January 28th, 2021

Radon Gas: An Invisible Threat in Our Homes

How You Can Reduce Your Risk

by Christopher Bloom and Jo Miller

This is the third installment in a three-part blog series. Read parts one and two.

January is National Radon Action Month. In our previous blogs (see parts one and two), we provided facts about radon, why it’s dangerous, and how to test your property for radon. If a test reveals dangerous levels of radon, a colorless, odorless, and tasteless carcinogenic gas that enters your home from the soil below, you’ll want to act quickly to limit how much you and others are exposed to it. In this blog, we’ll discuss various measures you can take to limit how much radon enters your home and how long it stays there.

Can You Radon-Proof Your Home?

As radon rises from the soil, it seeps into your basement through cracks in the basement floor, open drains, sump pump crocks, and openings for water and utility lines. While there’s no foolproof way to prevent radon from entering your home, there are several steps that you can take to reduce the amount of radon gas collecting inside. It’s important to point out that newer homes often have radon-reducing features included as part of their design, but that doesn’t mean that these newer homes are entirely free from radon, and it doesn’t mean that you shouldn’t take additional measures to reduce radon levels in your home. The same may be said for schools and other indoor spaces.

So what can you do? Like radon itself, we’ll start from the ground up.

The slab: What’s in your basement? Do you even have one? If you do have a basement, is it simply a dirt floor, or is there a concrete slab? Older homes with crawl spaces or dirt-floor basements may be more at risk for radon infiltration than other homes in the vicinity that have concrete floors. With nothing to impede its progress, the radon is able to rise easily through the dirt into the basement area. From there, it gradually circulates throughout your home.

The good news about having a dirt floor is that you can usually have a cement floor poured. It’s not inexpensive, but it does increase the value of your home while greatly reducing the amount of radon gas that enters your home (not to mention various pests who may be inclined to burrow in for a visit). Before the cement is poured, however, your contractor will cover the floor with thick sheets of plastic. The sheets create an additional barrier against the radon.

The sump basin: Does your home have a sump basin (also known as a sump pit or crock)? If your home has one, it’s the shallow well in your basement (about 30 inches deep). When the ground around your home is saturated by rain, a motorized pump inside the basin works to flush the excess water away before your basement begins to flood. It’s obviously a great feature, and you can hear it switch on even if you haven’t seen any water. Unfortunately, it can also serve as a tunnel for radon infiltration. In newer homes, the sump basin is sealed and will usually look like a wide black or gray disk on your basement floor; but in many older homes, you can stare into the opening. If you can see into the pit, you’ll want to seal that opening as soon as you can. If you’re doing the work yourself, make sure that your lid is installed tightly and well caulked around the outer edge as well as around any pipes or other structures that exit the pit.

Cracks and gaps: Caulking or filling cracks and gaps in the basement slab is another way to reduce the amount of radon entering your home. Will you hunt down and fill every single gap or crack? Probably not, and you don’t need to go crazy looking; but every little bit helps, so if you spot a crack or gap, caulk it. Be sure to check the perimeter of the basement where the walls meet the floor. It’s very common to find a long horizontal crack running along the base of the wall.

Windows and doors: A little fresh air can work wonders. Every time you open a door or window to the outdoors, you exchange fresh outdoor air for the stale indoor air inside your home. So open your windows and doors for a little while on the weekends and let the fresh air circulate around your basement and living areas. Running a fan to circulate more air out of the house is also very helpful. As an added incentive, fresh air exchange is highly recommended to improve your indoor air quality for many reasons, not just radon.

Radon Remediation: Passive Versus Active

Okay, let’s suppose that you’ve tested your home for radon, the results are in, and you’re looking at a level of 4 picocuries per liter. Since this level of radon in your home is considered to be very dangerous, you wisely decide to fix the problem. (“Remediation” and “mitigation” are terms used interchangeably in the industry; both essentially mean to reduce the effects of the problem.) There are two main ways that you can address it, though costs and results vary depending on the method you choose.

Passive: The first method is known as passive mitigation. Passive mitigation involves installing a hollow pipe in the basement, often starting from the sump pit. When installed during the construction process, this pipe runs through the basement ceiling, between the first and second floor walls, through the attic, and out of the roof, having as few turns as possible. In older homes, this can be a real challenge, so it’s common to have a pipe running out of the basement and up the side of the house. Passive systems offer a path of least resistance for the radon, and pressure changes (known as the “stack effect”) draw the gas from below the basement slab and vent it outdoors, where it will blend with outdoor air and become relatively harmless. A passive mitigation system generally costs about $700 to install, though it may be more expensive in some homes, depending on how they’re constructed.

Active: The second method is active mitigation. Active mitigation systems use most of the same tools as passive systems, but the big difference is that there’s a fan near the end of the pipe. Instead of casually relying on the radon to find its way out of your home via the path of least resistance, the fan actively draws the gas upward and forces it out of your home. The fan runs constantly, but it uses about the same amount of energy as a 75-watt lightbulb—figure about $100 per year. In order to run a fan, you must also have a electrical source nearby to power it, so an electrical outlet may need to be installed in the vicinity.

To install an active mitigation system may cost you between $2,000 and $2,500. Yes, it’s an expensive undertaking, but when was the last time you got an estimate for treating lung cancer? It isn’t cheap either.

Additional Problems

While following all of the steps we’ve described will undoubtedly make your home safer and possibly make your home more  raise the value of your home, there are a few potential pitfalls, and you should be aware of them as well.

The one great thing about having an uncovered sump basin is that you can see and hear the pump working on a rainy day. And your sump pump nearly always works, except for when the power goes out, which sometimes happens in a heavy rainstorm; and that’s the time when a working sump pump is necessary to prevent flooding, damage to your possessions, and mold problems. A smart purchase is a battery backup or similar system to ensure that the pump continues to run during a power failure. We also suggest you consider investing in a sump alarm, which will alert you when the pump stops working for any reason.

Our Recommendations for Homes with Radon

We’ve provided a lot of information about radon and how to limit your exposure to it, so here’s a quick summary:

  • Test your home for radon every few years. Any level above 4 picocuries per liter requires your immediate attention, but NCHH considers anything above 2 picocuries per liter worth mitigating.
  • Install a battery backup and a sump alarm for your sump if you have one.
  • Seal your sump basin.
  • Caulk or fill any large cracks in your basement floor.
  • Circulate fresh air throughout your home often when the weather allows.
  • Install gas-tight radon drains in your basement floor.
  • Install a radon mitigation system, either passive or active, depending on the results of your radon test.
  • Retest your home for radon regularly.

NCHH Resources for Radon

Want to promote radon awareness, learn more about government policies concerning radon, see how NCHH is studying radon, or simply learn more? Visit any of NCHH’s radon pages and resources below.

Other Resources for Radon


Christopher Bloom, Communications and Marketing Officer, NCHHChristopher Bloom is NCHH’s communications and marketing manager. He joined NCHH in 2008 after nearly a decade in the real estate industry. In a previous role at NCHH, he coordinated a national Renovation, Repair, and Painting (RRP) training program, one of the most successful in the nation. He holds a Bachelor of Arts degree in English Textual Studies from Syracuse University.



Jo Miller , Senior Development and Communications Officer, NCHHJo Miller, GPC, NCHH’s Senior Development and Communications Officer, has worked as a part of the NCHH team since 2016. A 20-year healthy housing and lead poisoning prevention veteran, she has worked with lead and healthy homes programs throughout the country to build stronger partnerships, innovative approaches, and secure grant funds. 

January 28th, 2021 | Posted By , | Posted in Blog, Indoor Air Quality, Radon | Tagged , ,