system, and how many suction points are needed.

After installing a professional remediation system, it's critical to retest the radon levels. This should be done between 24 hours and 30 days after the system starts running. To avoid any conflict of interest, the professional who installed the system shouldn't conduct this retest. Instead, they might provide the homeowner or new buyer with a test kit to do it themselves and then send it to a certified lab for analysis. Alternatively, they could arrange for another certified professional to do a retest.

It's essential to conduct this retest promptly to verify that the remediation system is effectively reducing radon levels. I've seen cases where homes with active remediation systems still had high radon levels. People often assume that if there's a system in place, or they see the installed manometer (a device to measure pressure), the system must be working and radon levels are low. However, testing is the only way to be sure.

Who Can Perform a Radon Test and Remediation?

Homeowners, buyers and sellers can test their own home for radon; however, it is recommended to hire a certified or licensed professional to ensure accurate test results and compliance. If your home has a radon remediation system, it's important to remember that any alterations should only be done by a certified or licensed radon remediator. This means that even well-meaning contractors like plumbers or electricians, if they're not certified in radon remediation, should not tweak or adjust the system's pipes or fans. Even small changes can disrupt how the system works. It could result in issues like condensation damage inside the house or, worse, increase the radon levels. So, always ensure that any modifications are carried out by a professional specifically trained and licensed for radon remediation.

If you take anything away from this article, it’s that Radon is normal – it's natural. However, it is dangerous and should be tested regularly and taken seriously to protect your health and the lives of those around you. If you haven’t had your home tested for radon, now is a great time to get started. Contact us to learn more.

Author Bio:

Pat Knight

A former home inspector, Pat serves as the Director of Training and Licensing for WIN Home Inspection, Pat has been in the inspection services industry for over 30 years and is an expert in performing and teaching 35+ essential services.