Air Sense Environmental’s Radon Testing Process Explained
Radon sneaks in quietly. It seeps through slab cracks, wicks along drain tile, and rides up through sump pits and utility penetrations. You cannot see it or smell it, yet it carries weight in lung health. Over years in the field, I’ve come to respect how local geology and building quirks conspire to pull radon into living areas, especially across the St. Louis region where glacial tills, karst features, and old basement construction intersect. Testing is the hinge point between worry and a plan, and the way you test matters as much as the number you get back.
At Air Sense Environmental, our process grew from hundreds of homes, townhomes, and small commercial spaces with real families, tenants, and owners attached. The following walk-through is not a lab brochure. It’s the working rhythm of how we approach radon testing, what we look for before we set a device, the choices we make about timing, and how those choices lead to better decisions on mitigation. If you’ve searched “radon mitigation near me,” or you’re weighing a radon mitigation contractor in the St. Louis market, context helps you read results with confidence, not confusion.
The science in the room, not in the abstract
Radon forms when uranium in soil and rock decays. The gas migrates through pores and fissures, then accumulates inside buildings where pressure differences draw it in. In winter, heated interiors act like chimneys and intensify the pull. In summer, central air can flatten or even reverse some of those pressure stacks, yet thunderstorms and rapid barometric dips can spike readings. This seasonal dance is why a single short test provides a snapshot, not a permanent label.
Risk isn’t theoretical. The EPA’s action level is 4.0 pCi/L, a point at which mitigation is strongly recommended. Many public health bodies suggest considering mitigation between 2.0 and 4.0 pCi/L, especially for long-term occupancy. We see plenty of homes around St. Louis radon geographies that flirt with those thresholds in winter and relax in summer. Good testing catches both behaviors and sets the stage for a radon system that handles the worst weeks, not just an average month.
What we do before any device comes out of the truck
Testing starts with the walk-through. I have learned to slow down here. A careful five to ten minutes can prevent two weeks of confusion later.
We start outside, reading the site like a topographic map. We look for gutters that dump against the foundation, downspouts tied into footing drains, and grading that drives rainfall toward the house. Clay-heavy soils typical of the region can hold water against footings, changing sub-slab pressures and altering radon entry patterns. Newer subdivisions on former farmland may show high readings in just a few foundations on a street, depending on fill and where the rock shelves. In older St. Louis City and inner-ring suburbs, stone foundations and brick mortar joints create a mosaic of entry points that behave differently than poured concrete.
Inside, we note the lowest livable area. If you have a finished or regularly used basement, that’s where testing belongs. If the basement is storage only and the first floor is the lowest level used more than four hours a day, we test on the first floor. We check for:
- Sump pits, sanitary lines, floor drains, hollow-block walls, utility chases, and any slab cracks, even hairline ones.
We also consider recent work. New windows or insulation can trap more radon by tightening the envelope. Fresh grading or a new patio could change subsurface pathways. If there is a radon mitigation system already in place, we note pipe size, routing, fan location, and manometer readings at the U-tube. Fans sometimes tire quietly. A system that ran fine five years ago can underperform today.
Choosing the right test: short-term, long-term, and continuous monitors
Not every house needs a long-term monitor out of the gate. The question is one of decision time and uncertainty tolerance.
Short-term tests, usually 48 to 96 hours, make sense in real estate transactions or when a homeowner wants to know whether mitigation is likely. We use state-calibrated continuous radon monitors (CRMs), which log hourly values. That hourly granularity shows daily swings driven by weather, HVAC cycles, or even a dryer vent that runs every evening. If someone opens windows during testing, we see temperature and pressure clues that prompt a retest. The device sits on a stand 20 to 30 inches above the floor, away from exterior walls, drafts, and heat sources, in a room that reflects regular occupancy. For a split-level with a partial basement and a lower den, we choose the area people actually use.
Long-term tests run 90 days to a year and average across seasons. We suggest these when a short-term test falls between 2.0 and 4.0 pCi/L, or when a homeowner wants a baseline before investing in upgrades or renovations. Long-term results reduce uncertainty, especially in houses with significant daily and seasonal variability.
For systems already mitigated, short-term CRM checks combined with a smoke test at suspected entry points often answer whether the current radon mitigation system still performs.
Preparing the home: closed-house conditions, without turning life upside down
For valid short-term tests, the EPA requests closed-house conditions for 12 hours before and throughout the test. That means windows shut and exterior doors used only for entry and exit. The HVAC can run in its normal cycle, and a kitchen or bath fan can run briefly for normal use, but continuous high-volume exhaust, like an attic fan left on for days, distorts results. In winter, people naturally keep windows closed, which often yields a genuine worst-case snapshot.
Life continues. Pets still move around, kids still watch TV in the family room. We place the device to reflect ordinary presence without inviting tampering or accidental kicks. If you’re worried about a curious cat or an exuberant toddler, we adjust placement and protection. We document placement with photos so that if a retest is needed, we can reproduce conditions.
How the continuous radon monitor gathers truth hour by hour
A good CRM is a steady witness. It takes an air sample, often every hour, and records radon concentration along with temperature, humidity, and sometimes barometric pressure. The hourly data tells stories. A storm front from the west can double the reading overnight. A sump pump cycling multiple times during heavy rain might correlate with an uptick as water movement opens and closes soil gas pathways. If someone leaves the sliding door cracked for two hours on a mild afternoon, we see a dip inconsistent with the rest of the series.
We don’t just hand over a single average. In our reports, we include the hourly graph, highlights of any anomalies, and a plain-language narrative that translates numbers into what they mean for decisions. Radon testing should not feel like reading a lab slip after a blood draw. It should feel like a guided explanation of your building’s behavior.
Interpreting results with regional sense
Over the St. Louis metro, we routinely see basements that average between 2 and 8 pCi/L in winter and drop to 1 to 4 pCi/L in summer. That range has outliers. Homes built over fractured limestone, especially where old quarrying or sinkhole activity shaped the subsurface, can spike into double digits even in mild weather. Newer constructions with tight envelopes but no sub-slab rough-in can hold steady above 4 pCi/L until mitigated. On the other hand, a slab-on-grade ranch on an exposed site with consistent wind may hover near 2 pCi/L year-round.
Here is how we convert readings into action:
- Below 2.0 pCi/L on a short-term test, with stable hourly data, we typically advise no immediate action and suggest a long-term follow-up if you want the fullest picture. If you’re already under contract to sell, the documentation reassures buyers. Between 2.0 and 4.0 pCi/L, we discuss your occupancy patterns, future plans, and whether a 90-day test makes sense. If the basement is a kid’s hangout or a home office for eight hours a day, you may choose to mitigate even at these levels to reduce lifetime exposure. At or above 4.0 pCi/L, mitigation is recommended. If the short-term test was run in summer at 4.0 pCi/L, we flag the likelihood that winter will be higher and treat the decision with more urgency.
If testing took place during unusual conditions, like sustained high winds or a power outage, we disclose it and may advise a retest. The goal is not to delay. It’s to anchor your decision in numbers you can trust.
Special cases and edge scenarios we see often
Finished basements with luxury vinyl plank over slab will sometimes mask expansion gaps and cracks that leak at the perimeter. The house tests high, yet visual inspection shows nothing obvious. Pulling a single quarter-round in a back closet can reveal a gap big enough to slip a coin, and a puffs-of-air smoke test tells you the rest. In these homes, testing is step one, but diagnosis saves time when scoping a radon system.
Sump pits with lids that do not seal, or lids cut to accommodate cords and discharge lines without proper grommets, let radon stream into mechanical rooms. During testing, that might create a gradient where a nearby family room reads higher than a distant spare bedroom. We place the device in the room where you spend time, not on a shelf in the mechanical corner, to reflect actual exposure.
Multi-level houses with a garden-level den and a deeper crawlspace need specific attention. The crawl, if open to the den through a framed chase, can be the engine. We test in the den, note air pathways, and, if results are borderline, sometimes run a secondary short test near the crawl entrance to see the differential. That information guides whether a single suction point handles both zones or if the radon mitigation contractor will need a separate suction field or a membrane in the crawl.
From test results to a mitigation plan you can live with
When the data points to mitigation, smart planning bridges cost, aesthetics, and effectiveness. Over the years, we’ve learned that homeowners care as much about noise, roof penetrations, and how a white pipe will look against their brick as they do about the final reading. A good radon mitigation system solves the problem while respecting the house.
In the St. Louis market, many systems route from a basement slab to an exterior fan, then discharge above the roofline. The suction point might be a core drill through the slab with a sealed connection to the sub-slab aggregate. If the home has drain tile, we tie in at the sump or an accessible section of the loop. We favor outside fans on exterior walls where noise is least intrusive, but in tight side yards or historic facades we search for attic routes. An interior route keeps the fan noise outside of living areas and hides most of the pipe, yet it demands meticulous sealing to prevent condensate issues and adhere to electrical code for the fan circuit.
For StL radon challenges in older basements with stone foundations, sealing is not cosmetic. Mortar joints often act like a honeycomb. We explain to clients that a radon mitigation system is more than a fan. Guided sealing of major pathways increases effectiveness and allows a lower fan speed, which usually reduces noise and energy draw. Likely energy costs for a typical fan run between 10 and 20 dollars per month. In freezing snaps, exterior fans can hum a little louder, especially if the discharge plume encounters cold siding. We position terminations to reduce re-entrainment and ice streaks.
If you started this process by searching “radon mitigation St Louis” or “radon mitigation near me,” you’ll find many choices. Focus on a contractor who reads your test in context, walks the site, explains suction options, and puts manometer checks and a post-mitigation test in writing. A competent radon mitigation contractor will set expectations: sub-slab communication tests during install, likely final levels, and what to do if a post-test lands a tick above the goal. Good companies own that last mile.
Post-mitigation testing is not optional
Once a radon system is installed, we return for a follow-up test. Often it is a 48-hour CRM placed in the same location as the pre-mitigation test to compare apples to apples. Successful systems in our region typically bring levels to 0.5 to 1.5 pCi/L on short-term tests, with winter values remaining under 2.0 pCi/L for most homes. If the post-test reads higher than expected, we troubleshoot: check the manometer, verify fan model and operation, and inspect for missed sealing or a suction field that doesn’t reach a separated slab section. In a home with multiple slab pours, a second suction point often brings the number down sharply.
We also advise homeowners to leave the manometer where they can see it and glance weekly. A fluid level that sits unevenly shows vacuum. If both columns equalize at zero, the fan is off or the tube needs service. A quick look prevents months of silent drift.
Real-world examples that shaped our process
A 1920s brick house in South City tested at 6.8 pCi/L in January. Hourly data showed a daily crest after sunset. The basement had painted stone walls and an open sump without a lid. The family used the rec area every evening. We coordinated a sealed sump lid, sealed the gap at the baseboard of a new stud wall, and installed a single suction point tied into the drain tile. The post-test came back at 0.9 pCi/L. The owner mentioned an immediate drop in that earthy basement smell, which is common when air pathways tighten up.
A 1990s two-story in Chesterfield showed 3.2 pCi/L on a summer short-term test, with light, steady wind during the period. The basement served as a guest space a few weekends a year. Rather than installing right away, the owners ran a 90-day test from November through January. The seasonal average landed at 5.1 pCi/L with peaks during two cold snaps above 8. A standard exterior system with one suction point through aggregate, fan on the rear elevation, brought winter levels to 1.2 pCi/L. That gap between summer and winter justified the wait, and the follow-up proved the point.
A slab-on-grade ranch in Florissant tested at 4.0 pCi/L in spring, dipped to 2.5 in August, then sat at 4.6 in January. The house had no basement and limited attic access. We routed through the garage with a fan mounted in the garage attic and discharge through the roof away from a second-story window of the neighboring house. Noise in the living space is near zero. The post-test: 1.1 pCi/L in winter.
Why the details of testing technique matter later
A radon test that respects placement, season, and house behavior prevents false economy. If you test on the wrong level or during a week of open-window weather, you risk a number that postpones action while exposure continues. Alternatively, an elevated test placed in a mechanical room beside a leaky sump might overstate what family members actually breathe in the den across the hall. Air Sense Environmental emphasizes placement in truly occupied rooms at the lowest livable level, because the final goal is not to win a spreadsheet contest. It is to lower inhaled radon where people sit, sleep, and play.
For real estate transactions, we work within timelines while safeguarding validity. Buyers and sellers both benefit from testing that stands up to scrutiny. If a retest is necessary due to weather or documented deviations from closed conditions, we say it plainly and schedule promptly. A candid report beats a disputed one every time.
Cost expectations, timelines, and what homeowners control
Testing is affordable compared to the stakes. A short-term professional CRM test generally runs a few hundred dollars, depending on distance and scheduling constraints. Results are typically ready the same day we retrieve the monitor, with a clear narrative report and recommendations.
Mitigation costs vary by house complexity and the path chosen for the radon system. In the St. Louis area, a straightforward single-suction exterior system most often falls in a band of 1,200 to 2,000 dollars. Attic routes, multiple suction points, or crawl encapsulation can push higher. Ask for a written scope: suction point count, fan model, exterior routing description, sealing plan, electrical details, and a commitment to post-testing.
Homeowners influence outcomes by keeping testing conditions stable, providing access to key rooms and mechanical spaces, and bringing any planned renovations into the conversation. If you plan to finish a basement next spring, design the mitigation now so that pipe routes and future walls work together. If a new patio is on deck, coordinate how it affects slab edges and potential suction locations.
How to read hourly data without losing the plot
The hourly graph in a CRM report sometimes troubles clients who see a spike and assume failure. Spikes matter if they repeat daily or persist for many hours, but a single jump tied to a thunderstorm or a door left ajar is noise, not policy. We guide clients to focus on the average and the rhythm. A tidy band near 1.0 to 1.5 pCi/L after mitigation shows stability. A saw-tooth pattern between 1.0 and 3.0 suggests a leak or a fan that cannot overcome sub-slab resistance. That’s when we evaluate adding a suction point or improving seals.
One owner called after his post-mitigation average held at 1.4 pCi/L, yet a two-hour window hit 2.9. A heavy downpour had filled the yard drains. The next day, values rested back near 1.2. We kept an eye on it through a 90-day span and stayed within the expected band. The system was doing its job.
The St. Louis backdrop: what geology and construction mean for you
Between the Missouri and Mississippi rivers, our ground is a blend of loess, clay tills, and, in many neighborhoods, underlying limestone. The karst legacy creates uneven risk over short distances. Two homes 100 yards apart can diverge by a factor of two or more. Builders across different decades laid foundations with different drainage philosophies. Some homes have continuous drain tile to a sump, others rely on perimeter gravel that stops short of corners. These things decide how easily a radon fan communicates under the slab, a key reason experienced eyes during testing and planning pay off.
In postwar bungalows with partial basements and crawl sections, a membrane over the crawl with a dedicated suction often changes the game. In larger two-story homes on uniform aggregate, a single centrally located suction point with careful sealing may do the trick. Our testing St louis radon process identifies which pattern you’re likely in before any hammer hits concrete.
What to expect when you call
Most clients first want to know whether they face a problem and how soon they can get an answer. We schedule the site review and device placement, set the test for 48 to 96 hours, and confirm closed-house guidelines. At pickup, we download and review the data on the spot. You receive a written report that day or within 24 hours, with a clear recommendation: no action, long-term monitoring, or mitigation consult. If mitigation is on the table, we outline likely paths and, if you wish, refer you to vetted local contractors who consistently deliver solid results in St. Louis radon conditions.
We stand by our testing and welcome your questions long after the monitor leaves your basement. Radon decisions carry long-term implications, and a few extra minutes of explanation can save years of second-guessing.
A brief homeowner checklist for a smooth test
- Keep windows closed 12 hours before and during the test. Use exterior doors only for entry and exit. Run your HVAC normally. Avoid running whole-house fans or leaving continuous exhaust on. Do not move or cover the monitor. Keep pets and curious hands at a distance if possible. Keep the test area as you ordinarily live in it. No special dehumidifiers or space heaters introduced just for the test. Let us know about any unusual events during the test: power outages, storms that caused water intrusion, or a window that was accidentally opened.
The quiet reward of a good process
When the process works, the reward is not dramatic. It is ordinary life, uninterrupted. A proper test, read with regional understanding, either sets your mind at ease or moves you cleanly toward a fix. A well-designed radon mitigation system lowers a number on a report and, more importantly, lowers what your family breathes. In the St. Louis radon landscape, results come from patient steps: a careful look at the house, a well-placed monitor, a report that treats you like an adult, and a mitigation plan that fits the building, not the other way around.
If you are ready to measure where you stand, or if you have a previous test that left you with more questions than answers, Air Sense Environmental is set up to meet you at that moment. Testing is our starting line. Clarity is the finish.
Air Sense Environmental – Radon Mitigation & Testing
Business Name: Air Sense Environmental – Radon Mitigation & Testing
Address: 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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https://www.airsenseenvironmental.com/
Air Sense Environmental – Radon Mitigation & Testing is a community-oriented indoor air quality specialist serving Edwardsville, IL and the surrounding Metro East region.
The team at Air Sense Environmental provides professional radon testing, radon mitigation system installation, and crawl space encapsulation services tailored to protect residential indoor environments.
Homeowners throughout Edwardsville, IL rely on this highly rated local company for professional radon reduction systems designed to safely lower elevated radon levels.
To schedule radon testing or mitigation service, call (618) 556-4774 or visit https://www.airsenseenvironmental.com/ to speak with a trusted local specialist.
View the business location and directions on Google Maps: https://maps.app.goo.gl/XTPhHjJpogDFN9va8 and contact Air Sense Environmental for professional indoor air solutions.
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/.
