Understanding Radon Gas Risk in Your Home: What Jefferson County Homeowners Need to Know
After a long day of work, most of us look forward to coming home and relaxing. But what if the very air inside your home carried a hidden hazard? For homeowners in Jefferson County, from Arnold to Festus, High Ridge to Hillsboro, that hazard could be radon gas. I have spent years working with Air Sense Environmental, testing thousands of homes across this region, and I have seen how easily radon gas risk gets overlooked until it is too late.
Radon is not something you can see, smell, or taste. It comes from the natural breakdown of uranium in soil and rock, and it seeps into homes through cracks in the foundation, gaps around pipes, and openings in crawl spaces and basements. The EPA has long identified radon as the second leading cause of lung cancer in the United States, yet many homeowners still assume it is someone else's problem. That assumption can be costly.
Why Radon Gas Risk Varies by Location
Radon levels are not uniform across the country. The EPA has mapped zones based on predicted average indoor radon levels, and much of Jefferson County falls into Zone 1, the highest risk category. This means homes here are more likely to have elevated radon levels than homes in many other parts of Missouri. I have personally measured radon levels in basements in Arnold that exceeded 10 picoCuries per liter, which is more than twice the EPA action level of 4 picoCuries per liter. The radon gas risk in Jefferson County is real, and it is not limited to any one type of home. New homes and old homes, homes with basements and homes on slabs, all can be affected.
One common misconception is that radon only affects homes with basements. While basements do tend to have higher concentrations because they are closer to the soil, radon can also enter through a crawl space or even a concrete slab. In a home I tested near Festus, the highest reading came from a first-floor bedroom directly above a crawl space with exposed dirt. The occupants had never thought to test there because they assumed the main floor was safe. That experience taught me that radon gas risk is not confined to lower levels; it can migrate upward through the house.
How to Know If Your Home Has a Problem
The only way to know is to test. There are two main approaches to radon testing: short-term test kits and continuous radon monitors. A short-term test kit is a simple, inexpensive device that you place in your home for two to seven days, then mail to a lab for analysis. These are a good starting point, but they only give you a snapshot. Radon levels can fluctuate with weather, season, and how you use your home. A single short-term test might miss a high reading that occurs during a cold snap or heavy rain.
A continuous radon monitor, on the other hand, records readings over days or weeks and provides a more accurate average. Air Sense Environmental uses these monitors for most of our radon testing because they give a clearer picture of long-term exposure. I always recommend a continuous monitor for any home where the initial test kit shows results near the EPA action level. The extra data helps us decide whether radon mitigation is truly needed or just something to watch.
Home inspections often include radon testing as an optional add-on, but not all inspectors are trained to interpret the results correctly. If you are buying a home in High Ridge or Hillsboro, insist on a radon test from a qualified professional. I have seen too many transactions where a quick test kit was placed in the wrong room or at the wrong height, leading to a false low reading that gave the buyer a false sense of security.
What Radon Mitigation Actually Involves
If testing confirms that your home has elevated radon levels, the next step is radon reduction. The most common and effective method is sub-slab depressurization, also called soil suction. This involves drilling a small hole through the basement floor or slab, inserting a pipe, and connecting it to a fan that draws radon from beneath the house and vents it safely above the roofline. The fan runs continuously, but it uses very little electricity, typically less than a 60-watt light bulb.
There are different configurations depending on your home's construction. For homes with a crawl space, we might install the fan in the crawl space and run the vent pipe through an exterior wall. For homes with a basement, we usually mount the fan on the outside of the house or in the attic. The goal is always the same: create negative pressure under the slab so radon cannot push its way inside.
RadonAway is a brand we rely on for many of our installations. Their fans are built to run for years with minimal maintenance, which is important because a radon mitigation system is a long-term solution. Once the system is installed, we always do a follow-up test to confirm that radon levels have dropped below the EPA action level. In most cases, we see reductions of 90 percent or more.
Key Components of a Typical Radon Mitigation System
- A suction pit dug into the soil beneath the slab or crawl space
- A PVC pipe running from the suction pit to the fan
- A fan, often a RadonAway model, mounted outside or in the attic
- A vent pipe that exhausts radon above the roofline
- A manometer that shows the system is operating correctly
It is worth noting that radon mitigation is not a one-size-fits-all solution. Every home is different, and a system that works perfectly in Arnold might need adjustments in Festus. That is why I always start with a thorough assessment of the home's foundation, soil type, and existing ventilation. A quick fix might lower radon levels temporarily, but it will not address the root cause.
The Cost of Ignoring Radon Gas Risk
Some homeowners hesitate to test or mitigate because they worry about the cost. A professional radon test with a continuous monitor typically runs a few hundred dollars, and a full mitigation system can cost between $800 and $2,500 depending on the home. Compared to the cost of treating lung cancer or the emotional toll of a health scare, that is a small price to pay for peace of mind.
I have worked with families in High Ridge who lived in their home for fifteen years before testing. When the results came back at 8 picoCuries per liter, they were shocked that they had never known. They installed a sub-slab system with a RadonAway fan, and their follow-up test showed levels below 1 picoCurie per liter. That kind of outcome is why I do this work, to give people the information they need to make their homes safer.
The radon gas risk in Jefferson County is not going away. The geology here produces radon consistently, and the only way to protect your family is to test and, if necessary, mitigate. I have seen homes in Hillsboro with levels over 20 picoCuries per liter, and I have seen homes in Arnold with levels so low that mitigation was not needed. You cannot guess your way to safety.
What to Expect from a Professional Radon Test
When Air Sense Environmental performs a radon test, we place the continuous radon monitor in the lowest livable area of the home. That might be a finished basement, a family room, or even a bedroom. We leave it in place for at least 48 hours, though we prefer longer tests during the heating season when windows are closed and radon levels tend to be highest. We also document the home's construction details, noting any cracks, sump pumps, or utility penetrations that could be entry points for radon.
After the test, we provide a detailed report with the average radon level, the range of readings, and recommendations. If the level is above 4 picoCuries per liter, we discuss mitigation options. If it is below that but still above 2 picoCuries per liter, we often suggest a second test during the winter to confirm. The EPA recommends fixing any home with a level of 4 picoCuries per liter or higher, but there is no safe level of radon. Lower is always better.
One thing I emphasize to homeowners is that radon testing is not a one-time event. Levels can change after renovations, after earthquakes, or simply as the soil settles around the foundation. I recommend testing every two years, or whenever you make major changes to your home's foundation or ventilation. If you install a mitigation system, test it annually to make sure the fan is still working and the system has not been damaged by weather or pests.
Final Thoughts on Radon Gas Risk in Your Home
Living in Jefferson County means enjoying beautiful landscapes and a strong community. It also means living with the geology that produces radon. The good news is that radon gas risk is measurable and manageable. With proper radon testing and, if needed, radon mitigation, you can reduce your exposure and protect your health. The key is to act before a problem becomes a crisis.
I have been in this field long enough to know that most people do not think about radon until it is brought to their attention. If you are reading this, consider it your attention brought. Test your home. Understand your radon gas risk. And if you find that your levels are elevated, do not wait. The solution is straightforward, and the peace of mind is priceless.