What Is Radon and How Does It Get In Your Home?

This radioactive gas may be an uninvited house guest, but you can breathe easy with the right mitigation strategy

Inspector pointing at a crack
Photo: CatLane / iStock / Getty Images Plus / Getty Images
Inspector pointing at a crack
Photo: CatLane / iStock / Getty Images Plus / Getty Images
Mariel Loveland
Written by Mariel Loveland
Contributing Writer
Updated November 5, 2023

Highlights

  • Radon is a naturally occurring radioactive gas.

  • Radon is the second leading cause of lung cancer.

  • Most radon exposure happens in homes and workplaces.

  • There are several ways to reduce radon levels in your home.

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Out of sight, out of mind, right? Much like a forgotten family photo album, radon gas hangs out in basements and crawl spaces and can seep into your living space. You can’t see it, you can’t smell it, and you can’t taste it. Is it really that big of a deal? Yes, but don’t worry, testing and radon reduction strategies can help protect your family from exposure.

What is Radon?

Radon is a radioactive gas that you probably encounter every day—albeit in harmless amounts. This type of gas naturally occurs when uranium breaks down in soil, rocks, and groundwater. Radon only becomes a problem when it gets trapped indoors and can’t dissipate in the atmosphere.

Many homes are built on soil that contains natural uranium deposits. The Environmental Protection Agency (EPA) created a handy map of the country’s radon zones for reference. Radon is a sneaky gas because it can enter a building through any sort of crack, gap, drain, cavity, or construction joint. Basements and crawl spaces tend to collect the highest levels because they’re closest to the ground, but it can be found everywhere, including in your drinking water.

The Health Risks of Radon Exposure

Radon exposure doesn’t make you sick overnight. You can breathe in radioactive radon particles for years before there’s ever a problem, but it’s still the second leading cause of lung cancer in the United States. The EPA estimates that radon gas is responsible for 21,000 lung cancer deaths every year. People who smoke are 25 times more at risk from radon exposure, but you’re also at risk if you:

  • Live in an area with high levels of radon.

  • Spend a lot of time indoors.

  • Spend a lot of time in rooms that are in contact with the ground.

  • Have a job where you’re exposed to radon (like coal miners).

Testing Your Home for Radon

Since you can’t see or smell radon gas, testing is the best way to find out whether your home contains dangerous radon levels. You can either hire a professional radon tester or use a DIY radon gas test kit, which is sold at most hardware stores for under $30. You’ll typically have to leave the kit out for three to seven days, and then mail it to a lab to get your results.

You can test for radon yourself, but it’s not as accurate as professional testing. Professionals have specialized equipment, training, and radon testing certification. They know where to test and how to test, but it will cost you. The average professional radon test costs around $400, but it’s a small price to pay for peace of mind.

What to Do if You Find Radon in Your Home

7 point of entry for radon gas into your home illustrated, including cracks below ground level, cavities in walls, and gaps around service pipes

If you find radon in your home, don’t panic. Even high levels of radon can be successfully reduced. The EPA recommends bringing in a radon mitigation professional if levels are at or above four picocuries per liter—though lower levels still pose a health risk. Common radon mitigation strategies that professionals will use to combat radon include:

Install a Radon Reduction System

A well-placed radon reduction system can reduce radon levels in your home by as much as 99%. These systems typically use a fan or a pump to create ventilation and move radon particles away from your home. Even those that passively create ventilation can still cut your existing radon level in half. Most radon reduction systems cost between $450 and $1,500 to install. While you can attempt to install a radon mitigation system yourself, it’s strongly recommended to hire a pro due to your exposure to harmful gases.

Seal Your Home

Sealing unfinished basements, crawl spaces, floors, and walls will help prevent radon from entering your home. It costs an average of $4,600 to seal an entire basement, but even just filling in the cracks with a radon sealant can help. 

Encapsulate the Crawl Space

A home’s crawl space is like an open front door for radon particles. It doesn’t take much for radon to rise from the open soil into your home. Encapsulating your crawl space using a radon membrane can help. Crawl space encapsulation can cost between $1,500 to $15,000, depending on the size of the crawl space.

Finish Your Basement

An unfinished basement is more susceptible to cracks and exposed cavities, which increases the likelihood of radon. Finishing a basements costs on average $18,000, but can vary depending on the size of your space and the features you want added. A very simple job, like adding insulation and drywall, will be on the lower end compared to a full remodel.

Use Radon Resistant Construction Materials

If you’re building a new house, ask your contractor about radon-resistant construction. It’s cheaper to build these features in than adding them after the fact, largely due to the additional labor. These features include:

  • Adding a 4-inch layer of gravel beneath your foundation

  • Putting plastic sheeting or a vapor retarder above the gravel

  • Installing a vent in the gravel that rises to the top of your home

  • Encapsulating the crawl space

What If There’s Radon in My Water?

Sometimes radon is found in water, though the main health risk is inhalation. You can test your water using an EPA-approved test kit. If you find radon, you can reduce the levels by:

  • Installing an aeration system: Aeration systems are 95% to 99% effective and cost between $4,000 to $5,000. They work by moving water into a tank and injecting it with air to separate out the radon. Then, the radon is vented out of the tank and way from your home.

  • Installing a charcoal scrubbing system: Charcoal scrubbing systems (also known as granulated activated carbon filtration systems) are 75% effective and cost between $500 and $1,500. They work similar to a charcoal filter. Carbon absorbs the radon, removing it from the water.

How to Find a Qualified Radon Mitigation Professional

The first step to ridding your home of radon is finding a qualified radon mitigation professional. Although there isn’t a federal licensing board for radon mitigation, some states require contractors to be licensed or registered. Additionally, your contractor may have a certificate from:

  • The National Radon Proficiency Program (NRPP)

  • American Association of Radon Scientists and Technologists (AARST)

  • The National Radon Safety Board (NRSB)

The truth is that radon mitigation strategies do work, and most of the time, they don’t cost much more than the average home repair. Whatever strategy you choose, always test your home after the work is done to ensure success.

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Learn more about our contributor
Mariel Loveland
Written by Mariel Loveland
Contributing Writer
Mariel is a writer from New York City who has a passion for helping renters and homeowners make their space unapologetically their own—and save a few bucks along the way.
Mariel is a writer from New York City who has a passion for helping renters and homeowners make their space unapologetically their own—and save a few bucks along the way.
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