Radon rarely makes headlines, yet it quietly affects homes across the St. Louis region. It comes from the natural breakdown of uranium in soil and rock, and it seeps through foundations into basements and living spaces. Because it has no smell or color, radon invites speculation. I hear the same rumors on jobsites, in inspection walk-throughs, and at neighborhood meetings. Some myths are harmless, others lead to costly mistakes or risky delays. Let’s sort the folklore from the facts, with a practical eye toward St. Louis housing stock, soil conditions, and weather patterns.
What radon is, and why St. Louis homes see it
Radon is a radioactive gas produced by uranium decay in the ground. Outdoors, it dilutes quickly. Indoors, it can build up to levels that increase the risk of lung cancer, especially with long-term exposure. The EPA action level is 4.0 pCi/L, but risk is continuous, so many families choose to lower radon when levels fall between 2 and 4.
The geological story matters here. Much of the St. Louis metro area sits on glacial till, loess, and limestone. Soil permeability varies street by street. In places like West County, with fractured limestone and numerous footing drains, negative pressure in basements during heating season can pull soil gases in quickly. Older brick homes in South City often have patchworked slabs, floor drains, and fieldstone foundations that act like open invitations for radon. Even new construction in fast-growing St. Charles County can test high if the builder skipped passive radon features or the soil under the slab is a good conduit.
I’ve seen two similar ranch homes on the same block in Florissant test at 1.8 pCi/L and 11.2 pCi/L, respectively. The only visible difference was a hairline crack line and an open sump basin in one basement. That’s how localized radon can be.
Myth: “My neighbor tested low, so I’m fine.”
Radon varies house to house due to micro-differences in soil pathways, foundation details, crawlspace vents, and pressure dynamics. If the neighbor has a deeper footing drain system or a sealed sump, they may score low while you score high. I have tested townhomes that share a wall, where one unit measured below 2.0 pCi/L and the adjacent unit measured just over 7.0. Construction gaps, plumbing penetrations, and HVAC return leaks can all shape the outcome.
Fact: Test your own home, not your neighbor’s. A $20 to $30 charcoal canister test under closed-house conditions will give you a baseline. If a real estate deadline is approaching, consider a continuous monitor for a 48-hour snapshot. For truer seasonal averages, long-term alpha track tests of 90 days or more are worth the wait.
Myth: “New homes don’t have radon.”
Fresh drywall and modern windows do not block radon. In fact, energy-tight homes can draw more vacuum on the slab and accumulate higher concentrations. Some local builders install passive radon features, such as a vent stack from the aggregate below the slab to the roof. Those systems sometimes keep levels below 4.0 pCi/L, but not always. I’ve activated plenty of passive systems in places like Wentzville and O’Fallon by adding a quiet fan and a few gaskets, and the levels dropped from the 6 to 10 range to under 1.5.
Fact: Age of the structure is not a reliable predictor. Ask during a purchase if the builder installed a passive radon system and if a post-construction test was performed. Plan on verifying with your own test.
Myth: “I don’t have a basement, so radon can’t be a problem.”
Basements often measure the highest, but slab-on-grade homes and homes with crawlspaces can also test high. Ground contact is the key, not the presence of a staircase to a lower level. In a one-story slab home in St. Peters, a single cold joint by the garage and unsealed utility penetrations pushed levels above 5.0 pCi/L. Crawlspaces can be bigger culprits than basements when the soil is exposed and the liner isn’t airtight.
Fact: Any home in the St. Louis region merits a test, regardless of foundation type. If you own a slab home, test in the lowest lived-in level. If you have a crawlspace, consider a test both near the crawl access and in the main living area.
Myth: “Radon is only dangerous for smokers.”
Smoking and radon multiply risk together, but radon on its own is still a known carcinogen. National data attribute a substantial number of lung cancer cases each year to radon exposure among non-smokers. I’ve worked with families who had no tobacco exposure, yet showed elevated radon for years before finally testing during a refinancing appraisal.
Fact: Everyone benefits from reducing radon. Think of risk like standing in the rain: smoking is a downpour, radon is steady drizzle, and doing both soaks you fast. Staying dry starts with mitigation when your levels warrant it.
Myth: “Opening a window during the test gives a realistic picture.”
Short-term tests are designed for closed-house conditions because that reflects typical heating and cooling habits. Cracking windows can dilute radon temporarily, but it also creates odd pressure patterns that sometimes increase radon elsewhere in the home. I have seen windows flung open in an attempt to “fix” a test, only to produce erratic readings that delayed a home sale and led to more questions from the buyer’s inspector.
Fact: Follow the instructions. Keep exterior doors and windows closed except for normal entry and exit twelve hours before and during a short-term test. Place the device away from drafts and vents. If you want to know the true average, run a long-term test and live as you normally do.
Myth: “Mitigation ruins curb appeal.”
Most St. Louis radon systems can be routed cleanly. With a bit of planning, a radon mitigation contractor can hide the stack along a rear elevation, tuck it into a corner, or run it through a garage and exit through the roof. On a two-story Chesterfield colonial, we tucked the pipe behind a downspout, used color-matched components, and the fan sat in the attic for near silence outside. The real impact on value comes from documentation and neat workmanship, not from a bit of PVC on the siding.
Fact: Buyers prefer homes with a professionally installed radon mitigation system and clear post-mitigation test results. In real estate transactions across the metro, a tidy system with a maintenance tag and a U-tube gauge usually calms nerves and accelerates closing.
Myth: “Radon mitigation is loud and energy-hungry.”
A standard radon fan draws about as much power as a small light bulb, commonly 50 to 90 watts. On your electric bill, that translates to a few dollars per month. The sound level depends on placement. A fan on an outside wall near a bedroom can hum on a quiet night, but putting the fan in a garage or attic and isolating the pipe with rubber couplings cuts vibration and noise dramatically.
Fact: Well-designed systems are quiet and efficient. If you can hear your fan across the yard or through a closed wall, the layout or vibration control likely needs a tweak.
Myth: “Sealing a few cracks is all you need.”
Sealing helps, but it rarely solves the problem by itself. Concrete moves, hairline cracks reappear, and there are more entry points than meet the eye. Radon finds the path of least resistance: gaps around plumbing, sump pits, cold joints, control joints, and even tiny pores in concrete. I’ve sealed miles of cracks for clients; best-case, levels drop a bit. More often, they bounce back within weeks.
Fact: The most reliable approach is active sub-slab depressurization, the standard Radon system design. It creates a gentle vacuum under the slab so soil gas is pulled into a pipe and vented safely above the roofline. Sealing is the supporting act, not the headliner.
What a solid St. Louis mitigation setup looks like
A practical, durable installation reflects the house, not a cookie-cutter diagram. Here is a lean, homeowner-friendly picture of a well-executed Radon mitigation system in our region:
- A single or dual suction point drilled through the slab, sized by manometer readings and test holes to find good sub-slab communication. A sealed sump cover with a removable, gasketed service panel and proper viewing port, tied into the suction if the drain tile communicates well. Schedule 40 PVC routed to minimize elbows, with a fan placed outside conditioned space or in a garage/attic, and the discharge terminating above the roofline away from windows. A U-tube manometer mounted where you’ll see it, labeled with baseline readings and a phone number for service, plus an exterior disconnect near the fan to meet code. Caulked slab penetrations, sealed utility chases, and, when present, a crawlspace membrane mechanically fastened and taped to a continuous perimeter seal.
This list could be longer, but the essence is airflow, safety, and serviceability. A thoughtful Radon mitigation contractor in the St. Louis area will also talk snow loads on roof penetrations, winter stack effect, and condensate management so the fan doesn’t freeze up during a January cold snap.
Myth: “Winter numbers don’t matter, it’s just the furnace running.”
Winter levels frequently spike because of stack effect. Warm air rising increases the pressure difference between the basement and soil, which pulls more gas in. The furnace is not the culprit; it is the building physics. I’ve tracked homes that hover around 3.0 pCi/L in September, then climb to 7 to 9 pCi/L by February. Those higher readings count, because families often spend more time indoors during winter.
Fact: Test in different seasons if your first result is near the action level. If your first winter test is high, treat it as real. Mitigation sized for winter loads will keep summer levels comfortably low.
Myth: “Radon is a scam cooked up by contractors.”
The science predates modern mitigation businesses by decades. Radon’s link to lung cancer emerged in miner studies, then in population research showing increased risk with long-term residential exposure. If anything, contractors are often the last to get paid in a real estate chain, and we spend a surprising amount of time talking people out of unnecessary add-ons. Skepticism is healthy, but the data on radon risk and the effectiveness of mitigation are not marketing copy.
Fact: Mitigation is a straightforward pressure and airflow problem with measurable before-and-after results. You can watch your levels drop on a calibrated monitor and verify with an independent test.
Pricing, timelines, and what to expect in St. Louis
For a typical single-family home in the metro, most installations fall between $1,100 and $2,000. Variables include the number of suction points, crawlspace encapsulation, attic routing, electrical distance, and whether we need to penetrate a concrete ledge or move ductwork. Homes with extensive crawlspaces that need a full membrane can run higher. In condos or row houses, coordination with associations and shared walls changes the scope.
A standard job takes half a day to a full day. You can normally test 24 hours after installation. We aim for post-mitigation levels under 2.0 pCi/L, and sub-1.0 is common when the sub-slab aggregate is cooperative. In areas with heavy clay, a second suction point might be needed to pull evenly under the slab.
Where “Radon mitigation near me” gets personal
Google will return a pile of options for Radon mitigation St Louis. The difference between a tidy, durable system and a headache often comes down to details that don’t show up in an ad. I’ve corrected systems where the fan was undersized for a dense clay pocket in Affton, where a gutter downspout blocked the discharge plume in Maplewood, and where a crawl membrane was taped to dusty brick and peeled off in six months.
When you talk to a contractor, ask how they verify sub-slab communication, whether they perform smoke tests for leaks, and how they handle condensation and ice. A firm with long experience in Stl radon work will have stories about fieldstone foundations in Tower Grove and about retrofitting sealed sump lids in older North County homes. That local fluency matters.
Myth: “Once I install a system, I never need to test again.”
Fans wear out, usually after 7 to 15 years depending on model and conditions. Landscaping projects add soil next to the foundation and change surface drainage. A basement remodel can unwittingly create new radon pathways by moving duct returns or cutting new penetrations. I’ve seen post-mitigation levels creep up years later because a fan slowed down and no one glanced at the U-tube.
Fact: Retest every couple of years, and anytime you replace the fan or alter the foundation. A quick charcoal test is cheap insurance. Also, look at your U-tube manometer monthly. If the levels equalize, the fan may be off or a tube pinhole may be fooling the gauge.
Myth: “A passive pipe equals a finished system.”
A passive stack is a start, not a guarantee. Without a fan, the pressure difference relies on natural buoyancy, which varies with temperature and wind. I’ve measured homes with a code-compliant passive stack that still read 5 to 6 pCi/L. Activating the stack with a fan and sealing a few joints typically cuts levels by two-thirds or more.
Fact: If your home has a passive radon stack, get a test. If it’s above your target range, activation is a modest step that reuses the existing pathway and typically avoids new exterior piping.
Testing details that trip people up
Where and how you test changes the reading. Putting a device next to a drafty door or over a floor drain can inflate or deflate the number. High humidity in a basement workshop can skew some devices. The test should sit 20 inches or more above the floor, away from walls and direct sunlight, and at least several feet from doors or registers. For multi-level homes, test the lowest level you use regularly. If you never enter the unfinished basement, it still counts if it pulls air into ductwork or if your family plans to finish it later.
If you are selling a home, expect the buyer’s inspector to use a continuous monitor, which records hour-by-hour levels and flags unusual spikes. Weather fronts, rain, and wind can change short-term results by 10 to 30 percent. Use those readings as a guide, not a life sentence. If you are near the action level, a follow-up test or an agreement to install a Radon system after closing is common in St. Louis contracts.
What your HVAC and plumbing have to do with radon
HVAC imbalances can worsen radon. A powerful return in a basement family room pulls on the slab. An unsealed return chase can turn a wall cavity into a vacuum. Bathroom exhaust fans and range hoods, while necessary, add to negative pressure when they run for long stretches in airtight homes. Plumbing penetrations and floor drains offer direct soil gas channels if not gasketed or trapped.
I often coordinate with HVAC techs to seal return leaks or adjust blower speeds in homes that struggle to come under 2.0 pCi/L with a single suction point. Simple fixes like sealing the return plenum and capping abandoned floor drains help stabilize readings.
Health context without the hype
Risk communications get complicated because radon risk is statistical and unfolds over St louis radon years. The relative risk for a non-smoker living with 4.0 pCi/L for decades is lower than that for a smoker at the same level, but still not trivial. Lowering from, say, 6.8 to 1.2 pCi/L is not about eliminating all risk, it is about taking a meaningful, permanent step that you can measure. If a family member is immunocompromised or you have toddlers who play on the basement carpet, those practical considerations often tilt the decision toward mitigation even when readings sit in the 2 to 4 range.
Choosing a Radon mitigation contractor wisely
Credentials signal competence, but the walkthrough reveals judgment. Pay attention to how the evaluator talks about your specific foundation and soil, not just brand names. They should take pressure field extension readings, or at least drill small test holes and use a smoke puffer to confirm air pathways. The proposal should indicate fan model ranges, not just “a fan,” and describe where the discharge will end up with respect to windows and property lines.
A strong local provider of St louis radon services will also handle permits where required, color-match exterior components when possible, and offer a reasonable guarantee, typically promising post-mitigation results under the EPA action level, with a plan for adding a second suction point if the first does not achieve the target.
Radon and real estate in the metro
Inspection riders in St. Louis commonly include radon. Buyers who grew up elsewhere may be new to it, but local agents know the drill: test, and if elevated, negotiate mitigation. Most sellers agree to install a Radon mitigation system before closing. The best path is to test early, well before listing photos, so you are not making decisions in a 48-hour scramble. If a system is already in place, keep your post-mitigation report handy and photograph the manometer reading on listing day.
VA and FHA loans do not forbid radon, but underwriting sometimes asks for documentation. A neat system with a labeled fan switch, exterior disconnect, and post-test certificate keeps underwriters and buyers at ease.
Common mistakes after installation
A few habits help the system do its job for the long haul:
- Do not store boxes tight against the suction point area under the slab, which can compress the gravel and reduce airflow under a small access cut. Keep the sump lid gasket clean and intact, and call for a replacement if it dries out or tears. Check the U-tube manometer monthly. Mark the initial reading with a pen on the label. Clear ice dams and heavy snow around the discharge in severe weather if the pipe exits near a valley or behind a dormer. If your fan fails, shut it off at the disconnect and call your contractor. Running a grinding fan can overheat the motor.
These are five-minute chores that prevent small issues from becoming service calls.
When DIY makes sense, and when it doesn’t
Handy homeowners sometimes install partial measures: seal a sump cover, caulk cracks, or add a passive pipe to a crawlspace. Those steps can help, but most of the cost and benefit hinges on sizing the fan to your sub-slab conditions and placing it correctly. Mis-routed discharge pipes can vent near a second-story window or draw condensate back toward the motor. If you are handy and curious, you can still save money by doing prep work: clear storage, mark utility lines, and expose the sump rim for a cleaner seal. Then let a professional handle suction point design and electrical.
The seasonal rhythm of St. Louis and radon management
Our freeze-thaw cycles move foundations and reopen hairline cracks. Spring rains raise groundwater and can change sub-slab airflow, sometimes lowering radon by backfilling voids, sometimes making it worse by diverting soil gas toward the footing drain. Summer air conditioning can suppress stack effect, but tightly closed homes still pull on the slab. Plan on a spring or fall check, when the weather is mild and you are more likely to catch a representative reading.
Anecdotally, homes along the Meramec and Missouri River valleys show more variability after big rain events. If your house sits near a swale or you added extensive downspouts, your radon pattern may shift. None of this means you should chase the number weekly; it means one data point is a snapshot, not a biography.
Final word: clarity beats folklore
Radon invites myths because it is invisible and slow to cause harm. Yet it is one of the simpler home hazards to measure and fix. If your test is low, great, retest in a couple of years. If it is high, a well-designed Radon system reduces levels predictably, often within a day. Local experience matters in St louis radon work, because the ground under our feet is a patchwork, and the housing stock runs from 19th-century brick to airtight new builds. When in doubt, test your own home, read the result plainly, and lean on a Radon mitigation contractor who treats your house as a specific problem to solve, not a template to rubber-stamp.
Air Sense Environmental – Radon Mitigation & Testing
Business Name: Air Sense Environmental – Radon Mitigation & TestingAddress: 5237 Old Alton Edwardsville Rd, Edwardsville, IL 62025, United States
Phone: (618) 556-4774
Website: https://www.airsenseenvironmental.com/
Hours:
Monday: 9:00 AM – 5:00 PM
Tuesday: 9:00 AM – 5:00 PM
Wednesday: 9:00 AM – 5:00 PM
Thursday: 9:00 AM – 5:00 PM
Friday: 9:00 AM – 5:00 PM
Saturday: Closed
Sunday: Closed
Plus Code: RXMJ+98 Edwardsville, Illinois
Google Maps URL: https://maps.app.goo.gl/XTPhHjJpogDFN9va8
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Popular Questions About Air Sense Environmental – Radon Mitigation & Testing
What services does Air Sense Environmental provide?
Air Sense Environmental provides professional radon testing, radon mitigation system installation, indoor air quality solutions, and crawl space encapsulation services in Edwardsville, Illinois and surrounding areas.Why is radon testing important in Illinois homes?
Radon is an odorless and invisible radioactive gas that can accumulate indoors. Testing is the only way to determine radon levels and protect your household from long-term exposure risks.How long does a professional radon test take?
Professional radon testing typically runs for a minimum of 48 hours using continuous monitoring equipment to ensure accurate results.What is a radon mitigation system?
A radon mitigation system is a professionally installed ventilation system that reduces indoor radon levels by safely venting the gas outside the home.How do I contact Air Sense Environmental?
You can call (618) 556-4774, visit https://www.airsenseenvironmental.com/, or view directions at https://maps.app.goo.gl/XTPhHjJpogDFN9va8 to schedule service.Landmarks Near Edwardsville, IL
Southern Illinois University Edwardsville (SIUE)A major public university campus that serves as a cultural and educational hub for the Edwardsville community.
The Wildey Theatre
A historic downtown venue hosting concerts, films, and live entertainment throughout the year.
Watershed Nature Center
A scenic preserve offering walking trails, environmental education, and family-friendly outdoor experiences.
Edwardsville City Park
A popular local park featuring walking paths, sports facilities, and community events.
Madison County Transit Trails
An extensive regional trail system ideal for biking and walking across the Metro East area.
If you live near these Edwardsville landmarks and need professional radon testing or mitigation, contact Air Sense Environmental at (618) 556-4774 or visit https://www.airsenseenvironmental.com/.