How soon can I test after mitigation?
Most contractors recommend waiting at least 24 hours after the system is turned on before starting a post-mitigation test. The reason is the system needs a little time to depressurize the soil and let things stabilize. A 48-hour short-term test or a 90-day long-term test will both give you a valid baseline, and many pros prefer the longer test because it captures more variation. Don't try to test the same day the fan gets switched on - you won't get a meaningful number.
Question linkMy contractor just left and the fan is on. Can I start my test kit tonight?
Give it at least 24 hours before you crack open that test kit. The system is still pulling equilibrium in the soil underneath your slab or crawl space. Starting a test too soon can give you an artificially low reading that doesn't represent steady-state conditions - or in some edge cases, a temporarily elevated one. Wait a full day, then start the test.
Question linkHow long should I wait before doing my post-mitigation radon test?
The EPA says at least 24 hours after installation before starting a short-term test. In practice, waiting 48 hours gives you a little more confidence you're seeing a stabilized reading. If you're doing a long-term test (90 days or more), you can start it within a day or two of installation - the longer window averages out any early fluctuations anyway.
Question linkMy mitigation system went in last week. My contractor said to test but didn't say when to open the test kit. Is now okay?
If it's been at least 24 hours since the fan started running, you're fine to open the test kit. The longer you wait from installation day, the more stable the reading will be. A week out is actually a comfortable window - go ahead and start your test.
Question linkWhat happens if I test too early after mitigation? Will the results be wrong?
Testing within the first few hours can give you a number that doesn't reflect how the system actually performs long-term. The sub-slab pressure field is still evening out. Results from a test started very early might read lower or higher than what the system will actually deliver over time. Most labs will still process the test - they just won't flag it - so the number becomes your baseline even if it's a bit off. Waiting 24-48 hours is the safest bet.
Question linkMy mitigation company said they'd come back for a follow-up test in 30 days. But it's been 60 days and I haven't heard from them. Who does the post-mitigation test?
The post-mitigation test can be done by the same contractor or by a separate testing company - it depends on the state and what you agreed to. Some contractors do follow-up testing themselves, others hand it off or expect you to hire someone independently. In Illinois, the post-mitigation test is supposed to be conducted independently of the contractor who did the installation. Either way, if 60 days have passed with no follow-up, it's worth making a call to figure out who's responsible for scheduling it.
Question linkIs a 48-hour short-term test after mitigation good enough or should I do a longer test?
A 48-hour short-term test gives you a quick answer, and it's what most people do first. But short-term tests capture a narrow window, and radon fluctuates by season, weather, and how the house is used. A 90-day long-term test after mitigation gives you a much more reliable picture of what you're actually living with. If the short-term test comes back well below 2.0 pCi/L, many people feel comfortable and leave it there. If it's higher or borderline, doing a long-term test is worth the effort.
Question linkMy radon dropped from 6.0 to 0.8 pCi/L in 48 hours after the fan was turned on. Is that real?
Yes, that's real and it's actually a pretty common pattern. A well-installed sub-slab depressurization system can pull radon levels down dramatically in the first 24-48 hours. Going from 6.0 to under 1.0 in that window isn't unusual when the suction point hits a well-connected aggregate layer under the slab. The system is doing exactly what it's supposed to. Even so, run a proper post-mitigation test to confirm the number holds over time - a 48-hour snapshot is encouraging but a full test locks it in.
Question linkShould I close windows and doors while doing my post-mitigation test?
For a valid closed-house short-term test, yes - keep windows and exterior doors closed as much as possible, except for normal entry and exit. This is the standard protocol for short-term testing. It's not meant to make the house airtight like a vault, just to avoid conditions that would artificially pull outdoor air in and dilute the reading. Long-term tests are generally done under normal living conditions.
Question linkMy mitigation was done in December. I tested and got 1.8 pCi/L. My neighbor says winter tests always run higher. Should I retest in summer?
Your neighbor is right that radon tends to run a little higher in winter - closed houses, stack effect, frozen ground - but 1.8 pCi/L is well below the EPA action level even accounting for seasonal variation. If your pre-mitigation level was significantly higher, that result says your system is working. You could retest in summer if you want a second data point, but 1.8 in winter is genuinely a good result and not a cause for concern.
Question linkI got mitigation installed but never got a post-mitigation test. What should I do?
Get one done now, even if it's been a year or two since installation. A post-mitigation test is the only way to confirm the system is actually working. You can order a mail-in test kit, use a licensed testing company, or reach out to whoever did your installation. Better to do it late than not at all - you'll sleep better knowing the number.
Question linkMy post-mitigation test kit sat on my counter for a week before I opened it. Does that ruin the results?
Unopened test kits are generally fine sitting on a shelf for a while - the charcoal inside is sealed. Once you open it, the 48-96 hour exposure clock starts. So if the kit was sealed and you just haven't deployed it yet, you're fine. Just open it and place it in the lowest livable level of the home now. If it was already open and sitting out, that's a different story - you'd want a fresh kit.
Question linkMy post-mitigation test came back at 2.1 pCi/L. Is that a success?
Yes. The EPA action level is 4.0 pCi/L, and anything below that is a significant improvement if you were over it before. 2.1 pCi/L is a solid result - it's well into a range most people feel comfortable with. The EPA does note that levels between 2.0 and 4.0 pCi/L carry some risk, so it's worth keeping an eye on it over time. But as a post-mitigation result, 2.1 is a real win.
Question linkMy post-mitigation test came back at 4.0 pCi/L exactly. Is the system a failure?
Not necessarily a failure, but it's a result worth paying attention to. The EPA recommends fixing when levels are at or above 4.0 pCi/L, so landing exactly at 4.0 means you're right at that threshold. A single test result can vary a bit based on conditions that week, so I'd recommend doing a second test or a long-term test to get more data. It's also worth having the contractor re-evaluate the system - there may be room to improve suction or address a gap in coverage.
Question linkMy radon is still 3.8 after mitigation. Is the system working?
The system is probably working - 3.8 is below the EPA action level of 4.0 - but it's not a result to just accept and move on from. The EPA says levels between 2 and 4 pCi/L are worth considering further action on because the risk is real, just lower. If your pre-mitigation level was 8 or 12 pCi/L, then getting to 3.8 is meaningful progress. But there may be room to optimize - a second suction point, a higher-capacity fan, sealing cracks - that could bring it down further. A follow-up conversation with whoever did the installation is worth having.
Question linkMy pre-mitigation radon was 12 pCi/L and my post-mitigation test shows 3.2. Is that good enough?
Getting from 12 down to 3.2 is a massive reduction and the system is clearly working. Whether 3.2 is "good enough" is a personal decision - you've eliminated the majority of the risk. The EPA says 2.0-4.0 is a range worth continuing to think about. Some people stop there; others ask their contractor if there's a way to squeeze it down to 1-2 pCi/L. Either choice is reasonable. The important thing is you didn't stay at 12.
Question linkMy post-mitigation test came back at 1.4 pCi/L. How do I know that's not just the outdoor air level?
Outdoor air averages around 0.4 pCi/L nationally, so 1.4 indoors is above that, but it's a very low level for indoor radon and generally considered a great result post-mitigation. Your system is very likely responsible for keeping it that low. You don't need to try to subtract out outdoor radon - just take the 1.4 as your indoor reading. It's a good number.
Question linkMy neighbor's mitigation brought them to 0.4 pCi/L but mine only went to 2.2. Is something wrong with my system?
Not necessarily. Every house is different - soil composition, slab type, foundation cracks, aggregate depth, and where the suction point was placed all affect final results. 2.2 pCi/L is a solid post-mitigation result. Your neighbor getting to 0.4 is great for them, but it doesn't mean your system is underperforming. If you were above 4.0 before and you're at 2.2 now, the system is doing its job. If you want to chase a lower number, it's worth talking to your contractor about whether there's a way to improve it.
Question linkHow do I know if my post-mitigation result is real or if the test kit was compromised somehow?
Reputable labs do quality control checks on every batch of test kits, and a blank or clearly anomalous kit gets flagged. Even so, test kits can be affected if they're placed near high airflow (directly next to a vent or fan), exposed to extreme humidity, or if the test cap was missing during the exposure period. If your result seems wildly inconsistent with what your consumer monitor shows or what you expected, running a second test is cheap and a reasonable sanity check.
Question linkWhat counts as a successful post-mitigation test result?
The EPA benchmark is below 4.0 pCi/L, and ideally as close to the outdoor average of 0.4 as reasonably achievable. In practice, most contractors and homeowners consider a result below 2.0 pCi/L a clear success. Below 4.0 is the minimum goal. Between 2.0 and 4.0 is improved but may be worth additional steps. Anything that brought a previously high level down significantly while staying below 4.0 represents a system that's working.
Question linkMy post-mitigation test said 2.8. My contractor said "that's great" but I feel uneasy. Should I be?
Your unease is understandable - 2.8 is below the EPA action level but it's not zero. Your contractor is right that it's a solid result. The EPA does acknowledge that any radon level above the outdoor average carries some risk, and levels between 2.0 and 4.0 are in a zone where continued attention makes sense. Retesting in a year, keeping the fan running, and not letting the system go unmonitored are all smart moves. 2.8 post-mitigation isn't alarming, but staying aware is the right instinct.
Question linkI did two post-mitigation tests at the same time in the same room and got 1.9 and 2.6. Which one is right?
Both are probably right - or more accurately, both are measuring different moments in time, and radon fluctuates. Consumer-grade test kits have some margin of variability, and even lab-processed charcoal canisters have a testing range. The average of 1.9 and 2.6 is about 2.25, which is what I'd use as your working number. The fact that both are well below 4.0 pCi/L is the key takeaway.
Question linkMy post-mitigation result came back at 0.9 pCi/L. I feel like that's too good to be true. Can I trust it?
It's not too good to be true - results below 1.0 pCi/L are genuinely achievable after mitigation, especially in houses with good sub-slab aggregate and a well-placed suction point. Near-outdoor levels are the target, and 0.9 pCi/L is right in that zone. Trust the result, especially if it came from an accredited lab. Cross-check it against your consumer monitor if you have one, and if they're roughly consistent, you've got your answer.
Question linkMy radon has been 1.0 pCi/L for 3 years since mitigation. Is an annual test necessary?
At 1.0 pCi/L with three years of consistent readings, you've got good data on your side. The EPA recommends retesting every two years when a system is installed, so you're actually ahead of schedule. Annual testing at that level is optional - it's not going to hurt, but many people in your situation test every other year and that's reasonable. The main thing is keeping the fan running and not letting years go by without any check at all.
Question linkMy mitigation system has been running for 5 years. When should I retest?
If you haven't tested in the past two years, now is a good time. The EPA recommends retesting every two years when a mitigation system is in place. Fans can wear down over time, soil conditions can shift, and new cracks can develop in a foundation. A fresh test every couple of years tells you the system is still delivering. A long-term test is ideal, but a short-term test gives you a current snapshot if you want a faster answer.
Question linkI've been testing every year since mitigation and the results always come back around 1.5. Can I slow down how often I test?
At consistently 1.5 pCi/L over multiple years, you have strong evidence your system is performing well. The EPA's guidance for homes with mitigation systems is to retest every two years. You could reasonably move to that schedule. If your monitor goes below what it had been or something changes in the house - renovation, new addition, foundation crack - bump the testing back up.
Question linkMy radon went from 8.4 before mitigation to 1.7 after. My wife wants to test every 6 months. Is that overkill?
It's not overkill from a safety standpoint - more data is always informative. But from a practical standpoint, if you consistently come back at 1.7 or lower, every six months gives you confidence without adding a lot of new information. The EPA says every two years for a system in good repair. If it makes your wife feel better to test more often, there's no harm in it. A continuous consumer monitor might actually be more useful than frequent lab tests - it shows you daily trends without the per-test cost.
Question linkMy Airthings dropped immediately after mitigation. Do I still need a professional post-mitigation test?
Yes, you still want a professional test. Your Airthings is a continuous consumer monitor and it's great for real-time trending, but it hasn't been calibrated to a national standard the way a lab-processed charcoal canister or electret has. A licensed post-mitigation test is your official documentation that the system works - it's what lenders, buyers, and state programs often require. Use the Airthings to watch the trend; use the licensed test as your record.
Question linkMy Airthings shows 1.2 pCi/L after mitigation. Should I be confident it worked?
1.2 pCi/L on an Airthings is a very encouraging sign. Consumer monitors are useful for tracking trends and getting a daily read on your home's radon level. The caveat is that these devices can read a bit higher or lower than a licensed test under some conditions. If you want confidence you can put in a file and show a future buyer, run a licensed test alongside it. But 1.2 on the Airthings? The system is almost certainly working well.
Question linkMy radon fan is on but the consumer monitor shows 3.5 pCi/L. Should I call someone?
Yes, that's worth following up on. 3.5 pCi/L is below the EPA action level of 4.0, but it's higher than you'd want to see after a mitigation system has been running for a while. A few things could be going on: the suction point may not be reaching all the soil under your slab, there may be a pathway the system isn't addressing, or the monitor may need to be moved (away from vents, corners, or areas with high airflow). Give the contractor a call and share the numbers. It may be a simple fix or an adjustment.
Question linkCan I rely on my continuous radon monitor instead of doing periodic lab tests?
Consumer monitors give you valuable ongoing data, and they're better than nothing between formal tests. But they're not a substitute for periodic licensed testing. Monitors can drift over time, react to humidity or temperature differently, and aren't held to the same calibration standards as lab tests. Use the monitor to watch for trends and get early warning of problems; use licensed tests every two years to confirm the system is still delivering.
Question linkMy Airthings is reading 0.5 pCi/L post-mitigation. Is it even accurate at that level?
Consumer monitors at the low end of their range have more relative variability - at 0.5 pCi/L, you're close to the background detection floor for many devices. The reading is probably approximately right, but don't put too much precision on the exact decimal. What it's telling you is that your radon is low - near outdoor levels. That's the signal that matters. A licensed test would confirm it with better precision if you want documentation.
Question linkHow long does my Airthings or RadonEye take to stabilize after I move it to a new location or after mitigation?
Most continuous monitors need 24-72 hours to produce a reliable reading after being moved or after significant changes in the environment. The first few hours after placing a monitor in a new spot (or after a mitigation fan kicks on) can show fluctuating numbers as the device samples air that's still changing. Wait at least 24 hours before reading the number as meaningful, and 48-72 hours before drawing conclusions about whether mitigation is working.
Question linkMy continuous monitor shows radon spiking every night and dropping during the day after mitigation. Is the system failing?
Not necessarily failing - diurnal variation in radon is normal. Radon tends to be higher at night and in early morning because the house is closed up, there's less air exchange, and temperature differences across the slab can affect soil gas movement. A mitigation system reduces overall levels but doesn't eliminate the daily pattern. What matters is whether the average is staying well below 4.0 pCi/L. If the nighttime spikes are pushing above 4.0 consistently, that's worth a look.
Question linkMy Airthings shows 2.5 and my lab test came back at 1.7. Which one should I believe?
Both are probably capturing something real - they're just measuring different time windows under different conditions. Lab tests average what happened over 48-96 hours under the specific conditions of that test. Your Airthings is giving you a rolling average that includes more variation. A difference of 0.8 pCi/L between the two isn't alarming - it's within the expected range of variability. Take both numbers as useful data points rather than trying to pick a winner.
Question linkI have a RadonEye and an Airthings in the same room and they're reading differently. Which one do I trust after mitigation?
Consumer monitors from different brands often read differently from each other - that's a known quirk of the category. Neither one has been calibrated to a reference standard in the field. The more useful thing to look at is whether both are trending in the same direction - if both came down after mitigation was installed, the system is working regardless of which number is "right." If they're diverging over time, one of them may be drifting. A licensed test tells you what the actual level is.
Question linkMy Airthings app shows a color chart and mine is showing green after mitigation. Is green "safe"?
Airthings uses a green/yellow/red color coding that roughly corresponds to below 2.0 / 2.0-4.0 / above 4.0 pCi/L. Green means you're below 2.0 on their scale, which is a solid result. The word "safe" is tricky with radon - any level carries some small risk - but green on the Airthings post-mitigation is the outcome you're looking for. Keep the fan running and retest with a licensed lab every couple of years.
Question linkMy Airthings keeps giving me hourly readings of 0.0 pCi/L after mitigation. Is it broken?
At very low radon levels, some consumer monitors hit their detection floor and display 0.0 or rounds down. It doesn't necessarily mean the monitor is broken - it may just mean the radon in your home is so low the device can't measure it with confidence. That's actually a good sign post-mitigation. If you're concerned about the monitor's function, move it to an unmitigated basement or area for a few days and see if it picks up a reading there. If it reads zero everywhere including before mitigation was done, then yes, it may need a reset or replacement.
Question linkShould I move my Airthings after mitigation is installed, or leave it in the same spot I used it before?
Keep it in the lowest livable level of the home - the same general placement guideline applies before and after mitigation. Keeping it in the same spot lets you make a direct before-and-after comparison, which is the most useful data. Don't place it right next to the suction pipe, the floor, or directly under a vent - those locations can give artificially skewed readings.
Question linkWhat is the manometer gauge on my radon system?
The manometer is a simple pressure gauge - usually a U-shaped tube with colored fluid inside - mounted on the pipe of your radon mitigation system. It tells you at a glance whether the fan is creating suction under your slab or in your crawl space. When the fan is running and pulling a pressure differential, the fluid shifts to one side of the tube. It's a visual indicator you can check without any tools or testing.
Question linkHow do I read the U-tube manometer on my radon system?
Look at the two columns of fluid in the U-tube. When the system is working correctly, the fluid will be higher on one side than the other - the side connected to the suction pipe (the lower-pressure side) will show a higher fluid column because the fan is pulling a vacuum. The amount of difference tells you the rough pressure differential the system is maintaining. Fluid displaced about an inch or more on one side is a normal operating sign. Fluid sitting perfectly level means no pressure differential - the fan may not be running.
Question linkThe fluid in my manometer looks level. Is my fan on?
If the fluid in both sides of the U-tube is sitting at the same level, that usually means there's no pressure differential being created - which suggests the fan may not be on, or it's not pulling effective suction. First, check that the fan is plugged in and the circuit breaker hasn't tripped. If the power is confirmed on and the fluid is still level, the fan may have failed or there may be a break in the pipe. This is worth investigating before you assume the system is working.
Question linkMy manometer shows no movement. Does that mean the system isn't working?
Very likely yes. The manometer is designed to show you that the fan is pulling a pressure differential through the suction pipe. No movement - fluid sitting level - means either the fan isn't running or there's a break or obstruction in the system that's preventing suction from reaching the gauge. Check your electrical first. If the fan sounds like it's running but the fluid is flat, there could be a problem with the pipe connection or the suction point. Worth a call to your contractor.
Question linkMy manometer fluid is all in one side of the tube. Is that normal or does it mean something is wrong?
Fluid displaced heavily to one side can actually mean the system is pulling very strong suction - or in some cases it means the tube lost fluid or isn't reading correctly. A small-to-moderate displacement (roughly half an inch to an inch or two) is normal operating range. If one column is completely empty and all fluid has gone to the other side, the tube may have lost calibration or the fan is creating more suction than expected. If everything looks and sounds normal otherwise, a strong displacement is generally fine - just check that the tube still has fluid in both sides.
Question linkWhat color is the fluid in a manometer supposed to be?
Most manometers come with red, blue, or clear colored fluid. The color itself doesn't have functional meaning - it's just to make it easier to see the fluid level. Different manufacturers use different colors. If the fluid appears discolored compared to what it looked like when installed, or if it's evaporated significantly, you may want to have it refilled or replaced. Some contractors use colored dye drops in water; others use a proprietary fluid.
Question linkMy manometer fluid is dropping. Does that mean I'm losing suction?
If the fluid level is actually decreasing over time - both sides getting lower - it may be slowly evaporating. Some manometer fluids will evaporate gradually, especially in warm or dry environments. This doesn't mean your suction is dropping; it means the fluid level itself is getting low, which will eventually make the gauge inaccurate. Most contractors can top it off easily. If the fluid shifts to one side it's suction; if both sides drop equally over months, it's evaporation.
Question linkSomeone told me to look at the manometer every month. Is that really necessary?
A monthly glance takes about five seconds and can tell you whether your fan is still running - which makes it worth doing. You don't need to take measurements or log anything. Just look and see if the fluid is still displaced from center. If something has changed - fluid suddenly level, fluid gone, tube cracked - you want to know sooner rather than later. It's the cheapest form of system monitoring there is.
Question linkThe indicator light on my radon fan is red. What does that mean?
Some radon fans include an indicator light or alarm - red typically means a problem, often that the fan has failed or that suction pressure has dropped below a set threshold. Check your fan model's documentation to confirm what the red light means for your specific unit. If the light is red and the manometer fluid is level, that's a strong indicator the system isn't creating the pressure differential it should be. Worth checking the power supply and calling your contractor.
Question linkIs there any electronic monitor I can buy to tell me if my radon fan stops?
Yes. There are radon system alarms designed specifically for this. Some are simple pressure switches that trigger an alarm if suction drops. Some newer fan models have built-in status lights or alerts. You can also use a smart plug with power monitoring to alert you if the fan loses power. These aren't standard on every installation, but they're worth asking about - especially if your fan is in an out-of-the-way location where you wouldn't notice a failure quickly.
Question linkMy mitigation fan is making a new noise. Should I be concerned?
A new noise from a fan that's been running quietly is worth paying attention to. Common causes include: debris pulled into the fan, bearing wear, moisture in the motor housing, or the fan mounting coming slightly loose. Some of these are cosmetic; others can lead to fan failure. If the noise is a rattle, grinding, or high-pitched hum it wasn't making before, it's a good idea to have your contractor take a look rather than waiting for it to stop running entirely.
Question linkMy radon fan is humming louder than it used to. Is that normal aging?
Some increase in noise over years is normal as motor bearings wear. A moderate increase in hum over many years isn't a red flag on its own. But if the change in noise level happened suddenly, or if it's accompanied by vibration, rattling, or a different pitch, that's more likely a sign the fan is reaching the end of its life. Radon fans typically last 10-15+ years, but that's not a warranty, and a loud sudden change in operating sound is worth checking out.
Question linkMy mitigation fan stopped. How do I know when it stopped?
Most people don't know exactly when it stopped - that's one of the arguments for having a manometer or a system alarm. If you notice the manometer fluid is level and the fan isn't audible near the pipe, it may have been off for days or longer. Check the circuit breaker and the outlet first. If power is fine but the fan isn't running, it's likely failed. If you have a continuous radon monitor, look at the historical trend data - you may be able to see exactly when radon started creeping back up.
Question linkMy radon system fan stopped and I don't know how long it's been off. Should I be panicked?
Don't panic - radon is a long-term cumulative risk, not an acute one. A fan that was off for a few days or even a week or two doesn't undo the protection you've had for years. What you want to do is get it restarted as soon as possible. Check the breaker and outlet. If the fan has failed, get it replaced. And once it's running again, consider retesting to confirm levels have come back down. You're not in danger right now - but don't leave it off.
Question linkMy radon system fan runs constantly. Is it supposed to run 24/7?
Yes - radon mitigation fans are designed to run continuously around the clock. They're made for it. Unlike a bathroom exhaust fan or a range hood, these run all day, every day, for years. Turning it off when you're not home or at night is one of the most common mistakes people make. The system needs to maintain continuous sub-slab depressurization to keep radon from building up.
Question linkShould I turn off my radon fan when we go on vacation?
Leave it running. The system needs to keep maintaining negative pressure under your slab the whole time you're away. Coming home to a house that's had the fan off for two weeks means radon has been accumulating and you're walking back into elevated levels. These fans use very little electricity - it's not worth the cost savings to turn one off, and the whole point is to keep the pressure differential constant.
Question linkHow loud should a radon fan be?
Most radon fans are designed to be relatively quiet - you might hear a faint hum or gentle whoosh near the pipe, but you typically shouldn't hear it clearly from across the house or through floors. How loud it is depends on the fan model, where it's mounted, and whether it's inside or outside the conditioned space. Fans on exterior walls with the motor outside tend to be quieter inside the home. If a fan sounds loud from normal living areas, it may be mounted in a location that's transmitting vibration, or it may be a higher-CFM model needed for your foundation conditions.
Question linkI can hear my radon fan but I don't know if it's actually pulling air. How do I check?
The manometer is your first check - if the fluid is displaced from center, the fan is pulling a pressure differential. You can also hold a piece of thin tissue or even a thread near the pipe interior and see if there's airflow. If you have a continuous monitor, compare current readings to what they were before installation. For a more definitive answer, a contractor can measure sub-slab pressure with a gauge to confirm the system is pulling properly.
Question linkHow long do radon mitigation fans last?
Radon mitigation fans are built to run continuously, and quality fans typically last 10-20 years - sometimes more. The most common brands used in the industry come with multi-year warranties (often 3-5 years), and many run well beyond that. But they're electrical motors and they do eventually wear out. Annual visual checks and periodic testing help you catch a failing fan before radon levels climb back up.
Question linkWhen should I replace my radon mitigation fan?
Replace it when it fails, when it starts making abnormal noise that suggests bearing or motor wear, when the warranty is up and you're seeing signs of age, or when a radon test shows levels are rising despite the fan appearing to be on. Many people replace fans proactively at the 10-15 year mark even if they seem to be running - similar to replacing a smoke detector battery before it fails. Don't wait until levels have gone back up.
Question linkMy radon fan warranty says 5 years. Does that mean I should replace it at 5 years?
The warranty covers the manufacturer's commitment to the product for that period - it doesn't mean the fan will stop working at year five. Most fans run well beyond the warranty period. Think of it like a car warranty: the coverage ends at a certain point, not the working life. Even so, once you're past the warranty window, it's smart to pay closer attention to how the fan sounds and to test more regularly so you know if performance is slipping.
Question linkMy radon fan is on the outside of my house and it's been making noise in cold weather. Is that normal?
Some noise change in very cold weather is normal - the motor seals and materials contract slightly, which can affect the sound profile. If it's a seasonal noise that settles down once temperatures moderate, it's likely not a problem. If the noise is persistent or worsening regardless of temperature, or if the manometer shows reduced suction in cold weather, it's worth a look. Some exterior fans are not rated for the extreme cold of certain northern climates, which can shorten their lifespan.
Question linkAfter mitigation, does the fan affect my electric bill significantly?
Radon mitigation fans are typically low-wattage - most range from about 20 to 80 watts. Running one year-round adds up to a modest amount on your electric bill - less than many other always-on devices in your home. It's a real but small ongoing cost, and it's worth it for what the fan does.
Question linkI bought a house with an existing mitigation system. How do I know it's working?
Start with the manometer - look at whether the fluid is displaced, which tells you the fan is creating suction. Then listen for the fan near the pipe. Most importantly, do a radon test. Don't assume the system is working just because it's there. Ask for any testing records from the previous owners. If records aren't available, a fresh test gives you a current baseline for the home as you're living in it.
Question linkThe house I bought had mitigation done 10 years ago but no recent test. Should I retest?
Yes - absolutely. Mitigation systems don't last forever, and a 10-year-old fan with no recent test could be running at reduced capacity or even failed. Soil conditions change, foundations shift, and fans wear out. Get a test done now. If you don't have records of the original post-mitigation test result, a current test is even more important as your baseline.
Question linkMy radon has gone up since mitigation was installed 2 years ago. What happened?
A few things could cause this. The fan could be failing or delivering less suction than it used to. There could be new cracks or pathways in the foundation that the system isn't addressing. The suction point may have lost connection to the aggregate layer it was drawing from. Or - if you've done renovations, added rooms, or changed how the basement is used - the airflow dynamics of the house have changed. Get the system inspected and do a fresh test to see where you stand.
Question linkCan radon come back after mitigation?
Yes - radon can rise again after mitigation if the fan fails, if the system develops a leak or obstruction, if foundation conditions change, or if the suction point loses its effectiveness over time. That's why retesting every two years is the standard recommendation even with a system in place. A mitigation system is not a permanent set-and-forget solution - it needs to be monitored.
Question linkMy mitigation system has been in place for 8 years and I've never retested. Is that bad?
That's too long to go without a check. A lot can happen in 8 years - the fan may have degraded, the foundation may have settled, and the soil conditions under the slab can change. The EPA recommends retesting every two years with a system in place. Get a test done now. If you're at a good level, great - and now you have a current baseline. If levels have crept up, you'll want to know.
Question linkWhat's the difference between a long-term and a short-term radon test, and which should I use after mitigation?
A short-term test runs 48-96 hours and gives you a quick snapshot. A long-term test runs 90 days or more and gives you a time-averaged result that captures seasonal and daily variation. For post-mitigation testing, either works, but long-term tests are often preferred because they smooth out the noise. If you want a fast answer after installation, start with a short-term test. If that looks good, a long-term test in the first 90 days gives you a stronger record.
Question linkShould I retest in the same spot I did my pre-mitigation test?
Testing in the lowest livable area is the standard protocol before and after - so yes, the same general zone. Keeping the test location consistent makes a before-and-after comparison meaningful. Even so, if your basement setup has changed (finished now, or rooms added), aim for the spot that represents how the space is actually used.
Question linkMy mitigation system has been in for 4 years and I just did my second retest. It came back at 1.6 pCi/L. Do I need to do anything?
1.6 pCi/L at four years out is a genuinely good result. Keep the fan running, glance at the manometer occasionally, and retest every two years as the EPA recommends. You're in good shape - this is exactly what a well-functioning mitigation system looks like over time.
Question linkShould I test in winter or summer for the most accurate post-mitigation result?
Either season can give you a valid result, but they'll often give you slightly different numbers. Winter testing tends to produce higher readings because of the stack effect - warm indoor air rising and pulling soil gas in through the slab. Summer testing tends to run a bit lower. If you want the most conservative (and protective) number, test in winter. If you want your best-case scenario, summer. Most experts say testing in two different seasons and averaging the results gives you the truest picture.
Question linkMy friend says I should do a long-term test right after mitigation to avoid gaming the result. Is she right?
She's not wrong - a long-term test right after mitigation captures the real operating average rather than an idealized snapshot under perfect test conditions. Short-term tests are done with closed windows, which doesn't represent how most people live year-round. A 90-day long-term test under normal living conditions is arguably a more honest result. If your goal is a number to live by rather than a number to check a box, she's giving good advice.
Question linkHow does the EPA recommend I maintain a radon mitigation system?
EPA guidance says to have the system inspected and retested at least every two years. In practice, that means: checking the manometer visually on a regular basis, listening for changes in fan sound, and doing a licensed radon test every two years. If you notice anything unusual - new noise, fluid shift on the manometer, or rising readings on a consumer monitor - address it without waiting for the two-year mark.
Question linkAfter mitigation, my radon spiked for a week before settling down. Is that normal?
It's not common, but it does happen in some cases. Installing a mitigation system involves drilling into the slab or floor, which can temporarily disturb soil gas pathways and cause a short-term fluctuation. Also, if the manometer fluid was settling or the suction point was finding its pressure equilibrium, readings can be unstable the first few days. If levels settled down to a good number after a week, the spike was likely temporary and the system is now working. If they spiked and didn't come down, that's worth investigating.
Question linkMy radon went down right after mitigation but then crept back up to 3.0. What gives?
This can happen when the system has a suction point that initially pulled a good vacuum but is now losing connection with the aggregate layer - either because the suction radius is limited, because a neighboring area of the slab isn't being reached, or because the fan is weakening. 3.0 pCi/L is below the EPA action level but higher than you'd hope for post-mitigation. Get the system inspected and have the contractor check suction pressure. There may be a second suction point needed or a fan upgrade.
Question linkMy radon test came back high after mitigation and the contractor says the system is working fine. Who do I believe?
Believe the test. The radon test tells you what the air concentration is in your home - that's the actual outcome that matters. A contractor saying "the system is working fine" based on a visual check or pressure reading doesn't mean your indoor air level is acceptable. If the test result is above 4.0 pCi/L and the contractor isn't taking it seriously, it may be time to get a second opinion from another mitigation professional.
Question linkMy mitigation system appears to be running but my professional post-test came back at 5.2. Is the system defective?
A result of 5.2 pCi/L after mitigation means the system isn't delivering an adequate result, whether or not it appears to be running. Possible explanations: the suction point isn't connected to the primary soil gas entry pathway, there are cracks or openings the system isn't addressing, the fan doesn't have enough capacity for your foundation size, or the system was installed incorrectly. This warrants a re-evaluation by the contractor. If they can't explain and fix it, get a second contractor in to assess.
Question linkMy radon keeps varying wildly on my continuous monitor since mitigation - from 0.5 to 4.0 in the same week. Is the system failing?
Wide swings can happen for a few reasons: changes in weather and barometric pressure, the heating system cycling and creating pressure differentials, windows being opened and closed, or the system having inconsistent suction. If the average is below 2.0 pCi/L, wide swings are less alarming than if the average is near 4.0. But if you're regularly spiking above 4.0 pCi/L even briefly, that's worth investigating. Share the trend data with your contractor.
Question linkMy contractor says my radon system needs a second suction point. Is that a common thing?
Yes, it's fairly common in larger homes or homes with complex slab configurations. A single suction point creates a pressure field that has a limited radius - in some soil and aggregate conditions, it doesn't reach the entire footprint of the slab. A second suction point extends the reach. If your post-mitigation test is higher than expected and the contractor has confirmed the fan is pulling adequate suction from the first point, a second suction point is often the next logical step.
Question linkMy post-mitigation radon is higher in one part of the basement than another. Is that possible?
Yes - radon levels can vary within a house, even after mitigation. A single suction point might depressurize soil under one part of the slab very effectively while another section is less influenced. If you're consistently measuring higher radon in a particular area, it may indicate the system needs an additional suction point in that zone. Sharing specific room-by-room readings with your contractor helps them diagnose whether the coverage is adequate.
Question linkMy house has two separate basement areas - finished and unfinished. My radon is low in the finished side but still high in the unfinished utility area. What's going on?
The suction point for your mitigation system is probably pulling well under the finished side but not covering the utility section as effectively. This is a known challenge in split or segmented basements. Sometimes adding a suction point in the utility area or sealing the slab in that zone solves it. It's worth flagging to your contractor with the specific measurements from each area.
Question linkMy post-mitigation test was fine but my Airthings spiked during a storm. Should I be worried?
Radon levels often rise during storms, even in mitigated homes. Falling barometric pressure allows more soil gas to move, and closed windows during rain reduce air exchange. A storm-related spike on a continuous monitor is a real phenomenon, not a malfunction. What matters is whether levels come back down after the storm passes. If they do, your system is functioning normally. If they stay elevated, that's worth a look.
Question linkCan a mitigation system affect other things in my house - like causing negative pressure issues or drafts?
In some cases, yes. A high-draw fan can affect house pressure, particularly in tightly built homes, which can interfere with combustion appliances like furnaces and water heaters or cause back-drafting. A well-designed installation accounts for this by confirming the suction point is in the soil, not pulling from conditioned air in the house. If you've noticed increased drafts, combustion issues, or doors that seem to want to close themselves since installation, mention it to your contractor.
Question linkMy mitigation fan is 12 years old. Should I proactively replace it?
At 12 years, you're in the range where proactive replacement makes sense, especially if it's been running continuously. Some fans last 20 years; others show wear earlier. Listen for changes in sound, check the manometer for consistent suction, and do a radon test. If all three look good, you may have more life in it. But at 12 years, you're no longer in the sweet spot where you can assume everything is fine without checking. It's also a good time to ask your contractor what model is in there and whether the manufacturer still warrants or supports it.
Question linkIf my radon fan dies, how long do I have before radon becomes a concern?
Radon can accumulate fairly quickly without the fan running - in some homes, levels can climb back toward pre-mitigation concentrations within days. The rate depends on your soil, foundation, and how sealed the slab is. This is another reason to have a continuous monitor - you'd see the level rising and know something changed. Don't leave a dead fan running for weeks before addressing it. Get a replacement fan on order as soon as you confirm it's failed.
Question linkIs it okay to replace my radon fan myself or do I need a contractor?
Fan replacement on an existing system is a more accessible DIY task than original installation, but it requires working with electrical connections and making sure the new fan is matched to your pipe size and suction requirements. In some states, radon work requires certification. If you're comfortable with electrical work and you can source the exact same fan model or a compatible one, it may be doable. But having a licensed radon professional do it means the system gets evaluated at the same time, not just swapped.
Question linkMy neighbor replaced their radon fan and said their radon went up temporarily after the swap. Is that normal?
Yes - any time the suction pipe is opened and the fan is disconnected, the system loses pressure for however long the swap takes. If it takes a few hours, radon may start accumulating in that window. After the new fan is installed and running, levels come back down. The temporary increase during the swap isn't a sign something went wrong - it's just the system being offline briefly.
Question linkWhat brands of radon fans are the most reliable?
The most common brands used in the industry include a major radon fan manufacturer and Festa Radon Technologies (formerly known as a major radon fan manufacturer and Festa). Both have long track records. There are also several other manufacturers whose fans are used regularly by licensed radon professionals. Rather than picking a brand on your own, I'd go with whatever your licensed radon professional recommends for your specific setup - they'll match the CFM rating and pressure requirements to your system's needs.
Question linkMy radon fan has been running since 2009. Is it time to replace it?
At 15+ years, it's overdue for close attention even if it seems to be running fine. Check the manometer, listen to the motor, and do a radon test. If the test result is still good and the fan sounds healthy, you may have more life in it. But I'd be planning for replacement soon rather than waiting until it fails. An unexpected failure means radon accumulates until you catch it - a proactive replacement means you control the timeline.
Question linkDoes a mitigation system come with a warranty?
Most reputable contractors warrant their labor for a period of time, and the fan itself typically has a manufacturer's warranty - often three to five years, sometimes longer depending on the brand. The warranty on the work (labor) and the warranty on the fan (parts) are separate. Get both in writing before the job is done. Also ask what happens if the post-mitigation test result isn't below 4.0 - a good contractor will have a policy on that.
Question linkMy mitigation system warranty expired. Now what?
An expired warranty doesn't mean the system stops working - it just means the free-repair window has closed. Keep up with periodic retesting every two years, listen to the fan for changes, and keep an eye on the manometer. When the fan eventually needs replacement, you'll pay for parts and labor, which is typically much less than the original installation. The most important maintenance is the radon testing itself.
Question linkMy contractor put in a basic fan. My neighbor's contractor put in a fancier one with an alarm. Does it matter?
The core function is the same - both fans create sub-slab depressurization. The fancier fan with an alarm gives you a notification if the system stops working, which is a genuine advantage. If you want that feature, it can often be retrofitted - either by adding an alarm to your existing setup or replacing the fan with one that has built-in monitoring. It's not required, but it's a useful upgrade, especially if your fan is in an out-of-the-way spot.
Question linkI just bought a house and the inspector said there's a radon mitigation system. What do I do first?
Check that the fan is actually running - listen near the pipe and look at the manometer. Then ask the sellers for any testing records, ideally the original pre-mitigation test and the post-mitigation test. If those records don't exist or the most recent test is more than two years old, do a radon test yourself. You want to know what the current level is, not what it was five years ago.
Question linkThe sellers said the mitigation system works great. Do I have to test?
Yes. Sellers often don't have current data - they may not have tested in years. A radon test takes a few days and costs very little compared to not knowing what you're breathing. Assume nothing until you have a test result from a licensed lab. "Works great" is not data.
Question linkI bought a house with mitigation already installed. How do I know if it was installed correctly?
Ask for the original installation documentation or a description of what was done. Key things to look for: the suction point is in the sub-slab soil (not in the living space), the pipe exits the house correctly, the fan is in a conditioned or protected space, the system has a manometer, and a post-mitigation test was done and shows results below 4.0 pCi/L. If records are missing, have a licensed radon professional inspect the system - they can evaluate whether the installation meets current standards.
Question linkMy real estate agent said the mitigation system means I don't need to test. Is that right?
No - that's wrong. The system lowers radon; a test tells you how much. You need both. The system could be underperforming, could have a fan that's failing, or could have been incorrectly installed. A test is the only way to know what the air quality in your home actually is. Don't skip testing because a system exists.
Question linkThe house I bought had a mitigation system but no manometer. Should I add one?
Yes - a manometer is an inexpensive addition that gives you a day-to-day visual indicator that the system is running. Without it, you have no way to tell at a glance if the fan is on and creating suction. Ask a state licensed radon contractor to add one to the existing pipe - it's a straightforward addition.
Question linkI found radon records from the original owners showing 0.7 pCi/L post-mitigation. That was 7 years ago. Should I still retest?
Yes. 7 years is well past the EPA's two-year retest recommendation. Fans can weaken, foundation conditions change, and the original result no longer tells you what today's level is. Do a test. You'll probably find it's still low - but you want to know, not assume.
Question linkThe previous owners mentioned the mitigation fan "might need replacing soon." What should I do?
Take that seriously. If they knew the fan was getting old or unreliable, get a contractor in to evaluate it now. You don't want to find out the fan failed after radon has been accumulating for months. A pre-emptive fan replacement or professional inspection is much better than discovering elevated levels after the fact.
Question linkMy house inspection said the radon mitigation system was functioning but the inspector didn't test radon levels. Is that enough?
No. A home inspector can check whether the fan is running and the manometer shows movement, but that only tells you the system is on - not that it's bringing radon to an acceptable level. Radon testing is what tells you the result. Ask the inspector to be clear about what they checked versus what a radon test would tell you, and then do the test.
Question linkThe house we bought has two separate mitigation pipes. Is that unusual?
Not at all - some homes require two or more suction points to cover the full slab area. Larger homes, L-shaped foundations, and homes with separated zones under the slab often need multiple pipes. Both should have a fan (or one fan serving both pipes in some configurations) and both should have manometers. Check that both appear to be under suction.
Question linkThe mitigation system in my new house goes out through the garage. Is that a good installation?
Routing through a garage isn't ideal but it's done when other routing options aren't available. The main concern is whether the pipe exits in a location where radon can safely disperse and doesn't re-enter the house through windows, doors, or HVAC intakes. If the exhaust is near a garage door that's frequently open, or near windows on that side of the house, it's worth having a contractor evaluate the discharge location.
Question linkMy post-mitigation test was done but I lost the report. How do I get another?
Contact the lab that processed your test - the testing company's name is usually printed on the canister or on a card included with the kit. Most labs keep records and can re-issue a copy of the results. If you don't know which lab processed it, check with the contractor who did your installation - they often keep copies. If all else fails, do a new test. Having a current result is more valuable than tracking down an old one.
Question linkIs there a central database of radon test results where I can look up my house?
No national database exists for individual home test results. Some states have radon programs that collect data, but it's not universally accessible at the individual property level. Your results are typically held by the testing lab and possibly your state radon program if they were submitted there. Keep copies of your own test results in a folder you can find.
Question linkI got mitigation installed but my contractor never gave me any paperwork. Is that a problem?
Yes - you should have at least a description of what was installed, the date, and ideally a post-mitigation test result. If you don't have documentation, ask the contractor to provide it. Good documentation becomes important if you ever sell the house or need to demonstrate to a buyer that mitigation was done. If the contractor won't or can't provide it, that's a red flag about the quality of the installation.
Question linkShould I keep records of every radon test I do?
Yes. Keep a simple file - physical or digital - with the date, testing method, result, and lab name for every test. This becomes genuinely useful when you sell the house, when a buyer asks questions, or when you need to compare current levels to historical ones. It's one of the easiest things you can do to document the safety of your home over time.
Question linkDoes my state require a post-mitigation test?
Requirements vary by state. Illinois requires a post-mitigation test conducted independently of the contractor. Other states have their own rules, and some states have no formal requirement at all. Contact your state's radon program to find out what's required where you live. Even if it's not required, doing an independent post-mitigation test is smart.
Question linkWhat does "independently conducted" mean for a post-mitigation test?
It means the entity doing the testing is separate from the entity that installed the mitigation system. The contractor who put in your system has an obvious interest in showing it worked - an independent tester has no stake in the outcome. Most states that require independent testing have lists of licensed measurement professionals who qualify.
Question linkCan the same company that installed my mitigation system also do my post-mitigation test?
In some states, yes - there's no prohibition. In others, like Illinois, post-mitigation testing must be independent of the installation contractor. Even where it's allowed, there's a reasonable argument for having it done independently so you're not relying on the contractor to evaluate their own work. Ask what your state requires, and if you have the option, independent testing gives you an unbiased result.
Question linkWhere can I find a licensed radon testing lab to process my post-mitigation test?
Your state radon program is the best starting point - they maintain lists of licensed labs and measurement professionals. The National Radon Proficiency Program (NRPP) and the National Radon Safety Board (NRSB) also maintain searchable directories of licensed testers. Some states have their own certification programs separate from national ones.
Question linkMy state doesn't have a mandatory post-mitigation test requirement. Should I still test?
Absolutely. The legal requirement and the practical recommendation are different things. Not testing after mitigation is like having surgery and not doing a follow-up appointment. The test confirms the system is doing what it's supposed to do. No requirement in your state doesn't mean it's optional from a health standpoint.
Question linkMy radon is always higher in winter. Is my mitigation system failing in cold weather?
Not necessarily failing - winter is when radon naturally runs higher in many homes, even with mitigation in place. The stack effect is stronger in cold weather (warm indoor air rises, pulling soil gas in through the slab), houses are closed up more, and frozen ground can affect soil gas dynamics. If winter levels are still below 4.0 pCi/L, the system is working within normal seasonal variation. If they're above 4.0 in winter, it's worth a closer look.
Question linkMy radon is at 0.8 in summer and around 2.2 in winter. Should I be doing something about the winter number?
2.2 pCi/L in winter is still well below the EPA action level, so the system is doing its job even in the harder season. Seasonal variation of that magnitude is common and not a failure indicator. If you want to be extra thorough, you can test in both seasons every two years to document the range. But 2.2 in winter is a result most people are comfortable with.
Question linkDoes the weather affect how well my mitigation system works?
Weather does influence radon levels even in mitigated homes. Falling barometric pressure, high winds, precipitation, and very cold temperatures can temporarily increase radon entry through the slab. A good mitigation system handles most of this variation and keeps average levels low, but short-term spikes during extreme weather events are normal. What you're looking for is a low average over time - not a flat line every day.
Question linkMy consumer monitor shows a big spike every time it rains hard. Is my mitigation system failing?
Weather-driven spikes on a continuous monitor are common and don't necessarily indicate system failure. Rain reduces barometric pressure, which allows soil gas to move more freely. The fan keeps running and typically brings levels back down after the storm. The key is whether levels normalize after the weather passes. If they do, the system is functioning. If radon stays elevated for days after the rain, that warrants a look.
Question linkMy radon is consistently higher on the lowest level of my three-story home. Should my mitigation system be handling that?
Radon is heaviest at the lowest level - that's where it enters and where it accumulates most if undisturbed. A properly installed mitigation system should be addressing that zone directly. If the lowest level is still showing elevated levels after mitigation, the system may need a suction point in that specific area or the coverage may not be reaching it. Share the level-by-level readings with your contractor.
Question linkWe had a major flood in our basement and now our radon is higher. Did the flood damage the mitigation system?
Floods can affect mitigation systems in a few ways: water entering the suction hole can temporarily block airflow, water can damage the fan if it's located low on the pipe, and changes to the soil saturation under the slab can temporarily change how soil gas moves. After the water recedes and things dry out, the system should resume normal function. But a radon test after a significant flood event is a good idea to confirm levels have returned to normal.
Question linkMy radon was at 1.5 for years and is now at 2.8. What changed?
A gradual rise like that warrants investigation. Possible causes include a fan that's losing output, new cracks in the foundation that provide additional entry pathways, changes to soil conditions under the slab, or changes in how the house is used (finished basement, new HVAC). Check the manometer for suction, listen to the fan, and consider calling a contractor to evaluate. 2.8 is still below the action level, but the trend matters - you don't want it to keep climbing.
Question linkMy family has been in the house since before we knew about the radon. Are we sick?
Radon doesn't cause acute symptoms - it's not going to give you a headache, sore throat, or make you feel tired right now. It's a long-term lung-cancer risk from cumulative radiation exposure over years. If you have health concerns about past exposure, that's a conversation to have with your doctor. What you can control going forward is keeping levels low with a working mitigation system, and you're doing that now.
Question linkNow that mitigation is installed, should I stop worrying about radon?
You don't need to obsess over it, but you shouldn't completely forget about it either. Check the manometer periodically, retest every two years, and listen for changes in the fan. Radon mitigation is more like maintaining a smoke detector than installing a one-time fix. The system is doing the work - your job is just to make sure it keeps running.
Question linkMy kids grew up in a house that had elevated radon before mitigation. Should I be panicked?
Radon is a serious long-term risk, but it's important to put it in context. It takes cumulative exposure over time to meaningfully elevate lung cancer risk. One particularly relevant factor is smoking - the combination of radon and smoking dramatically increases risk more than either alone. If you're concerned about your family's prior exposure, talk to your doctor. The most important thing now is that the system is installed and working.
Question linkCan radon exposure cause symptoms like headaches or fatigue?
No. Radon does not cause acute symptoms. Headaches, fatigue, sore throats, and similar symptoms are not signs of radon exposure - radon is an odorless, colorless gas that causes harm through radiation exposure to lung tissue over time. If you're experiencing those symptoms, look for other causes. Radon's risk is elevated lung cancer risk from long-term cumulative exposure, not day-to-day symptoms.
Question linkMy radon is at 1.8 after mitigation. Is it "safe" now?
Radon doesn't have a truly "safe" level - even the outdoor average of 0.4 pCi/L involves some small radiation exposure. But 1.8 pCi/L is a low level, well below the EPA action threshold, and the mitigation system has clearly done significant work if you were above 4.0 before. The risk at 1.8 is meaningfully lower than at higher levels. Keep the system running and retest periodically. You've done the right things.
Question linkMy doctor asked if we have a radon mitigation system. Should I show her the test results?
Yes - that's exactly the kind of information that helps a doctor understand your household's radiation exposure history. Showing pre- and post-mitigation test results lets her assess exposure context. Bring copies if you have them.
Question linkWhat should I ask a contractor when I'm getting a post-mitigation system check?
Ask them to: measure current sub-slab pressure at the suction point, check for any pipe leaks or disconnections, evaluate the fan for signs of wear, confirm the manometer is reading correctly, and review your most recent test result in context of what the system is capable of. A good contractor will document what they find and give you a clear picture of whether the system needs any changes.
Question linkMy mitigation contractor said my post-mitigation result of 3.0 is "as low as we can get it." Should I accept that?
3.0 pCi/L is below the EPA action level, but "as low as we can get it" should come with an explanation - not just an assertion. A contractor who says that should be able to tell you why: limited aggregate under the slab, impermeable soil, multiple entry pathways that can't be fully sealed. Ask for specifics. If the explanation makes sense and you've verified the suction is being correctly delivered, then 3.0 may genuinely be the realistic target. If you're not satisfied with the explanation, a second opinion is reasonable.
Question linkShould I use the same contractor for post-mitigation testing that installed my system?
In some states this isn't allowed - the test must be independent. Even where it is allowed, there's a practical argument for independence: an unconnected tester has no interest in whether the result looks good for the contractor. If you're in a state without independence requirements, it's your call. Either way, make sure the test is conducted by a licensed measurement professional using a NRPP or NRSB-accredited method.
Question linkMy radon contractor told me I didn't need a post-mitigation test because they "could tell by the suction." Is that right?
No. Suction pressure at the pipe tells you the fan is pulling - it doesn't tell you what radon concentration is in your living space. You need a radon test to know whether the system reduced levels below the threshold. Any contractor who discourages you from post-mitigation testing is giving you bad advice, regardless of their confidence in the installation.
Question linkI want to add a second radon suction point myself. Is that something a homeowner can do?
Drilling into the slab, locating aggregate, and tapping into the existing pipe system requires some knowledge and the right tools. It's not as simple as adding a second vent. In many states, radon mitigation work requires certification, so doing it yourself could be non-compliant. If you're a capable DIYer with concrete experience, it's technically possible, but getting a licensed radon professional to do it ensures correct placement and system integrity - and a professional installation can be documented for future buyers.
Question linkMy contractor offered a "lifetime warranty" on the mitigation. What does that actually mean?
Read the fine print carefully. Most "lifetime warranty terms" in this industry cover the contractor's labor if the system fails to keep levels below a specified threshold - often 4.0 pCi/L - under normal operating conditions. They typically don't cover fan replacement costs, don't transfer to new homeowners, and have conditions that must be met (like not altering the system). A warranty is a good sign of a contractor's confidence, but understand what's actually covered before you rely on it.
Question linkHow often should a professional inspect my radon mitigation system?
A professional inspection every few years is reasonable, especially as the system ages past 10 years. In between inspections, the visual manometer check and periodic radon testing do most of the monitoring work. If you notice the fan sound changing, the manometer shifting, or radon levels creeping up on your consumer monitor, don't wait for a scheduled inspection - call sooner.
Question linkMy post-mitigation test was done in a room I never use. Does the location matter?
Test results should reflect the lowest livable area of the home, regardless of how often you use that space. If you have a rarely-used basement, that's still where the test should go - it represents the worst-case area the system needs to address. If the contractor or tester placed the test kit in a main living area on an upper floor, you might be getting a lower reading that doesn't reflect the whole picture.
Question linkMy radon system is in the crawl space. Is the monitoring process any different?
The core approach is the same - do a post-mitigation radon test in the lowest livable space, check that the system is running, and retest periodically. Crawl space systems often involve sealing the crawl space with a liner and running the fan to pull air from under the liner. The manometer check is the same. One difference is that access to the fan may be less convenient, so inspections can be harder. A continuous monitor in the living space above the crawl helps with ongoing awareness.
Question linkMy mitigation pipe goes up through my living room and then out the roof. Can I paint it to match the wall?
Yes - the pipe itself (usually PVC) can be painted with appropriate paint. Make sure the fan housing is not covered or insulated in a way that traps heat around the motor, and don't block the exhaust at the top. Paint the pipe, not the fan unit, and you should be fine aesthetically.
Question linkMy house was mitigated before I moved in. Should I get a new test even if the result from the seller was 1.2 pCi/L?
Yes - even if the seller's test was recent and showed 1.2 pCi/L, doing your own test establishes your baseline as the new homeowner. You can verify the system is still delivering the same result under your occupancy patterns. It also gives you documentation in your own name. A 1.2 result from the previous owner is reassuring, but your own test closes the loop.
Question linkIs it possible the soil under my house ran out of radon after all these years of mitigation?
No. Radon is continuously produced as uranium in soil and rock decays - it's not a finite pool being depleted by your mitigation system. The source of radon is the geology under and around your home, which doesn't run out on a human timescale. Your mitigation system is continuously drawing radon away before it can accumulate indoors - not emptying a tank.
Question linkMy radon result has been 0.5 pCi/L for three straight tests over five years. Can I consider the problem solved?
The mitigation system has clearly been very effective, and 0.5 pCi/L is close to outdoor background levels. "Solved" is a reasonable way to think about it as long as the system keeps running. Keep up the periodic retesting - just because it's been stable doesn't mean you can stop monitoring. But five years of consistent low results is exactly the track record a good system should build.
Question linkI filled the manometer fluid back up but I'm not sure I used the right fluid. Does it matter?
Yes - using the wrong fluid can give you inaccurate readings or damage the tube. Most manometer manufacturers specify a particular fluid (often a red gauge fluid sold by radon supply companies). Water works in a pinch and is better than nothing, but it evaporates quickly. Ask the original contractor what fluid they used or contact the manometer manufacturer for the correct type. Refilling with the wrong fluid won't hurt the system - the fan will still run - but the gauge reading may not be reliable.
Question linkMy radon system runs through a finished wall and I can't see the manometer anymore after a renovation. What should I do?
You'll want to make the manometer accessible again or have a new one installed in a visible location. Hiding the manometer during a renovation is a common mistake - it defeats the purpose of having one. A contractor can often add a gauge tee to the accessible part of the pipe so you have a visible indicator without tearing into the wall.
Question linkAfter mitigation, does it matter if I open my basement windows regularly?
Opening basement windows significantly affects radon test results - that's why closed-house conditions are required for short-term tests. For long-term living, opening windows increases air exchange, which can help dilute radon. But your mitigation system works under all conditions and you shouldn't feel restricted from opening windows. Just be aware that if you're doing a short-term test, the standard protocol is closed-house conditions.
Question linkMy mitigation system is connected to a sump pump pit. Is that a reliable suction point?
Sump pits are commonly used as suction points because they already provide access to the sub-slab area. The effectiveness depends on how well the pit is connected to the aggregate and soil gas pathways under your slab. Some sump pits work extremely well; others have limited reach. If your post-mitigation results are good, the sump pit is doing its job. If results are marginal, adding a separate core-drilled suction point may extend coverage.
Question linkCan I add insulation around my radon pipe to reduce noise or condensation?
You can insulate the pipe itself, but leave the fan housing uninsulated - fans need airflow around the motor to dissipate heat. Condensation on the pipe is normal, especially where it passes through temperature transitions from conditioned to unconditioned space. Insulating that section reduces condensation without affecting system function.
Question linkMy neighbor says he tests his radon every month. Is that excessive?
It's not harmful, but it's more than what the EPA or most guidance recommends. Monthly professional lab tests add cost without adding proportionally more information - radon doesn't change dramatically month-to-month in a stable, mitigated home. If your neighbor wants that level of monitoring, a continuous consumer monitor would give him the same daily data without the cost of monthly test kits. Lab tests every two years, combined with a continuous monitor, covers the range well.
Question linkShould I be worried about radon in the air my mitigation fan exhausts outside my house?
The exhaust from a radon mitigation fan is concentrated radon gas being vented outdoors. Outdoors, it dilutes rapidly into the ambient air and is not a significant exposure risk. The key is that the exhaust point is away from windows, doors, and HVAC intakes so the radon doesn't re-enter the house. Standard installation practices account for this - the exhaust should terminate above the eave line or at a location that prevents re-entry.
Question linkDo I need to tell my HVAC company about my radon mitigation system before they do work?
It's a good idea to mention it. HVAC work can affect house pressure dynamics - adding or sealing ductwork, changing the furnace or air handler, or installing new ventilation can interact with your mitigation system. A major HVAC overhaul is a good reason to do a radon test afterward to confirm the system is still performing as expected.
Question linkMy mitigation system seems to be pulling hot air from the basement in summer and I think it's affecting my AC bill. Is that a real concern?
It's a real phenomenon. The mitigation fan is exhausting air from under the slab - that air has to be replaced by something, and in a house without a lot of air sealing, it pulls conditioned air. The effect on your energy bill depends on the fan's CFM rating and your home's overall air sealing. Most systems have a modest impact. If you're noticing significant effects, a contractor can evaluate whether the system is oversized for your conditions.
Question linkWhat if I stop running my mitigation fan to save electricity? Will levels come back up quickly?
Yes - radon will begin accumulating again as soon as the fan stops maintaining sub-slab depressurization. How quickly depends on your soil and foundation characteristics, but in high-radon homes, levels can return toward pre-mitigation concentrations within days. The electricity cost of running a radon fan is modest. Don't turn it off to save money - the risk trade-off isn't worth it.
Question linkI'm putting my house on the market in 6 months. Should I retest my radon now?
Yes - and now is a smart time to do it. If levels are still good, you have a recent test result to show buyers. If they've crept up, you have time to address it before listing. Buyers (and their agents) often ask for radon testing as part of purchase negotiations - having documentation that your system works and levels are current is a selling point, not a liability.
Question linkMy buyer's inspector ordered a radon test and it came back at 3.4 pCi/L after years of my system running well. What happened?
A result of 3.4 pCi/L during a buyer's inspection might reflect the inspection test conditions (sometimes short-term tests are done with windows open or in atypical conditions), a fan that has weakened over time, or genuine seasonal variation. Confirm your own system check - look at the manometer, listen to the fan - and offer to do a second test under controlled conditions. 3.4 is below the EPA action level, but if the system has been under-delivering for a while, it's worth having a contractor evaluate it.
Question linkMy Airthings sent me an alert that radon went above 4.0. What should I do?
Check the manometer first - is the fan on and creating suction? Check for any obvious changes: windows left open in the basement, a circuit breaker tripped, or anything that could have interrupted the system. Then watch the monitor over the next 24-48 hours to see if it returns to normal. If it doesn't come back down, and especially if the alert is recurring, it's time to call a contractor and schedule a professional test to confirm what the continuous monitor is showing.
Question linkMy neighbor's mitigation company came out for a free annual checkup. Does my contractor offer that?
Some contractors do offer annual or periodic system checks - it varies by contractor. It's worth asking when you have work done. Even without a formal checkup, you can do the main visual checks yourself: manometer, audible fan check, and a look at the exhaust location. A licensed radon test every two years is more diagnostic than a visual check alone.
Question linkI switched from a charcoal canister test to an electret test for my retest. Are the results comparable?
Both charcoal canisters and electret ion chamber tests are valid, EPA-accepted radon measurement methods. They measure radon by different mechanisms but are designed to give comparable results when used correctly. Differences in results between the two methods are usually within the margin of variability for radon testing rather than a systematic bias. You can meaningfully compare results across methods for tracking trends over time.
Question linkMy post-mitigation lab result said the result is plus or minus 0.4 pCi/L. What does that mean?
That's the measurement uncertainty - the range within which the true radon level likely falls. A result of 1.6 pCi/L ± 0.4 means the actual level is most likely between 1.2 and 2.0 pCi/L. It's a normal part of any measurement and reflects the precision limits of the test method. For levels well below 4.0, the uncertainty range doesn't change your decision. For a result right near 4.0, the uncertainty range is part of how you interpret it.
Question linkI'm about to refinish my basement. Will the renovation affect my radon levels?
Basement finishing can affect radon in both directions. Sealing the slab with flooring can reduce radon entry. But adding walls, changing air circulation, blocking access to the slab, or accidentally disconnecting or obstructing the mitigation pipe can create problems. Test after any significant basement renovation to confirm your system is still performing. And tell your contractor to leave the mitigation pipe accessible and undisturbed.
Question linkMy mitigation system is on an interior wall and I want to move it. Can I do that?
Modifying a mitigation system - moving the suction point, rerouting pipe, or relocating the fan - should be done by a licensed radon professional. The suction point location was chosen based on where aggregate exists under your slab; moving it without checking soil conditions could put the new suction point in an impermeable zone and eliminate effectiveness. If the current location is inconvenient, talk to your original installer or a licensed radon professional about options before you touch anything.
Question linkMy radon mitigation system makes the basement smell different - kind of earthy or musty. Is that normal?
The system is pulling air from the soil under your slab - that air can carry earthy or musty odors, especially when there's moisture in the sub-slab material. If the smell is coming from the area around the suction pipe or the fan, it may be that small amounts of soil gas (beyond just radon) are finding their way into the living space at connection points. Make sure all pipe connections are sealed and that there are no gaps at the slab penetration. A completely sealed system shouldn't be bringing soil odor into the house.
Question linkMy radon is 1.1 pCi/L and my contractor says I could turn the fan down to save electricity. Is that a real option?
Some higher-capacity fans are installed on variable-speed setups or with a damper that can be adjusted. If your system is pulling more suction than needed to maintain low levels, reducing the fan speed or restricting the airflow slightly can reduce electricity use without sacrificing radon control. This is an adjustment a contractor should make with a gauge and a follow-up test - not something to guess at. If levels stay below 2.0 pCi/L after the adjustment, you're fine.
Question linkDoes my homeowner's insurance cover radon mitigation or system failure?
Generally, no. Standard homeowner's policies don't cover radon testing, mitigation installation, or fan replacement. Some policies treat radon mitigation as a home improvement rather than an insurable event. There are specialty environmental coverage riders, but they're uncommon and rarely triggered by typical radon scenarios. Check your policy if you're uncertain, but don't count on insurance to cover radon work.
Question linkI had a radon test done before I renovated and one after. The after result was higher even though I have mitigation. What happened?
Renovations can disrupt mitigation effectiveness in a few ways: new cracks from settling or drilling, changes to basement airflow, temporarily disconnected pipes, or a modified floor layout that creates new radon entry pathways. A post-renovation spike is worth taking seriously. Have a contractor evaluate the system after any significant renovation to make sure nothing was disturbed and that coverage still extends across the full foundation.
Question linkMy radon has been rock-solid at 1.3 pCi/L for years. I'm thinking of skipping my next retest. Is that reasonable?
With that kind of track record, the risk of skipping one cycle isn't enormous - but the EPA's two-year recommendation exists because fans fail, foundations shift, and nobody catches it without testing. The cost of a radon test is small compared to the cost of not knowing. I'd keep to the two-year schedule even with a great track record. It's a low-effort confirmation that everything is still working.
Question linkWhat happens to radon levels after I seal foundation cracks, with the mitigation system still running?
Sealing cracks in addition to running the mitigation system typically helps - it reduces the pathways radon can use to enter the living space. You may see a modest improvement in your radon levels. It's a complementary step, not a replacement for the mitigation fan. The combination of active sub-slab depressurization and sealed pathways is the most effective overall approach.
Question linkMy radon is at 0.8 pCi/L with mitigation running. What do I do now?
Keep the fan running, check the manometer every month or so, and retest every two years. That's it. 0.8 pCi/L is near outdoor background levels - your system is doing exactly what it should. You've addressed this well.
Question linkMy radon test came back at 0.4 pCi/L after mitigation. My contractor said that's "basically outdoor air." Is that accurate?
Yes - the national average outdoor radon level is approximately 0.4 pCi/L. Getting to that level indoors with a mitigation system running means you've essentially brought your indoor radon down to ambient outdoor conditions. That's about as good as a mitigation system can reasonably achieve.
Question linkMy Airthings shows higher radon on the first floor than in the basement after mitigation. Is that normal?
It's less common but not impossible. Usually radon is highest in the basement and decreases on upper floors as it mixes with more outdoor air. If your first-floor reading is genuinely higher than your basement after mitigation, double-check that the first-floor reading isn't affected by nearby sources - like a crawl space under part of the first floor that the mitigation system isn't reaching, or a sump pit in a room that's partially above grade. Compare readings from the same time of day for a fair comparison.
Question linkMy contractor said after mitigation I should test once a year. My friend says the EPA says two years. Who's right?
Your contractor is being conservative - annual testing is more frequent than the EPA's guideline of every two years with a system installed, but it's not wrong. More testing gives you more data. Two years is the EPA's recommendation as a minimum. Your contractor may have good reasons to suggest annual testing for your specific situation. If your results are consistently very low, two years is defensible. If you've had any variability or marginal results, annual testing gives you faster feedback.
Question linkMy mitigation was done, I tested, everything came back low, and now I barely think about radon. Is that how it's supposed to work?
Pretty much, yes - that's the goal. You identified a problem, addressed it, confirmed the fix is working, and now it's a background maintenance item rather than a daily concern. The system runs, you glance at the manometer occasionally, and you test every couple of years to confirm it's still delivering. Low-maintenance peace of mind is exactly what a well-functioning mitigation system provides.
Question linkI referred a friend to a radon contractor and they said the contractor told them they didn't need to test after installation. Is that right?
No. That's bad advice. A post-mitigation test is the only way to confirm the system is actually reducing levels to an acceptable point. Skipping it means your friend has a system that may or may not be working effectively, with no way to know. Every mitigation installation should be followed by a licensed post-mitigation test - period.
Question linkWhat's the single most important thing to do after my radon mitigation system is installed?
Get a licensed post-mitigation radon test done. Everything else - checking the manometer, listening to the fan, getting the paperwork - is secondary to confirming the system is actually reducing radon to an acceptable level in your home's air. The test is the proof.
Question linkMy contractor installed mitigation and said "you're all set." Is there anything I should still be doing?
Yes. Schedule a post-mitigation radon test if one isn't already arranged. Learn how to read the manometer on your pipe. Mark your calendar for a retest in two years. And save all your documentation - installation date, post-mitigation test result, contractor info - somewhere you can find it. Being "all set" means the system is installed; it doesn't mean monitoring is done.
Question linkI want to set up some kind of automated alert for my radon system. What are my options?
A few options exist: a continuous consumer monitor like the Airthings Wave series sends alerts to your phone through its app if levels rise above thresholds you set. Some mitigation fans have built-in pressure alarms that sound if suction drops. Smart plugs with power monitoring can alert you if the fan loses power. And some security systems can be set up to monitor the outlet circuit. None of these replace periodic licensed testing, but they give you real-time awareness between tests.
Question linkMy radon results are all in pCi/L. My friend in Europe talks about Bq/m³. Are these the same thing?
Different units, same measurement of radon. 1 pCi/L equals 37 Bq/m³. The United States uses pCi/L; most of Europe uses Bq/m³. If you're looking at European guidelines or comparing to a foreign test result, multiply pCi/L by 37 to get Bq/m³, or divide Bq/m³ by 37 to get pCi/L. The EPA action level of 4.0 pCi/L is approximately 148 Bq/m³.
Question linkCan a plumber or HVAC tech inspect my radon system, or does it need to be a radon specialist?
For basic visual inspection - is the fan running, is the manometer reading, are there obvious pipe leaks - a plumber or HVAC tech might be able to help. But for a meaningful evaluation of system performance, sub-slab pressure testing, and interpretation of radon measurements, you want a licensed radon mitigation contractor. It's a specialized field. A general tradesperson can tell you if the fan is spinning; only a radon contractor can tell you if it's doing enough.
Question linkMy mitigation fan has a 5-year warranty but I just found out the manufacturer went out of business. Now what?
If the manufacturer is gone, the warranty isn't worth much in practice. Document what you have and focus on the performance of the system going forward - if it's running well and your radon tests are good, the lack of a warranty doesn't change anything today. Plan for eventual fan replacement as normal maintenance, and when you do replace it, use a current model from a manufacturer with an active warranty and good industry track record.
Question linkDoes radon mitigation reduce my home's value or raise it?
Having a mitigation system in place and documented test results showing success is generally viewed as a positive by informed buyers - it means the problem has been identified and addressed. An unmitigated home with elevated radon is more of a liability than a home with a working mitigation system. Good documentation and a recent low test result are assets in a real estate transaction, not negatives.
Question linkMy radon has been fine for years but I just had a new concrete crack patched in the basement. Should I test again?
Any time you have foundation work done, a fresh radon test afterward is a reasonable precaution. Crack repairs can change airflow dynamics - a sealed crack is good, but the work itself can temporarily disturb nearby pathways or confirm that additional cracks exist that weren't known. Testing a few weeks after the repair gives you a clean current reading.
Question linkI got mitigation installed, tested, and got 1.5 pCi/L. My aunt is worried it's still dangerous. What do I tell her?
Tell her the mitigation system worked. 1.5 pCi/L is a low level - well below the EPA action threshold and not far above the outdoor average. No level of radon is technically "zero risk" because that's how radiation works at the micro level, but 1.5 pCi/L represents a very low risk level and is a genuinely good result. The concern she'd have is appropriate for an unmitigated home; her house at 1.5 with a working system is in a much better position.
Question linkMy continuous monitor's battery is dying. Should I replace it right away or is it fine to wait a week?
Replace it soon - a dead monitor is a monitor that isn't watching. Even so, a week without a continuous monitor isn't a crisis if your mitigation system is confirmed to be running and you have recent test results showing low levels. It's not an emergency, but don't keep deferring it. The value of a continuous monitor is in the ongoing awareness it provides.
Question linkIs there a test that can tell me how well connected my suction point is to the soil under my slab?
Yes - a diagnostic sub-slab communication test involves inserting a tube into the slab through a small hole and checking whether the pressure differential from the suction point reaches that location. A radon contractor can perform this test to map how effectively the suction point is communicating with soil under different areas of the slab. It's a useful diagnostic if your post-mitigation results suggest incomplete coverage.
Question linkWhat if I live in a mobile home or manufactured home? Does radon mitigation work the same way?
Manufactured homes have different foundation types - some have a crawl space, some sit on a slab, some have skirted pier foundations. Mitigation approaches vary accordingly. A traditional sub-slab depressurization system works if there's a slab or confined crawl space. Open pier foundations are trickier - the open air flow under the home is actually somewhat protective. If you're concerned about radon in a manufactured home, a licensed radon professional experienced with that construction type is the right call. Don't assume a standard installation approach without getting it assessed first.
Question linkMy post-mitigation test was 2.9 pCi/L. My neighbor said I should still fix it more. My contractor says it's fine. Who's right?
They're both partially right. The contractor is correct that 2.9 pCi/L is below the EPA action level and represents a successful mitigation result. Your neighbor is right that the EPA acknowledges risk in the 2.0-4.0 range and says it's worth considering further action - the risk is lower, but real. Whether to pursue more reduction is a personal decision based on how low you want to go and whether the system can practically get there. 2.9 is fine; lower would be better. Call or text Bill and we can talk through what the numbers mean for your situation.
Question linkI've never had radon tested or mitigation done. I found this while searching online. Where do I start?
Start with a radon test - a basic mail-in charcoal canister test from a licensed lab will tell you what your current radon level is. Place it in the lowest livable level of your home for 48-96 hours, then send it to the lab. If the result comes back at 4.0 pCi/L or higher, the EPA recommends mitigation. If it's between 2.0 and 4.0, you're in a range worth thinking about. Fill out the form on the website or give us a call - we can walk you through what the numbers mean and what makes sense next.
Question linkMy radon spiked to 8.0 on my Airthings for a few hours and then dropped to 1.2. What caused that?
A short spike like that is usually caused by a pressure event - an especially strong wind that briefly reversed airflow through pathways in the foundation, a sudden drop in barometric pressure, or the HVAC system creating an unusual pressure differential. Brief spikes of a few hours that then return to a low baseline aren't necessarily a sign of system failure. If they become frequent or the level stops returning to its previous low, that's when to investigate.
Question linkMy radon monitor shows radon highest in the morning around 7am and lowest in the afternoon. Why?
That's a classic diurnal pattern driven by how the house breathes through the day. In the early morning, the house has been closed overnight with minimal air exchange - radon accumulates more during that window. As the day progresses, doors and windows open, HVAC cycles more actively, and temperature-driven ventilation increases. This pattern is completely normal and doesn't indicate a problem with your mitigation system, as long as the morning peaks are well below 4.0 pCi/L.
Question linkMy Airthings app shows radon spiking every time the furnace kicks on. Is that connected?
Possibly. Forced-air furnaces and air handlers create pressure changes in the house - they pull air from the interior, which can briefly alter the pressure differential across the slab and allow more soil gas in through any remaining pathways. Alternatively, the furnace may be pulling air from an area near the suction pipe and temporarily disrupting the mitigation field. If the spikes are brief and levels settle back down quickly, it's a quirk worth noting but not necessarily a crisis. If the average is climbing, a contractor should look at the interaction between your HVAC and mitigation systems.
Question linkMy radon system is in the utility room and the door to that room is usually closed. Does that affect anything?
It shouldn't - the mitigation fan exhausts outside the house and draws from the sub-slab soil, so the utility room door doesn't affect the suction dynamics under the slab. Where a closed door might matter is if your manometer is in that room and you never go in to check it. Make a point of opening the door periodically to look at the manometer, or ask a contractor to relocate it somewhere more visible.
Question linkMy contractor installed the mitigation fan in my attic. Is that a good location?
Attic installation is done in some setups - it keeps the fan out of living space and the exhaust can go through the roof or gable. The downside is that attics have extreme temperature swings, which can shorten a fan's life. Some fan manufacturers void warranties if the fan is installed in unconditioned spaces. Ask your contractor about the specific fan model used and whether attic installation is covered by the manufacturer's warranty. If it's not, a different location may have been a better choice.
Question linkMy mitigation contractor used the sump pit as the suction point but I also have a battery backup sump pump. Will the mitigation system interfere with it?
The mitigation system draws from above the water level in the pit - it's pulling soil gas, not water. A battery backup sump pump operates at the water level. These two systems generally coexist without interfering with each other. The main consideration is keeping the pit cover well-sealed around both the mitigation pipe and the sump pump discharge pipe. Gaps in the cover let radon back in from the open pit.
Question linkMy radon system draws through a pipe in the floor of my utility room and the pipe gets water pooling at the bottom sometimes. Is that normal?
Some condensation or water accumulation at the bottom of the suction pipe is normal - the fan pulls relatively humid air from the soil, and water can condense inside the pipe. Most installation designs include a low point in the horizontal run where condensation can drain back into the sub-slab area. If water is pooling significantly or backing up into the living space, the pipe may not have been pitched correctly or there may be an unusual amount of groundwater involved. A contractor should look at it.
Question linkMy fan makes a high-pitched whine sometimes and then it stops. Is that an early sign of failure?
An intermittent high-pitched whine that comes and goes can indicate a bearing that's starting to wear or that the fan is responding to changes in air resistance - sometimes debris near the intake causes temporary sound changes. If it's happening regularly and getting worse, the fan is likely in its final years of life. I wouldn't ignore it. A contractor can listen to it and give you a better read on whether it's cosmetic or something that needs addressing.
Question linkWhat does it mean when my radon system "short-cycles" - the fan seems to turn on and off?
Radon mitigation fans are designed to run continuously - they should not be cycling on and off. If the fan is turning off and on repeatedly, there's likely an electrical issue: a failing connection, a motor that's overheating and tripping thermal protection, or a controller or plug issue. A fan that's intermittently off is not maintaining consistent sub-slab depressurization. Get it looked at promptly.
Question linkI noticed my manometer reading has gradually decreased over the past year. Is that a problem?
A gradual reduction in the manometer reading - the fluid displacement getting smaller - could indicate the fan is losing efficiency, or that soil conditions under the slab have changed and resistance to airflow has increased or decreased. It's worth noting and sharing with a contractor. A follow-up radon test alongside the observation tells you whether the change in suction is affecting your radon levels. If levels are still low despite the reduced reading, it may not be a practical problem. If levels have risen, the reduced suction is likely the cause.
Question linkMy post-mitigation test showed 1.6 pCi/L but the testing company's report says to "consider mitigation." Does that make sense?
Some testing companies include boilerplate language on any result above a certain threshold (sometimes as low as 2.0 pCi/L) suggesting consideration of mitigation, even after mitigation is already in place. In your case, with a system already installed and running, 1.6 pCi/L is a good result. The language on the report may be generic rather than specific to your situation. If you already have a mitigation system delivering 1.6 pCi/L, the system is working - you don't need to re-mitigate.
Question linkMy neighbor says his radon test from the hardware store is not as accurate as a professional test. Is that true?
Consumer charcoal canisters from hardware stores vary in quality, and not all are analyzed by the same labs. Some are perfectly valid; others use less rigorous processing. The key is making sure the test kit is analyzed by a lab licensed by NRPP or NRSB, or by your state radon program. The canister itself is mostly just activated charcoal - the accuracy comes from the lab analysis. Check whether your hardware store test specifies which lab processes it and whether that lab is accredited.
Question linkI just moved to a new city and the home I'm renting has a radon mitigation system. The landlord says it was tested 4 years ago at 1.8. Should I get it retested?
Four years is past the EPA's two-year retesting recommendation, and as a renter, it's reasonable to ask your landlord to have it retested. If they're unwilling, you can purchase your own test kit and run it yourself - it's inexpensive and gives you current data. You have a right to know what you're breathing in your home.
Question linkMy radon mitigation contractor says I need to replace my fan every 10 years no matter what. Is that right?
That's a conservative rule of thumb, not a hard engineering requirement. Fans from major manufacturers often run 15-20 years with no problems. "Replace at 10 years" is a simple maintenance guideline some contractors use because it's before the period when failure becomes more likely. There's nothing wrong with that approach - it avoids an unexpected failure. But there's also nothing wrong with monitoring the fan closely (checking radon levels, listening to the motor, checking the manometer) and replacing it when actual signs of wear appear, rather than on a fixed calendar.
Question linkMy pre-mitigation test was 9.2 pCi/L and my post-mitigation test is 2.0 pCi/L. Is a 78% reduction good?
That's an excellent reduction. Going from 9.2 to 2.0 means the system is removing the vast majority of the radon that would otherwise accumulate in your living space. 2.0 pCi/L is right at the lower end of the EPA's "worth considering" range and well below the action level. Whether you want to try to push it lower is a judgment call - many people feel comfortable at 2.0. The mitigation system is clearly doing its job.
Question linkMy first post-mitigation test was 1.4 and my retest two years later was 1.9. Is that increase concerning?
A change from 1.4 to 1.9 over two years is worth noting but not alarming. Radon tests have inherent variability - different weather conditions during the test window, seasonal differences, or slight variation in test placement can all contribute to this range of difference. Both results are well below 4.0 pCi/L. If your next test comes in at 2.5 or higher, that's a more meaningful upward trend worth investigating. For now, keep monitoring.
Question linkMy radon test results over 5 years are: 1.2, 1.8, 2.1, 1.6, 1.9. Is there a trend I should be worried about?
Your results are bouncing around in the 1.2-2.1 range over five years. There's no clear upward trend - they're moving up and down within a band that's well below the action level. This pattern is normal variability from test conditions, seasons, and measurement uncertainty. The system appears stable. Keep retesting every two years.
Question linkMy radon test results have been: 1.1, 1.3, 1.2, and then suddenly 3.8 last time. What happened?
A jump from the 1.1-1.3 range up to 3.8 is significant and suggests something changed. It could be a fan that's starting to fail, a new pathway in the foundation (crack, settling), a suction point that's losing its connection to the aggregate, or conditions during the test itself. I'd start by checking the manometer and listening to the fan. Then do a second confirming test. If the second test also comes back elevated, get a contractor to evaluate the system. Don't let a reading like that sit without follow-up.
Question linkI retested 2 years after mitigation and the result was exactly the same: 1.7 pCi/L both times. Does that mean anything?
It means your system is remarkably consistent. Same result two years apart is a sign of a stable, well-functioning system. The identical number is partly coincidence (rounding and variability in testing could easily have given you 1.5 or 1.9), but the consistency it implies is real. Keep doing what you're doing.
Question linkMy summer test was 1.1 and my winter test was 2.6. That's more than double. Is the system failing in winter?
Doubling from summer to winter is at the higher end of seasonal variation but not unheard of in homes where the stack effect is strong. If winter levels are consistently around 2.6 and you're comfortable with that, the system is still doing meaningful work - without it, your winter levels could easily be 6, 8, or 12 pCi/L. If you want to reduce the winter level further, your contractor can evaluate whether additional sealing or suction can narrow the seasonal swing.
Question linkMy previous owner's test showed 0.6 pCi/L and mine came back at 2.1. Did something happen to the system?
It's possible, but there are also other explanations. The previous owner's test may have been done under different conditions - summer versus winter, different test duration, different room. Consumer-grade test conditions vary more than lab conditions do. Also, foundation settling, new cracks, or changes in how the house is used can change the result over time. Check the fan and manometer. If the system appears to be running normally, do a second test. If the second test also shows 2.1, bring in a contractor to assess whether more can be done.
Question linkMy post-mitigation test was 1.9 but my contractor said it should eventually settle lower. Is that true?
In some systems, levels do continue to decrease gradually as the soil under the slab gets better aerated over months of continuous operation. The bulk of the reduction happens in the first 24-72 hours, but some minor additional improvement can occur. Even so, 1.9 may simply be your equilibrium level. The contractor's statement is partially true - it's worth retesting in 6-12 months to see if there's further improvement. But don't assume the number will keep dropping significantly without a reason to think so.
Question linkMy contractor did my initial test and my post-mitigation test. Both times the result was 1.0 pCi/L. Did the system even do anything?
If both tests genuinely showed 1.0 pCi/L - before and after - it means either the system didn't change anything, the pre-mitigation test underestimated the true level (a single short-term test has variability), or your house was already at a low level before the fan went in. A 1.0 pCi/L pre-mitigation result is below the action level, so mitigation may not have been necessary in the first place. Review the test conditions - especially whether the pre-mitigation test followed closed-house protocol - and make sure the tests are comparable. If they are and the result was always 1.0, your house may simply be a naturally low-radon home.
Question linkI installed a whole-house ventilation system (HRV/ERV) after my radon mitigation. Does that affect the radon levels?
It can, in a positive way. An HRV or ERV brings in controlled outdoor air and exchanges it with stale indoor air, which dilutes radon in the living space. In some homes, adding ventilation on top of mitigation can push levels even lower. The two systems complement each other. Even so, an HRV doesn't replace mitigation - it dilutes radon rather than preventing it from entering. A test after the HRV installation will show you the combined effect.
Question linkMy house has a blower door test score below 2.0 ACH50 - it's very tight. Does that make radon mitigation more or less effective?
Very tight houses (low ACH) allow less outdoor air dilution, which means radon accumulates faster if the mitigation system has any gaps. The good news is a tight house also means the sub-slab pressure field from your mitigation fan extends more effectively - there's less competing airflow to disrupt it. In a very tight house, post-mitigation testing is especially important because the house doesn't self-ventilate to dilute radon the way a leaky older house might.
Question linkMy house has an open fireplace. Does burning a fire affect my radon levels?
Yes - a fireplace burning pulls air from inside the house and sends it up the chimney, which creates a negative pressure that pulls soil gas in from below. This can temporarily spike radon levels when the fireplace is in use. If your continuous monitor shows higher radon on evenings when you have a fire going, that's likely the cause. A glass fireplace door that seals when burning reduces but doesn't eliminate this effect. Mitigation helps, but fireplace-driven spikes may still show up on a continuous monitor.
Question linkMy house has a wood stove. My neighbor says wood stoves cause radon spikes. Is that true?
The same principle applies as with fireplaces - any combustion appliance that draws combustion air from the house interior creates a slight negative pressure that can pull more soil gas through the foundation. A wood stove in a tightly sealed insert is less problematic than an open fireplace. If you see radon spikes on monitoring data that correlate with stove use, it's worth noting. A radon mitigation system helps, but the combustion appliance is also pulling air from the house - addressing that separately (with an outside air kit for the stove, for example) can help.
Question linkMy home has a heat pump with no combustion - does that mean I don't have the negative pressure issues that cause radon spikes?
Without combustion appliances, you've eliminated one major source of negative interior pressure. Heat pumps don't burn air - they transfer heat electrically. This is one of the environmental benefits of all-electric homes from a radon standpoint. Your mitigation system still needs to run, but you're less likely to see combustion-driven radon spikes compared to a house with a gas furnace and water heater.
Question linkMy house has a lot of exhaust fans - bathroom fans, range hood, dryer. Do those affect radon levels?
They can, marginally. Every exhaust fan pulls air from inside the house, which has to be replaced by air coming in from somewhere - including potentially through slab pathways. In most houses the effect from bathroom fans and a range hood is relatively small compared to the mitigation system's output. But in very tight houses with many high-CFM exhaust devices running simultaneously, the combined depressurization can work against the mitigation system's effectiveness. If you suspect this is happening, a contractor can do a pressure diagnostics assessment.
Question linkCan opening and closing my garage door affect my radon readings?
Attached garages are known to influence radon readings - particularly if the house has air connections with the garage through walls, floors, or HVAC pathways. A garage door opening and closing changes the pressure in the garage space, which can briefly affect the pressure differential in adjacent spaces. If your radon monitor is in a room directly adjacent to the garage and you see brief spikes coinciding with garage door activity, that's likely the mechanism. It's typically a minor and brief effect.
Question linkMy basement is partially below grade and partially walkout. Is my mitigation addressing the below-grade section effectively?
The below-grade section of a walkout basement is where radon entry is most likely - soil is in contact with the foundation walls and slab below grade. The mitigation system should be pulling suction primarily from that zone. If the suction point was placed in a section of the slab that's primarily in contact with the below-grade portion, you're in good shape. If the suction point is near the walkout section, the system's reach may not extend as effectively to the deeper areas. Test specifically in the below-grade portion to verify coverage.
Question linkI have a finished basement with a dropped ceiling. Could radon be accumulating in the ceiling space above the tiles?
The space above a suspended ceiling is technically part of the building envelope, and radon can accumulate there. But the more relevant question is what's in the lowest living space - below the dropped ceiling - where you actually spend time. Monitor placement should be below the ceiling tiles at breathing height, not above them. If you're concerned about what's above the ceiling, an assessment of the overall basement levels is more useful than testing in the ceiling cavity.
Question linkMy radon mitigation was done in the basement but I work from home in my first-floor office. Should I monitor there too?
Radon typically decreases significantly as you go up from the basement to the first floor and above. The test should be done in the lowest livable level - the basement - because that's where concentrations are highest. If your office is directly above the basement with permeable flooring or gaps, it could have somewhat elevated levels. Placing a continuous monitor on the first floor alongside a basement one for a few months would tell you whether there's meaningful difference. For most people, if the basement is under 2.0 pCi/L, the first floor is well below that.
Question linkI'm a real estate agent and my buyers want to know if a mitigation system adds value to a home. What should I tell them?
A documented, well-functioning mitigation system with a recent low test result adds transparency and reduces buyer uncertainty. For buyers in states with high radon prevalence (like Illinois), a system already installed means no post-closing surprise and no remediation cost. Whether it adds measurable dollar value depends on the local market, but it's generally a positive feature, not a liability, when properly documented.
Question linkThe house I want to buy had mitigation done but the sellers can't find any records. Should I walk away?
No need to walk away - but get a fresh test done. Request it as a condition of the purchase or do it yourself during the inspection period. A current radon test tells you what the system is delivering today, which is the most relevant information. Missing historical records are a nuisance, not necessarily a deal-breaker, as long as you have current data.
Question linkMy house has two separate foundations - original and addition - and the mitigation pipe only goes under the original part. Is that a problem?
Yes, potentially. Each separate foundation footprint may need its own suction point if the soil under the addition isn't in communication with the suction point under the original section. If the addition has its own slab, test radon in that area specifically. If levels are elevated in the addition section, a second suction point is likely needed. If the addition is on a crawl space or has a different foundation type, a different mitigation approach may be required there.
Question linkMy basement was converted from a crawl space 20 years ago. The mitigation contractor said the sub-slab aggregate is very thin. Does that affect effectiveness?
Yes - suction-based mitigation works best when there's an aggregate layer (gravel, crushed stone) under the slab that allows the pressure field to spread. Thin or absent aggregate means the pressure field has limited reach. In some cases, contractors can improve conditions by drilling multiple suction points, using a higher-capacity fan, or sealing all slab cracks and penetrations to create a more effective system. A contractor experienced with challenging soil conditions can assess what's achievable in your specific case.
Question linkI'm building a new house. Should I install a mitigation system before I even move in?
If you're in a moderate or high-radon area (like most of Illinois), installing a radon rough-in or passive system during construction is highly recommended - and in some areas required. A passive system (pipe through the slab without a fan) can be activated with a fan later if needed. This is far less expensive than retrofitting after the fact. Test once you move in, and if levels are elevated, activate the system by installing a fan. If levels are already low, you still have the rough-in ready if that changes.
Question linkMy builder said a passive radon system is enough. Do I need an active one with a fan?
A passive system (pipe only, no fan) relies on natural pressure differentials to draw radon out - it works in some cases but is generally less effective than an active system with a fan. Test after moving in and see what your radon level is with the passive system. If it's below 2.0 pCi/L, the passive setup may be adequate. If it's above 2.0, adding a fan to activate the system is a straightforward upgrade that meaningfully improves performance.
Question linkMy house is on a slab with no basement. Does radon mitigation work the same way?
Yes - sub-slab depressurization works the same way for slab-on-grade homes. A suction point is drilled through the slab, a pipe is routed to the exterior, and a fan pulls air from beneath the slab and exhausts it outside. The principle is identical to a basement system. Post-mitigation testing and monitoring is the same as well. The only difference is that in a slab home, the entire living area is on the first floor, so radon doesn't have a "higher level" to dilute into.
Question linkCan radon enter through my basement walls, not just the floor? Does my mitigation system address that?
Radon can enter through both the floor and foundation walls, especially through cracks, joints, and porous concrete. Sub-slab depressurization primarily addresses entry through the floor and the floor-wall joint, which are the most common entry points. For wall entry, sealing visible cracks and penetrations complements the mitigation system. If your post-mitigation test shows levels higher than expected given the fan's suction, wall entry may be a contributing factor.
Question linkMy house has a block wall foundation. Do radon systems work differently?
Concrete block walls are porous and hollow - radon can travel through the cores of the blocks as well as through cracks. Sub-slab depressurization still works, but block walls may need additional treatment - sealing the interior wall surface or drilling into the blocks to create a pressure connection. Mitigation in block-wall homes can require a more comprehensive approach than in poured-concrete homes. If you're seeing higher-than-expected results after a standard installation, discuss block wall treatment with your contractor.
Question linkMy radon system has been installed for three months and the levels have been going down gradually. Is that normal?
Yes - some systems take a few months to reach their stable depressurized equilibrium, especially in homes with clay soil or limited aggregate where the pressure field spreads slowly. Gradually declining levels over the first few months is a normal and encouraging pattern. Once the system reaches equilibrium (usually within a few months), levels should stabilize. Do your formal post-mitigation test after that stabilization point for the most accurate baseline.
Question linkMy friend says I should seal the concrete floor in my basement along with mitigation. Will that help?
Sealing the floor is a complementary step that reduces direct radon entry through the concrete surface. Combined with active mitigation, it can help push levels lower. Sealing alone is not a substitute for a fan-based system - concrete is porous and seals eventually wear - but as an addition to an existing system, it's a reasonable enhancement. Make sure whatever sealant is used is appropriate for concrete and is genuinely a vapor barrier, not just a surface coating.
Question linkI live in an area with very high radon (some of my neighbors have pre-mitigation levels above 20 pCi/L). Is a standard mitigation system enough?
Very high starting levels - above 10 or 20 pCi/L - sometimes require a higher-capacity system: larger-diameter pipe, a higher-CFM fan, multiple suction points, or additional sealing. The goal is still getting below 4.0 pCi/L (and ideally below 2.0). Most licensed radon professionals in high-radon areas know how to design for more challenging conditions. Post-mitigation testing is especially important in high-radon zones to confirm the system is adequate. If the first test comes back above 4.0, the system may need to be upgraded rather than accepted as-is.
Question linkMy crawl space mitigation uses a fan to pressurize the crawl space rather than depressurize sub-slab soil. Is that normal?
Crawl space pressurization is a less common approach - it involves pushing clean air into the crawl space to keep it at slightly higher pressure than the soil, which discourages radon from entering. The more common approach in crawl spaces is sealing the floor with a heavy-duty liner and then depressurizing beneath the liner. Both can work, but depressurization with a liner is generally considered more reliable. If you have a pressurization system, the effectiveness should be confirmed with a post-installation radon test.
Question linkIs it true that you can't fully mitigate radon in some homes?
In rare cases - usually involving extremely porous soil, block foundations with extensive cracking, or very high geological radon sources - it's difficult to get levels as low as a typical installation achieves. But "can't mitigate" is extremely rare. Most homes, including difficult ones, can be brought well below 4.0 pCi/L with the right system design. What varies is the complexity and cost of the system needed to achieve that. If a contractor tells you a home "can't be mitigated," get a second opinion.
Question linkMy contractor said my radon problem is from the well water, not the soil. Does that change how I test or mitigate?
Radon can enter homes through both soil gas and well water (when water is used and radon is released into the air). Waterborne radon is more of a concern with private wells in high-radon geology than with municipal water. If your contractor suspects the water as a source, a water test is warranted alongside the air test. Mitigation for waterborne radon involves treating the water at the point of entry (typically an aeration or activated carbon system at the well), not the same fan-based system used for soil gas. The two sources require different fixes.
Question linkI have a radon mitigation system and my water tests show radon in the well water too. Do I need two different solutions?
Yes - soil gas mitigation (the fan-based system) and waterborne radon mitigation are separate systems for separate pathways. If both are contributing to your indoor air radon level, you need to address both to achieve the lowest possible indoor air concentration. A water treatment system (aeration or granular activated carbon filter on the well supply) handles the water-borne contribution; your sub-slab depressurization system handles the soil gas. Test both sources to understand how much each is contributing.
Question linkMy radon test result has a laboratory detection limit note. What does that mean?
If a lab reports "less than 0.4 pCi/L" or a similar detection limit notation, it means the charcoal captured such a small amount of radon that the lab can't distinguish it from background noise in their instruments. The actual level is somewhere between zero and the stated detection limit. For post-mitigation purposes, this is an excellent result - it means your radon is at or below the instrument's ability to detect it. It's not a problem with the test; it's a sign that levels are genuinely very low.
Question linkShould I test radon in every room of my house or just the basement?
Standard radon testing protocol is to test in the lowest livable area of the home - typically the basement or lowest floor where you spend time. You don't need to test every room. The basement is the highest-concentration zone and the critical measurement point. If you have concerns about a specific area - a ground-floor bedroom used regularly, a daylight-basement bedroom - testing there in addition to the lowest level is reasonable. But a single lowest-level test is the baseline that matters most.
Question linkMy whole family slept in the basement for a week during renovation of the main floors. Should I be worried?
One week in an elevated-radon environment is not going to cause a meaningful change in lifetime risk - radon risk is about cumulative exposure over years and decades, not short bursts. If the basement was above 4.0 pCi/L and you haven't mitigated yet, that's a reason to prioritize mitigation. But a single week isn't a cause for alarm. Radon doesn't cause acute symptoms or immediate harm - it's a long-term, cumulative radiation risk.
Question linkMy house is on a lake and has a walkout basement on the water side. Does proximity to water affect radon?
The geological factors under your home - soil type, rock type, uranium content - are what drive radon levels, not proximity to a lake or body of water. Lakeside homes can have high or low radon just like any other home. However, a walkout basement does affect how the foundation interacts with outdoor air - the walkout side is at grade and has more natural air exchange, which can dilute radon. The enclosed below-grade portion is where mitigation matters most. Test the below-grade portion and act on those numbers.
Question linkMy radon contractor says I need a fan with a higher CFM rating. What does CFM mean in the context of radon mitigation?
CFM stands for cubic feet per minute - it's a measure of the fan's airflow capacity. Higher CFM fans move more air, which can extend the pressure field across more of the sub-slab area. Contractors choose fan CFM based on what's needed to achieve adequate suction coverage under your specific slab size and soil type. If a sub-slab communication test shows the pressure field isn't reaching all areas, a higher-CFM fan or additional suction points may be the solution.
Question linkMy mitigation system has a U-bend in the pipe and I'm wondering if that causes any airflow restriction. Should I be concerned?
Pipe bends do create minor resistance, but a well-designed system accounts for this. Residential radon fans are sized to handle the resistance of typical pipe runs, including bends. A single U-bend is not going to meaningfully reduce the system's effectiveness. Where excessive bends and long pipe runs can matter is in systems where the fan was undersized or the run is very long. If your post-mitigation result is good, the pipe configuration is working fine.
Question linkMy post-mitigation radon is 2.0 exactly. The EPA says 2.0-4.0 is worth considering. Should I do more?
2.0 pCi/L is right at the threshold where the EPA says consideration is warranted. The EPA's framing is that this range carries real but lower risk, and individual homeowners have to make a judgment call. If your pre-mitigation level was much higher, getting to 2.0 is significant progress. If you want to try to get it lower, a contractor can evaluate whether more is achievable. If you're content with 2.0 and the system is running well, continuing to monitor it over time is the most important ongoing step. There's no wrong answer here - it's your home and your risk tolerance. Call or text Bill if you want to talk through what makes sense for your situation.
Question linkWhat pCi/L should I be aiming for after mitigation?
Below 4.0 pCi/L is the EPA's action threshold - the goal is to get there at minimum. Below 2.0 pCi/L is where most contractors and homeowners feel genuinely comfortable. Below 1.0 pCi/L is a great result. The closer to the outdoor average of 0.4 pCi/L, the better. Set 2.0 as your target and 4.0 as your floor.
Question linkIs 1.5 pCi/L a good post-mitigation result?
Yes - 1.5 pCi/L is a solid result by any measure. It's well below the EPA action level, in the lower portion of the range most people consider good, and demonstrates the system is working effectively. Keep the fan running and retest in two years.
Question linkMy neighbor's mitigation test was 0.3 pCi/L. Mine was 1.8. Should I be jealous?
0.3 is an exceptional result - near outdoor levels - and you can appreciate that without reading anything worrying into your 1.8. Your system is working. Results vary by house, soil, foundation, and test conditions. 1.8 is a legitimately good number.
Question linkMy radon came back high. I have mitigation. Am I supposed to call someone?
Yes. If your test result is at or above 4.0 pCi/L and you have a mitigation system in place, call your contractor. The system may need evaluation - fan check, suction measurement, possible additional suction points. You shouldn't have to accept a high result when a system is installed and running.
Question linkHow much does retesting after mitigation cost?
A mail-in short-term test kit can be had for a small amount through many licensed labs. A professional radon measurement service costs more but includes licensed handling. The specific cost varies, but retesting is one of the lowest-cost home maintenance tasks you can do - well worth it relative to the information it provides.
Question linkMy radon test instructions say to keep the test kit 20 inches off the floor. Why?
Test kits should be placed at breathing height - where people actually occupy space. On the floor, you're sampling air that's more concentrated at the slab surface; near the ceiling, you're sampling the more diluted upper air. About 20 inches off the floor (or higher, up to about waist height) represents the air at the level where a person sitting or sleeping in that space would be breathing. It gives you the most relevant measurement.
Question linkMy radon level dropped right after turning on the fan but then it leveled off higher than I expected. What's happening?
The initial drop is the system pulling the accumulated radon out of the air quickly. After that, the level stabilizes at whatever the system can maintain given the ongoing entry rate from the soil. If it leveled off higher than you wanted, the system is running at its equilibrium performance. Improving that equilibrium means either increasing suction (higher-CFM fan, additional suction point) or reducing entry pathways (sealing cracks, floor-wall joint).
Question linkShould I put my radon monitor in the same room as the suction pipe?
Not right next to the suction pipe - placing it directly beside the intake can give a skewed reading because the pipe is pulling from below the slab, not from room air. Put the monitor in a central location in the lowest livable space at breathing height, away from the pipe, exterior walls, and HVAC vents. That gives you the most representative reading of actual room air.
Question linkMy Airthings app says my radon "7-day average" is 1.4. Is that the number I should use?
The 7-day average is a useful rolling figure that smooths out day-to-day variation. For a general picture of how the system is performing, yes - the 7-day average is more meaningful than a single-hour reading. For comparing to a licensed test result (which typically averages 48-96 hours), the 48-hour or short-term average is more directly comparable. Use the 7-day for trend awareness and the shorter window to cross-reference lab tests.
Question linkCan I run my post-mitigation test while my house is for sale and people are coming in and out?
Standard closed-house short-term testing requires that exterior doors and windows remain closed except for normal entry and exit. If your house is being shown frequently with doors propped open, that will affect the test result. Try to schedule the test during a period when the house won't be actively shown, or use a long-term test method that doesn't require closed-house conditions and averages over 90 days or more.
Question linkMy family is asthmatic. Does radon make asthma worse?
Radon is not known to trigger or worsen asthma - it's a lung-cancer risk from radiation, not a respiratory irritant in the traditional sense. If your family has asthma, ensure good indoor air quality overall (low humidity, no mold, proper ventilation), but radon mitigation is about long-term cancer risk reduction, not asthma management. For any respiratory health concerns, talk to your doctor.
Question linkMy mitigation system is supposed to serve a crawl space and a basement. Can one fan do both?
In some configurations, one fan can serve multiple zones by drawing from both a crawl space and a basement slab through a shared pipe system. Whether a single fan has adequate capacity depends on the size of both areas and the resistance in the system. A contractor should assess whether the system is appropriately designed for the combined load. Test in both zones - crawl space and basement - separately if you can, to confirm coverage in each.
Question linkI just got a puppy and she sleeps in the basement. Should I be worried about radon for her?
Radon risk is primarily studied in humans - specifically, long-term lung cancer risk from radiation exposure. Animals have shorter lifespans, which reduces cumulative exposure, but the principle of keeping radon low in any living space is the same. If your mitigation system is working and levels are below 2.0 pCi/L, your basement is in good shape for your whole household, furry members included.
Question linkMy radon is 3.5 post-mitigation. My wife says we should move. That seems extreme. What do you think?
Moving because of 3.5 pCi/L with a mitigation system in place would be an overreaction - this is a manageable problem, not a reason to sell. 3.5 is below the EPA action level, and there's likely room to improve it further with adjustments to the system. A second suction point, additional sealing, or a fan upgrade are all options worth exploring before any drastic decisions. The system is working; it may just need optimization. Call or text Bill and we can talk through what the numbers mean for your situation.
Question linkMy post-mitigation result was 4.1 pCi/L. Is that a failure?
4.1 pCi/L after mitigation is a result that needs attention - you're right above the EPA action level. It's not a catastrophic failure, but it means the system hasn't achieved its primary goal. The contractor should be willing to re-evaluate the installation - additional suction points, a more powerful fan, sealing work, or a different suction location may bring it down. Don't accept 4.1 as your final answer when a working system should deliver better than that.
Question linkMy radon has been below 1.0 pCi/L for 6 years. Can I take the mitigation system out?
No. Without the fan running, radon will accumulate again. The system isn't eliminating the source of radon - it's continuously managing it. The low levels you've enjoyed for six years are a result of the system running every day. Removing it would let levels climb back toward your pre-mitigation concentration. Think of it like a sump pump - you don't remove it just because the basement has been dry for years.
Question linkMy post-mitigation test company sent me a letter saying the result is "below the reporting limit." What does that mean?
It means your radon level was so low that the lab's instruments couldn't reliably quantify it - it's somewhere between zero and the lab's detection floor (often around 0.4 pCi/L). This is the best possible result from a post-mitigation test. The system has driven your radon to near-undetectable levels. Keep the fan running and retest in two years.
Question linkShould I tell my kids' school or pediatrician that our house was mitigated for radon?
Sharing that context with your pediatrician is a perfectly reasonable thing to do - they may include it in a background health history. It's worth mentioning so they have a complete picture. You don't need to alert your kids' school - radon is a home-based exposure and doesn't affect the school. If the school building itself is a concern, that's a separate matter governed by the school district's own testing policies.
Question linkMy house was built in 1920 and has old stone rubble foundation walls. The radon contractor said standard mitigation might not work as well. Why?
Old rubble stone foundations have many small gaps and are porous throughout - there's no clean slab-to-wall joint, and the entire foundation wall is a potential entry point. Sub-slab depressurization works for the floor, but rubble stone walls are harder to address with a single suction system. Interior wall coatings or sealants, combined with active sub-slab mitigation, may be needed for the best result. Radon mitigation in older rubble-foundation homes is doable but often requires a more custom approach. Testing after whatever system is installed is especially important to confirm actual performance.
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Reviewed by Bill Dahlstrom, Illinois radon mitigation license RNM2018212.