Illinois radon testing questions can involve short-term kits, long-term kits, real-estate timing, placement, lab instructions, licensing, and what to do after a result comes back elevated. American Radon Systems focuses on mitigation, not testing service work, so this page is educational and referral-oriented. It helps homeowners understand testing options, why Illinois separates measurement and mitigation licensing, and how a test result fits into the next step. If you need a test first, Bill can point you toward appropriate testing options. If you already have a result or a monitor pattern, he can explain what the mitigation side of the home may need.
Illinois rules generally call for a radon test to be conducted during the real estate transaction process, and there are licensing requirements for who can legally perform that test. The test must typically be conducted by a licensed radon measurement professional, and the results are disclosed to the buyer. It's one of the more consumer-protective radon laws in the country - Illinois takes this seriously.
Question linkIllinois generally requires a minimum 48-hour test for real estate transactions. Short-term tests that run less than that typically don't meet the standard for a real estate deal in Illinois. The 48-hour minimum is there to get a reasonably representative reading rather than catching a fluke high or low period.
Question linkClosed-building conditions mean windows and exterior doors should remain closed except for normal entry and exit, for a set period before and during the test. Illinois rules typically require closed-building conditions to be maintained for 12 hours before the test starts and throughout the entire testing period. This is to prevent outdoor air from artificially diluting or elevating the radon reading - it needs to reflect the actual indoor environment.
Question linkAfter a radon mitigation system is installed in Illinois, the system generally needs to be verified with a post-mitigation test to confirm it's working. Illinois rules typically require this test to be conducted by an independent licensed radon measurement professional - meaning someone other than the company that installed the system. The goal is an unbiased result that confirms the levels have actually come down.
Question linkIllinois rules generally require the post-mitigation test to be performed by an independent licensed radon measurement professional - not the contractor who installed the system. This independence requirement exists so there's no conflict of interest in verifying the system's performance. The mitigator and the tester are supposed to be separate parties.
Question linkYes, Illinois rules typically call for an independent tester to handle post-mitigation verification. The radon contractor who installed your system cannot also be the one certifying that the system worked - those have to be separate licensed professionals. It's a good rule that protects homeowners from getting a rubber-stamp result.
Question linkIllinois rules generally require waiting at least 24 hours after the mitigation system is installed before starting a post-mitigation test. This allows the system to begin operating and for conditions in the home to stabilize. Some guidance suggests waiting a bit longer to get a more representative reading, but 24 hours is typically the floor.
Question linkIllinois rules typically require post-mitigation testing to be completed within 30 days of system installation. You don't want to wait indefinitely - the whole point is to verify the system is working. If you've had a system installed and haven't scheduled that independent follow-up test yet, getting it scheduled promptly is the right move.
Question linkThis is typically a negotiated item, but in many Illinois real estate transactions, the responsibility for the post-mitigation test is worked out between the buyer, seller, and mitigation contractor as part of the deal. In some cases the mitigation contractor arranges it; in others the buyer or seller pays separately. There's no universal rule about who writes the check - it depends on what your contract says.
Question linkNo - Illinois rules generally prohibit this. The post-mitigation test is supposed to be conducted by an independent licensed radon measurement professional, not the company that installed the system. This separation is intentional and it's one of the stronger consumer protections in Illinois radon rules. If a contractor offers to do their own post-mitigation test, that's a flag.
Question linkYes, Illinois is considered a moderate-to-high radon state overall, with significant portions of the state - particularly in the north and central regions - falling in EPA Zone 1 (highest risk). The geology of Illinois, including glacial deposits and soils that allow radon to move easily, contributes to elevated levels in many areas. Testing is genuinely important here, not just a formality.
Question linkNorthern and central Illinois generally show the highest radon levels based on testing data. Counties like DuPage, Kane, Lake, McHenry, Will, and much of the collar county region around Chicago are in EPA Zone 1 - the highest predicted radon zone. Downstate Illinois tends to have somewhat lower average levels, though elevated homes show up everywhere.
Question linkNorthern Illinois typically has higher average radon levels than southern Illinois, based on testing data and geology. The glacial soils in northern Illinois tend to allow radon to migrate upward more readily. Even so, radon varies house by house - you'll find high homes in downstate Illinois too, which is why testing matters regardless of where you are.
Question linkChicago and the surrounding collar counties sit in one of the higher-radon areas of Illinois. The geology of northeastern Illinois - glacial till, sandy soils - is favorable for radon movement. Homes in Chicago proper can have elevated radon, though dense urban construction and building characteristics vary quite a bit. Testing is the only way to know what's actually happening in a specific building.
Question linkYes. The Chicago metro area and the collar counties - DuPage, Kane, Lake, McHenry, Will, and Cook - are predominantly in EPA Zone 1, which is the highest predicted average indoor radon level zone. That doesn't mean every home is high, but the statistical risk in this region is real and testing is strongly recommended for any home, especially those with basements.
Question linkDuPage County is in EPA Zone 1, which is the highest predicted radon zone. Testing data from DuPage consistently shows elevated radon levels in a significant portion of homes. If you have a home in DuPage and haven't tested recently, it's worth doing - this isn't a low-risk area.
Question linkCook County falls in EPA Zone 1 for radon risk, and testing data supports elevated levels in many homes throughout the county. That includes Chicago itself and the surrounding suburbs. The risk varies by neighborhood and home type, but Cook County is not a place to assume radon isn't a concern.
Question linkLake County is in EPA Zone 1 and has some of the higher radon readings in Illinois based on available testing data. The glacial geology in Lake County is particularly conducive to radon migration. If you're in Lake County and haven't tested, you should - and if you have a basement, that's where to start.
Question linkWill County is in EPA Zone 1 for radon, and testing data shows elevated levels in a meaningful percentage of homes. The southwestern Chicago suburbs have produced enough high-radon test results over the years that it's taken seriously. Testing is the right call in Will County.
Question linkYes, Kane County is in EPA Zone 1, the highest radon risk category. Radon levels in Kane County homes can vary widely street to street, but the overall risk profile here is elevated. Don't skip testing because your neighbor's house tested fine - each home is its own situation.
Question linkMcHenry County is in EPA Zone 1 and has radon risk comparable to the rest of the northern Illinois collar counties. The glacial geology up there is particularly favorable for radon to come up through soil and into homes. Testing is genuinely worthwhile in McHenry County.
Question linkLiving near the Fox River doesn't directly cause higher radon - radon comes from the soil and bedrock beneath your home, not from surface water. The river valley geography in some areas can influence soil type and drainage, but proximity to the Fox River itself isn't a radon risk factor. The geology of the broader region matters more than the river.
Question linkRiver valleys in Illinois don't inherently have higher or lower radon - it really depends on the underlying geology and soil composition. Some valley areas have soils that allow radon to move easily; others don't. The terrain can affect how radon enters a home through pressure dynamics, but the only way to know what's happening in your specific home is to test.
Question linkOn average, downstate Illinois has somewhat lower radon levels than the northern part of the state, but "lower on average" doesn't mean low. Elevated radon homes appear throughout downstate Illinois, and without testing you can't know where your home falls. The EPA recommends testing everywhere in the country regardless of regional averages.
Question linkRockford is in Winnebago County, which is in EPA Zone 1 - yes, you should test. Northern Illinois in general has elevated radon risk, and Winnebago County has produced plenty of high-radon results over the years. Testing a newly purchased home regardless of location is good practice, and in Rockford it's especially sensible.
Question linkChampaign and Urbana sit in Champaign County, which is in EPA Zone 2 - a moderate predicted radon level. That's a step down from the northern Illinois collar counties, but it's not a low-risk area. Plenty of homes in Champaign-Urbana have tested elevated. Testing is still the right thing to do.
Question linkSpringfield is in Sangamon County, which is in EPA Zone 2. The risk is moderate compared to northern Illinois, but meaningful enough that testing is worthwhile. Illinois radon data from central Illinois counties shows elevated readings in a real percentage of homes, including in the Springfield area.
Question linkPeoria County sits in EPA Zone 2. Radon levels in the Peoria area are moderate on average, but individual homes can be well above the EPA action level. If you're in Peoria and haven't tested, it's a straightforward thing to do and worth knowing.
Question linkThe Illinois side of the Quad Cities - Rock Island and Whiteside Counties - are in EPA Zone 2 and Zone 1 respectively. Radon is a genuine concern in that region. Testing is the responsible thing to do for any home in the area, particularly those with basements or crawlspaces.
Question linkNaperville sits in DuPage County, which is EPA Zone 1 - one of the highest-risk counties in Illinois. Radon is a real concern in Naperville. It's one of the areas where we consistently see homes come in well above the EPA action level of 4.0 pCi/L.
Question linkAurora spans Kane and DuPage Counties, both of which are EPA Zone 1. Yes, radon is a genuine concern in Aurora. The collar county geology in that area is among the more favorable in Illinois for radon migration, and testing is strongly recommended.
Question linkElgin is in Kane County, EPA Zone 1. Radon is something to take seriously in Elgin. The area has a history of elevated radon readings, and if your home has a basement or sits on soil with good radon-migration conditions, testing is a sensible step.
Question linkJoliet is in Will County, which is in EPA Zone 1. Radon is definitely a concern in Joliet and the surrounding area. Will County has produced elevated radon readings across a broad range of neighborhoods and home types. Testing is the right move.
Question linkWaukegan is in Lake County, EPA Zone 1. Radon is a meaningful concern in Waukegan. Lake County has some of the more elevated average radon readings in Illinois. If you haven't tested your home there, it's worth doing - especially if you spend time in the lower levels of the house.
Question linkSchaumburg is in Cook County, EPA Zone 1. Yes, radon is something to think about there. The northwest suburbs of Chicago - which includes Schaumburg - have plenty of homes that come in above the EPA action level. Testing is straightforward and gives you an actual answer instead of guessing.
Question linkBolingbrook is in Will and DuPage Counties, both EPA Zone 1. That puts it squarely in Illinois's higher-risk radon region. Testing is genuinely worthwhile in Bolingbrook, and if your home has a basement you spend time in, that's exactly the kind of space where radon exposure accumulates.
Question linkBoth Palatine and Arlington Heights are in Cook County (EPA Zone 1) near the Lake/Cook county line. Radon is a real concern in both communities. The northwest suburbs have consistently shown elevated radon in testing data, and these are areas where testing before buying or after moving in is a smart practice.
Question linkOrland Park is in Cook County, EPA Zone 1. Radon is a concern there like it is throughout the south and southwest suburbs of Chicago. The Cook County suburban ring has enough radon history that testing should be a standard step for any homeowner.
Question linkPlainfield is in Will County, EPA Zone 1. Yes - Will County is one of the higher-risk counties in Illinois for radon. Plainfield has seen elevated radon readings in homes across various neighborhoods. Testing is a good idea, full stop.
Question linkLombard is in DuPage County, EPA Zone 1. Radon is a concern in Lombard. DuPage County has a long track record of elevated radon in residential testing, and Lombard is no exception. If you haven't tested, it's easy to do and worth knowing.
Question linkIllinois doesn't have a blanket statewide requirement for multi-family apartment buildings to test for radon in the same way it has structured requirements for single-family home sales. Some municipalities in Illinois have adopted local radon ordinances that go further than state law. If you're in a multi-family building and have radon concerns, checking whether your city or village has local radon rules is worth doing.
Question linkYes, radon is worth thinking about when renting in Illinois, particularly in the northern collar counties. If you're renting in a first-floor apartment, a garden-level unit, or a home with a basement, radon is more likely to be elevated. Bringing a short-term test kit or a continuous monitor like an Airthings is a reasonable way to get a read on your new place while you settle in.
Question linkA radon measurement license in Illinois authorizes someone to conduct radon testing. A radon mitigation license authorizes someone to design and install radon reduction systems. These are separate licenses, and not every radon professional holds both. If you're hiring for testing, verify the measurement license; if you're hiring for mitigation, verify the mitigation license.
Question linkIllinois rules generally prohibit the same company or individual from doing both the testing and the post-mitigation verification for the same property - the independence requirement means the person verifying the system can't be the person who installed it. However, a single company can hold both types of licenses; they just can't be on both sides of the same transaction for verification purposes.
Question linkIf a radon tester operating in Illinois for real estate purposes isn't licensed, their test results generally aren't valid for the transaction. Using an unlicensed tester in a real estate deal can create legal and practical problems - the test may need to be redone with a licensed professional. Beyond real estate, unlicensed testing for your own information isn't illegal, but for anything official you need a licensed tester.
Question linkYes, Illinois requires licensed radon professionals to maintain their credentials through continuing education. This keeps licensed testers and mitigators current with evolving standards, new technology, and updated protocols. It's part of why the Illinois licensing system is considered one of the more rigorous in the country.
Question linkIllinois radon professional licenses are typically valid for two years and require renewal. Renewal usually involves continuing education requirements and payment of a renewal fee. If you're checking a professional's credentials, confirm their license is currently active - not just that they were licensed at some point in the past.
Question linkSome Illinois county health departments offer radon resources, test kits, or referrals, though this varies by county and funding. Counties like DuPage, Lake, and Cook have more robust programs due to population size. Calling your county health department is a quick way to find out what local resources are available.
Question linkIt can, but it's unusual. Radon is a fixable problem - mitigation systems work very well - so most buyers and sellers work out a solution rather than killing the deal. A high radon test result is more often a negotiating point than a deal-breaker. It's worth knowing that going in, whether you're buying or selling.
Question linkYes. Seller representations about radon are only as good as the testing that supports them. If no recent test has been done, or if testing wasn't done by a licensed professional, you should still have an independent test conducted during your inspection period. A house can change, and what was true five years ago may not be true today.
Question linkRadon testing in Illinois real estate transactions typically happens during the inspection contingency period, which usually runs the first one to two weeks after an accepted offer. The test needs to be conducted by a licensed Illinois radon measurement professional. Plan ahead - you want enough time to get the test scheduled, completed (minimum 48 hours), and results back before your contingency period expires.
Question linkIf the test device was moved or the closed-building conditions weren't maintained during the test, the result may be invalid. Illinois rules take test integrity seriously - a compromised test should be flagged by the testing professional and may need to be redone. A good licensed tester will document conditions and note any integrity issues.
Question linkYes. The test report from a licensed radon measurement professional should be provided to you as part of the real estate transaction. That report should include the device type, test location, duration, test conditions, and the radon level result. Keep a copy for your records - it's useful context for future testing.
Question linkA buyer can waive the radon inspection contingency, but this is generally not advisable - especially in EPA Zone 1 counties. Waiving testing means taking on the risk that the home has elevated radon without knowing it. In competitive markets buyers sometimes waive inspection contingencies, but giving up the radon test is a risk worth thinking carefully about before agreeing to it.
Question linkWith respect to real estate agents, radon is a technical and health question - not really their area. Illinois is a high-radon state in many areas, and testing is the only way to know what's in a specific home. A good agent will support your right to test; one who actively discourages it is giving you advice outside their expertise. Test anyway.
Question linkYes, you should still test - or get the post-mitigation test result from the seller. A system being present doesn't automatically mean it's working correctly. Systems can develop issues over time, suction pipes can get blocked, fans can fail. Confirming the system is actually performing with a current test result is the right move before you move in.
Question linkAsk the seller to provide documentation. If they can't, arrange a test during your inspection period to verify the system is working. A system with no verified post-mitigation result is a system with unknown performance - you need actual numbers to know whether it did its job.
Question linkNo. Illinois rules generally require a licensed radon measurement professional to conduct the test for real estate purposes. A DIY kit from the hardware store doesn't satisfy that requirement - it doesn't have the chain of custody, licensed professional involvement, or documentation that an official real estate test needs. DIY kits are fine for your own general knowledge but not for a transaction.
Question linkChain of custody refers to the documented tracking of a radon test device from placement through lab analysis - who placed it, when, where, and who handled it. Licensed Illinois radon measurement professionals are required to maintain chain of custody documentation. It's part of what makes a licensed test result credible and legally valid for real estate purposes.
Question linkGenerally, no. Illinois real estate radon tests typically require laboratory-analyzed passive devices or approved professional-grade electronic monitors with proper calibration documentation. Consumer-grade continuous monitors like Airthings or RadonEye are useful for ongoing home monitoring but generally aren't accepted as the official test for real estate in Illinois. Your licensed tester will use approved devices.
Question linkOpening windows or exterior doors during the test period violates closed-building conditions and invalidates the test. If this happens, the test needs to be discarded and redone. If you suspect tampering with closed-building conditions during an Illinois real estate test, bring it up with your real estate agent - it's a serious protocol violation.
Question linkThe test result becomes unreliable and should be considered invalid. In an Illinois real estate context, intentionally violating closed-building conditions could also have legal implications - it could be construed as an attempt to manipulate the test result. Licensed testers are trained to document conditions and flag integrity concerns.
Question linkYes, and winter is actually a reasonable time to test because homes tend to be well-sealed, which produces readings more representative of normal winter occupancy conditions. Stack effect - warm air rising and creating suction at the base of the home - can draw more radon in during cold months, so winter tests sometimes run higher than summer tests. Either season can produce a valid real estate test.
Question linkBoth seasons can give you useful information. Winter tends to produce higher readings because of stack effect and closed homes. Summer with closed-building conditions gives you a controlled reading. For a real estate transaction, the test happens when the deal happens. For ongoing personal monitoring, testing in multiple seasons and averaging gives you a fuller picture.
Question linkFor a standard short-term charcoal canister test, the device is typically mailed to a lab after the 48-hour (or longer) test period. Lab turnaround is usually a few days to a week. Some labs offer rush processing. Electronic monitors used by licensed professionals can provide faster results. Your tester will give you a timeline estimate when they place the device.
Question linkIllinois uses the EPA's action level of 4.0 pCi/L. If your test result comes back at or above 4.0 pCi/L, the EPA recommends fixing the problem. Illinois doesn't set a different number - the state aligns with federal EPA guidance on this.
Question linkNo level of radon is completely without risk - it's a radioactive gas and a known carcinogen. The EPA action level of 4.0 pCi/L is a practical threshold for action, not a line between safe and unsafe. The EPA also notes that levels between 2.0 and 4.0 pCi/L are worth considering mitigation. Illinois radon guidance follows this same framework.
Question linkYes, Illinois aligns with the EPA on the 4.0 pCi/L action level. There isn't a separate Illinois threshold that differs from the EPA's. Some guidance - from the World Health Organization, for example - suggests even lower action levels, but in practical Illinois terms, 4.0 pCi/L is the standard trigger for recommending mitigation.
Question linkYou'll typically wait at least 24 hours after installation before starting the post-mitigation test, and the test itself runs for at least 48 hours. The post-mitigation test must be conducted by an independent licensed radon measurement professional - not the company that installed your system. Plan on the full process taking about a week from installation to having final results in hand.
Question linkNo - Illinois rules generally require an independent tester for post-mitigation verification. The company that installed your system shouldn't be the one verifying it worked. If a contractor is pushing to do their own post-mitigation test, that's a red flag. You need a separate licensed measurement professional for that step.
Question linkIf the post-mitigation test shows levels still above 4.0 pCi/L, the system may need adjustment - additional suction points, a more powerful fan, or addressing other entry points. A good mitigation contractor will come back to evaluate the system and make adjustments. Post-mitigation results above the action level mean the job isn't done yet.
Question linkIllinois post-mitigation testing generally follows the same protocols as initial testing - a licensed professional using approved devices under closed-building conditions for at least 48 hours. The key difference is the independence requirement. The testing protocol itself is similar to any other real estate or verification test.
Question linkIt's never too late to verify that your system is working, though if you're outside the typical 30-day window, the test is no longer technically a "post-mitigation" test in a formal sense - it's a regular follow-up test. You should still do it. Knowing your current radon levels is always worthwhile regardless of when the system was installed.
Question linkFor informal personal peace of mind, your Airthings can give you useful information after mitigation. But for formal verification under Illinois rules - especially in a real estate context - you need a licensed professional using approved devices. Consumer monitors are supplementary tools, not replacements for the formal licensed verification process.
Question linkThat's a very good result. The EPA action level is 4.0 pCi/L, and levels below 2.0 pCi/L represent a significant reduction in exposure risk. At 1.4 pCi/L, the system is doing its job well. No level is zero, but 1.4 pCi/L is well within the range of what properly functioning mitigation systems achieve.
Question linkKeep them in a safe place with your home records. They document that your system was verified to be working at a specific point in time. If you sell the home in the future, buyers will want to see this documentation. It's also a useful baseline for future retesting.
Question linkThe EPA generally recommends retesting every two years after a mitigation system is installed to confirm it's still working properly. System components can wear over time - fans eventually need replacing - and soil conditions can change. Illinois doesn't mandate periodic retesting for private homeowners, but doing it every couple of years is good practice.
Question linkNorthern Illinois was heavily affected by glaciers, which left behind soils - till, sandy sediments, gravel - that are permeable and allow radon gas to migrate upward easily. The glacial geology of the Chicago-area collar counties is particularly favorable for radon movement. Southern Illinois has different geology that generally, on average, produces lower radon levels, though elevated homes appear everywhere.
Question linkNorthern Illinois has glacial till, sandy soils, and loamy sediments that are permeable - meaning radon from uranium decay in the underlying rock and soil can move upward through them into homes. More permeable soil equals more radon pathway to the living space. This is a primary reason why the collar counties around Chicago see elevated radon in a high percentage of homes.
Question linkThe bedrock in much of Illinois contains naturally occurring uranium and radium, which decay to produce radon. The northern part of the state has geology - including some limestone and shale formations - that contributes to radon generation. This, combined with permeable overlying soils, creates conditions for radon to reach homes.
Question linkGranite is often cited as a radon source because it can be rich in uranium, but Illinois doesn't sit on the same granite-heavy geology as, say, New England. Illinois radon comes more from glacial soils and sedimentary bedrock. The mechanism is the same - uranium decay - but the geology is different than classic granite radon states.
Question linkYes. Concrete is porous, and radon can pass through it. Cracks in basement floors and walls, floor-wall joints, and penetrations for pipes and wires are all entry points. A properly installed sub-slab depressurization system draws radon from beneath the slab before it can enter, which is why that's the standard mitigation approach in Illinois homes.
Question linkRadon in well water can contribute to indoor radon levels in Illinois, but the majority of Illinois residents are on municipal water systems that process and aerate water before distribution - which removes most dissolved radon. If you're on a private well in Illinois, it's worth testing both your air and your water for radon. Most Illinois radon problems are soil-based, not water-based.
Question linkYes, if you're on a private well in Illinois it's a good idea to test the water for radon in addition to the air in your home. Aeration during bathing and cooking can off-gas radon from well water into indoor air. Municipal water users generally don't need to worry about this - the treatment process addresses it.
Question linkIllinois municipal water systems are required to meet EPA drinking water standards, which include limits on radon in water. Public water systems typically process and aerate water in ways that reduce radon. Radon in Illinois public water is not generally considered a significant indoor radon source - the primary concern is radon from soil.
Question linkRanch houses in Illinois often have higher radon levels because the living space is directly over the basement or slab - there's no upper story between you and the entry point. Two-story homes dilute radon across more air volume. But both types can have elevated radon; the measurement that matters is what's actually in your living space.
Question linkBoth can have elevated radon, but the dynamics differ. Basement homes in Illinois typically show more concentrated radon in the basement itself, but it moves upward into living areas. Slab-on-grade homes have radon entering directly into the living space. Both types are mitigatable. Neither is inherently "worse" - testing is the only way to know.
Question linkYes. Crawlspaces are a significant radon entry point in Illinois. Radon rises from the soil, enters the crawlspace, and then moves into the living areas above. Crawlspace mitigation - which often involves a combination of barrier and ventilation approaches - is well understood and effective. If you have a crawlspace in Illinois, testing is important.
Question linkNo - a finished basement doesn't block radon. Drywall, carpet, and paneling don't stop radon from coming up through the slab and walls. Many homes with fully finished basements in Illinois have elevated radon levels. Finishing a basement doesn't address the radon problem; mitigation does.
Question linkYes. New construction doesn't prevent radon - it's about the soil and geology beneath the home, not the age of the house. Some newer Illinois homes are built with radon-resistant new construction (RRNC) features like a sub-slab gravel layer and a passive pipe, which can reduce radon somewhat. But even those homes should be tested, and the passive systems often need to be converted to active systems if levels are elevated.
Question linkRadon-resistant new construction (RRNC) refers to building practices that include features to reduce radon entry - typically a gas-permeable layer under the slab, a plastic sheeting barrier, and a passive PVC pipe routed from beneath the slab to above the roof. Illinois building codes in some areas encourage or require these features in new homes, though it varies by jurisdiction. RRNC reduces radon but doesn't eliminate it - testing is still necessary.
Question linkYes. Sump pits are open pathways into the soil beneath the home and can be a significant radon entry point. In many Illinois homes, the sump pit is one of the primary spots where radon enters. A well-installed mitigation system will typically seal or address the sump pit as part of the overall depressurization approach.
Question linkFrench drain systems and interior drainage systems can be radon entry pathways because they maintain an opening to soil air beneath the slab. Some mitigation approaches involve connecting the drainage system to the active depressurization. It's something to discuss with a licensed mitigation contractor who can evaluate your specific setup.
Question linkRadon is unit-specific in townhomes. Adjacent units can have very different radon levels because each unit sits on its own section of foundation and soil, and construction differences between units matter. Testing your specific unit is the only way to know what's happening in your space - don't assume your level matches your neighbor's.
Question linkRadon dilutes significantly in upper floors of high-rise buildings. If you're on the fifth floor or higher in a solid high-rise, radon from the soil is generally not a concern for your unit. Ground-floor and garden-level units in multi-story buildings can still have elevated radon. If you're on a lower floor, testing is more relevant.
Question linkYes. Garden-level apartments - those at or below grade, often with windows at street level or below - are much closer to the soil and can have elevated radon. If you're spending significant time in a garden-level unit in Chicago, it's worth testing. Bring a monitor or get a test kit and see what the numbers look like.
Question linkThe standard approach in Illinois is sub-slab depressurization - a contractor creates a suction point beneath the concrete slab, connects it to PVC pipe, routes the pipe to the exterior, and installs a fan that continuously draws radon-laden air out from under the home before it can enter the living space. The result is that the pressure beneath the slab becomes negative relative to the indoor space, so radon moves away from the home rather than into it.
Question linkMost standard sub-slab depressurization installations in an Illinois home take about one day. A licensed contractor will core through the slab, install the suction pipe, route it through the home or along an exterior wall, and mount the fan. The system is operational the same day it's installed, and you can test 24 hours after installation.
Question linkYes. The fan that drives the system is electric and runs continuously. It's a low-power device - similar to a small light bulb in terms of energy use - but it does require a dedicated power connection. Your contractor will handle the electrical connection as part of the installation.
Question linkFor a licensed professional installation that satisfies Illinois requirements - particularly for real estate - you need a licensed Illinois radon mitigation contractor. Homeowners can legally do their own work on their own property in some circumstances, but a DIY installation won't qualify for a formal post-mitigation test under Illinois licensing rules and may not meet the technical standards for effective mitigation.
Question linkMinimal. The contractor cores a small hole through your basement floor, which creates some dust that's cleaned up. The pipe is routed through a closet or along an interior or exterior wall. Most homeowners can stay in the house during installation, and the work area is accessible again the same day.
Question linkNo - in fact, a properly installed and verified radon mitigation system is generally viewed as a positive feature. It documents that the radon problem was identified and professionally addressed. Buyers in high-radon Illinois counties are often reassured by seeing a system in place with documentation that it's working. A house with a system and verified low levels is in better shape than one with an unknown radon history.
Question linkThe fan is the main component that requires attention over time. Fan lifespan varies but is often in the 10-15 year range with continuous operation. A visual check of the U-tube manometer (the small gauge on the pipe) periodically tells you the system has suction. If the fan fails or suction drops, radon levels can rebound. Periodic retesting - every two years or so - is the best way to confirm the system is still performing.
Question linkIt's a small plastic tube shaped like a U, filled with colored liquid, that's attached to your mitigation pipe. When the fan is running and creating suction, the liquid levels in the two sides of the U will be uneven. If they're even, the system isn't generating suction - which means the fan may have failed or there's a problem with the pipe. It's a simple visual indicator you can check anytime.
Question linkFan noise that has changed - new rattling, grinding, or unusual hum - can indicate the fan is starting to fail or that debris has gotten into the system. It's worth having a licensed mitigation contractor take a look and do a diagnostic. Running a radon test at the same time gives you a picture of whether performance has been affected.
Question linkIf the fan fails, the system stops functioning and radon levels can return to pre-mitigation levels over time. The U-tube manometer will show no differential when the fan is off. Fan replacement is typically straightforward for a licensed contractor. If you notice the manometer showing no suction, get it checked and run a radon test.
Question linkNo. Radon doesn't cause headaches, fatigue, sore throats, or any acute symptoms. Radon's health risk is long-term - it's a radioactive gas that, when inhaled over time, increases the risk of lung cancer through radiation exposure to lung tissue. If you're feeling symptoms like headaches or fatigue, that's a different issue to look into, not radon.
Question linkRadon risk is about cumulative exposure - the combination of concentration and time. Living in a home with elevated radon for years or decades represents meaningful cumulative exposure. Short exposures are less concerning than long-term habitation. This is why testing the home you live in - not just the one you're buying - matters. Radon is the second-leading cause of lung cancer in the U.S. after smoking.
Question linkYou shouldn't panic, but you should act. 8.0 pCi/L is well above the EPA action level of 4.0 pCi/L, and it warrants getting a mitigation system installed. The good news is that mitigation works - properly installed systems routinely reduce levels by 80-99%. The risk was accumulating before you knew, but now you know and can fix it. That's what the testing system is designed for.
Question linkYes. Radon and smoking are a particularly dangerous combination. Radon significantly increases lung cancer risk in smokers - the two exposures together are synergistic, not just additive. If you smoke and have elevated radon in your Illinois home, that's a situation to address with real urgency on both the radon side and the smoking side.
Question linkAt 5.2 pCi/L you're above the EPA action level, and with children in the home, acting on this is the right call. Children breathe more air relative to their body size and spend a lot of time in the home - cumulative exposure adds up. Get a mitigation system installed and re-verify with a post-mitigation test. This is a problem you can solve completely.
Question linkThe same biology applies - radon exposure in enclosed spaces with elevated levels represents radiation exposure over time. Pet health from radon isn't as well studied as human health, but the physics of radon decay and lung exposure are the same. If you have elevated radon and pets that spend time in the lower levels of your home, that's another reason to address it.
Question linkRadon risk is about cumulative exposure over time. If you've been in a high-radon home for years, some exposure has occurred, but you can't change that now. What you can change is future exposure - get the system installed and bring levels down. For concerns about health impacts from past exposure, that's a conversation to have with your doctor.
Question linkIt's worth mentioning, especially if you've lived there for a significant time or if levels were very high. Radon is a recognized lung cancer risk factor, and your doctor may factor it into their assessment of your history. Radon doesn't cause symptoms your doctor can observe, but knowing your exposure history is useful context for long-term health monitoring.
Question linkRadon enters from the ground and is typically highest in the lowest levels of the home. But it distributes through the air in the home over time, so upper floors can have elevated radon too - just usually lower than the basement. The official test for real estate is placed in the lowest livable area, but radon isn't strictly "just a basement problem."
Question linkIf you're in northern Illinois - especially the collar counties - a continuous monitor gives you ongoing visibility into your radon levels rather than a one-time snapshot. Monitors like Airthings or Ecosense RadonEye let you see how levels change with season, weather, and changes to your home. For a high-radon region like much of Illinois, that ongoing awareness is genuinely useful.
Question linkAirthings monitors are generally considered reasonably reliable for consumer use. For highest confidence, you can run a concurrent short-term professional test alongside your Airthings to compare results. If the two are in the same general range, that's a good sign. For official purposes - real estate transactions, post-mitigation verification - a licensed professional test is still required.
Question linkThe EPA recommends testing every two years. In Illinois's high-radon counties, testing regularly makes sense because conditions can change - soil settling, new cracks in the foundation, changes in home use patterns. Two years is a reasonable interval; once a year if you want more frequent reassurance.
Question linkShort-term charcoal canister kits from reputable sources are a reasonable starting point for your own awareness. They won't satisfy Illinois real estate requirements - for that you need a licensed professional - but for personal knowledge they can give you useful directional information. Follow the instructions carefully, including the closed-building conditions requirements.
Question linkDaily variation in radon levels is normal. Barometric pressure changes, temperature differences between inside and outside (especially relevant in Illinois winters), wind patterns, and ventilation habits all affect how much radon enters the home on a given day. Looking at the rolling weekly or monthly average on your Airthings gives a better picture than any single day's reading.
Question linkFor the most relevant reading relative to Illinois testing standards, the basement is the more important location - especially the area you spend the most time in. If you have a finished basement where family members spend time, monitoring there tells you the most about exposure. Many monitors let you check multiple areas over time.
Question linkIllinois averages run higher than many states. Statewide, a meaningful percentage of homes - estimates from testing data often run 30-40% - come in above the EPA action level of 4.0 pCi/L in the collar county region. Average levels in northern Illinois homes without mitigation are often in the 3.0-6.0 pCi/L range. Even so, individual homes vary enormously - testing is the only way to know yours.
Question linkA properly installed and functioning mitigation system in Illinois typically brings levels below 2.0 pCi/L, and often below 1.0 pCi/L. The goal isn't to hit a specific number - it's to get as low as reasonably achievable. Most licensed Illinois mitigation contractors expect to bring you below 2.0 pCi/L at minimum. If your post-mitigation result is still above 4.0 pCi/L, the system needs adjustment.
Question linkSeveral factors converge in an Illinois winter to push radon higher. Homes are sealed up tight against the cold, reducing natural ventilation. The stack effect - warm indoor air rising and creating suction at the foundation - is strongest during cold snaps. Frozen or snow-covered ground can also trap radon in the soil and force it into the home. Winter readings in Illinois homes are often the highest of the year.
Question linkBarometric pressure drops before and during storms, which reduces the atmospheric pressure that partially counteracts radon's tendency to move from high-pressure soil into lower-pressure indoor air. When pressure drops, radon entry increases. It's a well-documented phenomenon - radon monitors in Illinois often show spikes corresponding to storm systems moving through.
Question linkYes, temporarily. Opening windows increases air exchange and dilutes radon indoors. But this is temporary - close the windows and levels return. Ventilation is not a long-term radon solution for an Illinois home with elevated levels. It doesn't address the source; it just dilutes what's already come in. A mitigation system addresses the source by preventing entry.
Question linkYes. Radon in Illinois homes typically peaks in fall and winter when homes are sealed and stack effect is strongest, and tends to be lowest in summer when ventilation is higher. This seasonal variation is why testing in multiple seasons, or using a continuous monitor, gives a more complete picture than a single short-term test.
Question linkThat's a smart instinct. Summer tests with open windows or in milder conditions can underestimate your annual average exposure. Running a long-term test (90 days or more) gives the best picture of your actual year-round average. If you want to check winter specifically, testing between October and March in a sealed house gives a representative look at your worst-case season.
Question linkFor a real estate transaction, you test when the deal is happening. For personal monitoring, fall and winter tests in Illinois tend to capture higher readings because of closed homes and stack effect - which makes them useful for understanding worst-case exposure. Long-term tests that span multiple seasons give the most accurate picture of average annual exposure.
Question linkWeather during the test period can influence radon levels - pressure changes, storms, and temperature swings all have short-term effects. This is part of why closed-building conditions and a minimum 48-hour duration are required for real estate tests - to reduce the impact of short-term weather anomalies. Longer tests average out more weather variation.
Question linkThat advice prioritizes their timeline over your health and information. Illinois is a high-radon state in many areas, and the radon test exists for a reason. If something comes up after closing - elevated radon you didn't know about - you've lost your negotiating leverage. Don't skip the test to speed up a deal. It takes 48 hours and it's worth knowing.
Question linkIt's a start, but you want to verify the system is still working. Request the documentation: the original test, installation records, and post-mitigation test results. Then do a current test - or at minimum use the post-mitigation result if it's recent - to confirm the system is still performing. Systems can deteriorate over time.
Question linkIllinois rules generally require a fresh test for a real estate transaction - an old result, particularly one more than a year old, typically isn't acceptable. The point is to know the current status of the home, and conditions can change. A fresh test conducted by a licensed professional during the current transaction is the standard.
Question linkPlacement affects results. Illinois protocols specify where the test device should go - lowest livable area, away from drafts and high humidity. If you have reason to believe the device was placed incorrectly, raise the concern with your real estate agent and the testing professional. A test with questionable placement may need to be redone.
Question linkSome licensed Illinois radon measurement professionals offer faster turnaround - some electronic monitoring devices can provide results within 48 hours without the lab shipping time required for charcoal canisters. Discuss timeline with your testing professional upfront. Even at rush speed, the minimum 48-hour test period is non-negotiable under Illinois rules.
Question linkConsumer monitors like Airthings aren't typically accepted as the official test for Illinois real estate transactions. The official test needs to be conducted by a licensed radon measurement professional using approved devices. The buyer's monitor can give them additional information, but it doesn't substitute for the licensed professional test.
Question linkNo. Radon is house-specific. Your home's radon levels depend on the soil directly beneath it, your specific foundation type, the pressure dynamics in your particular structure, and many other factors unique to your home. Your neighbor's result - whether low or high - tells you nothing about what's happening in your home.
Question linkIt's a significant gap in information. If you've been living in a home with elevated radon for 20 years in Illinois, that's 20 years of cumulative exposure you didn't have visibility into. The right move is to test now - even if you can't undo the past, you can change what happens going forward. And if levels are elevated, a mitigation system can resolve it quickly.
Question linkTerrain influences how pressure dynamics work around a home, but it doesn't reliably predict radon levels. Hilltop homes can have elevated radon; valley homes can have low radon. The soil and geology directly beneath your specific foundation are more predictive than topography. Testing is the only reliable answer.
Question linkSome home inspectors in Illinois include radon testing and some don't - it depends on whether the buyer requested it. If your inspection report doesn't mention radon, it likely wasn't tested, not that it was tested and found to be low. Check with your inspector, and if no test was done, arrange one.
Question linkHome inspectors know construction and systems - radon expertise is a different specialty. A statement that radon "isn't common in your neighborhood" isn't backed by testing data on your home. In northern Illinois especially, radon varies dramatically house by house, sometimes on the same street. The inspector's observation isn't a substitute for a test.
Question linkThe standard approach is to test the lowest livable area - typically the basement. This is where radon levels are highest and where the most relevant exposure typically occurs. You can test upper floors too, but the basement reading is the controlling factor. If your basement is unfinished and unused, testing the lowest floor where you spend time is the right approach.
Question linkYes, absolutely. Ask whether they build with radon-resistant new construction (RRNC) features - a sub-slab gravel layer, a plastic vapor barrier, and a passive PVC pipe routed to the roof. Many Illinois builders in high-risk areas include these as standard; some do it only on request. Even with RRNC features, plan to test the home after it's built. Passive systems often need to be activated to be fully effective.
Question linkA passive radon pipe is a start, not a solution. Passive systems reduce radon somewhat but often don't bring levels down enough on their own. You should test the home and, if levels are above 4.0 pCi/L (or in the 2.0-4.0 range and you want to reduce further), a fan can be added to the existing pipe to convert it to an active system. The pipe is an asset; whether it's enough depends on your actual test result.
Question linkBasement renovations can disturb the sub-slab conditions and potentially affect mitigation performance. Changes to floor plans, new penetrations, sealing or opening areas - all can interact with the mitigation system. It's worth testing after a major basement renovation to confirm levels are still in check, and talking to your mitigation contractor before the renovation about how to protect the system.
Question linkYes. Adding living space in the basement - especially a bedroom where someone sleeps - increases your household's cumulative radon exposure if levels are elevated. Sleeping in a high-radon space is a significant exposure because you're there for 7-8 hours straight. Retest after the renovation to make sure the basement levels are acceptable.
Question linkFive years is long enough that a lot can change - settlement cracks in the foundation, changes in how you use the home, changes to the HVAC system, or just natural variation in soil conditions. The EPA recommends retesting every two years. Five years out from a last test, retesting is the right call.
Question linkNo. Radon is colorless, odorless, and tasteless. There are no symptoms, no smells, no visible signs. The only way to know whether your Illinois home has elevated radon is to test it. This is why the testing infrastructure exists - there's genuinely no substitute.
Question linkSeveral things can cause a meaningful increase between tests: new cracks in the foundation, changes in how the home is used or ventilated, HVAC modifications, basement work that disturbed the soil or slab, or even just the test being done in a different season. An increase from 1.8 to 4.3 pCi/L is significant and worth investigating. If you have a mitigation system, have it checked. If you don't, now is the time to get one.
Question linkAt 2.6 pCi/L you're below the EPA action level of 4.0, but the EPA explicitly notes that levels between 2.0 and 4.0 pCi/L are worth considering mitigation - the risk is real, just lower. Whether to mitigate at 2.6 pCi/L is a personal decision. Some people choose to address it; others decide to monitor and act if levels rise. If you want to talk through what that level means for your specific situation, give us a call.
Question linkA well-designed mitigation system in Illinois can typically achieve levels below 1.0 pCi/L in most homes, and sometimes significantly lower. The practical floor is close to outdoor air radon levels, which average around 0.4 pCi/L nationwide. Getting below 2.0 pCi/L is the common goal; getting below 1.0 pCi/L is achievable in many homes with good sub-slab conditions.
Question link0.8 pCi/L is an excellent result. That's below typical outdoor average levels, which is about as good as you can achieve. The mitigation system is performing very well. Keep the system running, check the manometer periodically, and retest every couple of years to confirm it's maintaining that performance.
Question linkA home with a professionally installed and verified mitigation system has a known radon history - someone identified the problem and resolved it. That transparency is actually a positive attribute. A home without any radon testing history is an unknown. If all else is equal, the documented-and-resolved option is preferable to the unknown. But don't let radon alone drive the decision - test the other home too.
Question linkWe work in the Chicagoland area and have years of experience with the radon situations Illinois homeowners face - the collar county geology, the real estate transaction requirements, the post-mitigation testing process. If you have a question about your specific situation - whether it's a test result you're trying to interpret or a system you need installed - call or text Bill and we can talk through what the numbers mean for you.
Question linkConstruction next door can disturb soil and temporarily change pressure dynamics in the ground around your home. Some homeowners do see temporary radon spikes during neighboring excavation or foundation work. Running a monitor during the construction period is a reasonable way to watch for changes. Once the work is done and the ground settles, any disruption typically resolves.
Question linkRadon is unit-specific - it comes from the soil beneath each unit's foundation. Shared walls don't typically allow radon to pass from one unit to another in meaningful quantities. Each unit in a duplex should be tested independently. Your neighbor's result doesn't predict yours.
Question linkIf your properties are in northern Illinois collar counties or other high-radon areas, testing each one is worthwhile. Elevated radon is a material condition that affects habitability, rental value, and future sale negotiations. Knowing the radon status of each property in your portfolio - and having documentation - is a reasonable part of property management in a high-radon state.
Question linkHVAC systems don't create radon, but they can distribute it through the home and affect indoor pressure dynamics in ways that influence radon entry. A return air duct in the basement can draw radon from that space and circulate it through the home. Some mitigation strategies account for HVAC interaction. A licensed mitigation contractor can evaluate how your system is affecting radon distribution.
Question linkFireplaces can create negative pressure inside a home - drawing outside air in to feed combustion - which can also pull more soil gas including radon into the space. Homes with frequently used fireplaces and tight insulation can see elevated radon during operation. It's another factor in a home's overall pressure dynamics, which a mitigation system addresses by creating controlled sub-slab depressurization.
Question linkYes, it can. Tightening a home's envelope reduces natural air exchange, which means radon that enters accumulates to higher concentrations instead of being diluted by outdoor air. It's a common pattern - homeowners insulate and seal for energy efficiency and then discover their radon levels have risen. If you're doing energy efficiency improvements in an Illinois home, add a radon test to the follow-up checklist.
Question linkNew windows and doors improve the air seal on your home, which can raise indoor radon levels by reducing ventilation. It's a sensible follow-up test after significant weatherization work. The change in radon levels from window replacement alone is usually modest, but combined with other sealing, it can add up.
Question linkYes. Spray foam insulation significantly improves air sealing and can meaningfully raise indoor radon levels by reducing the natural air exchange that was previously diluting radon. This is a well-documented effect. Retesting after spray foam installation in an Illinois basement is the right thing to do - especially if you're in a high-radon county.
Question linkMobile and manufactured homes can have elevated radon, though the dynamics differ from site-built homes. A mobile home on a full foundation behaves more like a conventional house. One on a pier-and-beam system with an open crawlspace may ventilate more naturally but can still have elevated radon depending on the soil below and the floor construction. Testing is the right approach regardless of home type.
Question linkIllinois radon licensing and testing rules are primarily structured around residential real estate, but commercial buildings - especially those with occupied below-grade spaces - can have radon issues too. There isn't a blanket statewide mandatory testing requirement for all commercial buildings, but employers in Illinois have general duty obligations around workplace health. Building owners and tenants in high-radon counties should be aware of the issue.
Question linkIllinois doesn't typically require sellers to test before listing - the testing requirement is more commonly triggered during the transaction, often by the buyer during the inspection period. However, many Illinois sellers proactively test before listing because it allows them to address issues before buyers do and avoids surprises during negotiations. It's not legally mandated pre-listing but is practically useful.
Question linkYou should keep the original radon test report (pre-mitigation), the mitigation system installation documentation from the contractor, and the post-mitigation test result from the independent licensed tester. If you've done subsequent retests, keep those too. This file of documentation is what you'll need to present to buyers if you sell, and it's your record that the system was properly installed and verified.
Question linkStart by contacting the mitigation company that did the installation - they may have records. The independent tester who did the post-mitigation test will also have their results on file. If the mitigation was done as part of a real estate transaction, the real estate records or the title company may have copies. In a pinch, a current test run by a licensed professional can establish the present-day status, even without historical records.
Question linkRun a current test with a licensed Illinois radon measurement professional. If levels are below the action level, that becomes your current documentation. If levels are elevated, the system may need maintenance or adjustment. Either way, having a current licensed test result is what matters to buyers - the historical installation records are useful but a current verified result is what closes the information gap.
Question linkRadon is a naturally occurring radioactive gas that comes up from the soil and can accumulate in homes. You can't smell, see, or taste it. In Illinois - especially in the Chicago-area collar counties - it's a genuine concern because of the local geology. It's absolutely something first-time buyers should address during the home inspection process. The test is simple, inexpensive, and gives you important information before you commit.
Question linkYes, significantly. Working from home in a basement in Illinois means spending potentially 8+ hours per day in the space most likely to have elevated radon. That's substantially more exposure than someone who only passes through the basement occasionally. If you have a home office in an Illinois basement, testing is especially important and addressing elevated levels is a higher priority.
Question linkYes. Older adults who spend most of their time at home - including significant hours in lower levels - accumulate more cumulative radon exposure than someone away at work all day. The health concern is the same (long-term lung cancer risk from cumulative exposure), but the time-at-home factor makes awareness more important. Testing and, if needed, mitigation is a practical way to protect someone who spends a lot of time in the home.
Question linkRadon is a long-term lung cancer risk from cumulative radiation exposure - it doesn't cause acute birth defects or pregnancy complications the way some chemical exposures might. Even so, this is a health question for your OB or midwife. What you can do right now is get the mitigation process started so radon levels are reduced as quickly as possible. Increasing ventilation temporarily (opening windows when weather allows) can modestly reduce levels while you wait for mitigation.
Question link12 pCi/L is significantly elevated - three times the EPA action level. This is a home that needs a mitigation system promptly. The good news is that at 12 pCi/L, a well-installed mitigation system will produce a dramatic, visible improvement - systems routinely bring levels like this down below 2.0 pCi/L or lower. It's a fixable problem, and fixing it matters. If you want to talk through next steps, give us a call.
Question linkCracks in older slabs create more direct pathways for radon to enter from the soil beneath. An older, cracked slab isn't automatically a warranty of high radon - it depends on the soil conditions - but it is a risk factor. Mitigation through sub-slab depressurization works effectively on older slabs; the cracks don't prevent the system from working, and in some cases they make the sub-slab easier to depressurize.
Question linkPassive solar homes in Illinois often have significant concrete slab construction and may be designed for very low air exchange, which can contribute to radon accumulation. The thermal mass itself doesn't generate radon, but the tight building envelope and slab construction are factors. Testing is especially important in a tight, energy-efficient home - the same features that make it efficient can concentrate indoor pollutants including radon.
Question linkAn attached garage can be a radon entry point if it has a slab-on-grade floor and shares connections with the living space. Radon that enters the garage can migrate into the house through shared walls, doors, or HVAC connections. Illinois homes with attached garages where the garage connects to the basement or lower level should include the garage in their radon awareness. It's one more entry pathway to account for.
Question linkWalk-out basements have at least one wall fully above grade with exterior exposure, which can help with ventilation - but it doesn't eliminate radon risk. The slab and the below-grade walls are still in contact with soil, and radon still enters through those surfaces. Walk-out basements in Illinois high-radon counties have elevated radon plenty often. Testing is still necessary.
Question linkBoth matter, but for different reasons. The basement level is where radon enters and is typically highest - this is the controlling reading for whether you need mitigation. The first-floor level tells you how much radon is reaching your primary living space. For official testing purposes, the lowest livable area is the standard test location. For your own awareness, knowing both levels gives you a fuller picture.
Question linkNo. Radon is odorless, and the mitigation system removes it from beneath the slab before it enters the home. The system itself - a fan, pipe, and discharge point - doesn't introduce any odors. In fact, some homeowners notice a slight reduction in musty basement smells because the same depressurization that removes radon also removes other soil gases. But you won't smell the radon going away.
Question linkThe best framing is this: radon is the second-leading cause of lung cancer in the United States, behind smoking - that's not a small thing. It comes up through the soil into homes all across Illinois, particularly in the northern counties. It's colorless, odorless, and you can't detect it without testing. The EPA recommends fixing any home above 4.0 pCi/L, and in Illinois a significant percentage of untested homes are above that level. Testing takes 48 hours and costs very little. The risk is real, the fix works, and the test tells you where you stand.
Question linkRadon is classified as a Group 1 human carcinogen by the International Agency for Research on Cancer. The EPA, the Surgeon General, and the World Health Organization all recognize it as a serious health concern. The science behind radon - uranium decay, radon-222, alpha particle radiation in lung tissue - is well-established physics and biology. Testing and mitigation is a legitimate public health intervention, not a sales scheme. The proof is in the post-mitigation test - an independent tester verifies the system actually works.
Question linkYes. The EPA action level of 4.0 pCi/L is the recommended threshold for action, and 4.1 pCi/L is above it. "Just barely over" still means you're above the guideline. Mitigation at this level will work, and the result will likely come down to well below 2.0 pCi/L. The EPA guideline isn't a cliff edge - it's a practical marker for when action makes sense, and 4.1 pCi/L clears that marker.
Question linkThe World Health Organization does recommend a reference level of 100 Bq/m³ (approximately 2.7 pCi/L), which is lower than the EPA's 4.0 pCi/L action level. In practice, Illinois uses the EPA standard. If you want to be conservative and follow the WHO guidance, that's a reasonable personal decision - mitigation at 2.7 pCi/L is perfectly feasible. The point is that no level is risk-free; the thresholds are just practical guides for action.
Question linkHistoric designation can impose restrictions on exterior modifications - including where mitigation pipes and fans are routed and how visible they are from the street. A licensed mitigation contractor with experience in homes can design a system that meets performance standards while working within the aesthetic requirements of your historic district. It requires some creativity but is routinely done.
Question linkTest the home after you've been living in it for a few months with normal occupancy patterns. If the passive system is keeping levels below 2.0 pCi/L, it may be sufficient. If levels are above 4.0 pCi/L - or in the 2.0-4.0 range and you want to reduce further - a fan can be added to the existing pipe to convert it to an active system. The pipe the builder installed is the foundation; whether a fan is needed depends on your test result.
Question linkThe Illinois Department of Public Health tracks cancer incidence data including lung cancer rates, and radon is recognized as a contributing factor in lung cancer statistics statewide. The correlation between high-radon counties and lung cancer rates in Illinois has been studied. This data is one of the reasons Illinois invested in its state radon program - the public health impact is real and documented.
Question linkRadon levels fluctuate throughout the day - they tend to be higher at night and in the early morning when homes are closed and ventilation is lower. However, for real estate and formal testing purposes, the test runs for at least 48 hours to average out these daily fluctuations. There's no specific start time that's required. For personal continuous monitors, looking at rolling averages rather than any single hour gives a more useful picture.
Question linkQuestions are fine too. Call or text Bill, or send your address and contact info, and he will take it from there.
Reviewed by Bill Dahlstrom, Illinois radon mitigation license RNM2018212.