Radon. It’s not a bug spray. It’s not an alien villain from a 1950s Sci-Fi film. It is, however, a gaseous villain. The name may be familiar if you’ve ever bought a home or read a rental agreement.
Rental agreements may have a disclosure statement of radon gas levels. If a homeowner has knowledge of radon gas they are required by law to disclose the information to all potential buyers, but only in some states. It’s a pretty serious subject and yet, not all states have written or passed radon disclosure legislation to help prevent exposure to this dangerous toxin.
I am guilty of blowing through the small print in rental agreements and when home buying. We should all take some time to learn about radon and what we can do about it just like any of the potential dangers in an old house.
Read on to learn what radon gas is, what the dangers of radon are, how you can test for it, and how it can be mitigated.
what is Radon Gas?
According to the EPA, Radon gas is an extremely toxic, naturally occurring, radioactive element derived from the radioactive decay of radium.
Radium is found in Uranium and Thorium in soil and rocks. When the gas escapes the ground into the outside air, which it does everywhere, it is diluted so quickly that it poses no threat to humans. It’s when it seeps into buildings that we need to be concerned. Breathing in high levels of radon gas over time is known to cause cancer.
Radon gas was first discovered by physicist Ernest Rutherford in 1899, but Friedrich Ernst Dorn was credited for it when he discovered radium as the source for the gas in 1900. Many chemists and physicists, including Marie Curie, worked with radon and the name “radon” was not settled upon until 1923. Before that, it went by many names including radium emanation, exradio, radeon, and niton.
While radon gas has been affecting miners for hundreds of years, it was not until the 1970s that scientists realized it. Wired Magazine says epidemiologists found that miners were getting lung cancer at higher-than-average rates. The tunnels they worked in were full of radon gas.
In 1984, Stanley Watras, a worker at the Limerick Nuclear Power Plant located in eastern Pennsylvania set off radiation alarms, but not from exposure at work in the facility. He brought radon into work from his home. Safety officials did extensive testing and found that his home contained the same levels of radon gas as you would find in a uranium mine. This event was highly publicized and was the catalyst for the involvement of the EPA.
By 1986, the EPA established indoor radon risk exposure levels and continues to work to raise awareness today. Though radon is a cancer-causing health hazard in large doses, in small doses, it has been used beneficially. Marie Curie used radon in hollow needles to sterilize infected tissue in soldiers, it’s used as radiation therapy for cancer, and it’s used in gas and liquid leak detection.
Why you should be radon educated
In short, at concentrated levels, it’s toxic to humans. It is invisible, it has no taste, it has no smell, and it shows no immediate symptoms of exposure, and well, that sounds pretty scary. In fact, radon gas is the second leading cause of lung cancer in the U.S., smoking being the first.
According to the American Lung Association (ALA), Radon-related lung cancers are responsible for an estimated 21,000 deaths annually in the United States.
Radon levels are measured in units of picocuries per liter (pCi/L). The EPA recommends taking action to reduce radon if the result is 4.0 pCi/L or greater and to consider similar actions when the radon level is between 2 and 4.0 pCi/L. They estimate that 6% of homes in the U.S. have concentrations of radon above 4 picocuries per liter (pCi/L). The CDC says every state in the United States has homes with measured radon levels above the EPA recommended concentration.
Radon gas enters into buildings from the ground, through cracks and holes in walls and floors, including basement floors and slabs. It may also enter buildings from underground water supplies and natural gas appliances, but less frequently.
Radon gas dilutes quickly outside and does not pose a health risk to humans at low levels. It’s only when it gets trapped in confined air spaces like workplace buildings, houses, or schools, that humans should be concerned.
You can’t base your home’s radon levels from your neighbor’s testing. Just because your neighbor may have very high or very low levels, this does not mean your house will measure the same. The AHA says your home can have elevated levels of radon while your neighbor’s home does not. Testing is the only way to determine if you have a problem or not. The first place you can start is by looking at the EPA’s Map of Radon Zones to see what’s been reported in your area.
Many states have some form of law in place to spread awareness and reduce the risk of radon exposure, but many do not. Here is a quick look at some testing and disclosure laws in place in the U.S.
States that DO require some form of radon testing
Oregon, Colorado, Kansas, Minnesota, Iowa, Illinois, Indiana, Idaho, Michigan, Ohio, Tennessee, Virginia, West Virginia, Florida, Maryland, Delaware, New Jersey, New York, Connecticut, New Hampshire, Maine, Rhode Island
States that DO NOT require sellers to disclose known radon levels in the sale of a home
Idaho, Wyoming, Utah, Arizona, New Mexico, North Dakota, Missouri, Arkansas, Alabama, West Virginia, Virginia, Vermont, Massachusetts, Georgia
While laws at a federal or state level may not be in place in your state, other organizations have taken the initiative to help reduce radon exposure. This handy map by LawAtlas is a great start for research in your state. You should also check with the health and environmental agencies in your state. The EPA provides a list by the state to get you started.
It’s never too late to test and to mitigate if radon levels are too high. The levels in your home may have been fluctuating over time even if they are high during short or long-term testing. Even if you have lived in your home for decades with radon gas you should still invest in a radon mitigation system if your levels are too high.
How To Test For Radon Gas
The first place to start as a homeowner is to check your home inspection report if you’ve had one. Some inspectors will include a radon test with the inspection. If you are renting, check with your landlord. They may have a report they can share with you. Even if the report shows safe levels of radon gas from years ago, it is cheap enough to test again. The EPA recommends testing every 2 years to be sure the levels remain low.
If you do not have access to a report or it has been more than 2 years, there are some different options for testing, ranging in price and procedure.
Short-term kits take 2-7 days of testing They can be purchased on Amazon or at your local home improvement store as low as $13 and may or may not include lab analysis in the price. Also, check to see if they have 1 or more tests per kit. You may want to consider more than one test area if you have a large home, have multiple sealed rooms, or have several floors. Sometimes follow-up tests may be required if levels are high. I will be using First Alert’s Radon Gas Test Kit for my first test.
Long-term kits are 3-12 months of testing. They cost from $20-30, and may or may not include lab fees. Long-term tests tend to be more accurate as they collect more data.
Radon Detectors will give you radon readings within 24 hours, but cost from $99-300. They will give you both short-term and long-term radon measurements and work just like a smart smoke detector. Radon detectors are often used after a mitigation plan is implemented to check for improvements in air quality and/or for continued monitoring in high-level radon areas.
Professional Radon Services will also give you radon levels for short-term and for long-term tests. This is the most expensive option but will give you the most accurate measurements. These inspection and testing services cost between $100-500 depending on the size and requirements of your building. Check to see if your state has laws requiring radon mitigation businesses to be certified for radon inspections before choosing a business.
After testing is complete you will receive a report from the lab or professional radon mitigation service showing the short and/or long-term radon gas levels in your home so you can figure out how to resolve your radon gas problems.
How To Mitigate Radon Gas
There are a number of ways that radon gas is prevented from concentrating in your home. Your home’s foundation construction type is what determines the radon mitigation system used.
The three different types of foundations are basement, slab-on-grade, or crawl space construction. In some cases, you could have a basement under one part of your home and slab-on-grade or crawl space in another. Some basements may have a dirt floor where others have a concrete foundation.
Generally, three types of mitigation systems are used. Sub-slab systems, sub-membrane systems, or use existing water extraction systems that are already in place. There may be variations of these depending on your home’s needs and could either be active or passive systems. Most systems use a fan to remove radon gas from the soil beneath your home. This is an active system. Others are passive, using a pipe extending from the soil to the roof without a fan. The chimney effect draws the gas from the soil and releases it into the environment.
All systems use suction or depressurization in some way to remove the radon gas before it can enter your home. These systems could cost anywhere from $500 to $2500 and usually can be installed within a day for average homes, but much depends on the size of the building, the soil, the amount of radon gas present, and the methods required to keep the radon at bay. Let’s take a look at these systems.
Active Sub-slab Suction or Depressurization
This system is fairly simple and used with basements with concrete slabs or homes with slab-on-grade construction. A small hole is made in the concrete floor where a pipe will be inserted just below the slab.
Next, a small chamber in the soil is dug out around the hole beneath the slab. A pipe is inserted into the chamber through the hole and sealed. This pipe will extend either through the walls or closets of your house and out through the roof where the gas is released.
A fan is used in line with the pipe to create suction beneath the house to draw out the radon gas. This fan is typically installed in the basement or attic, but in some cases, the pipe is redirected through an exterior wall and runs vertically, along with the fan, until it is above the roofline. This method can also be installed from the exterior only for homes with slab-on-grade construction.
Active Suction using Water Intrusion Systems
A variation of this system sometimes uses either drain tile or sump systems that are already in place rather than a chamber below the concrete slab. These systems are used to remove water from the soil to prevent water intrusion.
Rather than a pipe inserted into a chamber in the soil, it is tapped into the perforated pipe, drain tiles, or sumps already installed below the concrete slab where both water and gas can be extracted.
Active Sub-membrane Suction or Depressurization
A house with a dirt-floor basement or crawl space uses an active system that works similarly to the sub-slab system above. It extracts the gas from below the home but requires a membrane over the soil. This thick plastic membrane is placed over the soil and lapped up, and sealed against the exterior walls. A pipe is inserted below the membrane and using a fan, extracts radon gas from the soil.
A lot of testing and planning goes into developing the right system for your building. One or more systems above, or alternative systems, may be needed to keep your home safe from radon. If you are in need of radon mitigation services or prefer to have a professional do the testing, you can check with the National Radon Proficiency Program or National Radon Safety Board for certified radon mitigation businesses.
For more detailed information about the systems above, a good start is the EPA’s Consumer’s Guide to Radon Reduction.
don’t freak out!
Remember, the point of this guide is to inform, not to create fear. This can sound like scary stuff, but as a reminder, it’s only long-term exposure to high levels of radon gas that could cause lung cancer. The good news is testing is cheap and easy, and if you have high levels of radon, mitigation services are affordable as well.
The American Lung Association says every home should be tested for radon. Thousands of lung cancer deaths could be avoided each year if home and building owners acted to test and fix. I would agree and that is why I am testing this week.
Hope you do too!
Founder & Editor-in-Chief
I love old houses, working with my hands, and teaching others the excitment of doing it yourself! Everything is teachable if you only give it the chance.
1 thought on “The Homeowner’s Guide to Radon Gas”
Thank you for the sharing. Plenty of useful information here. Radon gas is not something you should ignore simply because it doesn’t have an instant impact. Once you’ve discovered your home has elevated levels of radon, you need to have a radon mitigation system installed.