Importance of Testing for Radon Before Buying a New Home

Home May have Radon Gas
Radon Could be Lurking in any Home

With the Environmental Protection Agency estimating that nearly 1 out of every 15 homes in the U.S. has elevated radon levels, you may have heard about radon testing for homes. If you have not, do not fret – we will explain in this article the basics of radon in residential homes and what you need to know about it. Reading this statistic might make you a little nervous about buying a home, but do not fear! Information is the best antidote for fear, which is part of why having a radon test done before finalizing the home sale is a smart idea, regardless of whether or not it is required in that jurisdiction. Below, we answer a few questions you might have about radon and explain the basics about radon and why it is a concern in our homes.

What is radon?

Radon is a naturally occurring, radioactive gas that results from the long radioactive decay chain of uranium-238 in the soil deep within the earth. Because it is a gas, radon rises through the earth’s crust and then tends to enter buildings such as our homes at their lowest point, such as your basement and/or crawlspace. Radon is a common but unknown invader in most homes and the levels and amounts of radon gas in our homes varies due to lots of factors including geological structure of the earth beneath the home, seasons, weather patterns, and more. This odorless, tasteless, invisible gas released from under the surface of the earth diffuses into the air and can dissolve into groundwater.

Radioactivity has always been a part of the natural earth sciences. As uranium deep within the earth begins to decay, it eventually transforms into Radium and then into Radon gas that moves up toward the surface and then travels through cracks and fissures in the earth’s geological structure. It typically enters into homes through cracks and other penetrations in the foundation, via sump pits, or through exposed earth/soil such as in crawlspaces or basements or cellars without concrete slab floors. Unless properly ventilated, the radon gas can then become trapped inside your home where it can collect at potentially hazardous levels. Even homes without a basement or crawlspace (i.e. slab foundations) can have problems with radon gas.

Why is Radon a Concern?

Radon is very common and we are exposed to it daily. Radon gas is present in every state in the U.S. So why is it a concern? Remember when we mentioned that it is a radioactive gas? Because it is a radioactive ion, radon gas emits something known as Alpha particles. When inhaled, these radioactive particles can damage the cells that line the lung.  Alpha radiation, unfortunately for us humans, can lead to cancer. Therefore, radon gas is a known carcinogen, or cancer-causing agent.

No level of ionizing radiation is completely safe, but health experts here in the U.S. have set a threshold for which they believe is a reasonable and tolerable risk level for the average person. The EPA suggests an “action level” of 4 picoCuries per liter (expressed as 4 pCi/L) of air. When it accumulates past a level of 4 pCi/L, the U.S. National Cancer Institute has studies that have shown that it increases the risk of lung cancer in humans. In fact, radon is the second-leading cause of lung cancer in the U.S.! About 15,000 to 22,000 lung cancer deaths nationwide annually are estimated to be attributed to exposure to radon. 

What are the Odds My Home Has a Radon Problem?

With the EPA estimating that 1 in every 15 homes has elevated levels of radon, the chances of a home having a radon problem are something to consider. According to the American Cancer Society, elevated radon levels are found in every state. This EPA map of radon zones shows you some detail about Maryland and Pennsylvania:

Maryland and South Pennsylvania EPA Radon Zones
US EPA Radon Zones for Maryland and South Pennsylvania

Unfortunately, there are no immediate signs or symptoms to alert you to the presence of radon. You cannot predict a home’s radon level based on state or local radon measurements or on test results taken in other homes in the neighborhood. A next-door neighbor’s home may have safe Radon levels while your home may have dangerous levels or vice-versa.  The only way to know whether a home’s radon level is safe or not is to have it tested! 

How Often Should You Test Your Home for Radon?

In general, most experts recommend testing homes at least once every 2 to 5 years. Unfortunately, a lot of people think that if a test shows radon levels below the EPA action level, you are all set. However, radon testing should not be thought of as a single event. It is something that needs checked at periodic intervals because radon levels can and will vary with changes in seasons, weather patterns, geological events, and more. Therefore, you should think of radon testing in your home as a part of the maintenance cycle for your home and get testing done every few years.

However, when you sell your home, depending on your jurisdiction, you may need a radon test that has been performed within the past two years as part of the real estate transaction process. Also, if you have had any major work done to the home since the last test, you may need a more recent test performed. Home buyers typically want an independent party who is not involved in the home sale to perform the test, and this, of course, is a good idea if you are the one buying a home.

What Happens When a Home Has Unsafe Levels of Radon?

Is Radon Lurking in Your Home?
Does Your Home Have Safe Radon Levels?

Radon problems can be fixed!  If your home has high radon levels, there are ways to fix it. Even very high levels can be reduced to acceptable and healthier levels. Typically, the way to effectively and regularly reduce radon levels in a home is to have a mitigation system installed. The EPA Consumers Guide to Radon Reduction says that the type of mitigation system you need depends on the home’s foundation. I can help you understand the basics of radon mitigation systems and explain how they work so that you will be informed before seeking the services of a professional radon mitigation contractor. The contractor will survey the home to determine the proper type of mitigation system, design and install the system, and seal cracks, holes, and other openings in the home’s structure to minimize Radon entry into the living space. Costs vary based on home construction, design and the climate, but the national average cost for installation is around $1,200.

After you have a mitigation system installed, schedule an independent Radon Test with us to ensure that your new system is in fact reducing the Radon levels in your home to within safe limits as recommended by the EPA.

Do Sellers Have to Disclose Unsafe Radon Levels?

The United States overall has no uniform radon disclosure, but at least 29 states, including Maryland, require disclosure of radon hazards at sale, according to the National Conference of State Legislatures. Also, at least nine states, including Maryland, require all new homes to be built following radon-resistant new construction standards.

As a home buyer, it is smart to request a radon test of the property from an independent party early in the process. If unsafe levels of radon are detected, you may be able to negotiate your home purchase to include mitigation. You may be able to ask the seller to install a mitigation system, request a buyer’s credit, or perhaps the cost of mitigation can be split between buyer and seller, depending on negotiations. In any case, radon should not be a “deal killer” or the end of the sale. Buying a house with high radon levels is a challenge that can be overcome, and you will likely learn more about your new home through the process and you will rest easier in your new home knowing that radon is one less worry for you.


As a professional home inspector serving Maryland and Pennsylvania, I encounter potential hazards in homes each and every day. Although some hazards might be obvious and visible such as electrical or safety issues, our homes also have potentially dangerous hazards that we may not necessarily see, smell, or even know exist in our homes! This article exposed one of these less-obvious yet potentially dangerous hazards that may be present in your home: Radon gas. Radon gas might exist in your home at unhealthy levels and requires special testing in order for you to know whether or not your home has a radon problem. We have also explained that you can have harmful levels of radon gas mitigated and/or reduced to safe levels for you and your family.

If you would like to know if your home has safe Radon levels, please call Absolute Assurance at 443-939-HOME (4663) for all of your Home Inspection needs including mold inspection and testing, radon testing, and water testing! We can provide these services as well as full and partial home inspections for buyers/sellers/investors, rental inspections, annual home inspections, and more!

Portions of this article are not the author’s original work and were sourced under copyright permission courtesy of Mackenzie Kirk at HomeLight.